NTS MX5 Build

[Johno]

Hi Nathan,
Any chance of a few piccy's of your progress for the MX5 build codenamed "Bumble Bee" or will you be keeping it under wraps untill it's finished?:)

ps... How's Spud doing, haven't seen any posts lately from him..
Johno

[shh120m]

Iv just got the cage to finish and interior panels before the final fitment of the bodywork and finishing off, i was hoping to get it lokking pretty before i put some photos up but il put some up on photobucket tonight for ya,

ps johno can you pm me the address to send the crush tubes, lost it lol

[shh120m]

Sorry for the delay, iv been trying to catch up this week. Its been a bit bitter sweet the last couple of weeks regarding the mx5 build. A couple of weekends ago id sorted out the wiring loom and got all the fluids bled so i decided it was time for a proper run down round the industrial estate to find any proplems before i started putting the bodywork on. So, as one does I spent a good hour and a half checking bolts, tiying back any loose wiring/tubing etc. I popped the battery in the passenger footwell, turned the key and started driving slowly around the industrial estate in first and second. I went back to the unit and gave it a once over, everything looked dandy so i decided to give it the beans down the road. Going from first to second at speed there was an almighty bang, and i was hit by something hard from behind. The prop was laid on the floor and the diff was snapped in two. Like a complete knob i had forgotten to put the spreader plates under the diff bushes so the diff was hanging by just its rubbers. The torque was too much for it and it gave way, snapping the rear casing in half and wrecking the UJ in the prop in the process. I pushed it back for what what seemed to be a lifetime, with an almighty bruise on my arse from the diff twating me!

The good news was that there was no damage at all to the chasiss, so theres no problems there. David bowlam was very kind to let me have a replacement, but as it was a 1.6 diff it has different pcd shaft flanges and it was open, i really wanted to keep the torson lsd so a quick call to mx5 city got me a free new casing (providing i show their stickers on the car in the mag features!)


The diff is now back in the car with its new casing. I have also fitted a pair of these: http://www.ebay.co.uk/itm/Mazda-MX-5-Rear-Diff-Mount-Bush-SPORT-polyurethane-STRONGFLEX-/270890908682?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item3f125b3c0a

and made some 8mm spreader plates to go underneath.

So, whatever you do, dont hang the diff without the original plate with the castlated bush or polybushes and a substansial spreader or this will happen!

http://i1264.photobucket.com/albums/jj482/ntsengineering/Saturn%20X5/SAM_1040.jpg

http://i1264.photobucket.com/albums/jj482/ntsengineering/Saturn%20X5/SAM_1015.jpg

http://i1264.photobucket.com/albums/jj482/ntsengineering/Saturn%20X5/SAM_1039.jpg

I cant thank mx5 city enough, there a real good bunch of blokes who really know their mx5s, and they'll sell you anything from a nut to a full donor!

[shh120m]

Anyway the diffs back in place now, im just finishing tidying up the wiring and hoses, then its onto the interior panels and rollcage followed by the bodywork which is all trimmed ready for fitting. I just cant seem to find the time at the moment, but theres a trackday looming on the 10th of april and im determined to make it. I may have to piss the missus off and put in some overnighters!

couple of sneaky pics from the old brick...

http://i1264.photobucket.com/albums/jj482/ntsengineering/Saturn%20X5/SAM_1026.jpg

http://i1264.photobucket.com/albums/jj482/ntsengineering/Saturn%20X5/SAM_0988.jpg

made up some sexy looking headlight brackets for the 5 inchers tonight...

http://i1264.photobucket.com/albums/jj482/ntsengineering/Saturn%20X5/SAM_1028.jpg

[CTWV50]

Glad I'm using 1.6mm steel for the seat back.:cool: Just in case!! Looks great. good to see it moving along.

[Eternal]

Love the light bracket.

[MarkB]

Toblerones needed methinks as in triangles

[Johno]

Hi Nathan,
I bet that was a scary moment...:eek:
When we bolted our diff in we decided to use the diff washers mounted to a bracket welded to the underside of the diff plate.
http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Diff%20Mounts%20and%20Brkts/29122011348.jpg

The problem is my diff washers are badly corroded and I am looking to buy some second hand ones as I can't source new ones (unless somebody knows where).
The question I now ask is are these the only areas to look at? On the MX5 they have a substantial frame bolting the diff to the gearbox, I personally am now looking at my diffs rubber mount as well and will probably beef this up. Also I am going to insert a pressed plate between the two diff mounts taking out any twist between the two mounting points.

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Chassis/reardiffsupport.jpg

Probably overkill I know but looking at your photo makes me shudder...


You said you had no other damage to your chassis so was the diff rubber mount ok?
You also mention a spreader plate but not sure what you mean by this, so any photos or diagrams would help.

Sorry to hear about the setback ...Johno

[MarkB]

Triangulation is stronger and a better bet than just adding even more heavy gauge plate because heavy cars hit things harder......light 'n triangulated is the way to go

[MarkB]

Take a look at the rear of any of the cars Jeremy Philips has designed and you will see much goodness and a distinct lack of girders.:cool:

[Big Vern]

Did you not have the diff side bolts fitted? (where the power plant frame bolts up)

[jenks]

Is it just me or does looking at the photo of the point of failure and actually reading Nathan's description of what happened / how he mounted it, make it clear this had nothing to do with a need for extra triangulation, 'girders' or any modification to the diff cage at all!!! The thing snapped a diff IN HALF before having a chassis failure!!!

What actually happened in this case, if you fit a winged diff just by running a bolt through the crush tube directly the mounting point the load is completely suspended by the rubber bush with no limit in travel... Put a large turning force through it, one wing is pressed hard up against the chassis while the other is pulled down hard pulling / flexing the bush as far as the rubber part will stretch... This can only go so far before something goes crunch!

If you mount the diff with no caps on the bushes, even on the original MX5 subframe and and drive it hard will pull itself to pieces...

The fact it wripped a diff in half and didn't budge the diff cage plates proves Andrews design is sound... Just make sure you fit the thing correctly with no missing parts

[MarkB]

Is it just me or does looking at the photo of the point of failure and actually reading Nathan's description of what happened / how he mounted it, make it clear this had nothing to do with a need for extra triangulation, 'girders' or any modification to the diff cage at all!!! The thing snapped a diff IN HALF before having a chassis failure!!!

