New clutch – jerky during feathered take off - ?

[oz]

Greetings.
I rebuilt my 302 this year, installed a new Ram clutch and had the flywheel resurfaced but I am having a problem when I try to accelerate from a standstill. If I let the clutch out slowly it grabs intermittently (the car jumps and jerks). What can cause this?

A mechanic said it was because the car sat around for several months between assembly of the clutch to flywheel and when I drove it the first time. He said it was probably just surface rust on the flywheel. I have driven the car a fair amount recently and the condition has not improved.

This may not have any effect but my long tube headers are very close to the clutch fork. I actually had to clearance one tube so the fork would disengage all the way. Any chance the fork is cocked and putting uneven force on the clutch when partially engaged (making contact non-parallel)?

Anybody else have this problem?
Any suggestions?

THANKS!

 

[Ozsum2]

It sounds like a surface problem, either from like the mechanic said, or from slippage. Is there an adjustment?

 

[gjz30075]

I've stored cars for many months and never had a clutch shudder problem because of storage. Yes, the surfaces might have had some rust on them and you can usually hear the difference with the first couple of engagements until the surfaces clean up, but never a shudder. I think you're on the right track to check mechanical issues such as your fork movement.

Did you lightly lube the splines when you installed the clutch? There could be rust there as a result and the disc now cannot move smoothly back and forth.

 

[oz]

I don't remember lubing the splines... I wouldn't be surprised if that was the problem.
My buddy helped me install the clutch and the trany to the engine before i dropped it in and when I asked him about this, he says his does it too... would make sense if we both made the same mistake.

Makes even more sense when I think about it. Some times it shudders enough to pop your fillings and other times it does not shudder at all. You never know what you're going to get.

Let me guess - there's no way to correct this without pulling the trany? I wonder if I could losten it and pull it back an inch or so - enough to get a grease gun hose or drop of oil on the splines....?

Am I going to ruin my new clutch if I don't get this corrected right away? (or is it too late???)

THANKS!!!

 

[SandSprite]

I also have clutch chatter occationally, usually from sitting in traffic. You are supposed to seal the threads when you bolt the flywheel to the crank (since 302 cranks are drilled all the way through). I didn't do that on mine, so some oil may have worked its way through and gotten to the flywheel/clutch interface. My other concern is the janky z-bar setup I have. It doesn't sit right with the 302 adapter for the z-bar.

 

[oz]

I did seal the flywheel bolts to the crank so I think I am ok there.

More Info:
I checked the release fork and I have enough clearance to the pipe such that it is loose with the pedal up. The fork return spring (new from NPD) seems really weak but I am sure that there is no preload on the disk. I wrapped it around the push rod so that it wouldn't rub against the tube when the pedal is pushed (and cause a 'ringing' sound in the pipe). This routing did not change the function of the pushrod at all.

I did not change the fork when I did the swap and I probably should have. It did show some wear where it contacts the throw out bearing. I cut off the little tabs at the outer end and put a little notch in the edge of the fork (for the pring to seat into) that extends beyond the pushrod for more clearance to the pipes. I saw no other reason for the extension but to locate the spring and I don't think this has any effect on function.

The flywheel was machined flat and had a nice circular cross hatch pattern on it. I saw no hairline cracks in it.

The old clutch was completely worn out (into the rivets).

I may break down and stop by a local transmission shop to see if they will take a look at it.

 

[nds03]

i had that problem until i checked the bolts holding the belhousing to the engine, and they were not there(I know, im an idiot)

 

[oz]

Sorry to laugh at your misfortune but I couldn't help it...

I assembled my trany to my engine with the engine out of the car (on the hoist) and I know the bolts are installed...

 

[D.Hearne]

Only the 80-up 302/5.0's need the thread sealer on the flywheel bolts. The earlier cranks aren't drilled thru to the other side. Sounds like he just has a simple case of clutch chatter, it'll go away with regular use. Used to be a very common problem with new clutchs

 

[oz]

I know for a fact that the holes in the crank for the flywheel are open to the crank case (on my engine at least). I remember seeing the holes when I was cleaning up the crank for machining and thought "huh, I wonder if I have to seal those holes?". I also refered to the 'How to rebuild your small block Ford' book the whole time and they made special reference to them. Are you sure it isn't the other way around (the '82 and up 5.0's don't need sealer anymore)? I thought Ford eliminated the through holes then.

I'm taking it to a trany shop tonight to get it looked at. The problem seems to be getting worse with use, not better. Hopefully they won't sell me a bunch of stuff I don't need....

 

[YellowMach69]

I know for a fact that if oil seaped onto flywheel it will shudder also so if theres any type of leak like intake manifold or whatever you might need to look closly for that

 

[jpctln]

Hmm. I just got finished putting in a new King Cobra clutch into my 93 5.0L. I'm having the same problem with the jerkiness at takeoff. It doesn't really matter what combination of clutch/gas I give it, it still jerks. Have you fixed it yet? Any ideas?

