C2 Clutch Problems

**William G.** · August 23, 2019, 01:01 PM

Re: C2 Clutch Problems

Ok........ Turns out I should have read the archived posts! As I've not had any replies I'll read the archived items and hopefully find my answer. But to answer a potential responder with questions I'll add that this clutch was purchased from Paragon and I'm thinking it was manufactured in Korea. Probably not a good choice but I'd be surprised if Paragon would take it back. A response to an archived item I just read stated that the bearing should not be less than 1/32" short of 1 1/4". As I recall measuring it before the installation it would have trouble making 1 7/32" but then the pressure plate may not measure quite to specs either. Having said all that I still question that if tolerances are that fine how can a shop manual say that it could be possible to install a 1 7/8" bearing on a bent finger clutch? Also, if these clutches from Paragon might cause serious issues (like having to adjust the pedal rod to the point of the lower nut just about falling off the end and still have 2 1/2" free travel) how can Paragon continue to sell them? Guess simple economics come into play but that could lose them a lot of business. I sometimes wonder if people from these companies ever read this forum and if so what conclusions do they come to? I need to get back to the archived posts. I'll reply to my own post if I find an answer.......otherwise it is time to pull things apart--again! Thanks for any help.

**William G.** · August 23, 2019, 02:24 PM

Re: C2 Clutch Problems

Back again. I've read some archived C2 clutch posts and Timothy Bond did an excellent job with his. Looks like maybe the answer to my clutch difficulties lies in buying the most expensive/best clutch you can find (locally?) and get an iron clad return policy. However I need to supply additional details regarding this situation so that a potential responder has more background to go on. This clutch is being changed ONLY because a rebuilt engine has been installed. The old clutch worked fine: NO ISSUES. The pedal push rod with the old clutch was in the middle of the swivel travel and with the new clutch the adjustment is way at the VERY end of the pedal push rod and the free travel is 2 1/2"! Other than the three part clutch kit from Paragon the only other changes were to replace the bell housing with an identical GM item (part # ending in 8403)....the original bell hsg had numerous cracks (a LUCKY person could probably continue to use the original cracked item but my luck doesn't seem to run that well). We used the ball pivot for the fork fulcrum that came with the eBay bell housing as they looked the same (this might be a potential source of my problem but at this time it seems a little doubtful). These two are the only changes made other than the engine which is a '66 item with a cast number of "174" and the flywheel from the original engine (refaced!! as per Tim Bond, perhaps a problem but read again my earlier comment about putting a 1 7/8" throughout bearing with a bent finger diaphragm! That shop manual statement seems a little crazy) was used. Admittedly some of the linkage parts MIGHT not be original to the car but the fact remains that the clutch being replaced (with a New Departure throughout bearing....wonder if New Departure still makes that item?) worked FINE and the only parts replaced were the 8403 bell housing and the ball stud. The pedal push rod measures 19 1/4" and the clutch rod 9" with only about 1/2" between the eyes where the springs attach--I don't have a big block clutch rod to compare with. We've tried the fast clutch adjustment but my manual doesn't say whether (in addition to the bracket repositioning on pedal lever) to change the pedal push rod (under dash) attachment to the bracket. Changing the bracket attachment to the pedal lever resulted in no improvement to the 2 1/2" free travel situation. Any comments or help?

**Joe L.** · August 23, 2019, 04:00 PM

Re: C2 Clutch Problems

Originally posted by William Gast (13928)

Back again. I've read some archived C2 clutch posts and Timothy Bond did an excellent job with his. Looks like maybe the answer to my clutch difficulties lies in buying the most expensive/best clutch you can find (locally?) and get an iron clad return policy. However I need to supply additional details regarding this situation so that a potential responder has more background to go on. This clutch is being changed ONLY because a rebuilt engine has been installed. The old clutch worked fine: NO ISSUES. The pedal push rod with the old clutch was in the middle of the swivel travel and with the new clutch the adjustment is way at the VERY end of the pedal push rod and the free travel is 2 1/2"! Other than the three part clutch kit from Paragon the only other changes were to replace the bell housing with an identical GM item (part # ending in 8403)....the original bell hsg had numerous cracks (a LUCKY person could probably continue to use the original cracked item but my luck doesn't seem to run that well). We used the ball pivot for the fork fulcrum that came with the eBay bell housing as they looked the same (this might be a potential source of my problem but at this time it seems a little doubtful). These two are the only changes made other than the engine which is a '66 item with a cast number of "174" and the flywheel from the original engine (refaced!! as per Tim Bond, perhaps a problem but read again my earlier comment about putting a 1 7/8" throughout bearing with a bent finger diaphragm! That shop manual statement seems a little crazy) was used. Admittedly some of the linkage parts MIGHT not be original to the car but the fact remains that the clutch being replaced (with a New Departure throughout bearing....wonder if New Departure still makes that item?) worked FINE and the only parts replaced were the 8403 bell housing and the ball stud. The pedal push rod measures 19 1/4" and the clutch rod 9" with only about 1/2" between the eyes where the springs attach--I don't have a big block clutch rod to compare with. We've tried the fast clutch adjustment but my manual doesn't say whether (in addition to the bracket repositioning on pedal lever) to change the pedal push rod (under dash) attachment to the bracket. Changing the bracket attachment to the pedal lever resulted in no improvement to the 2 1/2" free travel situation. Any comments or help?