What actually happened in this case, if you fit a winged diff just by running a bolt through the crush tube directly the mounting point the load is completely suspended by the rubber bush with no limit in travel... Put a large turning force through it, one wing is pressed hard up against the chassis while the other is pulled down hard pulling / flexing the bush as far as the rubber part will stretch... This can only go so far before something goes crunch!

If you mount the diff with no caps on the bushes, even on the original MX5 subframe and and drive it hard will pull itself to pieces...

The fact it wripped a diff in half and didn't budge the diff cage plates proves Andrews design is sound... Just make sure you fit the thing correctly with no missing parts

I would imagine the rear frame work is twisted after the forces needed to snap a casting like that have been put through it.

[shh120m]

I would imagine the rear frame work is twisted after the forces needed to snap a casting like that have been put through it.

Not at all mark, everything is still square, no cracked welds, no stress fractures just a bit of scratched powdercoat.

The rear casting on the mx5 diff is actually pretty poor in terms of stregnth, it weighs less than 1 kilo and when inspected, there are large air bubbles within the alloy, you could drop one from less than a meter and shatter it to bits. The only ones that are stronger are the smooth cased castings used on some of the early viscous diffs which are crap in comparison to the torsens, they are rare as rocking horse shit though, iv heard of the drift boys paying £250 just for a case to fit to locked torsens

[Big Vern]

Not at all mark, everything is still square, no cracked welds, no stress fractures just a bit of scratched powdercoat.

The rear casting on the mx5 diff is actually pretty poor in terms of stregnth, it weighs less than 1 kilo and when inspected, there are large air bubbles within the alloy, you could drop one from less than a meter and shatter it to bits. The only ones that are stronger are the smooth cased castings used on some of the early viscous diffs which are crap in comparison to the torsens, they are rare as rocking horse shit though, iv heard of the drift boys paying £250 just for a case to fit to locked torsens

As I stated in my earlier post, have you not mounted through the fixings on the side of the Iron part of the diff assembly where the PPF mounts to? This is the strong part of the diff - the two rubber mounts on the wings are just to stabilise side to side motion of the powerplant assembly which in the donor vehicle is two rubber mounts on the engine at one end and two on the diff at the other end. If you mount the diff only through the rubber mounts then you'll just keepp tearing them out.

BV.

[shh120m]

Yes as per chassis design

[Big Vern]

Yes as per chassis design

I have looked at your design, it doesn't use the diff side mounting system the same way as the donor. You have just a bit of plate with an ex engine mount. The diff is therefore free to 'wobble' around on the rubbers under torque. To work you'll have to mimic the power plant frame to diff mount, on the chassis. All rubber mounted diff is never gonna work, the rubbers would have to be very stiff, shore 95+ or something similar. The westfield system is much more robust and they still cracked diff housings.
The diff to power plant frame is the main fixing for the diff.

BV

[Davidbolam]

If you look at the mnr chassis this is mounted in a similar way to the nts/saturn version and it seems to work for them. I am sure that once the plates are on both sides of the rubber mount this won't happen again. Here is a picture of the mnr version. The westfield version also seems very similar. Both of these only seem to use the front mounts ( in the steel section) to stop this rotating forward and backwards.

http://www.google.co.uk/imgres?q=mnr+mx5+differential+mount&um=1&hl=en&biw=1366&bih=621&tbm=isch&tbnid=L1N8BTzA7XCD5M:&imgrefurl=http://locostusa.com/forums/viewtopic.php%3Ff%3D35%26t%3D9631%26start%3D75&docid=_HBhB86-ue7rJM&imgurl=http://i750.photobucket.com/albums/xx145/first350/Locost/P1020963.jpg&w=1024&h=768&ei=tWxzT7ipHIe-0QWG9cAK&zoom=1

[MarkB]

The MNR works because it's a mass of triangulated tubes not open rectangles/squares, that and Marc Norden knows how to grow onions:D

[jenks]

Sorry @MarkB , I don't see the logic in your posts at all... Are you saying this diff failure wouldn't have happened if the diff cage / chassis was further reinforced? Not trying to be offensive, I'm just not sure what you're trying to get at!

Can understand the need for more rigid mounting on the nose of diff but the overall cage / rear frame design and support of the diff wing has nothing to do with this failure. The tortional forces on the wing bushes are nothing compared to those on the nose mounts. Use the correct bush caps, mount the nose properly and diff won't dismember itself.

A more contructive input would be telling everybody where you think this additional triangulation needs to go (?)

[Big Vern]

Sorry @MarkB , I don't see the logic in your posts at all... Are you saying this diff failure wouldn't have happened if the diff cage / chassis was further reinforced? Not trying to be offensive, I'm just not sure what you're trying to get at!

Can understand the need for more rigid mounting on the nose of diff but the overall cage / rear frame design and support of the diff wing has nothing to do with this failure. The tortional forces on the wing bushes are nothing compared to those on the nose mounts. Use the correct bush caps, mount the nose properly and diff won't dismember itself.

A more contructive input would be telling everybody where you think this additional triangulation needs to go (?)


Rather than guess at the problem or assume someone else has solved the problem on their design. (westfield still have problems with their solidly mounted arangement.) lets try to understand the problem and then solve it!

Firstly the failure mode needs to be understood. Currently no one other than Jenks seems to have correctly identified what actually happened to cause the failure and so we make no progress in resolving the problem we just create a pile of broken diff carriers!

To understand what has happened we first need to understand how the power plant assembly in the donor vehicle works.

The engine and gearbox are rigidly bolted together and the powerplant frame is tightly fitted to the gearbox and the diff. This creates a complete unit which is mounted to the front subframe by two mounts on the engine which primarily are to control the engines verticle movement over bumps and reduce vibration transmitted to the passenger cabin and two rubber isolators on the diff carrier which are to isolate vibration. They provide some small resistance to rocking side to side motion but cars with a power plant assembly such as the MX5 have very little side to side movement under even the hardest accels due to the powerplant all being connected together and the torque forces largely canceling each other out. The torque reaction to the driven wheels is resisted as the diff cannot lift the engine/gearbox assembly attached at the other end of the powerplant frame and thus the diff is constrained totally in movement in this direction.

In mounting the diff in isolation the nose of the diff needs to be tightly constrained and herein lays the cause of the failure. The ex engine mount is being used in tension for which it was not designed and can therefore not sufficiently prevent the diff nose from moving vertically upward under drive as the diff reacts to the torque appplied at the rear wheels. The two mounts on the diff carrier were never designed to work in this way and the diecast ally case fails exactly as described.

