Need input on beefing up N/A rearend
 

I am putting a 20b n/a in my GTUs.

I am going to stay with the n/a rear. And yes I do have a TII transmission. The car is a street car and maybe a track day here and there. No drag launches or hardcore racing. I will probably be in the 330-350rwhp range.

I want to beef up the rear but am not sure of the exact points of weakness. I think in my searches I have come to understand that the output shafts will break. It seems like I read that the differential is pretty tough.

Is an output shaft the same thing as a stub axle?

Anyway, I am going to cryo the output shafts.

I am doing this because it is twenty pounds or so lighter than the TII rear end. If it breaks then I will get a TII rear.

Does anyone have any other suggestion to make a n/a rear stronger.

If you are going to tell me just put a TII rear in then how bout you go start your own thread about your opinions on the subject.

I am clearly and only asking for input on how to make it stronger not whether your ass thinks I should do it or not. ;)

ring and pinion maybe

Not everyone uses the same terminology. To me the output shaft is the half shaft, not the stub axle.

They use essentially the same diff in Miatas and there's some quite powerful ones over there that use it with no real problems. You're probably ok with yours, and if you want stronger axles, might I suggest using TII axles with some sort of spacer/adapter between them and the NA stubs (I do believe the TII shafts are shorter due to the diff being wider). That way when/if it does go you've already got the correct, stronger axles in place for the TII rear end swap. It's probably cheaper and easier than getting the NA ones strenghtened (cryo might help a bit, but its not magic, TII should be stronger).

I'd reccomend you get an S4 LSD and rebuild it, as it'll be strong enough to handle that. The S5 unit you've got isn't an LSD any more, or at least not much of one, I can guarantee you that. A Miata torsen could probably handle the power/torque, but it might break, so the S4 unit's probably your best bet.

So can I put a S4 diff into an S5 housing?

I would suggest the S4 LSD like Black91 mentioned

good mounts and something like a pinion snubber to keep the diff snout from snapping up and you will have no problems

my stock s4 na rearend has done 1.5xx's and tons of 1.6xx's 60fts (slicks/DR's) with no problems at all (sort of to my suprise)

just a pinion snubber

Yes, you can swap the inner workings of the S4 diff into your housing. Be sure to rebuild it though, as it'll be rather weak after all those years on the road and a rebuild will do wonders for its performance. The mounts is a good suggestion too. The Mazda Comp ones are a good choice, about 40% stiffer than stock, so it's stiffer, but it doesn't negatively impact NVH like solid mounts would.

You need to edit your sig, no swearing.

Already got the Mazda Comp rear diff. mounts. Thinking about a 1.5way.....

What signature???? :) :)

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