clutch chatter

[Jimbug57]

My super beetle clutch has recently decided to be real grabby when I release it in first gear. No problems other than that.

Any thoughts?

Thanks, Jim
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[airschooled]

Hi Jim,

Does the clutch pedal behave itself once the drivetrain warms up with 20+ minutes of city driving?

Things that can cause clutch chatter, that you can check without removing the engine:
- Too little bowden tube preload
- Bad/loose engine or transaxle mounts/bolts
- Misfiring/out of tune idle

Things that can cause clutch chatter that require removing the engine to repair:
- Contamination of the friction surfaces (clutch/flywheel/pressure plate)

Clutch system contamination can further be broken down into corrosion from storage, corrosion from moisture, damage from heat/improper use, or oil contamination, most commonly from a flywheel o-ring or main seal leak.

If you're sure the exterior parts are in good shape, you'll be removing the engine to fix the problem. Good luck!

Let us know if you have questions about any of the systems,
Robbie
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[Tim Donahoe]

When mine did this, it was grease that had flig onto the clutch plate. Oil does it, too.

Tim
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Richard O'Brien

[runamoc]

[ashman40]

After you check your mount bolts are tight and the mounts are not cracked, take a look at your bowden tube and make sure there is sufficient bend liek the pic below.

If too straight the clutch will chatter just as it engages the flywheel. This chattering is caused by the normal flex in the engine/transmission changing the distance from the frame to the end of the bowden tube. The bend in the tube allows for this change in distance without pulling/pushing on the clutch cable.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[airschooled]

Ashman, while your post is 100% on, do you think the sag in the photo looks a bit excessive? The bowden tube connection to the chassis seems to be a bit more horizontal on later cars as well, in my experience.

I have found excessive sag to cause a clutch disc to “grab” the flywheel with a thud, but then engage smoothly as the pedal is released.

Robbie
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Learn how your vintage VW works. And why it doesn't!
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[ashman40]

It was just a pic from the gallery I found to illustrate the point.

Conceptually, as long as the bowden tube never fully straightens out, it serves its purpose. If while the engine/transmission flexes in its mounts the bowden tube were to straighten out, any additional flex would result in the clutch cable pulling on the release arm. This could disengage the clutch which would reduce the engine flex which results in the clutch re-engaging which causes the engine to flex which disengages... in a repeating cycle... which appears as clutch chatter.

I've not experienced the "grab" you speak of. There is a recommended amount of flex in the tube. I don't have my service manual in front of me. Maybe someone can post? I normally stick to this spec.
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AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

[Ovally]

[xaquinn]

Does anyone have a picture/cartoon illustrating the mounting bolt locations?

I got a 1970 recently that wasn’t running at the time of purchase. After I got it fired up, I found that there was clutch chatter in first only when starting from a stop. Got a new Bowden tube and shimmed to proper droop with no change. I checked the weld to the cable tube in the tunnel and that is good. Almost at the point of dropping the motor, but would prefer not to.

[runamoc]

[xaquinn]

Are there any good videos or write ups on how to do this with motor/trans still installed?

[runamoc]

[VW_Jimbo]

[xaquinn]

Thanks! I saw Chris’s video right after posting the question. I wish I have a garage and lift! Ordering a new front mount today. Going to give it a shot this weekend and will report back!