This problem has a well trodden path and the solution lays in controling the diff nose. Triumph had the same problem in the 1950's when designing the triumph herald/spitfire and they resolved it by bolting a bracket to the diff nose and stiff mounts to the chassis and I would suggest a similar arangement with some sort of laser cut bracket that can fix to the mazda PPF mounting and via suitable mounts to the chassis.

Hope this has helped people to understand the problem and enable all to work toward a solution.

BV:)

[MarkB]

Sorry @MarkB , I don't see the logic in your posts at all... Are you saying this diff failure wouldn't have happened if the diff cage / chassis was further reinforced? Not trying to be offensive, I'm just not sure what you're trying to get at!

Can understand the need for more rigid mounting on the nose of diff but the overall cage / rear frame design and support of the diff wing has nothing to do with this failure. The tortional forces on the wing bushes are nothing compared to those on the nose mounts. Use the correct bush caps, mount the nose properly and diff won't dismember itself.

A more contructive input would be telling everybody where you think this additional triangulation needs to go (?)

The diff was able to move so it broke that is simple to understand. The diff needs to fixed so it can't move or at best severely restrict how much it can by using the correct rubber mountings. My choice would be solid mount the diff and triangulate the chassis.
It's obvious where the rear cradle is weak as it is open rectangles with no triangulation and the diff is fixed to this........less is more usually and take a good look at how Marc Norden has done the MNR, simple yet very effective.

[Big Vern]

It's obvious where the rear cradle is weak as it is open rectangles with no triangulation and the diff is fixed to this.

Before we all start getting emotional on this lets understand the problem!

It is how the diff is mounted to the chassis not chassis flex itself that has caused the problem. The diff has moved because its not fixed to the chassis in a way that constrains the movement of the diff nose. Quite simply the diff nose mounting rubber has too much movement in it. The nose of the diff rises as a reaction to the road wheels driving forward, the twist on the alluminium diff carrier exceeds the strength of the carrier and it fails exactly as in the pictures NTS posted.
What is needed is a better diff nose mounting arangement to constrain the movement. As said previously, Mazda designed the diff mounts for vibration isolation rather than to constrain torque reaction.

I like the way MNR have mounted the two rear mounts but they do still have diff problems - just view the locost usa site and have a look.

BV:)

[K4KEV]

I would tend to agree with BV ....I have seen the diff cage in question and there is NO evidence of any weakness/distorsion whatsoever ...if fact there was barely a scratch which is testament to a good design rather than poor

[CTWV50]

I've used two volvo engine mounts top and bottom orientated so that the top one is resisting vetical movement and the bottom one horitantal movement. So I'm covering any rotational movement. It looks nasty in this image as I haven't finished bracing the chassis brackets and tidying them up.

http://farm7.staticflickr.com/6114/6323611395_c16fd1e342_b.jpg

Not a great picture. I'll try and get a better one in good lighting.

[MarkB]

Before we all start getting emotional on this lets understand the problem!

It is how the diff is mounted to the chassis not chassis flex itself that has caused the problem. The diff has moved because its not fixed to the chassis in a way that constrains the movement of the diff nose. Quite simply the diff nose mounting rubber has too much movement in it. The nose of the diff rises as a reaction to the road wheels driving forward, the twist on the alluminium diff carrier exceeds the strength of the carrier and it fails exactly as in the pictures NTS posted.
What is needed is a better diff nose mounting arangement to constrain the movement. As said previously, Mazda designed the diff mounts for vibration isolation rather than to constrain torque reaction.

I like the way MNR have mounted the two rear mounts but they do still have diff problems - just view the locost usa site and have a look.

BV:)

Persactly what I was getting at but it's a package and both ends of the diff need to be fixed properly which also means the chassis needs to be able to take the force. It all needs to work together.

[Big Vern]

Persactly what I was getting at but it's a package and both ends of the diff need to be fixed properly which also means the chassis needs to be able to take the force. It all needs to work together.

I agree it all needs to work together but that can only happen when we understand how it works. To this end we must understand how it was originally designed to work in the donor vehicle. (See my earlier post.)
I have seen no evidence to suggest the chassis doesn't take the forces placed upon it which arn't great in the donor vehicle anyway. The two mounts for the diff carrier are just as they are in the vehicle I looked again at the ones in my MX5 at lunchtime. Whilst I suspect the NTS/Saturn front bracket would crack adjacent to the weld that was not the point of failure in this case. It was the rubber ex-engine mount not being the correct type to restrain the diff nose verticle movement that has caused the failure and judging by some posts on locost usa some MNR builders are having similar problems. Two or three bloggers I looked at last night are experimenting with different stiffnesses of mount to try and overcome diff carrier cracking so I'm by no means convinced MNR have it right either, and I know the westfield miata has had problems.
CTWV50 has the right idea but I seriously doubt engine mounting rubbers will be sufficiently stiff to control the diff voided bushes will still have too much movement. Something along the lines of a poly bush at around shore 90 acting as CTWV50 has his will control the diff leaving the two isolators in the diff carrier largely to do what they do in the donor car which is to soak up vibration.
Indeed it may make more sense to ingore the two mounts on the diff carrier altogether and go for robust mounting of the diff via the PPF mounting system.
Has anyone considered using the back part of the PPF and mounting that to the chassis I wonder.

BV:)

[CTWV50]

Hmm, thanks for the costructive critisism, I'm only running a cheap 1.6 open diff atm so if it does fail with this design I'll upgrade to a torsen and rethink the design. I think most people will of thought about a solid mounting to the chassis but surely you would end up with alot of vibration through the chassis which would cause other reliability issues.:)

edit: Have you got any links BV for the failures on locostusa? What's your source for the westield miata issues?

Cheers

Chris

[TQ_uk]

http://www.mmmiata.com/images/products/MM147-BRPPF6.jpg

May be of some help in visualising things...

[sven8t4]

I've used two volvo engine mounts top and bottom orientated so that the top one is resisting vetical movement and the bottom one horitantal movement. So I'm covering any rotational movement. It looks nasty in this image as I haven't finished bracing the chassis brackets and tidying them up.

http://farm7.staticflickr.com/6114/6323611395_c16fd1e342_b.jpg

Not a great picture. I'll try and get a better one in good lighting.

Hey Just a quick note I used to play with 850 T5's and my V70AWDr these original rubber mounts fail all the time on the T5's the poly bush variants are much much better.

