Does anyone know the ring and pinion ratio on a 90' GTU, and a 87 TII...? Or where I could find that information...?

I'm thinking about swapping out my 90GTU rear end for a 87TII rear that I have laying around.

What are my options here...?

Am I better off swapping out the entire rear...? Doesn't that require using a TII driveshaft and halfshafts...?

Or can I just swap out the guts and use the N/A housing and halfshafts w/the TII insides...?

Thanks...!

 

the automatic 1990 rearend is 3.69 ratio and the manual is 4.10.

 

and i would think you could just change the hog head if its only the spline cound thats different. but the t2 rearend is lsd, so rember that too.

 

TII is a 4.10.I don't think the TII rear will fit in a N/A housing the ring gear is bigger than on a N/A.

 

Memphis....every last one of your posts that I have read, you have given people false and wrong information. If you don't know what you are talking about, please do not respond.

The automatic N/A rear end ratio is 3.909. If they are both 5-speed rear ends , then they both will have a 4.10 ratio. The turbo rear end is not the same as the N/A. It will have an LSD for one, whereas the S5 GTU one will most likely not. But in addion to that, it is not even the same size. You will need the T2 axles, and Im not 100% sure on the driveshaft but I think that will not bolt up either. The internals are also different, the T2 uses an 8" ring and the N/A is 7".

 

The pinion flange must be machined so that the N/A driveshaft can bolt up. This is assuming he will still be using the N/A tranny.

 

You can find that information, as well as 75% of the other information asked on this forum, in the factory service manual. Both of the links below offer free online manuals.
http://www.iluvmyrx7.com/
http://fc3s.org/

Mazdatrix is taking pity on the poor 2Gen crowd, and offering their driveshafts with mixed TII/NA components. This is a special order item only, but from what I hear, the price is not increased.
http://www.mazdatrix.com/

 

THANKS FOR ALL THE INPUT GUYS. I've been doing my own thinking too while away from the computer...

Ok... My 90GTU "WAS" an automatic. I converted it over to 5speed as soon as I bought it. So I guess this means I have a 3.90ratio according to RXMFN7's reply.

I know the TII rear is LSD, that's my point in wanting to change it, plus now knowing the TII ratio, 4.10's will liven it up some tooo...

1ST: THE DRIVESHAFT: My MAZDA manual calls the piece on the rearend that the driveshaft bolts up to the "Companion Flange". (I see EVILAVIATOR calls it the pinion flange, I'm not that good with the "BOOK" terms.) Couldn't you remove the big bolt in the middle and swap this out between the two rears to accept the N/A driveshaft on the TII rear...?

or... couldn't I bring the driveshaft to a shop that builds custom driveshafts and put the TII driveshaft tail, on the N/A driveshaft..? A custom driveshaft to put a TII tranny in my 1st gen only cost $180 (and that was for a NEW driveshaft from front to back with replacement universal joints.)

2nd: THE HALFSHAFTS: I know they are different, but does it end there...? Will the halfshafts bolt up to the N/A axle hubs..?

Sorry for all the detailed questions... but this is my dailydriver and I need it to get back and forth to work EVERYDAY... So I need to find out as much info as possible before I go attempting to swap out rearends and something doesn't work.

I know there has got to be some TII converts who've done this before with first hand experience.

THANKS.

 

When I said that you would need the Turbo2 axles, those are the half-shafts that I was talking about. And yes Im sure the driveshaft shop could make you a custom driveshaft to fit the N/A tranny and bolt up to the T2 rear end pinion flange.

 

Axles, halfshafts... whatever you want to call em'. The question I was trying to reask was... Are the TII's axles or halfshafts a bolt up to the N/A wheel assembly...?

Again... Anyone know about removing the pinion flanges to swap out between the two rears to accept the N/A driveshaft on the TII rear...?

 

Length wise, in therory the N/A half shafts should bolt on, however, they may need to be compressed completely, which may or may not be an issue (if they can actually compress that far).

 

I think n?as and TII use the same hubs so the halfshafts should fit fine.As for changing the pinion flange I don't think I would try it as I think it requires diassembly of the differentail housing.

 

Yes, you could get a custom driveshaft made. You probably don't want to waste your time modifying the old driveshaft because there probably isn't much life left in it. The 2Gen U-joints wear much faster than the 1Gen U-joints, usually showing beginning stages of binding around 80K miles.

I don't understand why you are making so much trouble out of the issue. You can get a non-turbo 4.10 or 4.30 LSD as a direct replacement for your 2.909 rear end.

More info:
http://www.mazdatrix.com/g5.htm

 

It's not trouble at all. I have a 87TII rearend minus the halfshafts left over from the doner car I used to convert my 1st gen to T. It's sitting in my garage collecting dust... And it's FREE... Soooooo I'd like to change it. I'm asking how to do it in hopes of before I get under the car, remove a rear and attempt to put in the next, I already have an idea of what problems I'm going to run into so my car isn't on jackstands for a week.

 

Ok... so which model N/A comes with a LSD 4.10 or better ratio...?

 

Double post

 

Most of this info is in the FAQ at the top of the forum...:
all 86-88 GXL 5-speed(auto will have a LSD, but 3.909 gears)
all 87-91 T2
the 88 GTU
and the 89-90 GTUs model(will have 4.3 LSD)

 

I don't mean to be a jerk or anything, but I have to agree with this.