William------

First of all, a 1-7/8" clutch release bearing cannot be used with ANY Corvette clutch except early 1955. L-1955-1963 used a 1-1/4" bearing. 1964-1980 used a 1-7/32" bearing. 1981 used a 1-1/4" bearing. The 1-7/32" bearing was long ago discontinued and replaced by the 1-1/4" bearing for ALL L1955-81 Corvette SERVICE. I know of no current source for a 1-7/32" bearing.

If your clutch was working OK, you should have re-used it, replacing only the friction disc. I do not recommend re-surfacing a flywheel or pressure plate unless there is significant surface cracking. Even then, an absolute MINIMUM cut should be taken.

I do not know what make of clutch is supplied by Paragon. However, the LUK and Sach manufactured clutches are the closest thing to stock that is currently available. Many have used these without problems.

Your '403' bellhousing might not have had actual cracks. These bellhousings are a die casting and often have "casting marks" that look exactly like cracks, but are not. In any event, if you replaced with another '403', that should be fine.

Your pedal pushrod sounds of the correct length. The fork pushrod should be about 8-1/2" so you may have measured wrong. There is no 9" rod.

New Departure has not made a clutch release bearing at any time in this century.

**Edward D.** · August 23, 2019, 06:41 PM

Re: C2 Clutch Problems

Check the length of the clutch fork pivot stud. There are several available, the 1-1/2" long one should be used with the Sachs or LUKS clutch. The 1-3/8" (used from 66-75) will be too short and will result in the excessive pedal travel you are seeing. Both are good clutches, but I like the Sachs kit as it has a better throwout bearing. The LUKS kit bearing is half composite, flimsier IMHO. I think the Paragon supplied clutch is the Sachs but I'm really not sure as I have not ordered any of these from them.

**William G.** · August 23, 2019, 08:04 PM

Re: C2 Clutch Problems

Joe,
Well, the fact that New Departure Hasn't made a release bearing in the last 20 years is good to know........that's how "old" the clutch is then. At some time the former bearing must have "exploded" as the pressure plate and inside of the 8403 (hence the cracks) are pretty well dinged up ......so......the pressure plate must be older than that. But then maybe someone was able to locate the New Departure bearing gathering dust on some shelf. I'm holding the New Departure bearing in my hand and it is stamped "OT-24K". The O could be a C or a Q. The New Departure Bearing is 1 1/4" thick and it looks more substantial the the new replacement which is now in the car and non-operational. Yes, the bell housing is cracked but could be welded.......at some cost, though. So if Paragon says that their clutch is a Sachs it is OK to use? If it is Sachs then my problem lies elsewhere.........perhaps the pivot stud is the incorrect length. But the one in this 1966 certainly appears to measure 1 1/2" WITH the "nut" that holds it which may not be the way to measure it. And you say in 1966 the factory changed to the ! 3/8" length. Please tell me how to measure the pivot stud. It doesn't appear to me that it couldn't measure 1 1/2" or even 1 3/8" without the "nut" (because of the allen wrench depression). Also, someone in an earlier post (archived) said that the cross shaft levers should be displaced 135 degrees from each other. Mine seems to be closer to 150 degrees. But again, the old clutch worked fine. Perhaps I need to find a good release bearing and go with the "old" parts. The bearing shows a little wear and is a TAD bit rough. More help is needed, please........summer is waning! Oh, before I go and cut myself off short, the old clutch disc measures .300" and the pressure plate from the face (against the disc) to the ends of the bent fingers 2 1/4". Opinions on those dimensions? Thanks for any help.
Bill

**Joe L.** · August 24, 2019, 12:55 PM

Re: C2 Clutch Problems

Originally posted by William Gast (13928)

Joe,
Well, the fact that New Departure Hasn't made a release bearing in the last 20 years is good to know........that's how "old" the clutch is then. At some time the former bearing must have "exploded" as the pressure plate and inside of the 8403 (hence the cracks) are pretty well dinged up ......so......the pressure plate must be older than that. But then maybe someone was able to locate the New Departure bearing gathering dust on some shelf. I'm holding the New Departure bearing in my hand and it is stamped "OT-24K". The O could be a C or a Q. The New Departure Bearing is 1 1/4" thick and it looks more substantial the the new replacement which is now in the car and non-operational. Yes, the bell housing is cracked but could be welded.......at some cost, though. So if Paragon says that their clutch is a Sachs it is OK to use? If it is Sachs then my problem lies elsewhere.........perhaps the pivot stud is the incorrect length. But the one in this 1966 certainly appears to measure 1 1/2" WITH the "nut" that holds it which may not be the way to measure it. And you say in 1966 the factory changed to the ! 3/8" length. Please tell me how to measure the pivot stud. It doesn't appear to me that it couldn't measure 1 1/2" or even 1 3/8" without the "nut" (because of the allen wrench depression). Also, someone in an earlier post (archived) said that the cross shaft levers should be displaced 135 degrees from each other. Mine seems to be closer to 150 degrees. But again, the old clutch worked fine. Perhaps I need to find a good release bearing and go with the "old" parts. The bearing shows a little wear and is a TAD bit rough. More help is needed, please........summer is waning! Oh, before I go and cut myself off short, the old clutch disc measures .300" and the pressure plate from the face (against the disc) to the ends of the bent fingers 2 1/4". Opinions on those dimensions? Thanks for any help.
Bill