 

[restomod22]

Sorry for the hi-jack, but I was interested in the "holes through the crank to the crank case" debate. I recently installed a T5 and didn't seal the flywheel-to-crank bolts. I'm also noticing what seems to be oil leaking from where the tranny meets the bell housing at the bottom. I know it could be leaking from elsewhere, but wondered if the bolts may be the problem. Anybody else want to weigh in on this???

 

[D.Hearne]

Sorry for the hi-jack, but I was interested in the "holes through the crank to the crank case" debate. I recently installed a T5 and didn't seal the flywheel-to-crank bolts. I'm also noticing what seems to be oil leaking from where the tranny meets the bell housing at the bottom. I know it could be leaking from elsewhere, but wondered if the bolts may be the problem. Anybody else want to weigh in on this???

The oil could come from one or more places, the rear main seal, the flywheel bolts ( if the holes go thru to the crankcase), the cup plug in the rear of the cam, or the oil gallery plugs. Another source could be the rear of the intake.

 

[Route666]

I know it's a bit late and some of these things have been mentioned already, but I found this on the Centerforce website in their FAQ.

WHAT COULD BE THE CAUSES FOR CLUTCH CHATTER?


CHATTER PROBLEMS CAN BE CAUSED BY MANY PROBLEMS. POSSIBLE CAUSES MAY BE AS FOLLOWS:

FLYWHEEL HAS EXCESSIVE RUN-OUT.
FLY WHEEL WAS NOT RESURFACED BEFORE THE NEW CLUTCH WAS INSTALLED.
FLYWHEEL WAS RESURFACED IMPROPERLY OR HAS IMPROPER SURFACE FINISH.
FLYWHEEL HAS SEVERE HARD SPOTS OR HOT SPOTS.
FLYWHEEL RESURFACED IMPROPERLY (I.E. INCORRECT FLYWHEEL STEP).
DAMAGED OR EXCESSIVELY WORN CV JOINTS.
BAD U-JOINTS IN DRIVE SHAFT OR U-JOINTS MISALIGNED.
EXCESSIVE BACKLASH IN DIFFERENTIAL.
EXCESSIVE DRIVE-LINE ANGLE.
BAD LEAF SPRINGS, BUSHINGS OR MOUNTS.
IMPROPER GEAR RATIO VERSUS TIRE DIAMETER.
DEFECTIVE PRESSURE PLATE AND/OR DISC.
DISC HAS INADEQUATE OR NO MARCEL (NOT ENOUGH CUSHION BETWEEN THE FRICTION FACINGS).
OIL OR GREASE CONTAMINATION ON CLUTCH FACINGS.
WORN OR DAMAGED CLUTCH LINKAGE.
BENT COVER ASSEMBLY AND/OR DISC .
IMPROPERLY TUNED ENGINE.
WORN OR DAMAGED ENGINE MOUNTS OR TRANSMISSION MOUNTS

 

[TIGGER]

When I was in highschool, I put a new Napa clutch in my 6cyl and it chattered like crazy. I surfaced the flywheel and replaced all 4 pieces. It ended up being the pressure plate. Napa gave me a new one and it was much better but not totally gone. On warm days, in stop and go traffic, it would tend to chatter. I drove it like that for another year and then decided to rebuild the motor. While in the machine shop, I had the engine balanced. The guy used the flywheel and pressure plate to balance the motor. The pressure plate ended up being out of balance. The machinest welded a small piece of metal to balance it. Once back in the car, the chatter was gone. Nothing changed in the clutch but the balancing? I would check the balancing of the pressure plate if the chatter gets too bad.

 

[oz]

reviving an old post...

I took the car out last night for the first time this spring and the chatter was as bad or worst than ever... tore few holes in the yard just trying to ease it into the garage...
I have read that new motor mounts and a torque strap sometimes help the chatter. Can anyone vouch for this solution?

 

[Steve69]

I also had bad clutch chatter. My whole care would shake when I took off.
The Problem I had was the Pressure plate bolts were slightly to long. When
I torqued to 25 pounds the pressure plate was still not a tight as it should
be on the flywheel. I bought some new ARP bolts and installed a new
Clutch and PP since I had it tore apart problem solved. I also put some
thread sealer on the Flywheel bolts to be safe than sorry. I don't want
to have to take this apart again for a long time.

 

[68conv4sp]

I'm sure this fix is not in the textbook, but my clutch chatter was mild, consistent, and bothersome. My fellow Mustanger suggested a few hard, high rev launches. It was hard to do that to the car after babying it, but the problem went away after 4 or 5 aggressive launches. Must have cleaned up some glazing perhaps? Good luck.

 

[oz]

Those are both good ideas... I want to try as many 'non major tear up' solutions as I can before I get under the car. My old clutch was completely shot when I took it out (worn down into the rivets) so I am afraid that my resurfaced flywheel has some 'hot spots' that are not visible now. There was never any chatter before though.

I will try the hard launches but my tires are so old and hard that they spin very easily (in EVERY gear) even though I am making under 300 hp. I may actually be better off setting the parking brake and letting the clutch drag a little to warm it up...
What about a few 2nd gear, 4000 rpm launches?

Thanks.