4200/GP/QP Transmission and Ancillaries

CatmanV2

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48,557
Can you hear the engine revving up? The graph isn't that granular but how long is the shift time? I recall mine, you really didn't have to lift...

C
 

lambertius

Banned
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Shift time is fractions of a second. You can't hear the engine revving up, its too quick. I really only started looking for it because the only description that fits what is happening is bad clutch timing.

If it is bad clutch timing then it can only be software or bad wiring. Considering it reports the data to the OBD port I'd be guessing its software, and since I have the latest version of the software it may just be a versioning issue. Again something I can't confirm without more data!

I drove an 05 Gransport and I don't remember this being an issue. But a few people have said to me that they used to drive their cars like a manual, and I got a comment on the other forum saying that his used to do the same thing. A wrecker in Sydney is going to send me a TCU to test with which may help with diagnosis.

Also, I was able to access the second version of the TCU today! The only thing I've done is repair a bit of wiring in the paddle shifters!

And while I was searching for TCUs, I came across a TCU with the MAC10F43 software version. This is the earliest version that people say was the best right? I didn't get it because its so much older than my car and the different gear ratios in my box - but if someone wants it for a Coupe I'm happy to help out for science!
 

Zep

Moderator
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9,110
I see said the blind man. So, some of the shifts seem to be well synchronised and others (the last two particularly) seem to have the biggest variance.

My experience with my car was that depending on how hard you were trying the shift quality was variable. Once the PIS was tightened, high engine speed, high throttle opening shifts were smooth and fast, low speed low throttle were less smooth. Can you overlay throttle position on your graph?
 

lambertius

Banned
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341
I'll have a look and see if I can!

This really is an exercise in defining normal more than it is solving a problem!

The way you describe the driving is bang on what I've got going on. If you drive low and casual the RPM rises by a larger percentage relative to the gearbox which makes engagement harsher. The faster you're accelerating or the later you shift the smoother the change. So the earlier gears are smoother, but as you start to cruise and the gears change at lower RPM the engagement is noticeably less smooth, which is reflected in the graph.

But again the problem comes back to 'is that normal?' I'm happy to drive to any style, just so long as I know that is the driving style intended by design!
 

tulit

Member
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110
How aggressively do you have your PIS set? It has a big impact as well on the harshness of shifts I found.


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CatmanV2

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48,557
Having been in Zep's car, I think his definition of 'harsh' is, well 'harsh' I found them no more harsh than my 4200 which again certainly never even felt like I'd consider there was a remote possibility of an issue.

But I do feel your pain

C
 

Zep

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Having been in Zep's car, I think his definition of 'harsh' is, well 'harsh' I found them no more harsh than my 4200 which again certainly never even felt like I'd consider there was a remote possibility of an issue.

But I do feel your pain

C

Harsh for me, not for you :p
 

lambertius

Banned
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How aggressively do you have your PIS set? It has a big impact as well on the harshness of shifts I found.


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When I had the broken transmission it was set at 5.3, now It is set at 4.98. Any more than that and on hot days the car will stall if on an incline (though it does noticeably drive better at 4.85). Being Perth, hot days are common. I found that after changing the transmission there was a point where it was smoothest engagement and it got worse either side of that.
 

Zep

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I think mine was 4.3, but I imagine there is a variation between cars.
 

lambertius

Banned
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341
The only other car in the area I could get access to (couldn't drive it) was set at 4.05! I remember driving that one mid last year just after the new clutch was installed and it was smoother than mine. I suspect that number gets smaller the more often the fly wheel is resurfaced.
 

conaero

Forum Owner
Messages
34,594
Spoke to Ask yesterday and explained the issue and before I even finished my sentence he said torque tube to gearbox o ring. This will give a clunk on gear change and they can fall out during the swap.

I have now just sent him your video, let’s see what he says having now actually heard it.
 

lambertius

Banned
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341
Wouldn't that be magical!

There is an issue with M5s when changing the flywheel that its easy to bend some of the teeth and it throws an engine fault code. Its pretty much impossible to diagnose unless you've seen it before but ultra easy to fix. It would be nice if this situation is that.

I'm still getting people saying that their cars are the same, and others saying it isn't meant to be like that - but if the O-ring gets lost on clutch changes... well...

*Edit: I've been looking through diagrams but can't work out what part you're describing!
https://www.eurospares.co.uk/parts/...dals/gearbox-cover-gearbox-oil-radiator-28179
https://www.eurospares.co.uk/parts/...mission-connection-tube-and-insulations-28184
https://www.eurospares.co.uk/parts/...transmission-pedals/clutch-and-controls-28174
 
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lambertius

Banned
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341
So the plot thickens a bit. I had a chat with a fellow in Melbourne who has been helping me when he has the time - but he is very busy. After that I decided to plot the hydraulic circuit pressure against the RPM plots.

66390

When the car is stationary the accumulator will hold above 40 bar for more than 3 minutes (I stopped timing after 3 minutes and it had only dropped 4 bar). According to our lord and saviour http://craig-waterman.com/?tag=maserati-accumulator there should be enough circuit pressure to supply three gear changes when the accumulator reaches 50 bar.

You can very clearly see in the graph that the rough shifts are happening when the shift happens at low circuit pressure, dropping just below 40 bar in some cases. The pump itself is cycling properly to try and maintain pressure which is why it never fails to get into gear. So can anyone provide any insight into why the pressure drops so significantly during actuation?

It also seems to be losing pressure much faster while the car is moving, even if I don't change the gear but I'll need to go somewhere quite so I can drive around in gear for 3 minutes to see if the hydraulic pressure falls faster compared to stationary.
 
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CatmanV2

Member
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48,557
Personally I fear you may be reading a little too much into what is a very limited set of data. To me looks like the pressure is cycling fine, but logically you'd expect some shifts to take place when pressure is low. Correlation does not equal causality.

I could be wrong :D

C
 

lambertius

Banned
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341
Unfortunately that is the problem I'm facing. Until I can see someone else's data its hard to compare.

I did run another test though - as soon as the engine is on, circuit pressure is only maintained for <20s. I think that is weird though. I can't see why the engine running should affect the circuit pressure at all.
 

CatmanV2

Member
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48,557
Unfortunately that is the problem I'm facing. Until I can see someone else's data its hard to compare.

I did run another test though - as soon as the engine is one, circuit pressure is only maintained for <20s. I think that is weird though. I can't see why the engine running should affect the circuit pressure at all.

As soon as the engine is what?

C
 

CatmanV2

Member
Messages
48,557
So pressure is maintained for minutes with the engine off, and only 20 seconds when it's on and idling?
That does sound very odd indeed

C