85 Corvette 4+3 clutch question

[Dan Barlow]

Last winter I took the engine and trans out and replaced the engine and put it all back in . All the clutch stuff looked fine and the disc itself still looks good on both sides but the pressure plate and the flywheel have heat spots on them . I will also add that all the hydraulics were new before the engine got mortally wounded . I'm assuming something is causing the disc to slip . We have bought already a new clutch kit ,(isc - pressure plate - throw out bearing ) , but it worries me to put all this in not unknowing what caused it . I'd hate to have to go in a 3rd time . Here's pics off both sides of the disc and the pressure plate surface as well as the flywheel surface . Any ideas ?

[Dan Barlow]

[Loren]

Wow that's as fried as I've ever seen. Unless it's been driven abnormally, something must be preventing full engagement and allowing slip. When the pressure plate is bolted on is the last fraction of an inch or so compressing it as it should? Is there a possibility some incorrect part or fitment is not letting the throwout bearing all the way off? (I personally never trust a hydraulic clutch.) While driving, especially in a higher gear like fourth, surely it would have been noticeable, you'd see the tach running up a bit then back down when giving it some gas then backing off.

Once I put 2.73 gears for highway driving in my BBC El Camino but still used it for towing, I did smoke a clutch or two doing things like having to back a loaded trailer up a steep driveway in a pinch, which would qualify as abnormal driving, but I don't think it got that bad.

Weird fact: You probably know that 15lb 10.5" flywheel is the same as used in L88 big blocks. If yours can't be surfaced, there's more around that aren't too expensive.

[anotheridiot]

you can get new flywheels on rock auto for you combination for 43.00

my unknowing eyes would still check the adjustment. We had the push rod in the hydraulic brakes adjusted too tight and they never released fully so I wonder if its an adjustment that is not allowing full engage or disengage

[Dan Barlow]

Loren- He had been saying that it was slipping on slightly more than moderate acceleration . If I remember correctly it did need pulled together .
Another - I'm not aware of any adjustment other than bleeding the hydraulics on the master and the slave ( ram ) . At this point , time it is more of the essence than the money difference between buying it out of a brick an mortar but I do appreciate your effort .

[Loren]

I'd think, when it's back together on the car and the clutch release all in but without the transmission installed, get yourself jammed in there behind it with a drop light and have somebody press the pedal while you observe operation. Things will want to flop around a little without the trans input in there and I'd imagine you'd want to have an alignment tool in place to hold the disc in place and help you know where the throwout bearing should center. The thing is, when the pedal is released and the clutch engaged, you should with finger pressure be able to pull the throwout back off the clutch diaphragm a little further...there shouldn't be anything holding it tight. Then take a measurement on the trans to confirm that when it's installed there will still be a little distance that the throwout can slide back along, as it will need to with wear. Finally you'll want to have checked that the bearing does indeed slide freely along the input and doesn't bind up for any reason.

This is just the stuff I would do, something I learned when I had a buddy helping me install a clutch/trans the night before leaving on a trip and when it was all together and ready to go, it turned out he'd put the disc in backwards. Confirming operation without the trans in first would have been a hassle but would have saved us all the hours between midnight and three a.m. that it took to pull it all apart (driveshaft, shifter, everything) and correct the mis-install.

If I'm getting any details wrong (it's been awhile), still the main thing is to confirm all is working properly before the trans goes in and you still have a chance at observing/confirming operation.

[Dan Barlow]

Thanks , I hear what your saying and will do my best once I get this flywheel resurfaced or get another one ( testing ). Not sure if the throw out will stay up against the fingers of the pressure plate but I'll see .I do know the disc was facing the correct way as it is stamped in the metal which side faces the flywheel plus I checked pics on the internet before putting it together last time . I am wondering about the throw out bearing and it sliding down the shaft . Thanks again .

[anotheridiot]

Loren- He had been saying that it was slipping on slightly more than moderate acceleration . If I remember correctly it did need pulled together .
Another - I'm not aware of any adjustment other than bleeding the hydraulics on the master and the slave ( ram ) . At this point , time it is more of the essence than the money difference between buying it out of a brick an mortar but I do appreciate your effort .

I dont mean that adjustment, I meant the push rod from the pedal going into the hydraulic master. We had no travel at the brakes so when everything heated up, it stayed pushed in a little and kept a little pressure at the brake calipers. I usually think about what nobody else does, and I know I am usually wrong, but I figured that would be a place that would keep pressure on the clutch when everything gets hot.

[Dan Barlow]

Another - It's a good idea and I will keep it in mind . If I need to I could shorten the ram or rod by grinding some off of it .

Loren - This just in I got it resurfaced today but they say it's a light weight. The surface is more like 10 and 7/8 but they said it was a lightweight . I just weighed it and came up with 13 pounds .

[Dan Barlow]

Incase anyone is curious here are the numbers I found on it . Since it's not my car I really don't care one way or another as long as it works .