Help: Clutch not fully disengaging

[Pranav]

I'm baffled by this one on my LT1 t56 car.

Replaced the motor.

Flywheel, PP, clutch disk, throwout bearing, clutch fork, and trans were all 100% OK and untouched when I swapped the motor, didn't even resurface the flywheel. I put the engine/trans package together on the garage floor and put it all in the car, noticed the pedal was stiff but still had full travel.

The clutch fork just sits loose in there (after clipping it on to the TO bearing) but tightens up once I get the slave cylinder bolted in place. On stands I cannot easily get the car into gear, and once I do with the clutch all the way in, the driveshaft/wheels spin. I notice if I take the big aluminum clutch slave/fork cover/spacer/block out from between the slave and the bellhousing and simply tighten the slave cylinder down further, I get full engagement.

I did also go ahead and pull the trans and took the clutch/pp/to apart and put it back together again, it is all torqued on straight. I've tried bleeding the slave/master multiple times, might try swap the pair out with a spare that I have on hand to see if that does anything. Driveline is also not making any funny noises...

Do I just need to find a longer clutch rod? I've also heard of removing the pivot T bolt and shortening it as being a solution. Not thrilled about pulling the trans a 2nd time but I gotta do what I gotta do. Thoughts? Any of you LT1 guys run into this on clutch swaps?

[GlennCMC70]

Call me.

[AllZWay]

Bleed the clutch/master cylinder. Take the slave loose at the transmission. Open the cap on your resevoir and from under the car....by hand push the rod in and out several times with the slave raised as high up next to the transmission as possible. I usually push the rod against one of the lips on the side of the transmission.

[Pranav]

Glenn I'll call you when I get back home and with the car, you around 4pm?

James thanks, I was pushing the rod against the ground downwards to try bleed it, will try that.

Before I left for work I took a quick look, turns out the existing slave cylinder stops about 1/4" short at the end, when compared to a new spare I have on hand. Coincidentally the entire problem appears to be me lacking that last 1/4" of travel.

The clutch fork, however, is suspect, just feels loose as hell when I clip it in.

[AllZWay]

The clutch fork, however, is suspect, just feels loose as hell when I clip it in.

Are you sure you have it pushed back up in place within the pressure plate? It will have a little slack, but not much.

[Pranav]

Yeah, its in the big collar that surrounds the throwout bearing. When I leave the big block/cover out and put the cylinder into position, I had someone else step on the clutch and could see the TO bearing pulling the PP back, just not all the way.

[Casey_SS]

Is the fork contacting the pressure plate?

[Pranav]

The backside of the fork against the PP shell? No.

Headed home in a little bit to swap out the cylinders.

[y5e06]

Are you sure you have it pushed back up in place within the pressure plate? It will have a little slack, but not much.


I suspect a similar issue. the arm doesn't actually 'clip' or 'detent onto the TB instead that felt detent is the retaining bolt w/ that partially rounded bar and a spring clip on the arm. I suspect you just didn't push the arm far enough to clip it into place. so although the arm is pushing against the flange of the TB you aren't leveraging the TB far enough w/ the change in fulcrum location.

[Casey_SS]

Reference point - the LT4 pressure plate has a notch on the T/O bearing which needs to be facing down to fully engage the fork. The LT1 pressure plate does not have the notched T/O bearing - fork should go all the way on no matter what position it's in.

[Pranav]

Yeah my TO isn't notched, looks like I have the right TO bearing.

Glenn brought up a good point that I had thought of but dismissed earlier: the pilot bushing needed breaking in.

I set the rear wheels back down on the ground, started it up in neutral and could not get it into gear for the life of me. Shut it off and put it in 1st, started it back up and the engine bogged like hell, had trouble getting it out of first. Started it it in neutral again and shoved it into first, engine bogged some more then cleared up after a few seconds.

Now with the wheels on the ground I am able to get in/out of all the gears easily. It still spins the driveshaft a little in neutral while up on stands, but I am still able to get in/out of gear easily. Looks like the fork/slave/TO movement was all fine, just needed to "break in" that new pilot bushing!

I'll report back if I have any issues on the first test drive, need to re-mount my rad and hook the brakes back up before I do...

[Pranav]

Not sure if my previous, perceived issues were related, but I broke something in the clutch during R4 yesterday. Sounds like the clutch pivot broke, will find out when I pull the trans tonight or tomorrow...

[Pranav]

Not sure if my previous, perceived issues were related, but I broke something in the clutch during R4 yesterday. Sounds like the clutch pivot broke, will find out when I pull the trans tonight or tomorrow...

Clutch fork and TO bearing were fine. When I pulled the trans I noticed the PP fingers where crooked causing the TO bearing to sit crooked. As soon as I unbolted the PP, the clutch disc and the pilot bushing fell out. Clutch disc springs were intact, but there was a chunk of friction material missing from the PP side.

Attached are pics, I'm not sure what caused what to fail. Hoping the pilot bushing is worn out and not the big hole in the crank...

1315
1316
1317

[Al Fernandez]

Last time I bought a clutch the TO bearing wasnt seated right on all of the PP fingers...glad I noticed before I installed it. Maybe yours was the same.