mx5 diff problems

[Short]

Surley, if there was the slightest doubt in the weld, if someones got any common sense, they will get someone else to weld it. Im no welder - I will openly admit that. I employ 4 of them. I tack it/set it up, they weld it for me. There all coded and I trust them.

As for people questioning the Saturn build guide - ITS A GUIDE!!! Its not a foolproof way. Its a learning curve. That's why im building one. to 'play' and have something worthwile at the end (plus I need an excuse to leave the wife indoors with the 2 toddlers!!)

Im not wishing to call anyone down, and I feel kinda guilty for Phil getting a kicking on a thread I started.

Your all great engineers. You've all got guts to take a project on like this, and I admire the talent that there is. Ive got to admit, ive copied some of your ideas (not saying whos )and theres one or 2 builds that I aspire to challenge. Keep up the great work, ALL of you.

[Numplumb]

Hi everyone I wanted to mount the diff nose on rosé joints with poly inserts,this was the idea but when I mocked up a bracket like Phil's there doesn't seem to be enough room between sb4 to be able to do anything but a solid connection, the drive axles don't come out central between sb1 and d11 they are slightly forward is this correct, I have placed the plates cp26 as per Saturn alterations to the build show with the measurements as shown but I would like to move the diff back a bit to give me room to mount the nose as I wanted to do nothing is welded yet no suspension brackets or the cp26 plates, also my chassis was built as per the book for Sierra donar so top damper mount has to be moved forward so if I could move the diff back it would save me doing that, anyone got any suggestions?.
Regards Mick.

[PorkChop]

Why would you mount the diff on rod ends? I can't see any advantage to doing it...

[Numplumb]

Maybe I've not explained properly not rod ends more like the suspension mounts like Caterham mount theirs but just two not four
Regards Mick.

[skov]

Originally Posted by Numplumb

...the drive axles don't come out central between sb1 and d11 they are slightly forward is this correct

Yes, that's correct. Bear in mind that if you do bring the diff back you might need to make the wishbones longer (which wouldn't be a bad thing as the rear wheels are very close to the chassis on mine).

[StruveD]

I went the route of solid mounting the nose combined with poly diff bushings. I don't know how common it is on your side of the pond, but state side its pretty common to either switch to poly bushings or go with a solid aluminum bushings for the diff carrier, with the only negative side effect being increase vibrations and noise. Also doing either of these is effectively solid mounting your diff. Prior to fabricating the nose bracket I had just the poly bushings installed and was only able to move the diff nose 1mm. So solid mounting the nose would have very little effect on things.

[Numplumb]

Hi StruveD thanks for that information, can I ask do you hang the diff underneath the diff cage like we do over here and what do you use under the bottom poly bush? I was thinking of using a large washer approx 3 and half inch.

I was looking at a forum Locostusa and on a build blog Johns he mounted his above the diff cage and made poly inserts at the front have you seen that build blog?.
Regards Mick.

[StruveD]

Originally Posted by Numplumb

Hi StruveD thanks for that information, can I ask do you hang the diff underneath the diff cage like we do over here and what do you use under the bottom poly bush? I was thinking of using a large washer approx 3 and half inch.

I was looking at a forum Locostusa and on a build blog Johns he mounted his above the diff cage and made poly inserts at the front have you seen that build blog?.
Regards Mick.

So the bushing kit I purchased is from a company called "energy suspension". They have a kit specifically for the miata diff and its a 2 piece poly set with a crush tube/sleeve. The upper portion is pressed into the carrier, and the lower portion just slips over a portion of the crush tube. You then use the factory washers to press everything together and hold it in place. See the pictures below.

[jason 82]

Cheers for that, when people use these bushes, are they getting breakages of the diff arms at all please ? I have ordered my gbs diff mounting kit which is coming in at a whopping £150, but with this bracket kit, you cut the arms off the diff completely. I don't know how this works exactly, because when I went on my tour of gbs, there was no diffs available to look at, which was a bit of a shame really. But, if your bushing at £35 pounds each ( if my conversion rate is right ? ) , will be a much better deal. I know you have to include shipping, but still would work out a lot cheaper.

[Short]

Looking good Struve. 1 thing I will suggest, where your nuts are at the bottom of the diff nose, id put a plate approx 25x75x5mm (1inch x 3 inch x 4g) with 2 holes in to take the nuts. It will spread any load over more of the diff, reducing the chance of cracking at the hole.