The Stovebolt Site Forums The Shop Area Engine Shop New Challenge; New Question

I put a rebuilt 235 in my 57 Stepside last year and I'm getting some serious clutch chatter on take-off.

I had the flywheel re-surfaced and bought a new NAPA clutch and pressure plate.

I adjusted the clutch as instructed in the shop manual but I'm getting a serious vibration on take-off. I can feather the clutch and get it going ok, but I can't just lift and go like I used to.

I was sure to clean all surfaces before installation.

What should I be looking for? What's the fix?

Thanks.

Jerry

Jerry A,

Adjustment isn't usually a factor in clutch chatter. You did everything right to begin with...new clutch and PP along with a re-face of the flywheel. This cures chatter 99.9% of the time.

A loose flywheel (rare) or oil contamination of the disc would be my first thought. Anything to address this problem will require you to pull the assembly apart and all will be revealed then. Whatever has happened, plan on a new clutch disc. My bet is oil contamination of the disc.

Oil can flow from the crankcase through a flywheel attachment bolt hole if any bolt has been left out. This is a direct route to the disc.

Stuart

Thanks atomarc. I was really hoping you weren't going to say that. I pretty much thought it had to be something on the clutch disc.

Make sure the engine mounts are in good condition first. I suppose a loose drivetrain component could cause that sensation too. So check U-jointsand rearend springs/bushings also. Some of the aftermarket discs are kind of rough when new. Sometimes they need to be "burned in" to clean them up some. Just don't over due it and create hotspots,
Scott

While you're in their, in addition to all the above suggestions, you might want to eyeball the pilot bushing in the end of the crank. If it is sloppy it can cause you engagement issues. It's a low-ticket item that is occasionally overlooked and it's function is to center and support your transmission main shaft. BTW...it should not be lubricated as it is self-lubricating. There should be no slop.

Dave

I also put a new pilot bearing in when I did the job. I'll take a look to see if it's doing anything strange.

front tranny input seal can also contaminate the clutch disc with gear oil....

sounds like ya like got some contamination of the clutch disk goin on ,
i would run her a bit more to see if it clears itself before tearin down if ya have no obvious drips comin from somewheres indicatin a bad seal.

how does a pilot bearing "self lubricate".

Darin367,


There is a bronze (SAE 871) that is called 'Oilite'...it is porous and impregnated with oil. Sometimes bushings that can't be manually lubricated are made from this material. There are also graphite plugged bronze bushings.

The clutch gear, or input shaft is usually turning the same speed as the engine, so this little bushing doesn't see tons of wear...only when the clutch is disengaged.

Stuart

Jerry, an old timers trick to a little grease on a clutch disc was to set the parking brake and engage the clutch with the tranny in gear to allow for some small amount of slipping. It will heat up the disc and burn of the grease or so the theory goes....
..well I'm hesitant to suggest this but maybe a little dab ul doya.

53moneypit,

My experience has been just the opposite. Once the disc is contaminated with oil, any attempt to heat it and cook the oil out only results in a hard coating of Kryptonite like material that is baked on for good. Without stemming the flow of oil into the clutch, it's a loosing battle.

Stuart

If you have to tear the assembly apart, make sure that they did not give you a clutch without dampening springs on the hub. No dampening springs = lots of chatter on take off during ordinary driving. My $.02

I haven't pulled the truck apart yet but I did drive it a bit this weekend. If I start from first gear, I have a serious chatter unless I work pretty hard to 'feather' the clutch. I can start it out in second without any vibration though. Does that give you any more clues to the problem?

Jerry A,

That's pretty standard. I think it has to do with the RPM's and amount of slip to get the truck going in second gear. Did you ever pull the little gravel shield and look inside the bellhousing? Is there any oil or oil mist clinging to the interior surfaces.

Scott mentioned motor mounts...with the parking brake on hard, you can put the truck in first or low and slowly let the clutch out. Do this with the hood open and a friend watching the engine. When the drivetrain starts to lock up, the engine shouldn't move much...if it rocks over "inches" this could be the problem. This is usually evident from inside the cab as the shifter flops with the rocking engine.

Stuart

Stuart..I was referring to a "little grease" on a clutch disc from re-assembly and slipping it to get the heat to burn it off. Obviously I wasn't talking about a continious oil leak which must be fixed.