Steve

[CTWV50]

Hey Just a quick note I used to play with 850 T5's and my V70AWDr these original rubber mounts fail all the time on the T5's the poly bush variants are much much better.

Steve

Cool!:cool: LOL!

[Big Vern]

Hmm, thanks for the costructive critisism, I'm only running a cheap 1.6 open diff atm so if it does fail with this design I'll upgrade to a torsen and rethink the design. I think most people will of thought about a solid mounting to the chassis but surely you would end up with alot of vibration through the chassis which would cause other reliability issues.:)

edit: Have you got any links BV for the failures on locostusa? What's your source for the westield miata issues?

Cheers

Chris

I have long suspected the westfield miata suffers chassis cracking because of solidly mounting the diff, but the sierra diff is solidly mounted and does not throw up any problems.
As said already your design shows you have been thinking about how to mount the mazda diff and the unusual problems its design has created.
Heavy duty engine mounts perhaps rally spec would get the job done.

I came across the problems with westfield miata when I strumbled across the build thread for the car flyin' miata built.
The others including the locostusa came yesterday when I did a google search for MX5 miata diff mount problems.

Sorry I didn't do any links to these sites I was just havin' a beer and surfin':D

Well done TQ uk - I like the gold brace on your RX8/Current MX5 rear end. That would be a good way of dealing with the problem, maybe just use the rear 6-8inches of the power plant frame or a lazer cut and folded substitute. That brace would constrain the diff nose and assist the two mounts in the diff carrier.

BV:)

[jenks]

I think Big Vern and CTWV50 pretty much have it sussed... Mr Gibbs designed the framework of the seat back to soak up the torsional loads of the diff, so that's where we need to send them in this design too. If we can do that and get some vibration isolation (poly bushes) then it's win-win, jelly and icecream for everyone!

Does anybody have a 3d cad file of the Saturn chassis with a model of the diff in place? (SolidWorks, Inventor or the like)

I'm thinking of something along the lines of a bracket mounted at 90 degrees to the right-hand seatback upright then a mount along the lines of Skov's diff nose mount but with 2 polly mounts fixed a 90 degrees, spaced a good distance apart to spread the loads acting under tension and compression...

Skov's design looks really nicely engineered but the mounts will be under shear forces when they're designed for compression (and I think they're rubber)

http://1.bp.blogspot.com/-rANr4WQ7IXY/T1aBQ_qAGmI/AAAAAAAAIN0/oFLfMMzrNmA/s1600/diff_mount_fitted.jpg

http://3.bp.blogspot.com/-MVpVJo0hIs4/T1aBQ5HWxBI/AAAAAAAAIN4/aT8R66oMM8Y/s1600/diff_mount_fitted_2.jpg

[Johno]

Well had a play about with the diff mounting today and managed to fit a welded frame to the nose of the diff and two rubber mounts.

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Diff%20Mounts%20and%20Brkts/2012-03-31-057.jpg

Bit of a tight fit but it all goes in....just.....:)
Also fitted the spreader plate to one side of my diff bolted to my chassis bracket.

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Diff%20Mounts%20and%20Brkts/2012-03-31-054.jpg

Obviously the spreader plate is in line with the bush and the spreader is at an angle to the diff housing. Does anybody know if this is the case on the MX5 or is the chassis mounting at an angle to run in line with the diff housing.

Johno

[Johno]

Well I guess it's pretty much covered by BV and Jenks.
I guess the difference between the Sierra diff and MX5 is the Sierra doesn't have arms sticking out both sides making any torque movement worse. Sodily mounting the front nose of the diff will only cause metal fatigue and fracture of the chassis sometime in the future. Mazda realised this and fitted a PPF as standard. Triangulation of the chassis will only make things worse resulting in a weld faiure along the HAZ of a weld.
I spoke to Nathan Sunday and the only reason the diff broke was because he forgot to fit the diff washers....LOL..
Ok he agrees the diff mounting below the diff wasn't upto the job but this didn't brake.
Basically if the front nose of the diff was to be solidy mounted as per Westfieid and others who grow onions then Mazda could have saved a lot of RD money.
Well just my thoughts I guess others will disagree........:D
But I look at it this way, if Mazda fitted it it's good enough for me...

Johno

[MarkB]

You do realise that IVA inspectors monitor forums like this :D

[CTWV50]

MarkB please get a life!

[MarkB]

MarkB please get a life!

Ti's true, I'm wasting my time but then I call it irratainment as it makes me chuckle the things people do and how they do them. Sometimes I comment sometimes I just laugh.

[CTWV50]

What you're doing on this forum is nothing new to most people, it's quite clear you enjoy trolling this forum for your own reasons. I guess the best thing people can do is just ignore your posts as they really serve no useful purpose.

You may enjoy this little youtube video.

http://www.youtube.com/watch?v=HaMOcJfsksI

For anyone who doesn't know what Mr. MarkB and his aliases is up to....

http://en.wikipedia.org/wiki/Troll_(Internet)

[MarkB]

What you're doing on this forum is nothing new to most people, it's quite clear you enjoy trolling this forum for your own reasons. I guess the best thing people can do is just ignore your posts as they really serve no useful purpose.

You may enjoy this little youtube video.

http://www.youtube.com/watch?v=HaMOcJfsksI

For anyone who doesn't know what Mr. MarkB and his aliases is up to....

http://en.wikipedia.org/wiki/Troll_(Internet)

Indeed I'm best ignored, I never listen to anything I say as it's 99% tripe:D

[TQ_uk]

Well done TQ uk - I like the gold brace on your RX8/Current MX5 rear end. That would be a good way of dealing with the problem, maybe just use the rear 6-8inches of the power plant frame or a lazer cut and folded substitute. That brace would constrain the diff nose and assist the two mounts in the diff carrier.

BV:)

Not mine I'm afraid, found it when Googling to help people visualize the problem.

From here:

http://www.mmmiata.com/catalogsite/suspension01.php

[shh120m]

Ti's true, I'm wasting my time but then I call it irratainment as it makes me chuckle the things people do and how they do them. Sometimes I comment sometimes I just laugh.

