Inliners International Forums General Discussion Drive Train New Clutch Not Disengaging

I just put a new Centerforce 2 clutch behind my fresh 292 in a '68 Chevy C/10. The clutch doesn't disengage the trans from the engine. It won't shift right. I use the same geometry as the old stock clutch linkage. Some components were replaced but the original dimensions were preserved. A machinist suggested a taller bellhousing pivot ball -- but I'd still need to pull the SM465 4-speed to get at this piece w/a 3/8" allen key.
Could I have the wrong Throw-out bearing? I'm using the shorter one. I thought that was correct.
We had a similar problem when we put a Centerforce 2 clutch behind a V8 350 in my '71 GMC 4x4, a few years back. We wound up adding about 5" to the clutch push rod (lower) and joggling the ears of the Z-bar to clear hedders.
Anyone else had similar problems?

Hope much play in the pedal do you have before It touchs the pressure plate fingers? But I think?? if i remember my diaphram clutchs took the Long bearing and the long style/ borg beck clutchs take the short bearing?? I'd have to go dig them out to see for sure. I mit be thinking this backwards?? DID you call centerforce.?? Lakewood also Sells a adjustable pivit ball. hope this helps }[oooooo]

There is zero play. The clutch pedal goes all the way to the firewall w/o disengaging the clutch. I did buy the adjustable pivot ball at the hot rod shop. Some shortcut! The tranny has to come out to change it too. I'll only use it as a last resort. The OEM pivot ball is bombproof, the hotrod shop goodie is kinda wimpy.
I did get the thick throw-out bearing at Napa. Maybe that's the magic bullet. The Centerforce has the fingers type. And little counterweights that are supposed to fly out with centrifugal force and make the clutch stick better.
My machinist asked me if I'd installed the friction disc backwards. !?!!
Haven't talked to Centerforce yet. With the last truck they insisted their proprietary throw-out bearing was superior to sliced bread. I held it up side by side to an AC Delco and they were identical. Same mill marks and factory numbers.
Dropping the tranny is a problem because I don't have enough altitude from my jackstands to get a tranny dolly under there.
Back at it tomorrow.

originally posted by '68OrangeSunshine:
My machinist asked me if I'd installed the friction disc backwards. !?!!

If you go to this Team Chevelle Transmission Tech Forum and search for "clutch plate" you'll find a lot of things that can go wrong!
http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=search;search_forum=28

The likely ones are:
1)The disc has to go in with raised portion of hub facing away from flywheel.
(what the machinist is getting at)
2) Linkage not right/ no free play.
3) Disc is stuck to flywheel.
Of course there's more! : )

I'm hoping it's just the throwout bearing. I got a long one and we'll try that tomorrow. Interesting thread about the coating on the friction disc. I did not know that. I'll look for that too.

It's the pressure plate is what they meant came coated.
You'd want to clean with a non-oily cleaner like brake cleaner.
I'd clean the flywheel, pressure plate, and the disc at this point.

Well it hit 106 or 109 today and it's still humid from the recent monsoon rains. At MCAS Yuma -- where I built my last engine many years ago -- they flew the blackball flag from the control tower under these atomspheric criteria and all flight line work stopped. So I'm not surprised when my good buddy called to tell me his landlady was on his back to cut up a fallen tree in his backyard and he couldn't come out to my shaded carport to pull an sm 465 on the day shift... So I'm kinda stuck until I can wrangle a new crew for an XMSN extraction.

I think Twisted6 had your answer, somewhat, regarding pedal play. I believe what he was asking was how much play to you have in the clutch pedal at the top, not at the bottom.

There should be some play at the top of the clutch pedal when you initially press the clutch pedal in. There should not be immediately disengagement. There should be some freeplay travel - perhaps 2 or 3 inches, as I have with mine.

With your vehicle off make sure you can press the pedal with your hand and get some travel before you encounter some resistance. If not then an adjustment is necessary so that you do not prematurely wear your clutch. That's the first thing to do.

Second thing is to check the fork travel distance. Bending the fork may solve your problem, if it's one of the later thin metal forks. If it's the older cast iron type fork then all bets are off.

The newer throw-out bearings are "taller" than the older OEM style. So you won't get as much travel if you use your original clutch fork. You have to compensate for this by either finding a newer fork or making mods to your old one.

One or more of these has to be what's causing your problem, assuming no parts are defective.

-magic mike-

Mike- It's the cast iron fork. They're all identical. No way to modify them. My buddy and I will take a stab at it tomorrow.

The symptoms of a clutch disc installed backwards are:

1) Gears won't engage with engine running
2) Shut down & engage 1st, restart, release clutch, everything immediately locks up and you stall.

If the truck moves, it's probably something else.

Putting one in backwards is not that difficult when you're on your back looking up. It came very easy to me.

Well -- we swapped the slim throw-out bearing for a fat one and all of a sudden I could shift. Then, while up on jackstands I ran thru the gears, all nominal. Finally we decided to run a test- and- check around the block and see how well it ran. . . .
I got 6 feet in reverse and it popped. Something was not clutching any more. Best guess is the cast iron clutch fork popped off the pivot ball. I have a Mr. Gasket adjustable pivot but it looks kinda sketchy, except it has a flat backsurface which might trap the clutch fork retaining clip better.
Lots of foot pressure need to activate clutch before it went out. Twice what would be necessary. Can't get back to project til end of next week due to work committments.

A couple of ideas...

Disconnect the clutch rod and give the fork a hard pull to be sure the ball is in the divot on the fork. Be sure the rod is pushing strait into the fork... not causing the fork to bind up or pop off the ball.

Clyde

Pulled the Centerforce pressure plate and took it back to the hot rod shop. They sent it back to mfr's Prescott plant. Word is, it was bent, and Centerforce is sending me a new pressure plate.
Now how could a pressure plate get bent? Factory defect? It was installed according to directions. I know at one point my machinist tack-welded a small counterweight on it. He said it was out of balance. Supposedly these things are factory balanced, though. Makes me wonder if it wasn't already bent new-in-the-box?

With a new pressure plate from Centerforce, and a very long throwout bearing, the truck will shift real good. [As luck would have it, the original old T/O bearing finally popped out of the woodwork and we were able to match the part numbers with a new one.]So I'm back on the road as soon as I solve a few carburation issues and pass emissions.