Play in flywheel and prop shaft

Hi guys,

My tech is doing some work to my TT6 at the moment and he has discovered two things that may need some attention.

Firstly the car has had a new OEM flywheel only a few hundred miles ago, but there seems to be quite a lot of play in it; around an inch. Is this normal?

The car is also suffering a bit with lash both on and off the throttle. There appears to be about half a turn in the propshaft before it engages which may explain it. Does anyone have any experience with this? We have noticed that the 'O' seal has perished so going to replace this, but wondering what else might be needed.

If anyone could help give us a steer that would be great.

Regards

James

Here's how you measure your flywheel movement.

Here's how you measure your flywheel movement.

 

http://www.mkivsupra.net/vbb/attachment.php?attachmentid=228979&stc=1&d=1535544348

Thanks Mike, that's really useful. I spoke to the tech who fitted the previous flywheel last year and it turns out the former keeper supplied a used solid flywheel, not an new OEM DMF. On this basis it doesn't seem unreasonable to think it might have reached the end of it's life. I will pass that diagram to my pal who is working on the car so he can check it.

Does anyone have any idea about the lash? The car lurches quite a bit both on and off the throttle, even with just a gentle throttle input.

Rubber propshaft doughnut perhaps?

They usually are perished at this age and twist round while everything catches up, worth a look.

Rubber propshaft doughnut perhaps?

 

They usually are perished at this age and twist round while everything catches up, worth a look.

Thanks Ric. The doughnut is indeed perished, so we are going to be replacing this. Do you think this alone would explain the car lurching when coming on and off the throttle?

Thanks Mike, that's really useful. I spoke to the tech who fitted the previous flywheel last year and it turns out the former keeper supplied a used solid flywheel, not an new OEM DMF. On this basis it doesn't seem unreasonable to think it might have reached the end of it's life. I will pass that diagram to my pal who is working on the car so he can check it.

 

Does anyone have any idea about the lash? The car lurches quite a bit both on and off the throttle, even with just a gentle throttle input.

If it's a solid flywheel, then there should be no movement at all. Sounds like something isn't right

Thanks Ric. The doughnut is indeed perished, so we are going to be replacing this. Do you think this alone would explain the car lurching when coming on and off the throttle?

Ive never experienced it but a few threads on here say it's part of the problem.

Ive seen threads about this before and nobody seems to pinpoint the reason. Some people even said "its just how they are" Mine does it and it really bugs me.

Ive done the gearbox mount, all diff mounts, checked the subframe bolts. Like you say, the prop rotates more then expected before it engages so I can only assume its diff related?

Ive seen threads about this before and nobody seems to pinpoint the reason. Some people even said "its just how they are" Mine does it and it really bugs me.

Ive done the gearbox mount, all diff mounts, checked the subframe bolts. Like you say, the prop rotates more then expected before it engages so I can only assume its diff related?

 

/QUOTE]

 

We’ve also changed the diff seals and bushes also and it didn’t cure it. Interesting to hear others are facing the same problem too. A lot of the answers to mechanical questions about MKIVs seem to end up being ‘they all do that’!

 

- - - Updated - - -

 

Ive seen threads about this before and nobody seems to pinpoint the reason. Some people even said "its just how they are" Mine does it and it really bugs me.

Ive done the gearbox mount, all diff mounts, checked the subframe bolts. Like you say, the prop rotates more then expected before it engages so I can only assume its diff related?

 

/QUOTE]

 

We’ve also changed the diff seals and bushes also and it didn’t cure it. Interesting to hear others are facing the same problem too. A lot of the answers to mechanical questions about MKIVs seem to end up being ‘they all do that’!

Squiffy have you had a new dual mass flywheel amongst all the other new stuff?

My old 6 speed na had lash, you could make it do it at rolling pedestrian speeds but semi clutch dumping, ie rapid uplift to the bite point. I'm sure mine was a worn flywheel as the diff wasn't really being stressed in this scenario, you could probably try it with the handbrake fully on to fully rule out the diff?

Also open diffs can be had for cheap and swapping in is pretty easy if you wanted to check that way.

Thanks Scooter. The lash is very noticeable at low loads/ speeds. You can be rolling along in second and just lifting off the throttle quite gently, or gently re-engaging it will be enough to make the car lurch back or forth.

In that case perhaps changing the current - seemingly shot - solid flywheel for an OEM DMF might improve it, especially if replacing the prop doughnut too. Just wanted to try and ensure we’ve covered all bases before putting her back together again as I’d rather not have to go through it again.

Only thing is, that doesn’t seem to explain why there is so much turn in the prop shaft. My tech Marcus said there is about half a turn before it engages???

The back lash will no doubt be in the diff, have you ut the car in gear and tried it? There's supposed to be a bit of free play in it

Squiffy have you had a new dual mass flywheel amongst all the other new stuff?

 

My old 6 speed na had lash, you could make it do it at rolling pedestrian speeds but semi clutch dumping, ie rapid uplift to the bite point. I'm sure mine was a worn flywheel as the diff wasn't really being stressed in this scenario, you could probably try it with the handbrake fully on to fully rule out the diff?

 

Also open diffs can be had for cheap and swapping in is pretty easy if you wanted to check that way.

Mine does it on and off the throttle when it's in gear without touching the clutch

Anyone news for the lash ?

If your "tech" puts the handbrake on with the gearbox in neutral with the car on a ramp and can turn the propshaft back and forth half a turn then the pinion or crown wheel is missing a few teeth and the car would be undriveable. Some CWP backlash is normal, necessary in fact. Half a turn of the propshaft...? Nah, not having that, the CWP would have to be totally goosed. It's troubling a tech would expect changing differential casing seals would affect backlash, he's not ON the lash is he?

I would put an OE or one of my uprated OE clutches in it and a new dual mass flywheel, solid flywheels on a MKIV Getrag equipped road car are dreadful and put extra stress on a hard to maintain or replace manual box.

Has the Diff been opened and inspected?