The thing is mark, that some find it offensive. I just find it intensively stressing, when all i was trying to do was makesure no one makes the same mistake as me. My heatbeat rises everytime i look on the forum to see what im being flamed for next. I now understand what andy was going through, as i feel pretty sick aswell now with the stress, i think i may be in a pretty dark place at the moment, so for now im going to stay away from the forum as i feel that a small percentage of people have turned it a bit nasty. Everybody i know used top post regular updates on their builds, but now i speak to builders who dont want to incase they get a load of bad critisism. Everyone needs a bit of a boost/ positive encouragement now and again, and sadly i think that has all but dissapeared from the forum. Im a pretty hard f@cker, so its a bad day when a grown up bloke starts welling up sat infront of a computer on an internet forum

Im sorry if im putting more of a downer on things, but i just want to get how i feel out in the open. Ive tried to make an effort with certain people, yourself included. I try and treat people how i would like to be treated, iv never said anything that i wouldnt say in person.

Yes the saturn mx5 isnt perfect, (and neither a voodous for that matter) but then again andrew made the plans as a guide for free download. Its up to individual builders to decide wether they want to follow the guide or modify it to suit their requirements. At the end of the day its just a guide. Ive given my car an extreme thrashing trying to break it and it hasnt broke, I drove it over a curb at forty miles an hour the other day in reverse for gods sake so im confident that the chassis is strong enough.

Anyway, ive said what i had to say.

Well wishes to all, im out of here

Nathan

[CTWV50]

I have to agree I don't post as much on my build thread or on the forum at all for that matter as I don't want to receive overly critical demotivating posts.:rolleyes:

[wylliezx9r]

The thing is mark, that some find it offensive. I just find it intensively stressing, when all i was trying to do was makesure no one makes the same mistake as me. My heatbeat rises everytime i look on the forum to see what im being flamed for next. I now understand what andy was going through, as i feel pretty sick aswell now with the stress, i think i may be in a pretty dark place at the moment, so for now im going to stay away from the forum as i feel that a small percentage of people have turned it a bit nasty. Everybody i know used top post regular updates on their builds, but now i speak to builders who dont want to incase they get a load of bad critisism. Everyone needs a bit of a boost/ positive encouragement now and again, and sadly i think that has all but dissapeared from the forum. Im a pretty hard f@cker, so its a bad day when a grown up bloke starts welling up sat infront of a computer on an internet forum

Im sorry if im putting more of a downer on things, but i just want to get how i feel out in the open. Ive tried to make an effort with certain people, yourself included. I try and treat people how i would like to be treated, iv never said anything that i wouldnt say in person.

Yes the saturn mx5 isnt perfect, (and neither a voodous for that matter) but then again andrew made the plans as a guide for free download. Its up to individual builders to decide wether they want to follow the guide or modify it to suit their requirements. At the end of the day its just a guide. Ive given my car an extreme thrashing trying to break it and it hasnt broke, I drove it over a curb at forty miles an hour the other day in reverse for gods sake so im confident that the chassis is strong enough.

Anyway, ive said what i had to say.

Well wishes to all, im out of here

Nathan

From what I can see its always the same person being negative towards the roadster. Just ignore him. I've heard it all from the same person : the roadster understeers, its huge, its heavy now going on about the design of diff carriers, what next ?. If I thought a car was that shit I wouldn't frequent around the forum designed for enthusiasts who are building the car.

[Big Vern]

MarkB only comes on here to stir things up, he's not a builder or a problem solver. he snipes from the sidelines at other peoples builds and in my opinion has nothing useful to contribute.
He seems to have failed to understand the problem Nathan had with the diff failure and has tried to use that as a way to attack the basic chassis design which has already been proven. (Are the Sierra based chassis's failing - NO)
He tried to use an example to highlight his point but the builders of that car are having EXACTLY the same diff problems!
His argument is as flawed as his engineering knowledge. Waster

Sorry AshG - I accept a wrap over the knuckles for such strong statements but we don't need this guy poisoning the forum.

BV:)

[Johno]

Hi all,
Having not been on this forum for too long I'm not sure of the history of certain members...
In my opinion Andy of SSC and Nathan of NTS have done an outstanding job. The amount of times I have asked them questions about the build and recieved a swift answer is second to none...
Without them there would be many ppl out there scratching their heads..
Nathan delivered a bodykit personally on a Sunday to us in Norfolk. How can anybody complain about the devotion this guy is willing to give towards many peoples hobby/dream.

I for one can only take my hat off to him for the job he has undertaken.

Where would many builders be if he hadn't take on what Andy Hugil started.
I can only guess....:(

I personally started this as a hobby and looked forward to visiting the forum to look at other ppls ideas and hopefully things I have done may have helped some ppl I don't know.
One thing I do ask regulary when I do post something is "if you see a problem with what I have done please let me know". If somebody points out a problem I'm only too happy to take their advice, but some of the posts ppl write are not constructive in any shape or form.:(

Everybody has a right to say something but if you have nothing good to say then say "NOTHING"

Johno

[Bonzo]

Hi Nathan,

Please don't let the verbal garbage of just one sad sorry individual drive you away from the forum. :(

You have a great deal of respect from the genuine forum members on here.
These are members who are actually building a Roadster & look towards the suppliers for help, parts & moral inspiration.

Take some time out to chill mate.
With a little luck you'll take some heart in knowing others feel the same way about our " Resident, forum troll " ;)

Speaking from personal experience, I have been daft enough in the past to let this, sad sorry individual get me down ( Leading to some very public & childish outbursts on my part ) :o
It got to the point that I have now decided to take a back seat on the forum, worse still, I have completely lost all interest in completing my own Roadster build & this has now sadly fallen by the wayside.

Good news is, I have now bought a road registered 7 in need of a full refurbishment.
Fortunately the majority of the Roadster parts can be re used :)

As I am no longer building a Roadster I don't see much of a future for me on this forum as I will no longer have anything in common with all of the good folk on here.
That said, I do still read most posts as I am genuinely interested in each & every build in progress.

Take care Nathan, don't be away too long.

[K4KEV]

the way I see it is... if anyone decides to boycott the forum because of those who intimidate via these threads, then they have won, so the best thing to do is just simply ignore and carry on posting...... the wealth of knowledge that is and can be found on this forum is way to valuable to be lost, so I would implore both Nathan and Andy to come back and talk to those who would benefit from their input as they have done in the past and recent present. The vast majority of members on here including myself NEED the likes of you around to further the roadsters life cycle....howay lads git yersels back on ere

[MarkB]

Never made a car in my life or so much as looked at a tub of resin so quite why I comment on things is beyond me.


Think triangles and all will become clear

[CTWV50]

Sarcasm and abstract sentences. Wow!

[wylliezx9r]

Never made a car in my life or so much as looked at a tub of resin so quite why I comment on things is beyond me.


