Clutch Problems

[Leif A.]

Re: Clutch Problems

I received the new cross shaft along with new ball studs and installed. The pedal pushrod is not long enough to go thru the fitting for adjustment. It lacks about 1/4 inch of starting into the fitting (see picture). [ATTACH=CONFIG]107493[/ATTACH] Before the cross shaft broke I could adjust the clutch but just barely. All parts are correct for a 327 application (fork pushrod 10 9/16 inch, pedal pushrod 18 inches). The only part I cannot verify is clutch fork. I pulled the rubber boot and it is on the stud and seems ok. I even started the motor and pulled the fork by hand and observed it making contact with the pressure plate fingers and it was very smooth with no wobbling or any distortion I could see so I'm ruling out the clutch fork as being bad. What bothers me is I could adjust the clutch before and I want to rule out other damage I cannot see or am should be aware of checking for. I've ordered the 19 1/4 inch pedal pushrod and I think that will take care of the adjustment problem. I just don't want to overlook a problem that was caused by the cross shaft breaking last week. Any advice would be greatly appreciated.

This could be your "shortness" issue. The fork rod should be 9" and the pedal pushrod should be 19 1/4". If your fork rod is actually almost 10 9/16" you should be able to visualize how the geometry would push the z-bar further away from the pedal pushrod. You've ordered the correct pedal pushrod...now, order the correct fork rod and, I believe, your problems will be solved.
Again, I would recommend Doc Rebuild for your correct parts...Genuine GM NOS part.

https://shop.docrebuild.com/1964-1966Corvette327ClutchForkPushRodGenuineGM3844209NOS.aspx

[Bill B.]

Re: Clutch Problems

This could be your "shortness" issue. The fork rod should be 9" and the pedal pushrod should be 19 1/4". If your fork rod is actually almost 10 9/16" you should be able to visualize how the geometry would push the z-bar further away from the pedal pushrod. You've ordered the correct pedal pushrod...now, order the correct fork rod and, I believe, your problems will be solved.
Again, I would recommend Doc Rebuild for your correct parts...Genuine GM NOS part.


https://shop.docrebuild.com/1964-196...844209NOS.aspx

Thanks Leif. I saw your prior post after I had already ordered the cross shaft from another vendor. I'll order a new fork pushrod and along with the 19 1/4 inch pedal pushrod hopefully my problem will be solved. It just bothers me that before the cross shaft broke I could adjust and that was with the hardware I'm using now. I appreciate your input.

[Leif A.]

Re: Clutch Problems

Thanks Leif. I saw your prior post after I had already ordered the cross shaft from another vendor. I'll order a new fork pushrod and along with the 19 1/4 inch pedal pushrod hopefully my problem will be solved. It just bothers me that before the cross shaft broke I could adjust and that was with the hardware I'm using now. I appreciate your input.

The combined lengths of the rods you currently have (and, were using) and the combined length of the correct rods are almost identical. Your current rods are combined 28 9/16" in length, the correct rods combined are 28 1/4" in length. But, being the lengths being in the incorrect locations possibly put and inordinate stress on the z-bar and over time caused it to fracture. Just a hypothesis, but it could answer as to why the old combo worked...until it didn't.

[Bill B.]

Re: Clutch Problems

According to the info that I have the fork push rod should be 10 9/16 inches and the pedal pushrod 18 inches. Both rods are those lengths. Assuming the cross shaft I received today from a reputable vendor is correct the only thing left is the clutch fork which I can't get to since its installed and it's only getting removed as a last resort. I just don't want to miss something in my troubleshooting and that's why I'm asking for responses. I feel if everything is correct and I still can't adjust the clutch then the new pedal push rod I ordered today will fix the problem but it will still leave me wondering why and concerned the real problem will rear it's ugly head at the least opportune time. I've also thought of taking the 18 inch pedal push rod to a welding shop and have 2 inches added to it. I do appreciate your input and I thank you.

[Joe L.]