Bill-------

First of all, if the clutch worked and adjusted properly before you replaced the clutch assembly and you did not replace any components of the actuating linkage, then your adjustment problem could have nothing to do with the clutch actuating linkage. So, that can be ruled out of the "problem equation".

The ball stud is measured from end-to-end. Your original ball stud was 1-3/8". This was discontinued from SERVICE 23 years ago and replaced by the 1-1/2" ball stud. I know of no source for the 1-3/8" stud and I would not use one, anyway. I believe that the 1-3/8" stud was an "experiment" by GM to help solve some of the "finicky" Corvette actuating system adjustment problems. After about 10 model years they finally admitted that the "experiment" failed and they went back to the 1-1/2" stud for L1975-81 as had been used from 1955-65. I recommend using the 1-1/2" stud for your application. In fact, if what you had found installed was the 1-1/2" stud and your clutch worked and adjusted properly before the replacement then, once again, you know the 1-1/2" stud works fine.

The same thing is true of the release bearing. The 1-1/4" release bearing was used for Corvette clutches from L1955-63. Then, I believe as an "experiment" to help solve the "finicky" Corvette clutch adjustment, they went to a special 1-7/32" bearing. That "experiment" lasted a lot longer but they finally gave up on it and went back to the 1-1/4" bearing. I know of no source for the 1-7/32" bearing and I would not use it, anyway. I recommend the 1-1/4" bearing.

The cross shaft levers for a 1966 Corvette small block cross shaft should be about 135 degrees apart. 1966 big block and all later were about 155 degrees apart. Once again, though, if your clutch worked and adjusted OK before the clutch replacement, then your cross shaft is not a problem, whatever it is.

As far as release bearings go, the old New Departure-Hyatt bearings were discontinued in September, 2000. The Delco part number was CT-24. Yours apparently is suffix K. There were many iterations of the CT-24 bearing over the years with different suffix codes. I don't know when the "K" code was produced.

The current version of the CT-24 bearing is CT-24KVAL. It is also known as GM #19245400. This is an OEM quality bearing and GM lists for about 85 bucks but you can get one from a Delco dealer for about 50 bucks, or less. This is an all metal bearing. However, it's made in China. If you think Chinese made parts are bad, then don't buy a new car because there will be a huge number of China-sourced parts. These, and the 19245400 bearing, are sourced from Tier 1 Chinese suppliers. Many aftermarket Chinese sourced parts come from Tier 2 or lower suppliers. You can also obtain an aftermarket quality bearing from AC Delco. It's GM #19312070. About 30 bucks from Delco dealers. It's all metal, too. Your choice.

I can't comment on the clutch disc thickness since I do not know the specs on the original disc.

One thing I can tell you, though: a 1963-81 Corvette clutch adjustment can be very "finicky". One often ends up with too little free play when complete clutch disengagement occurs at full pedal travel OR within spec free play but no full disengagement at full pedal travel. All of the system components have to be just right and as close to the original specs. This is why, among other things, I do not recommend surfacing of flywheels or pressure plates. That alone can throw the whole thing enough out of spec to cause adjustment problems.

Why do you suppose I obtained a 500 year supply of original GM pressure plates, clutch discs, flywheels, and release bearings [none for sale] before they were long ago discontinued? It's because from my own experience I mightily fear just the problem you've encountered. Even with all original components satisfactory adjustment can be daunting. I cringe at the thought of adding aftermarket parts to the mix.

**William G.** · August 30, 2019, 09:15 PM

Re: C2 Clutch Problems

Joe,

Thanks for the very detailed information on this topic. I can now appreciate the issue and it is satisfying to learn that I am not alone in having adjustment problems with 50 year old parts, including the flywheel. I have the free travel adjusted way to the end of the push rod and about 1 1/2" plus a little (maybe) free travel and hope to have the car running in a day or two. Joe, your dedication to helping others with their issues is most appreciated and, although you are not alone in giving freely of your time, commendations are still due you for all the great information. Thanks again. The hobby would suffer GREATLY were it not for you and others with the same helpful attitude.

Bill

C2 Clutch Problems

C2 Clutch Problems

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Debug Information