Think triangles and all will become clear

I don't think anybody is doubting your knowledge or technical ability its your ATITUDE . You have helped me in the past and for this I'm greatful but why do you seem to be constantly digging at people with cryptic comments that don't help anybody ?

[Bonzo]

Never made a car in my life or so much as looked at a tub of resin so quite why I comment on things is beyond me.


Think triangles and all will become clear

There it is in a nutshell mate !! :p :D

You honestly believe that you are the only one who has ever opened a tin of resin or allegedly built a kit car.
Again, I think you honestly believe that you are the only one who knows how to grow Onions ( As you put it )

Sorry to be the bearer of bad news, some of the local boat builders down here also know their Onions, that's how they manage to stay in business.
If I were feeling in a spitefull mood, I might say that they could make your work look like apprentice pieces but I won't :D
Same can be said of some of the kit car manufacturers, again, they manage to stay in business just fine.

Lot more technicaly minded folk out there, a good few on this forum ;)

Get over yourself mate & move on with whatever floats your particular boat.

[trick-kit]

Now here's a theory, given that this problem isn't solely confined to Locosts but exsists in MX5's too, maybe it's not the mounting of the diff that causes the problem (OK, if it's allowed to move around too easily then it may highlight the weakness) but MX5's that have broken the diff have pretty much the same thing in common.

They have been involved in an accident.

The diff has a cast sacrificial point in it designed to break to prevent the PFF puncturing the tank. Now given that most of the kit cars using the MX5 as a donor are built from wrecked MX5's maybe we are inheriting the fault without noticing it.

As i said, just a theory :rolleyes: :D

TK

[CTWV50]

Your correct it does appear they've made a point at which they want it too fail so actually what we need to do assuming we don't have a crash damaged diff is to protect the diff from violent movement which makes sense.

[Big Vern]

Now here's a theory, given that this problem isn't solely confined to Locosts but exsists in MX5's too, maybe it's not the mounting of the diff that causes the problem (OK, if it's allowed to move around too easily then it may highlight the weakness) but MX5's that have broken the diff have pretty much the same thing in common.

They have been involved in an accident.

The diff has a cast sacrificial point in it designed to break to prevent the PFF puncturing the tank. Now given that most of the kit cars using the MX5 as a donor are built from wrecked MX5's maybe we are inheriting the fault without noticing it.

As i said, just a theory :rolleyes: :D

TK

It is true some of the donors used may have been involved in accidents but by no means all of those being used have been in accidents - many are now cheap enough (mot failures etc) to be used as donors without any accident history.
Not aware of MX5's suffering diff carrier failures. Anything likely to compromise the diff will like as not cause it to fail though there's always the 'exception that proves the rule'
Usually in a front or rear impact the power plant frame bends downward twisting the nose of the diff down to the road to avoid pushing through and puncturing the tank, this action usually fails the diff carrier so few would have made it on to other cars for further use or be available for sale as salvage.
The diff failure, as happened to Nathan, is something I've seen before and on diff carriers that were known not to be compromised, though I get the point we should all be vigilant and inspect all used parts in the build for signs of damage/fatigue.

[trick-kit]

http://www.mx5oc.co.uk/forum/forums/t/34429.aspx

This thread lists a few examples and shows the diff in the MX5 subframe.

TK

[Big Vern]

http://www.mx5oc.co.uk/forum/forums/t/34429.aspx

This thread lists a few examples and shows the diff in the MX5 subframe.

TK

This is accident damage or the result of, and cracked diff that may have been missed by the repair shop if they wern't looking for it. I accept there might be the odd rogue part that has cracked but not completely failed at the time of the acceident and that could get onto another car as a salvage part - as I said we should all be vigilant in checking the condition of our used parts.

Not aware of any in service failures of cars that have not been in some sort of accident so I don't believe this is an inherant failure of the MX5 dif when used in an MX5.
As I've said elsewhere in this post its only designed to resist rotational forces about the propshaft axis. When used in isolation and without proper constraint the diff can and will rotate about the driveshaft axis or indeed any fore aft movement as you have pointed out will cause the diff to fail as it did on Nathan.
As I have previously stated Nathan would do well to implement a better way of contraining the the diff movement as the method he has used hasn't worked. I can fully understand why he did what he did and he's not the first to have tried something like that nor is he the first to have had such a diff failutre.
As I have said all along the key to this is understanding the forces involved and engineering a solution to constrain them. Some good suggestions as to how that could be done have already been presented.
Did the diff Nathan originally use come from an accident damaged car? I thought not if it was the one Saturn started out with.

[skov]

As I have previously stated Nathan would do well to implement a better way of contraining the the diff movement as the method he has used hasn't worked.

This particular failure was due to Nathan forgetting to fit the two big washers that restrict the rotational movement of the diff.

It still remains to be seen whether the design as intended works or not.

[trick-kit]

This is accident damage or the result of, and cracked diff that may have been missed by the repair shop if they wern't looking for it. I accept there might be the odd rogue part that has cracked but not completely failed at the time of the acceident and that could get onto another car as a salvage part - as I said we should all be vigilant in checking the condition of our used parts.



Agreed, and i did state this fact in my post, the point i'm trying to make is that people are assuming that the failures of the diff when used in LSIS kits is because of poor location when it would seem that as it does not affect every kit made but just a small percentage, rather than the builder just being lucky there is some other reason.

It would be interesting to find out from those who have suffered diff failure in an MX5 LSIS how many of them used cars that were insurance write offs. I bet there would be a high percentage.

TK

[Big Vern]

Agreed, and i did state this fact in my post, the point i'm trying to make is that people are assuming that the failures of the diff when used in LSIS kits is because of poor location when it would seem that as it does not affect every kit made but just a small percentage, rather than the builder just being lucky there is some other reason.

TK

Not every kit has poor location of the MX5 diff, a study would need to be carried out to determine who's kit did or did not break the diff. From what I have seen all those experiencing trouble do not have the diff properly constrained! a point I have been making through out this thread.
Failures of the MX5/RX7 diff when used in isolation are due to poor mounting design with insuffiecient constraint of movement. This is a known problem and there are plenty who have come across this problem - just google search and you will find.
Poor location will cause diff failure as I have tried to explain, Nathan failed to fit the diff washes and that contributed to unconstrained diff movement. A compromised diff could also cause failure but I am aware of people building westfield miata's amongst others including the MNR who are also having failures where the diff has not come from an accident damaged car.
Whilst I get the point you are making RE: the need to be vigilant in checking the parts we use for building cars don't assume that the failure was neccessarily because it must have previously been in an accident and blindly go on believeing the inadequate mount arangement will be alright. Nathan forgetting the washers for the rear isolaters may well have played a part in this.

