Well I have a GTUs thats in horrible mechanical condition. Suffice it to say, it needs a lot of new EVERYTHING. Anywho, I also have an S5 GXL. The frame is bent on the GXL so im most likely going to swap the engine and a lot of other parts into the GTUs, basically mix and matching to bring the GTUs back to almost stock condition. The tranny on the GTUs has bad syncros in 5th gear, but other than that it shifts pretty well. I dont know how much it would cost to get it rebuilt, and I wont have the money for it right away, so I will use the tranny from the GXL. Heres the question. What will be the differences between using the GXL tranny and the GTUs tranny with the 4.3 diff? I know the GTUs tranny is geared a little differently to compensate for the 4.3 diff, and the rate of speed differs on the tach compared to the regular NA tranny. Will using the GXL tranny make the car slower than using the GTUs tranny?

 

The GTUs has a VLSD rear end with a 4.3 gear set. The S5 GXL has a open differential with a 4.1 gear set. The transmission gear ratios are both the same for 1st thru 4th and reverse. The only difference between the transmissions is the 5th gear ratio. The 5th gear ratio for the GXL is 0.697 whereas for the GTUs is 0.756.

Hot_Dog
90 RX7 GXL

 

The tranny is identical, gears and all. There's a couple of fubbed places that published the TII gear incorrectly.

 

True...with the exception for 5th gear. Both transmissions had different 5th gear ratios.

Hot_Dog
90 RX7 GXL

 

The 5th gear is the same between the NA and the GTUs tranny, some places fubbed and put the TII 5th gear on the GTUs when really it's the same. Take them apart and they're identical.

 

I've rebuilt both S5 GXL and GTUs transmissions -- The 5th gear sets are different. If you look at the Mazda parts listing, than you'll see that there are different p/n's for these 5th gear sets.

Gear, counter
M507-17-308 (w/o turbo, nor. susp) --> S5 NA excluding GTUs
M508-17-308 (w/o turbo, hard susp) --> GTUs

Gear, over top
M512-17-611 (w/o turbo, nor. susp) --> S5 NA excluding GTUs
M514-17-308 (w/o turbo, hard susp) -- GTUs

I've bought these gear sets before, so I'm well aware of the differences.

Hot_Dog
90 RX7 GXL

 

And every set I've ever ordered has always been the same. I was kind of upset when I got my set from MT and apparently they've been that way for as long as they could remember. I've pulled apart 3 GTUs trannies in the past year of which all were the same as the standard NA counterpart. I did speak to Mazda about this before, and they suggested that they probably no longer make the GTUs set and ship standard sets instead.

Hard to say, but I'm positive at least the one tranny was 100% original to the car and never rebuilt.

 

well if you want it I have an 89 GTUs tranny here in great condition for $300 shipped

 

+1

I just looked them up in my NAPA catalog (where I buy my rebuild parts) and I can say that Hot Dog is correct.