mx5 diff problems

[Numplumb]

I have removed the bushes and bought Flow-Flex poly bushes which arrived today, they are like Stot's solid. Ones I was thinking of placing a large washer at the bottom so that they would be like solid mounted but with the poly bush giving a small amount of movement, I am thinking of mounting the nose of the diff with rosé joint type eyelets with poly inserts if that makes any sense.
Regards Mick.

[TSM Locost]

Keith Tanner http://www.cheapsportscar.net/diary....ate=1980-01-01

[PorkChop]

Originally Posted by TSM Locost

Keith Tanner http://www.cheapsportscar.net/diary....ate=1980-01-01

Thanks for that Mike; saved me the effort To save pople flicking through, Keith Tanner's nose mount design is very similar to Phil's design.



On another note, I think people are being too sensitive here. I didn't see Phil criticise any one person. Bear in mind, I've got a SSC based MX5 chassis (well, I have 2) and I've actively contributed to discussions with other builders both on this forum and IRL on different aspects of improving the design. I don't feel offended.

Phil does have a point though about welding quality. If your welding isn't up to scratch (which is a very real possibility with a home build, not saying anyone in particular is not up to it), then should you really be building a car capable of going over 100mph?

I think he's also spot on with the diff mounting designs. It is incredibly frustrating to have the same topics come up again and again with carbon copy proposals and outcomes (not that I'm blaming you Short in the slightest, you are contributing with an alternative design). Plus, like I said, the Americans have already examined this in detail. It seems counterproductive to not use their findings as our basis and tweak the designs to suit the Roadster.

Phil has also highlighted the one thing about the SSC design I believe could be bettered; the threaded adjusters. At one level, I would look at using a different thread pitch on the wishbones so that a standard rose joint can be used.

An alternative could be to use the adjustable wishbones to set up the car, then make a second set of fixed (or semi fixed) wishbones to those settings. This is what Formula Student builders are advised to do rather than have rod ends acting as outboard ball joints, which usually fail. Although, I would point out I saw a Northern saloon car championship RS200 (replica I assume) at Stoneleigh this year with a very similar threaded adjuster design to that laid out by SSC and the book.

Another option might be to see if an adjustable system similar to OEM Mazda, or shims, could be implemented with fixed wishbones.

WRT the rear upper wishbones, I think it will be difficult to find a way around this without redesigning the outboard end of the wishbone a la Johno's latest design. I do think that it should be possible to have an acceptable set up for the rear suspension using the SSC design.

[CTWV50]

Originally Posted by PorkChop

On another note, I think people are being too sensitive here. I didn't see Phil criticise any one person. Bear in mind, I've got a SSC based MX5 chassis (well, I have 2) and I've actively contributed to discussions with other builders both on this forum and IRL on different aspects of improving the design. I don't feel offended.

If Phil post was constructive about the possible failures of the Saturn chassis then that would be fine or peoples welding but it doesn't come across like that at all to me. Apparently he can't sleep at night thinking about it's short comings! A bit dramatic. No?

Originally Posted by PorkChop

Phil does have a point though about welding quality. If your welding isn't up to scratch (which is a very real possibility with a home build, not saying anyone in particular is not up to it), then should you really be building a car capable of going over 100mph?

We all know this and it's a good point so do destructive tests on your welds and make sure they're not going to let you down. That's what I did. There's no need to describe possible builders as "a less then proficient person" which is very polite insult to my mind considering the tone of his post.

Originally Posted by PorkChop

An alternative could be to use the adjustable wishbones to set up the car, then make a second set of fixed (or semi fixed) wishbones to those settings. This is what Formula Student builders are advised to do rather than have rod ends acting as outboard ball joints, which usually fail.

Thank you, this is useful information and something I hadn't thought of.

Originally Posted by PorkChop

WRT the rear upper wishbones, I think it will be difficult to find a way around this without redesigning the outboard end of the wishbone a la Johno's latest design. I do think that it should be possible to have an acceptable set up for the rear suspension using the SSC design.

I don't see this as much of an issue and like you think it's a workable design.


With regard to the diff support design, I see this as one of the fun/interesting bit's of the build, something we can all throw ideas around with. I enjoy the discussion. I'd like to avoid solid mounting if I can but if that's what it takes then so be it.

With regards to how solid a rubber mounting needs to be, I can jack the rear of my car up using the nose of the diff (obviously only a part built car at the time)
and it does not move at all in relation to the car chassis but that might change during a hard 1st gear launch, maybe 2nd gear launches could avoid this issue completely which might not be as daft as it sounds considering the weight of the vehicle.

[PorkChop]

Originally Posted by CTWV50

If Phil post was constructive about the possible failures of the Saturn chassis then that would be fine or peoples welding but it doesn't come across like that at all to me. Apparently he can't sleep at night thinking about it's short comings! A bit dramatic. No?

I read the not being able to sleep bit as either tongue in cheek, or he's like me. I sometimes go over what I need to do with this bit or that bit of the build.

Originally Posted by CTWV50

We all know this and it's a good point so do destructive tests on your welds and make sure they're not going to let you down. That's what I did. There's no need to describe possible builders as "a less then proficient person" which is very polite insult to my mind considering the tone of his post.

I remember Albert posting up a youtube vid of someone showing you how to weld, where it was more like how NOT to weld. People may not be as thorough as you are with weld testing etc. And Phil did say 'may' not 'is'.

[CTWV50]

Originally Posted by Talonmotorsport

I have been waiting to get that of my chest for the past 2 -3 years and I will never have any thing to say about the Saturn design ever again. But I will say this to all those that I have had conversations with about it .... see 'I told you so'!

Once again, hugely constructive, thanks Phil!

[TheArf]

So I will make this my last input on this subject (well at least for tonight as the cider monster is taking hold) but Phil have you ever completed the build of a haynes because I have never seen anything posted with a completed car built by your good self if you have I appologise if not don't slagg off other peoples efforts and designs

Good night

Arfon