BV:)

[Big Vern]

This particular failure was due to Nathan forgetting to fit the two big washers that restrict the rotational movement of the diff.

It still remains to be seen whether the design as intended works or not.

Good point well made - hhmm where did I miss that vital bit of evidence:o
The rotational movement they are designed to restrict though, is about the propshaft axis not the driveshaft axis. The type of failure Nathan has experienced exibits all the hallmarks of a failure about the driveshaft axis, the cause of which has been encountered by others as poor diff mounting and constraint of movement of the diff nose.
This failure is due to poor diff constraint but perhaps due to technician error rather than design.
BV:)

[robo]

I think big vern is right, the nose of that diff needs to be well and truly controlled. When you think that a few thousand rpm and a dropped clutch that pinion is trying to climb that crownwheel, that beam across the back is only there to hang the diff unit in place the rest of the forces go to the front mount. i had a quick look round the mx5 fourms and there are dozens of failures with a thousand reasons why, I dont know if I would want something as hit and miss as that an inch from my spine. You could also fabricate a steel brace to run the whole length of the thing and bolt it through the ali bit. It could crack then but at least it would all stay in there.

Bob

Edit: An extract from another forum


Join Date: Jun 2005
Location: Arizona
Posts: 2,007

They do break there very easily.

I also think the alloy or casting method somehow makes them excessively brittle too.

I had an diff assembly accidentally roll off a floor jack close to the floor and produced the exact same break off with a really minor impact. The exposed cross section's inside looked like classic metal fatigue.

[Big Vern]

I think big vern is right, the nose of that diff needs to be well and truly controlled. When you think that a few thousand rpm and a dropped clutch that pinion is trying to climb that crownwheel, that beam across the back is only there to hang the diff unit in place the rest of the forces go to the front mount. i had a quick look round the mx5 fourms and there are dozens of failures with a thousand reasons why, I dont know if I would want something as hit and miss as that an inch from my spine. You could also fabricate a steel brace to run the whole length of the thing and bolt it through the ali bit. It could crack then but at least it would all stay in there.

Bob

Thank you Bob, at least there are a few of you who can see the problem.
Using an the old mx5 engine mount as the front diff mount ain't gonna work. Engine mount is not designed to work in tension!
1.8 mx5 puts out 149N.m torque/5000rpm at the flywheel.
=183N.m/4070rpm to the propshaft in 5th gear (0.814:1)
Diff ratio= 4.3:1
=787N.m/946rpm at the driveshaft. Thats whats trying to twist the diff out of the chassis:eek:
There's no way the tired old engine mount can handle anything like that tension - the rubber will tear away from the steel backing - just try lifting an engine out of the car without undoing an engine and you'll easily see its not up to the job.

Nathan,
I'm trying to pee on your bonfire, far from it, If only I lived closer I'd come round to see for my self and help out with a solution. There are a few good ideas already coming on here.
Do you have a dxf of the chassis in that area I might be able to look at possible solutions a bit easier.

BV:)

[robo]

http://www.solomiata.com/images/RX7pinion.jpg

How about an upgrade to an rx7 diff. No problem with these they have beefed up the whole thing but the prop would be short, the diff mount would end up in the tunnel.

Just thoughts

Bob

[SeriesLandy]

http://www.solomiata.com/images/RX7pinion.jpg

How about an upgrade to an rx7 diff. No problem with these they have beefed up the whole thing but the prop would be short, the diff mount would end up in the tunnel.

Just thoughts

Bob
That is what spud originally started out using as an alternative donor. However stopped and went for the mx5 instead

[Big Vern]

http://www.solomiata.com/images/RX7pinion.jpg

How about an upgrade to an rx7 diff. No problem with these they have beefed up the whole thing but the prop would be short, the diff mount would end up in the tunnel.

Just thoughts

Bob

They also need to be properly constrained - They'll still break the diff hangers if they're allow to rotate about the driveshaft axis - The RX7/8 and the MX5's all use the powerplant assembly principle so a strong front mounting system is still essential.
BV:)

[costlow7]

I have been thinking about mounting the diff in a better way and have read all the posts. I am thinking of mounting it the same way as mazda did with a light weight aluminium beam, using the same bolts spacers etc. Can anyone find a problem with this? I reallise the beam with have to be strong but it will be a little shorter and therefore stronger, with a little thought to the design I think this can be done. the mazda beam was only aluminum anyway.

As for the people who post nothing but unhelpful comments, these people are very shallow minded and are easy to root out. I just look at there previous posts and if most of there comments are unhelpful, I just ignore them. And there posts are usally short.

[robo]

http://www.mmmiata.com/images/products/MM147-BRPPF6.jpg

May be of some help in visualising things...

I think that something along these lines is a no brainer as its basically reducing the amount of strength needed at the mounting point and acting as a torque control arm. It is reproducing the long snouted rx7 concept with a simple bracked. It would not be hard to mount within the gear tunnel and could be done on rubber bushes rather than an engine mount. The longer the better, mind if it was behind me in a car I would still like to see some steel bolted to the cast arms.

On the subject of input from certain members I think there are enough intelligent people on here to sift through some of the crap and make their own logical decisions. As far as this diff problem goes its in the interests of the forum members to iron out any bugs to keep things safe. No one wants to go down the road with a diff banging around behind them and a broken prop flailing around a gear tunnel. The mx5 concept is reasonably new and will have the odd issues but nothing insurmountable we have to just keep bouncing ideas about to find that eurika moment.

[alga]

Engine mount is not designed to work in tension!
1.8 mx5 puts out 149N.m torque/5000rpm at the flywheel


Interesting juxtaposition. 149 Nm with acting on a lever arm of ~30 cm results in 500 N force pulling on one of the engine mounts (minus half the weight of the engine, which I guess is about the same). On any engine with a bit more torque than standard the engine mount works in tension!

[Johno]

Hi guys,
I know this is getting a bit of a concern but this is what I have came up with.
I decided to make a brace between the top of the diif mountings to tie the two together as if it were a chassis. I've fitted two rubber mounts off the back seat rail one in compression and one in tension at all times (tight bugger to fit)....LOL but seems rigid enough.

