When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
During operational check of everything on my 65 project car I ran into a problem with the clutch not working properly.
I checked the shifter adjustment today and its spot on correct. I re-adjusted the clutch linkage and while the pedal doesn’t feel like I think it should I do feel its close enough that it should work.
Engine Running - Transmission will not go into any gear with engine running. Reverse grinds and cannot move shifter into 1-4 position (no grinding just won’t move)
Engine not Running - Can shift into gears 1-4 and R
I can put transmission in 1st gear, press in the clutch, start engine and with a little RPM I can ever so slightly feel the car wanting to move forward. So this tells me I am not getting full release of the clutch with the pedal.
Attached are some pictures, does anyone see anything out of the ordinary? The only questionable non 427 part is the 327/300HP, Clutch Cross Shaft (Z-Bar).
Did you change out the T/O bearing? If so, did you get the correct one? Chevy made two of them, one for passenger cars and one for the Corvette. I installed the wrong one in my 68 and could only get it to shift by adjusting the clutch linkage at its limits. It would still grind when it got hot. I ended up pulling the tranny and replaced the bearing, all is good now. Jerry
As JohnZ stated “There is only a very slight difference in the angular relationship between the upper and lower levers on the BB and SB cross-shafts” 135 deg (small block) VS. 155 deg (big block) arm separation so I just can’t see this being the problem.
Jack – I did install a new pilot bushing
Jerry – The T/O bearing is also new and came with the LUK clutch kit. I have been doing this a lot of years and never heard of a T/O bearing being unique to a Corvette??? I have heard of short and long T/O bearings but that would not apply here.
Mike – I adjusted the clutch push rod all the way to it limits (end of threads) and while the pedal does feel better it had no effect on the problem at hand.
I was just out in the garage playing with this and am pretty confident that the clutch is not fully releasing. It’s not your typical stuck clutch problem where you put it in gear and car moved forward while cranking with the clutch in.
Rad Azz for sure. Not sure what’s left to do at this point other than pull the transmission and see what’s going on with the clutch setup. Pulling a transmission on jack stands has got to be the most miserable job to do on a C2 Corvette.
Jerry – The T/O bearing is also new and came with the LUK clutch kit. I have been doing this a lot of years and never heard of a T/O bearing being unique to a Corvette??? I have heard of short and long T/O bearings but that would not apply here.
Sorry, it does apply here. Corvettes (which use "bent-finger" diaphragm clutches) use a "short" 1-1/4"-long throwout bearing, but passenger cars and trucks (which use "flat-finger" diaphragm clutches) use a "long" 1-7/8" throwout bearing. If you use a "long" throwout bearing in a Corvette, it can have the same symptoms you describe.
Mike – I adjusted the clutch push rod all the way to it limits (end of threads) and while the pedal does feel better it had no effect on the problem at hand.
This is condfusing. It feels better but it had no effect on the problem? Is "feels better" the same as functionally "works better"?
You haven't mentioned your free play. What is it? If you have "some" free play and the clutch won't release you may have other problems.
My suggestion was simply going by the adjustment in your picture.
Measure all your clutch rods...upper and lower to make sure they are matching what is called for your your car/application...according to JohnZ's post..
"'63-'65 used used the "short" (18") pedal pushrod and the "long" (10-9/16") fork pushrod. '66-'67 used the "long" pedal pushrod (19-1/4") and the "short" (8-9/16") fork pushrod.
"
If you mixed up some lengths of rods it will cause some issues/problems
Sorry, it does apply here. Corvettes (which use "bent-finger" diaphragm clutches) use a "short" 1-1/4"-long throwout bearing, but passenger cars and trucks (which use "flat-finger" diaphragm clutches) use a "long" 1-7/8" throwout bearing. If you use a "long" throwout bearing in a Corvette, it can have the same symptoms you describe.
If I have a long throw out bearing in this car than LUK miss packaged the clutch kit. I installed what was in the kit.
This is condfusing. It feels better but it had no effect on the problem? Is "feels better" the same as functionally "works better"?
You haven't mentioned your free play. What is it? If you have "some" free play and the clutch won't release you may have other problems.
My suggestion was simply going by the adjustment in your picture.
Feels better just means stiffer due to the clutch push rod being adjusted all the way out. I have tried adjusting with free play, without free play doesn't make any difference.
Measure all your clutch rods...upper and lower to make sure they are matching what is called for your your car/application...according to JohnZ's post..
"'63-'65 used used the "short" (18") pedal pushrod and the "long" (10-9/16") fork pushrod. '66-'67 used the "long" pedal pushrod (19-1/4") and the "short" (8-9/16") fork pushrod.
"
If you mixed up some lengths of rods it will cause some issues/problems
I bought new 427 clutch push rod and clutch fork rod from LICS. I have the 327 setup that came out of the car setting on a shelf in the garage. But I will remove all the clutch linkage and re-measure everything.
1965-1966E BIG-BLOCK:
3872962 Cross-shaft - 155 deg arm separation, 4.65” and 4.0” hole centers
Do you know what ball stud you have installed in the bell housing? With the clutch engaged (pedal at rest) is the fork reasonably close to the front of the opening in the bell housing?
Do you know what ball stud you have installed in the bell housing? With the clutch engaged (pedal at rest) is the fork reasonably close to the front of the opening in the bell housing?
Dan, the ball stud I'm assuming is OEM stock as is the bell housing. It's all original to the car.
With the pedal at rest the clutch fork is pretty much at the most forward edge of the clutch fork opening. I would have to measure to be sure of the actual position.
08-09-2015, 02:26 PM
Having problems with clutch releasing
