Clutch judder in 1st - 915 box

[Jonny Hart]

I had the clutch fork go on mine. Starts with a judder, then the biting point gets lower and lower until you lose it completely (one side of the fork comes off) which for me happened 100 miles from home. Unbelievably, I managed to drive home without the clutch and without stopping. I stopped well short of any red light and would creep forward in first until the lights changed!

[Northy]

I had some weird shifting on mine. Engine hanger bolts had come undone. One side completely out, other side on final few threads. Worth a check!

[Bootsy]

Thanks. That’s seems to come up quite a lot so will check

[911hillclimber]

Highly likely the gearbox bolts. Had one shake loose in my hillclimb years with the 3.2 in it. The bolts are a bit unusual on my 2.4 chassis, I think M12 but the fine metric thread, not the common coarse thread pitch.

Really easy to get cross threaded and if so done in the past the threads could be damaged and hence 'difficult' to get good and tight for fear of stripping.

The engine end mounting long bolts IIRC are metric coarse and clinch nuts.

[Bootsy]

Went to the shops at lunchtime - joy of living in a small village with nothing near you is you have to (or you make sure) it’s an hour round trip.

I experienced the shudder once! And then at the next junction I released the clutch relatively quickly it’s fine - possible hot spots?

Gratuitous picture at the shops because for no reason other than I can…




Sent from my iPhone using Tapatalk

[Gary71]

Drive harder sounds like a good fix

Car looks sweet anyway

[Bootsy]

Cheers Gary. A couple of interesting comments from my research.....

'I had the same problem on a 80 911SC. I was frustrated and thought, nothing to loose with this clutch. From a standstill I reved and dropped the clutch like it was an old muscle car. I did this 2 or 3 times until I could smell clutch. For the next 30K miles the clutch worked flawlessly without any chatter.
My only guess is by taking the clutch to a much higher than normal temp I removed oil or other contaminants.'

'I have always known it as clutch chatter
its hot spots on the flywheel
they get there from how you drive it. mainly how you pull off from a stop. too much slipping the clutch will put hot spots on it.
if you ever look at a flywheel with them you will see "blue" spots on it. you may get away with block sanding it or it can be bad enough it needs to be cut.
when I got my 930 it had a little clutch chatter. I had to be careful when starting off. now it does not do it.
try not reving the engine so much and release the clutch a little quicker.'

[911hillclimber]

FWIW:
My wife has a humble Skoda Citigo, a slow car with a sweet gearshift. Allegedly with 60 bhp somewhere. 26K very gentle ' 61 mpg' miles.

On several occasions, the last being 3 days ago, the gears really did not want to engage and reverse would crunch. I slipped the clutch 'badly' in first 2 times in succession.
All is well, and has been ever since. Just like new.

Almost an 'Italian Service' but on the clutch.

No smells etc so not too abusive.