4200/GP/QP Transmission and Ancillaries

[lambertius]

The early QP M139 transmission is the same as the 4200/GS right? I know the GS had a taller 6th gear than the 4200 but otherwise all ancillaries (pumps, accumulators, actuator lines etc) are the same between all three cars, and the transmissions could be swapped between all three cars (if you were okay changing the gear ratios)?

I've recently swapped out a transmission from my GS and am looking to rebuild it into a spare. I've found a few good priced ancillaries from QPs and 4200s and want to know if I can build the transmission successfully with those parts!

Thanks!

 

[Gp79]

What failed on your old one? Never really hear of any issues?

I always use eurospares website to cross reference part numbers, this might give you the answer if gearbox shares the parts across QP and coupe models. I’m sure it does as they look the same.

 

[lambertius]

No idea, when I crack it open I'll let you know.

It was grinding something awful, particularly when I could get it in reverse. It was unnecessarily harsh shifting to the point the rear of the car would unsettle, sometimes it would get stuck in auto mode, sometimes it would refuse to go into reverse. Error codes were always inconsistent from down shift sensor not working, to no engine RPM. When turning at low speeds (especially in reverse) you could feel the diff load up and bind. When the oil was inspected it was glittery with metal but no chunks. When it was in any gear though it ran perfectly fine.

Considering how cheap the parts are, its just more cost effective to the ole swapperoonie than bother trouble shooting.

Current guess is that there was slop internally on the transmission which was throwing out some sensor(s), possibly combined with some other issues with faulty switches. Since the swap there have been no issues (touch wood). What I do know is that before I got it, the transmission oil and hydraulic fluid hadn't been done in at least 7 years, so it could be worn bearings or unnecessary wear on the diff. Or it could've just been fine with an oil change.

It was the harsh shift that was the most noticeable. 1st-2nd was always fine regardless of mode or how I was driving. The rest of the gears were like being rear-ended 90% of the time and every now and again it would be a nice shift.

 

[lambertius]

Went through the part numbers on Eurospares and I can confirm that the early QP ancillaries are the same as the 4200 and GS by part number. Hope that helps someone in the future.

And if anyone is feeling helpful, would someone be able to record some sound on their phone of the shifting from inside the car? I don't have a lot of cars (read any) to go and test against as a reference for how how harsh or smooth the transmission should be. I remember driving them previously and the transmission never stuck in my mind as particularly harsh - it just felt like a manual. I don't remember hearing the back end of the car thunk even when wringing its guts out. I'm sure I have a bit more troubleshooting as I go ahead and it would be nice to have a reference point for how smooth the transmission should be.

If anyone has any info on troubleshooting and diagnosing particularly harsh shifts that would be helpful as well. There is a very helpful tech in Melbourne who I've spoken to who has said that when he has resolved it before he has swapped actuators with known good cars and has found it to be the actuator, but doesn't know why or what's wrong with them.

Cheers

 

[conaero]

9/10 it’s the diff.

 

[lambertius]

Well some good news on the transmission is that a lot of the issues were resolved when it was swapped. The binding during turning and a lot of the noises disappeared. The gear changes are noticeably smoother to the point that my fiancee noticed it when she drove it, so it wasn't just me wanting it to be better!

That said, I want to know if I need to be chasing anything else any further or if I'm being too picky? I've put up a video of gear changes on some regular driving and would like any input that people have compared to their own cars. I've only had the opportunity to drive one of these cars before and I don't recall it being quite so loud on gear changes, and being a low volume car they're not easy to find around the place to go and drive another one to compare against.

If anyone has any diagnostic advice that would also be appreciated. They Hydraulic system primes to 42 bar and then holds steady, the self-learn always completes fine.

Cheers

 

[Evo Cymru]

Hmm watching that vid it seems louder/more noticeable than on my GS with both normal and sport changes.... Sometimes hard to tell on a vid though - any movement/shunt felt in the cabin?

 

[spn]

Sounds like the clutch and throttle are out of sync (or it's not backing off correctly). There's slip on disengagement and a bang (too much throttle) as the clutch engages. Similar to changing a manual without coming off the throttle sufficiently.

 

[Wanderer]

I recorded my QP tonight but is was too quiet to hear anything at all, I certainly don't get thumps like that maybe the odd shunt on dead cold start but that's it.

 

[lambertius]

Hmm watching that vid it seems louder/more noticeable than on my GS with both normal and sport changes.... Sometimes hard to tell on a vid though - any movement/shunt felt in the cabin?

Before changing the transmission it was like getting rear-ended it was so severe, and that was with the PIS set to 5.38! Since then the transmission engagement is 'direct' as in you can feel it, but it isn't messing up with the way the car moves.

My worst case scenario at this point is to buy all the ancillaries and swap them over one at a time but I would prefer a less scattergun approach! My current plan is to run the car with the wheels in the air and see if I can locate the sound specifically, but any diagnostic tests and suggestions would be appreciated!

 

[lambertius]

Sounds like the clutch and throttle are out of sync (or it's not backing off correctly). There's slip on disengagement and a bang (too much throttle) as the clutch engages. Similar to changing a manual without coming off the throttle sufficiently.

I agree that is what it sounds like, but you made think when you said that 'well that's a control problem'. When I hook up my Launch X431 I get two options for the TCU computer, and mine works with the first version and not the second. I thought that this seemed strange as my car is a 2007. I wonder if the TCU has been swapped out with one from an earlier car? Does anyone know if this is even a thing?

Anyone know how to identify specific TCUs, or a list of software versions?

 

[hunta]

Obvious (irrelevant?) question... What's the status of the clutch?

 

[lambertius]

50% life, checked against a few computers and I've got service records so I'm confident it's mostly correct.

 

[Mr S]

Sorry if its a stupid question, but is it a mount/bush at all?

 

[philw696]

I'm with a gearbox mounting after watching that.
I broke one on my 360 Modena F1 on a forum track day after hooning her all day in Sports mode.

 

[lambertius]

Gearbox was swapped over and nothing was said about the mount. I don't believe that is the issue, but I will follow up with it anyway just in case it was missed.

I hooked up my launch and went to the absolute extreme settings I could on the PIS 4.6-5.5 to see what difference that made. The sound is proportional to the PIS setting, but never really goes away entirely. Obviously too much slip at 5.5 to be practical but it was just about seeing if there are any relationships between different parameters.

 

[Navcorr]

I hooked up my launch ...

There's plenty of material to suggest that Launch software isn't the most sophisticated.
Recall Voicey posting about the inaccuracy of PIS achievable when compared to SD3/Leonardo.
That was a few years ago now, and software may well have improved, but do you have other options.

 

[lambertius]

There are a couple of shops that have an SD2 nearby, but for what I was doing this was working. It was adjusting the PIS, and it was making the change. I drove it with a few different PIS settings to just make note of the change.

 

[CatmanV2]

There are a couple of shops that have an SD2 nearby, but for what I was doing this was working. It was adjusting the PIS, and it was making the change. I drove it with a few different PIS settings to just make note of the change.

I suspect you were adjusting the PIS and it was making a change. Might be enough for what you want at this point, though.

C

 

[lambertius]

Yes, it was making a change. Sorry just had my wisdom teeth pulled a few hours ago and life is somewhat more confusing than usual right now.

I was hoping to gain just a bit of trouble-shooting info by changing it. The clutch setting is at least partially responsible for the sound, so it does give credibility to a busted mount or something that is timing clutch engagement incorrectly.