Re: Clutch Problems

According to the info that I have the fork push rod should be 10 9/16 inches and the pedal pushrod 18 inches. Both rods are those lengths. Assuming the cross shaft I received today from a reputable vendor is correct the only thing left is the clutch fork which I can't get to since its installed and it's only getting removed as a last resort. I just don't want to miss something in my troubleshooting and that's why I'm asking for responses. I feel if everything is correct and I still can't adjust the clutch then the new pedal push rod I ordered today will fix the problem but it will still leave me wondering why and concerned the real problem will rear it's ugly head at the least opportune time. I've also thought of taking the 18 inch pedal push rod to a welding shop and have 2 inches added to it. I do appreciate your input and I thank you.

Bill------


The pushrods and cross shaft were used as a SET and differed from early to late 1966 small block. Early used pedal pushrod which was GM #3819154 and 18" overall length, fork pushrod GM #3844209 which was 10-9/16" overall length, and cross shaft GM #3832857.

Later 1966 small block used pedal pushrod GM #3888213 which was 19-3/16" overall length, fork pushrod GM #3872960 which was 8-37/64" overall length, and cross shaft GM #3888279.

The angularity between the levers of the above-referenced cross shafts differs.

The parts sets I described above must be used together. They cannot be "mixed-and-matched".

[Bill B.]

Re: Clutch Problems

Bill------


The pushrods and cross shaft were used as a SET and differed from early to late 1966 small block. Early used pedal pushrod which was GM #3819154 and 19-3/16" overall length, fork pushrod GM #3844209 which was 10-9/16" overall length, and cross shaft GM #3832857.




Later 1966 small block used pedal pushrod GM #3888213 which was 19-3/16" overall length, fork pushrod GM #3872960 which was 8-37/64" overall length, and cross shaft GM #3888279.

The angularity between the levers of the above-referenced cross shafts differs.

The parts sets I described above must be used together. They cannot be "mixed-and-matched".

Joe..The part numbers you reference are on the car now, Pedal pushrod 3819154 and measures exactly 18 inches. Fork push rod 3844209 which measures 10 9/16 inches. Only thing I can't measure or confirm is clutch fork as it is installed. As far as I can tell I have all the correct parts. I may pull the cross shaft off and try to measure the angle between levers but I just received it today from Zip Corvette so it is probably correct. I just ordered the later pedal pushrod 3888213 that should work but then I'll have a mix and match as you say. I also think the 3888213 is a service replacement for my car.

[Joe L.]

Re: Clutch Problems

Joe..The part numbers you reference are on the car now, Pedal pushrod 3819154 and measures exactly 18 inches. Fork push rod 3844209 which measures 10 9/16 inches. Only thing I can't measure or confirm is clutch fork as it is installed. As far as I can tell I have all the correct parts. I may pull the cross shaft off and try to measure the angle between levers but I just received it today from Zip Corvette so it is probably correct. I just ordered the later pedal pushrod 3888213 that should work but then I'll have a mix and match as you say. I also think the 3888213 is a service replacement for my car.

Bill------


Yes, I erred when I said the 3819154 pushrod was 19-3/16". It should be 18" and I've corrected my post. So, if you have the 3819154 and the 3844209, then you must have the wrong cross shaft.

The 3888213 pedal pushrod was used in PRODUCTION for later 1966 Corvettes. But, it was used with the fork pushrod and cross shaft I previously described.

I don't see how you could have the wrong clutch fork. Your car may have originally used fork GM #3844493. However, the L1966-81 fork, GM #3887177, replaced it for SERVICE in February, 1967. So, the two forks should be functionally interchangeable.

[Frank D.]

Re: Clutch Problems

I don't want to detract from all the good advice, but check your clutch pedal for side-to-side movement while you're doing this other work. Seems like when some linkage or other issues evolves it takes more force to engage/disengage the clutch and the pedal can let go at the upper weld (they often do anyway).

https://youtu.be/8IpVWKceDiA

[Bill B.]

Re: Clutch Problems

I don't want to detract from all the good advice, but check your clutch pedal for side-to-side movement while you're doing this other work. Seems like when some linkage or other issues evolves it takes more force to engage/disengage the clutch and the pedal can let go at the upper weld (they often do anyway).

https://youtu.be/8IpVWKceDiA

I've already checked the pedal and it looks fine. However, I'll check it one more time.

[Bill B.]

Re: Clutch Problems

I just rechecked the side to side pedal play and I have roughly 1/4 inch side to side play. I'm not sure if that is acceptable but inspecting the upper weld it seems to be intact.

Bill B.