Author Topic: Testing clutch operation on the bench  (Read 326 times)

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Offline jayson.devries

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Testing clutch operation on the bench
« on: 06 February 2020, 01:49 »
I've just replaced the clutch and throwout bearing in my AutoStick gearbox. Before I put it back in the car I'd like to ensure it is operating properly. So on the bench, in gear, I turn the input shaft by hand and the axle flanges turn. Great!  With the clutch arm and servo arm adjusted, I draw a vacuum with my Mityvac hand pump. The clutch arm pulls all the way with the expected resistance. Now I turn the input shaft and.... the axle flanges are still turning! Hmmm.. ??? (scratches head).
 
Have I assembled something wrong? I'm quite certain the clutch fork was positioned between the clutch cover and the TO when I attached the bell housing - besides, the arm moves with the expected resistance. Am I missing something? Any ideas?
1973 1303 Autostick
1984 930
1985 Iltis

Offline Tom K.

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Re: Testing clutch operation on the bench
« Reply #1 on: 21 February 2020, 22:14 »
My process to reassemble the clutch appears on the bottom of this thread

https://www.thesamba.com/vw/forum/viewtopic.php?t=714131&start=40

Offline jayson.devries

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Re: Testing clutch operation on the bench
« Reply #2 on: 01 March 2020, 01:14 »
Thanks Tom - great post and pictures!

I did finally solve this. The only thing that made sense was that the new clutch had stuck itself to the pressure plate and/or the carrier plate. A piece of critical information that I thoughtlessly left out of my first post was that it had been sitting for over a year since I assembled it. Since the oil plan was already attached, I really wanted to avoid opening it up (I gotta start making my own gaskets like you Tom). So I bolted levers to the axle flanges, carefully clamped on to the input shaft, pulled a vacuum on the servo, and tried my damndest to snap it lose... to no avail.

Out of options, I did finally open things up and did find the clutch stuck to the carrier plate. Not so much rust as just clutch material. I'll post pictures tomorrow.
1973 1303 Autostick
1984 930
1985 Iltis

Offline jayson.devries

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Re: Testing clutch operation on the bench
« Reply #3 on: 02 March 2020, 15:24 »
Here are a few pictures of the clutch material (asbestos?!) rusted/stuck to the pressure plate and the carrier plate.



1973 1303 Autostick
1984 930
1985 Iltis

Offline Tom K.

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Re: Testing clutch operation on the bench
« Reply #4 on: 10 March 2020, 04:15 »
Bummer. I had the same issue. I used a razor blade and then light sanding to clean the pressure plate. Pictures appear in one of the first pages on my build thread with link above.

 

anything