Clutch

[Robert G.]

Hi all,
I have a '66 L79 and my throw out bearing is just beginning to "whistle" for a short time after I start the car, so it's time to replace the clutch system. Clutch, pressure plate and throw out bearing, I see from all the Corvette suppliers there are two clutches, one with a 10.4 in diameter and the other with an 11 inch diameter. Question, how do I tell which one is for my car?
I don't want to take it apart and then order, but would rather replace it right away.
Thanks for Your Help,
Rob Goodrich

[Joe L.]

Re: Clutch

Hi all,
I have a '66 L79 and my throw out bearing is just beginning to "whistle" for a short time after I start the car, so it's time to replace the clutch system. Clutch, pressure plate and throw out bearing, I see from all the Corvette suppliers there are two clutches, one with a 10.4 in diameter and the other with an 11 inch diameter. Question, how do I tell which one is for my car?
I don't want to take it apart and then order, but would rather replace it right away.
Thanks for Your Help,
Rob Goodrich

Rob-------

All 1963-68 Corvette small blocks were originally equipped with a 12-3/4" flywheel and 10.4" clutch. You can help to confirm that before you even disassemble the clutch system. Just look at the casting number on the bellhousing. If it's 3840383 or 3858403 that will pretty much confirm you have the original clutch configuration.

[Robert G.]

Re: Clutch

Rob-------

All 1963-68 Corvette small blocks were originally equipped with a 12-3/4" flywheel and 10.4" clutch. You can help to confirm that before you even disassemble the clutch system. Just look at the casting number on the bellhousing. If it's 3840383 or 3858403 that will pretty much confirm you have the original clutch configuration.

Joe, thank you!

[Edward J.]

Re: Clutch

Bob, becareful when using the pilot bearing, some of the clutch kit come with a sindered Iron bearing, which are prone to noise. i believe that the National make a bronze bearing. If you take a magnet and the pilot bearing is magnetic, throw it away.

[Robert G.]

Re: Clutch

Joe,
I just jacked up my car, put it on jack stands, crawled underneath it and saw no casting or parts number on the underside of the bell housing. I looked as far up on both sides and still nothing.
Somebody mentioned something about the starter bolts, they are staggered with the outside bolt much higher up than the inside bolt.
Did I miss that casting number or would it be on the top side?
Thanks for Your Help,
Rob\
robgoodrich49@gmail.com

[Joe L.]

Re: Clutch

Joe,
I just jacked up my car, put it on jack stands, crawled underneath it and saw no casting or parts number on the underside of the bell housing. I looked as far up on both sides and still nothing.
Somebody mentioned something about the starter bolts, they are staggered with the outside bolt much higher up than the inside bolt.
Did I miss that casting number or would it be on the top side?
Thanks for Your Help,
Rob\
robgoodrich49@gmail.com

Rob------


I've never seen one without a casting number, usually very prominent. However, your description of the starter bolt configuration also confirms the 12-3/4"flywheel/10.4" clutch configuration.

[Tom D.]

Re: Clutch

As in Paragon or other:
Simply find a parts catalog with photos of the metal dust cover (covers the bottom 1/3 of the "front" of the bell housing, behind the oil pan).

Note the shape of the small block (and '65 396) version where the starter hole is, then look at yours. There is a round hole for the starter on 427 11" clutch set ups. In this metal shield, the hole for the starter is not a round hole when you have the smaller clutch.

[Tom D.]

Re: Clutch

https://corvetteparts.com/item/cover-10-5-amp-quot-flywheel-inspection-327-engine-1966-1968?gclid=CjwKCAiA8ejuBRAaEiwAn-iJ3nSYRoHZlHfYorXoq1dJNFVInCq0an6zT8hyEgqF4eWq-bVyMrSiiRoC-KsQAvD_BwE

Or, click this ad for a photo.

[Joe L.]

Re: Clutch

https://corvetteparts.com/item/cover...RoC-KsQAvD_BwE

Or, click this ad for a photo.

Tom------


Not related to the issue here, but note the little "tangs" on either side of the crankshaft flange cutaway. Those are designed to clip onto the oil pan rear flange in order to prevent contact of the crankshaft flange with the cover. They are excellent to have this feature and I HIGHLY recommend it. However, original 1963-68 covers, GM #3788422, did not have this feature. The cover pictured in the ad is actually a GM #354497 which replaced the former for SERVICE and was never actually used in PRODUCTION for any Corvette.

I should have mentioned that some SERVICE examples of the 3788422 cover do have the tabs. However, I think these were added via a change in the specifications for the part number after the cover was no longer being used in PRODUCTION.

[Duke W.]

Re: Clutch

Hi all,
I have a '66 L79 and my throw out bearing is just beginning to "whistle" for a short time after I start the car, so it's time to replace the clutch system.
Rob Goodrich

It's common for guys to confuse a clutch release bearing problem with a front transmission bearing. When the clutch pedal is "up" the clutch release bearing is under no load, and any unusual noise is often the front transmission bearing, which can make a "growling" sound if it's beginning to spall. Push in the clutch pedal, and it goes away.

If you hear an unusual noise with the clutch pedal to the floor, then there may be a problem with clutch release bearing or the pilot bushing.

If you only hear this "whistle" noise for a short time after engine start and not at any other time I don't see the logic of connecting it to the clutch system.

Duke

[Robert G.]

Re: Clutch

Thanks Duke, I might hold off and see if it gets any worse. It's put away for the winter now, so I'll see in the spring.
Rob