I recently rebuilt my in-liner engine(82 F150/4speed w/ overdrive) and replaced all the clutch components while it was all apart. I've only put 300 miles on it since the rebuild. The clutch works fine for the first 15-20 minutes after starting and driving. Once everything gets up to full operating temp and everything is hot then the the truck shakes and bucks violently when I engage the clutch from a stop in 1st gear. The clutch is fine thru the rest of the gears. Let me say I'm pretty sure there is no oil on the disc or flywheel as it works fine during warm-up. I know my main bearing clearances are tight and I wonder if they are heating up the crank which conducts into the flywheel(just a wild theory) which then warps and affects the contact area of the disc. Any ideas? Thanks.

 

Does it do any clunking or anything in the other gears? I was going to say mount bolts, but nevermind, it would do that cold. Sorry. You might have to tear it apart to find out. Good luck

 

The only problem(albeit serious) is the wild shaking starting from stop in 1st gear. The engine runs beautifully and all else is normal. No other sounds anywhere, period. Any validity to my too hot crank conducting heat to my flywheel/disc theory? Thanks.

 

It doesn't seem likely, but I suppose anything is possible.

 

Sounds like the flywheel needs turning or the clamping pressure from the Pressure plate is lacking. These will cause clutch studder on take off. Does it do this in reverse?

Pat

 

Ya know, I never thought to check if it does it in reverse from a stopped position...good idea. Like I said in my earlier thread, all the components of my clutch are brand new but I guess they could be defective....all the stuff came from Autozone. Can anyone recommend a good brand for quality clutch hardware? Also....I had the flywheel resurfaced at the local NAPA store in hooterville.LOL.

 

I got the same problem with my truck, it happend over time though, not after any work was done. any ideas from anyone?

 

We use LUK clutches at our shop haven't had any problems with them.
Most of the time when we see this kind of problem the clutch has been smoked a few times or it has a lot of wear on it. Some of the cheaper clutch sets don't have the even clamping pressure they should have and this will cause skipping and chattering. These problems are amplified in vehicles with tall gears.I've also seen bad flywheel turn jobs, we had one machine shop that was taking a belt sander to them. They haven't gotten any more bussiness from me since.

Pat

 

Remember.....This violent shaking only occurs after the truck gets to full operating temp, about 10-15 minutes. Before that it behaves good like the new clutch that it is. Would not that rule out things like linkages, pressure plates, mounts....stuff that temp wouldn't seem to effect. For example, wouldn't a bad flywheel turn job cause the truck to buck at all times, hot or cold?

 

Not necessarily as the pressure plate heats up it loses clamping pressure.
This natural and happens on all clutches to some degree. In most cases it is so slight you never notice.
Also flywheels develope hot spots these spot are hardened and have lesser expansion rate than metal around them. This causes the surface to look rippled and as temps increase this becomes more exagerated. This uneven surface causes the clutch disc to jump and skip on take off.

One of my mechanics just reminded me that this can also becaused by the the throwout bearing not contacting the pressure plate fingers squarely. This will not allow the clutch engage evenly. A common side effect of this is the fingers will be worn more on one side than those across from them. We see this on vehicles where poeple set at stoplights with the clutch depressed. But most times it as simple as a worn ball or clutch fork.
Just a thought hows the rear trans mount look?

Pat

 

Pat, This is all good info and food for thought. I love to learn about the physics of stuff like this so feel free to teach me more. I can't get to it until this weekend so I
I guess I'll pull it all apart....again!! When you say "tall gears" is that a high or low numeric number? I always forget. Trans mount is brand new....ball and fork looked good.Should I just take it all apart right away or can you think of any tests to perform that can give me further insight to the problem? Where is LUK clutches available....Autozone,Summit,Northern?

 

Tall gears low numbers.
I get my LUK clutches from O Riellys I'm not sure if they are a nation wide chain.
You should be able to look them up on line for a dealer near you.
I believe there is a link to them here on this site.
Taking it apart is the only option to examine the clutch. We know the problem is there now we have to pinpoint the cause. When you disassemble pay very close attention to every detail. Are things aligned properly/ ,Does anything bind or not slide freely?, Is the pilot bearing in place and in good shape?, before removing the pressure plate look at the fingers are they even? Take pressure plate lay it face down on the floor and push the fingers with a board working your way around each side. Are the fingers worn evenly? Does it feel firm and even all the way around? Are there any markings shiney spots on the flywheel and pressure plate surfaces? Are the springs in the clutch disc loose broken? Is anything discolored? Check the fork is it worn where it rides on the ball or holds the bearing? Does the fork rock smoothly on the ball? Are there any burrs or grooves in the throwout bearing slide?
Some times the problem is not readily obvious and is a combination of any of these things. You know a little ware here and there across the spectrum can equate to big problems. If I was a gamblin man I'd put my money on the clutch disc or p-plate.

Pat

 

Thanks for all the help....especially Pat's knowledge!!!