4 bolt rear swap

[fast90GSX]

alright i did try searching but if i missed feel free to kick my ass, anyways i acquired a car with a 4 bolt rear and i want to swap this in favor of my 3 bolt but heres my main question, my car is a manual and this is an auto, are these running the same gear ratios? my car is non abs and i believe this one is so would that make a difference? it wouldnt have lsd if it is abs correct? like i said i do apologize if i overlooked a thread like this and i did search but any help is appreciated. thanks

 

[Matt300ZXT]

I'm curious...why would you take a car with a 4 bolt and put a 3 bolt in it? It's a downgrade, and is probably a pain in the ass to do.

 

[fast90GSX]

i got a 92 with bad motor, no interior and an auto but has the 4 bolt and i want to swap that in my car and take out my 3 bolt

 

[sbiggi]

Autos and manuals have a different gear ratio.
You would have to swap the diff on to the existing ring gear and transfer the shims.

The earlier cars equiped with abs did not have a LSD. Easily identified by looking at the rear diff cover, it should a have a sticker that says LSD on it.

I swapped the 4bolt from our 93 auto to my 90 manual.
It was easy. The seals are the same. The shims in both diffs were the same thinkness.
I did have a issue with the 3 bolt ring gear bolts, they all streched.
The bolts off the 4bolt ring gear were much better bolts.


-Seth

 

[fast90GSX]

ok thanks thats what i as looking for, and the 92 the sticker is half way off and covered in grease so i cant tell for sure but thanks thats what i was looking for

 

[fast90GSX]

could i just put 4 bolt axles into my 3 bolt housing? would this be the same thing and save me the trouble of switching the whole rear?

 

[Slippi84]

Other than the seals for the diff where the axles go in did you guys have to change any seals on the wheel end where the cup is or does it just bolt up?

 

[4pistons]

could i just put 4 bolt axles into my 3 bolt housing?

No. The 4 bolt axles are thicker. That's why you're swapping them. They will not fit in a 3 bolt diff.

did you guys have to change any seals on the wheel end where the cut is or does it just bolt up?

I'm not sure what the 'cut' is you're referring to, but you need to change out the 3 bolt cups for the 4 bolt cups so the axles bolt up. You don't need any seals on that end.

Here's all you need - 4 bolt rear install

Rick - '91 GSX

 

[Slippi84]

Sorry that is suposed to read cuP not cuT

 

[bento]

It will not work. The 3 bolt axles are different from the 4 bolt axles. 4 bolt axles are thicker in diameter, spline is different in the differential.

 

[4pistons]

Sorry that is suposed to read cuP not cuT

DOH!! Shoulda figured that!

Rick - '91 GSX

 

[toofast82]

This is what is needed:
The correct rear differential or ring&pinion(ex auto trans/auto diff or gear and than 3 or 4 bolt.)
The correct axles and cups for differential(3 or 4 bolt)
*Note that you have to have the appropriate lsd/nonlsd axles
3bolt axles will not work for 4bolt and vice-versa
Same with the axle cups
Differences in rear gear ratio between manual and auto makes either the differential to be swapped or the ring and pinion.
This has all been mentioned in this thread except for maybe the lsd thing which may only apply to 3bolt if im not mistaken
I think the vfaq makes it pretty clear the advantages of 4bolt setup