'92 Q Transmission into a '95 Q?

[GseaQ]

Hi all,

Well, we're the new owners of a '95 Q45t formerly known as "Quella". We also still have our old '92 Q which had a brand new (not rebuilt) transmission installed by the dealer in 1999. In 2001 (maybe 2000) we had a B&M transmission cooler installed bypassing the radiator tank "heat exchanger". About this time we also installed a '93 TCU for 1st gear start. It's had regular flushes using Mobil 1 synthetic (every year or 2). I trust it to be trouble free for at least another 3-5 years (80,000-150,000 kms).

I'm not so sure I can trust the '95's transmission at all. It has "slipped" twice - at least that's what it felt like. She was fully warmed up, waiting for a minute or less in gear at a stop sign each time and when started to drive the engine revved for a second and then the transmission felt like it engaged with a bit of a thud or soft clunk. It's only happened twice, but we haven't driven more than 500-1000 kms.

So, the question is can we swap the transmissions - '92 into the '95 and the '95 back into the '92? Should we swap the TCU's with the trannies or can/should the '95 TCU stay in the '95 car? Are there compatibility issues with the '95 vis a vis the TCU/ECU (JWT) interacting? We'll probably have to do this in the next couple of weeks because of available shop time to get both cars up in the air side by side.

All input gratefully received.

Thanks,Glenn

[maxnix]

It would be best with the 1993 TCu for first gear start and shift programming matching the two lower ratios of the early transmission.

I was thinking Rex was getting Quella for some reason. I guess he has too many already. That's a great car.

[Q45tech]

We've never mismatched the tannies since we were always concerned about the loss of acceleration from difference in 1st and 2nd gears in 94-96.

Physically and externally the case/housing are identical and tcu use same circuitry and connectors.

Not sure you can perfetly equate years to miles.....................I've never kept a 90-93 transmission more than 7 years but that was 180k of miles.

[GseaQ]

Thanks maxnix. They actually raised the 1st & 2nd gear ratios in '93 when they went to the 1st gear start. I'm not sure if the ratios are the same as the '94-96's, but I suspect so. I know putting the '93 TCU in our '92 raised our 1st to 2nd gear shift point to about 7100 RPM, but I don't let it get that high as there's no point without an ECU that makes power that high. Easing off a fraction at 6500-6800 gives a quick solid shift.

[GseaQ]

Thanks Dennis. As for acceleration, we're going the "other" way with the gear ratios, although my only concern is to start our life with Quella with a healthy transmission. Maybe the current original one is healthy, but I'm not confident and I really like the quick, solid shift feel of our '92's. We're changing the diff back to the original 3.54 so I think the lower 1st and 2nd gear ratios may make the change less painful. I had read somewhere here in the archived posts that the '95 TCU was different than the '93-94 and that the '95's had some necessary interaction with the ECU that the '93-94 did not. Does this ring any bells with you? If so, it would be necessary to keep the '95 TCU with the car, wouldn't it? Quella does have a JWT ECU, though. I don't know if it's different than the JWT ECU for the '94. I think I'll have a look out of curiosity.

Glenn

[GseaQ]

For what it's worth, JWT's site shows ECU's for '90-93 & '94-95. Four of their 5 TCU's say '90+ and the other one makes no mention of a year. So, I guess I shouldn't need to keep the '95 TCU in the '95 car. Just in case the '95 TCU softens the shifts for a luxurious feel or something.

[Q45tech]

Mismatching the tcu only results in changes in WOT shift speed and these were under 5% in 1st and 2nd. To make sure the shifts occurred before redline and fuel shut off. 6500<6900.

[GseaQ]

Thanks Dennis.