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Diff%20Mounts%20and%20Brkts/2012-04-07-093.jpg



Sorry no triangulation just old plain engineering....LOL

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Diff%20Mounts%20and%20Brkts/2012-04-07-066.jpg

Also fitted lower diff washers as per photo...


http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/Diff%20Mounts%20and%20Brkts/2012-04-07-077.jpg

Well if that's not good enough I'm going to get a sore backside as well, because that's what I'm fitting to my car...

Have a good weekend Johno..

[Johno]

Ok then whats the verdict,
What do we have to do to make this safe?
I don't think it's possible to make a frame to go along the transmission tunnel as per the MX5 unless you widen the tunnel. My son is going to be the first passenger so i need to get it right.

Johno

[mark]

Ok then whats the verdict,
What do we have to do to make this safe?
I don't think it's possible to make a frame to go along the transmission tunnel as per the MX5 unless you widen the tunnel. My son is going to be the first passenger so i need to get it right.

Johno

Simple, 6 bolts 2 brackets and a ford diff :D

[robo]

I spent some time looking at this and noticed that all the broken beams I have looked at on the net <dozens of them>are broken on our nearside . That I reckon it is due to the diff being mounted on the offside and when the diff is loaded its putting the beam on the nearside under a lot more pressure. A bit like a tripod with unevenly spaced legs. That brace gadget thing I saw spreads the diff loadings at the nose of the diff evenly. Just a theory I will keep eating the toblerone

Bob

[CTWV50]

I don't think you have anything to worry about Johno, if you are worried still use steel for the tub back and make sure you have and inch of play at the gearbox end of the propshaft. That's what I'm doing anyway! And test first without child. :D

[CTWV50]

Robo they are design to fail on that side.

[robo]

Well all I can say is something needs doing, the yanks have dealt with the problems with the braces. In normal hairdressers mode the car probably has no issues but these things are going to get a spanking and as the mx5 fails so will the roadster version. Needs looking at.

bob

[costlow7]

I have just noticed something, I dont know if it is that important but if you look at the saturns/nts mx5 build guide revision 3 page 30 you will see the diff in the car. If you look closely you will see two very small cut outs notches top and bottom on the right hand side of the ally casting, if you look at nathans post you will see that the diff broke at this point. I know it broke because of other reasons and this has probably nothing to do with it, apart from this being a bit weaker. I have not checked my diff yet for these marks, just thought I would mention it.

[robo]

http://forum.miata.net/vb/showthread.php?t=349293


http://t0.gstatic.com/images?q=tbn:ANd9GcTByuTpv-O9FRQUe8YvwivU2A67sE5e_I299afipnBhU7U06neswg

There is a mod. worth reading. A frame that bolts the diff to the gearbox. What I dont understand is that if mazda fitted this as standard on some cars called a ppf <and they break> how come they have they have been omitted in the roadster builds.

Bob

[trick-kit]

I have just noticed something, I dont know if it is that important but if you look at the saturns/nts mx5 build guide revision 3 page 30 you will see the diff in the car. If you look closely you will see two very small cut outs notches top and bottom on the right hand side of the ally casting, if you look at nathans post you will see that the diff broke at this point. I know it broke because of other reasons and this has probably nothing to do with it, apart from this being a bit weaker. I have not checked my diff yet for these marks, just thought I would mention it.


Yep, that's the Mazda designed in safety point, designed to break at this point in an accident so the PPF doesn't pierce the fuel tank. It is a built in weak point.

TK

[PorkChop]

http://forum.miata.net/vb/showthread.php?t=349293


http://t0.gstatic.com/images?q=tbn:ANd9GcTByuTpv-O9FRQUe8YvwivU2A67sE5e_I299afipnBhU7U06neswg

There is a mod. worth reading. A frame that bolts the diff to the gearbox. What I dont understand is that if mazda fitted this as standard on some cars called a ppf <and they break> how come they have they have been omitted in the roadster builds.

Bob

Bob

The PPF frame is standard to all mark 1/2/2.5 MX-5s (not 100% sure about the mark 3, but I would be surprised if it's different).

It's essentially an ali C section beam (about 5mm material thickness) that is hard mounted to the diff nose via 2 x 8" bolts. The beam runs alongside the prop (and covers the O/S side of the prop) and is hard mounted to the gearbox tail, again with 2 x 8" bolts. It's worth noting that the PPF is the only mounting on the front of the diff. The only compressible mountings (AFAIK) are the diff ear rubbers and the engine mounts on the front subframe. Therefore, any rotational movement about the driveshaft axis will be affected by the moment of the engine/gearbox.

As an aside, I read on miata.net that Mazda say that if the rear upper top hat washers are removed, they render the PPF scrap.

It might also be worth seeing what sort of upgrades Flyin Miata or Performance 5 do for the rear diff area (FM have built a 800+bhp Miata and offer lots of tuning bits).

[robo]

If thats the case then the sooner someone knocks up a torque control arm that replicates the job of the mx5 jobby the better. Me thinks.

bob

[Johno]

Hi,
I know this subject has been a sore point for many but there are quite a few MX5 builders now on the forum and Iv'e been looking at Keith Tanners build of the Locost with MX5 donor, quite interesting.
I guess many of you have already viewed it (1439 entries,,,pheww ) but I found it very interesting.
Originally he had a rubber mounted bracket from the front top of the diff to the chassis rail on the transmission tunnel. This after some time failed,


Here's the failure

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/IMG_8522.jpg

He then decided to make a small frame bolted to the front of the diff top and bottom and solidly mount it to a plate welded in the tranny tunnel,

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/IMG_8885.jpg

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/IMG_9016.jpg

It was bolted to the thick plate towards the rear of the tunnel with three bolts with captive nuts welded to the diff bracket.
He used the car for track days and after a few years decided to change the diff.

This is what he said,

"August 1, 2008: Since it's out, here's a shot of my PPF substitute."

http://i1199.photobucket.com/albums/aa472/JohnoSS1/MX5%20Build/IMG_9717.jpg

"I don't think I ever took a good picture of it before. This bolts on to the front of the diff, and then three bolts are run through the side of the transmission tunnel. Everything was still nice and tight when I removed it and it's undergone a fair bit of abuse in the last few years - so I think it's fair to call this little bracket a success.

Less successful was the fact that I managed to pull the driveshaft out of the transmission while removing the diff. I'm not sure I have access to that without pulling the interior transmission panels - I hope I don't have to do that!"

Hope this may be of some help to some people.

Johno