M6 gearbox fault

[jcolley]

mycool said:

Many thanks for the advice so far...

and the fault codes are in....

4F80 - SMG Transmission
4F82 - SMG Engage 1/R gear not possible
5F401 or 5F41 and/or 5F40 - must have misheard this one as cant find it - any ideas?
4F85 - SMG Engage 4/2 gear not possible

My Indy says all pointing to clutch (and possibly flywheel). They will pull the box tomorrow to find out for sure.

Other than getting the release bearing and sleeve done whilst its out, anything else I should be considering?

I hate to say it, but I doubt replacing the clutch is going to solve this.

Looking at the SMG hydraulic schematic below, it would seem the gearbox hydraulics are unable to operate the shift rods for the 1/R cylinder and the 4/2 cylinder. Note that these do not share the same branch proportional valve but are separate. This would imply that both proportional valve branches share a common fault. The thing that is common for that is the clutch valve, which directs fluid pressure to the clutch slave cylinder and also ports fluid to the supply port for both proportional valves.

The cause could be simple such as insufficient hydraulic fluid level or more complex/spendy as in the clutch valve itself. If the SMG has an Achilles heel, it's the clutch valve, as it provides a mechanical interlock to prevent gear selector rod operation without the clutch being opened. Look at the schematic and you can see that in order for fluid to be provided to the two proportional valves, there must also be fluid provided to the clutch slave. This means anything that goes wrong with this clutch valve affects the entire system.

Since you do not have an clutch position related errors, I can't see in being PLCD related.

Since you do not have any errors regarding pressure undershoot, hydraulic pump duty cycle, or anything similar, it indicates the pump and motor are building pressure fine within the specs of the design.

This is the point where a BMW dealership will stop trying to figure it out and replace the whole hydraulic unit. Bloody expensive in comparison to a skilled tech figuring it out in a couple of hours, but most dealers don't have hydraulic system experts on hand and burn through labor quick.

[mycool]

Ok thank you for this.

Its not at a dealer but an independent garage at the moment but I suspect the same is true with respect to hydraulics experts.

Is there anyway for them to test this to diagnose the cause?

[mycool]

The garage did try clearing the fault codes and telling the car it was ok yesterday. They managed to get the car to shift into gear (more than I did when it happened) - When they did, it moved but then stalled and the codes I posted yesterday were what remained after this "test".

i dont know if that sheds any further light on it?

[mycool]

Bit of an update for those interested....

It was the clutch, the inner plate had "exploded" and the outer was down to the rivets. Unfortunately the flywheel was toast too.

Fingers crossed now, that it is happy when its all back together and the adaptation (calibration!) is done.

[Noblebenn]

I've found this posting very interesting as I am currently looking for an E60 M5 or E63 M6.
Intersted to hear if many others have found that this reset / adaptation of the clutch has solved any problems that were initially thought to be disastrous or misdiagnosed by a dealership / Indy. Also if it just simply improved the characteristics of the gearbox.

[Schermerhorn]

Noblebenn said:

I've found this posting very interesting as I am currently looking for an E60 M5 or E63 M6.
Intersted to hear if many others have found that this reset / adaptation of the clutch has solved any problems that were initially thought to be disastrous or misdiagnosed by a dealership / Indy. Also if it just simply improved the characteristics of the gearbox.

A reset or adaptation without a physical hardware change is just a temporary fix. The clutch/flywheel etc are both physical items that are subject to wear and tear. The adaptation won't prevent that from happening but it'll smooth it out for a while.

I did that on my M6 for a while before I had to inevitably change the dreaded clutch and flywheel.

It's still a bargain when you think about it. No Ferrari or Lamborghini (which is what these cars are on par with performance wise) will let you buy a clutch/flywheel from Eurocarparts/GSF/Andrew Page for less than £1000 and then fit it, adapt for another £500 or so.

Now these cars are around the £15-18k mark, what else can touch them for performance, luxury and sound.....OMG....the sound this V10 makes, especially in a tunnel.

[mycool]

Well mine is back from having clutch, flywheel and release bearing sleeve done at my local indy. Total bill for those interested or wanting to budget for such things was £2,103.50.

Probably could have saved a small amount sourcing the parts myself but I have saved significantly over what a BMW dealer would charge for the same work.

Now seriously considering the comprehensive BMW warranty to give a bit or certainty around future big bills. However saying that it is unlikely that the clutch and flywheel work would have been covered as it wasn't obviously related to any release bearing sleeve defect (as has been documented on other threads).

Question not is what xs to apply (£00 or £250) as they do not offer a zero xs option.

Also anyone with first hand experience with Warranty Direct on an E60 M5, as I keep getting offers of 15%off a 3year warranty from them, which apparently covers some wear and tear items?

[Schermerhorn]

Go via Mondia or ring this company

https://www.bmw-warranty.co.uk/login/index

I wouldn't use anything else.