Slipping Clutch in my 71

[Billy]

Is there any way to adjust a slipping clutch? I have looked at that dealer service manual and there is only a peddle adjustment. There was a note in there that says that there are two different throw out bearing applications for the 71, a tall and a short one. The local GM dealer and parts store claim there is only one throw out bearing listed. Has anybody run into this problem before? Did the LT1 come with a heavy duty clutch? Any help will be greatly appreciated.

 

[Stingray6974]

Billy,
The pedal adjustment is the only adjustment for the clutch. If you set it to where you have about one inch pedal free-play and the clutch still slips then you have a worn out clutch. GM used two types of diaphram pressure plates in the 70's, one usesd a long throwout, the other uses a short one. It was impossible to mis-match them...... the clutch would never work. Whenever you buy a clutch, always buy a kit, that way everything is matched.
Mike

 

[Jack]

pilot bushing and...

Billy:
Mike's right, and a kit'll help ensure you'll have the right parts.

Are you gonna do the work? If you are, you might take your stuff to parts store and match 'em up. You'll also need a clutch pilot tool to center the clutch disc on the flywheel... tool is available locally and cheaply.

The transmission input shaft should have either 10 or 26 splines... verify your new clutch disc has the corresponding number.

A kit should contain a clutch friction disc, a pressure plate and a throwout bearing. BUT, one thing that I've never seen in a kit is a pilot bushing or pilot bearing. This is a small, rather inexpensive item that fits into rear of crankshaft... this pilot bushing supports the forward-most tip of transmission input shaft. They do wear out but are often overlooked when doing a clutch R&R. While trans is out, make sure your's gets a new one... available locally.

Also, be prepared to have your flywheel resurfaced at auto machine shop. It is possible the clutch disc's rivits might have scored the flywheel face and / or the face may've become overheated evidenced by blue spots on flywheel face and / or you may find galling or micro-cracks (visible w/naked eye) in swept area of flywheel face. All three conditions are common finds. Resurfacing flywheel is not so expensive... don't scrimp on this either.

Also, check the teeth on the flywheel's starter ring gear... if they're badly worn, now's the time to fix... on some flywheels the ring gear can be simply "flipped" while others require new ring gear. Neither solution is terribly expensive.

While trans is out for clutch R&R, that'll be good time to replace front and rear transmission seals... also available locally & inexpensively.

Also, check the clutch release fork for undue wear/cracks. Hope this helps. JACK:gap

 

[redmist]

Might as well tear down the engine too. Just kidding Jack.
In addition to Jack's comprehensive advice regarding the pilot bushing you need to decide on a roller bearing or oilite (bronze) version. There are arguements both ways. If you choose the roller be sure to install it the right way or the grease won't stay in. Also if you get a carbon(kevlar) based pressure plate you MUST have the flywheel resurfaced (according to the manufacturer). Also as Jack mentioned, replace the rear transmission seal and use thread sealant and gasket sealer as well when installing, also replace the shaft bushing. All cheap maintance which will eliminate (almost) leaks and yoke wear.

 

[Billy]

Slipping Clutch

Thanks for the response. It nice to have a place to get advice. The transmission rear seal will have to be replaced it is leaking along with the rear main seal in the engine. Everything else seems to be ok. I was planning to replace the pilot bearing also.

Thanks

Billy