jpattt24

71 vette 5-speed tremec. 621 gm bell housing . all new super street mcleod clutch, pressure plate and release bearing. new fly wheel. new gm clutch fork, stock corvette clutch fork ball stud. new z-bar and both clutch rods. my ? is my release bearing touches the clutch fingers before the fork meets the ball stud. if I adjust the release bearing so its not hitting the clutch fingers the fork is a 1/4" from the ball stud and I have half a clutch pedal. if I adjust the release bearing tight to the clutch fingers the pedal is up where it should be. and the clutch fork is seated to the ball stud. the clutch will work like this but the release bearing is spinng at all times. and not good for it. I think I need a longer or adjustable clutch fork ball stud so it meets the fork correctly ? any imput on this would be appreciated. thanks jp

drwet

drwet

Above is some of the information I used when I set mine up. There is no shortage of ways to get the geometry wrong. Most common mistake is to get the wrong release bearing. GM made several different lengths. Then there is the possibility of the wrong clutch fork and/or pivot ball. Hope this helps.

lars

A couple of facts:

1. Chevrolet has used only two sizes of throwout bearings for decades - 1-7/8" for passenger cars and trucks (flat-finger clutches), and 1-1/4" for Corvettes (bent-finger clutches).
2. The ONLY clutch fork ball stud that's "correct" is GM #3729000, 1-1/2" long. The other one which you will sometimes see, GM #3887159, 1-3/8" long, was released in error for '66, and after hundreds of field failure reports, was cancelled and replaced in production by the good old #3729000 stud on April 4, 1966, which remained in production through the mid-80's. Check and verify that you have the correct length ball stud.

If you have the correct ball stud, be aware that aftermarket pressure plates (or machined/surfaced flywheels) will often require the use of a ball stud that's about 1/8" longer that the stock ball. We install the Lakewood adjustable ball (part number 15501) on almost every clutch job we do to assure proper geometry. If you set the adjustable ball up to produce a ball height 1/8" taller than the stock ball, you will usually be in good shape.

Lars

jpattt24

thanks for the reply. what can cause this to be off so much ? fly wheel deck height ? do you think this fix will clean up some of the knotchy shift feel I get. or make the clutch disengage better ? thanks jp

lars

See also my post about this issue here:
https://www.corvetteforum.com/forums...vel-range.html
and info added in my revised post above.
Lars

Sky65

I used a McLeod Super Street clutch in my 65 SB and also had some trouble getting it set up right. I am also using a GM L88 flywheel to be accurate. My pressure plate has flat fingers. I ended up with an adjustable ball stud and used an intermediate length release bearing. It is a Hayes 70-104. The short bearing was a little too short and the long bearing was way too long. The clutch works great. Plenty of adjustment range in the clutch linkage, smooth operation and great holding power.

Tom

jpattt24

thanks for the reply. am I thinking in the right direction ? you use the adjustable ball to get 4.75 " between the ball stud and the face of the bellhousing presuming the flywheel deck height is around 0.960" ? and the extra height in the release bearing to get the correct angle on the clutch fork and good pedal height ?

ddawson

I used this Super street Pro that came with a bearing
https://www.summitracing.com/parts/mcl-75224

And the Mcleod racing Steel flywheel, stock fork and ball stud.

No issues with this.

jpattt24

yes that's the same clutch kit I have. but I bought a cheap flywheel from summit. and I think that's where I am coming up short. when I get the trans out im going to check all my measurements and get it right this time I hope.

Sky65

I did not work to those dimensions. I didn't know them. I made up this tool to serve as my transmission so I could see what was happening and make adjustments without lifting the trans in and out. The tool was made with hand tools so it is pretty basic and I was working on jack stands in my garage. No lift. I did it this way because many of the parts are not stock.

SB engine, stock bell housing, L88 light flywheel, McLeod 10.5 clutch, Richmond non-OD 5spd trans.I installed the clutch pressure plate, disc, release bearing and fork, and adjustable ball stud and installed the bell housing to the engine. I removed the trans front bearing support and installed it on the tool. Installed and adjustable ball stud on the tool and bolted the tool to the bell housing and hooked up the clutch linkage. I now had a working clutch.The forward motion of the release bearing stops of course when it contacts the fingers of the pressure plate. The rearward motion stops when the bearing hits the base of the trans bearing support. The release bearing supplied with my clutch kit was so long it contacted the pressure plate fingers and the bearing support at the same time. Obviously too long. The stock short bearing seemed to leave allot of lost motion when operating the clutch fork. The intermediate length bearing seem to fit best. Next I set the ball stud length to put the fork at a slightly forward angle at rest and a similar angle rearward with the clutch pedal fully depressed with ~ 1" of top free play. Sounds complicated to read my process but it really wasn't and the clutch works great!



The 4 bolts in the center are to bolt the trans bearing support on. The 4 bolts at the bottom are stored there.They fit through the outer 4 holes to bolt the plate to the bell housing. The other holes is for access to the adjust the adjustable ball stud.

If you want to borrow the tool I'll send to you. May be more than what you need.
Tom

jpattt24

lars

I posted all the facts about this in my post #4 above.
Lars