Clutch chatter
 

Maybe not F body specific necessarily but after reinstalling my engine (searching for low oil pressure thread) I’m having issues with clutch chatter. My car is a 77 T/A that I 4 speed swapped maybe 8-10 years ago. That setup featured a stock flywheel I had resurfaced, LUK clutch kit, factory fork and the remainder of the clutch linkage was aftermarket. That setup worked great until around 5 years ago.

I pulled the engine at that time and since the trans had some noise I was unsure about I decided to have it refreshed/rebuilt. To make a long story short, that shop gave me a plethora of headaches on top of the fact that I had new clutch chatter that wasn’t there. I don’t know if they tried to do a burnout or what. The owner offered to replace the clutch kit but wanted me to pay for the parts. I wasn’t about to take the car back. So I dealt with it. Fast forward to my recent engine-pull, and I replaced the flywheel and got a new LUK clutch kit. I reused the throw out bearing as I forgot the LUKs come with one that is part plastic so I took a chance on reusing the other one since it didn’t have that many miles on it.

I cleaned the new flywheel and pressure plate surfaces. I didn’t wipe the disc surface but was careful about not putting greasy fingers on it.

I’m planning on pulling the trans (easier than the engine I feel) and going to inspect everything, clean the flywheel and pressure plate surfaces again and can/should I clean the disc with brake cleaner too or no? I’ll probably replace the TO bearing while I’m there.

Any other thoughts?

Clutch disks with a sprung hub have a definite forward face/aft face orientation. Maybe it got installed backwards? The fact that it worked great and then suddenly started chatter after being apart makes that idea come to mind.

Hope this helps,
Eric

Possible. Guess I’ll just have to see. That’d be an easy fix though

following. i get an occasional very light chatter on my 78 4speed too, but its very rare & only happens when the stars are aligned properly. ;) meaning its only at a certain situation like starting from a stop on a hill & not having enough rpm for the short time it takes to release the clutch pedal & get moving. its easily stopped by slipping the pedal for a brief second & raising the rpm a couple hundred. its now just a habit to be sure the rpms are a little higher than just off idle when getting going & rarely if ever occurs. everything in the trans works great otherwise. sorry i dont have any suggestions for fixing it but am curious what others have to say.

I should clarify, the setup worked flawlessly after I installed it for years until the bogus trans shop got ahold of it around 2017. Chattered after that. Now, I replaced flywheel and clutch kit a month ago and that new stuff chatters as well.

Another thing to check would be the condition and proper installation of the pilot bearing and input shaft bearing. If the input shaft isn't held to a good stable centerline, it may cause chatter.

Just guessing.....
Eric

Well, the pilot bushing was installed back when I did the swap to 4 speed 8-10 years ago. I’ve never had any issues mating the transmission to the engine that would cause an bushing issue but I guess that doesn’t mean the shop didn’t mess something up. I really never looked at it because I assumed my old chatter issues were due to the hot spots on my old flywheel and PP.

Is the trans input shaft just a by-feel thing or when I pull the trans can I measure the play?

A new rule for you,you change clutch disc,throwout bearing and pilot bearing whenever you SEE them!Pulling that crap is a huge PITA!Tom

Agreed. And fair.

Alright well, I finally got some time to pull the trans anger putting some miles on everything. Chatter seemed to improve a bit (enough that I could manage with it) but not enough that I left it alone. Last Sunday I worked on getting the trans out and messed up my wrist in the process so I had to wait till today to finish.

I’ll defer to the experts here but to my relatively untrained eye I’m not seeing a smoking gun (except maybe one) so I’m hoping one of you sees something I don’t.

Pictures below of the pressure plate, flywheel and both sides of the disc.

One thing I did find is the throwout bearing appears to have excessive play. Don’t know if that could cause chatter but I’ll replace it anyway.

https://youtube.com/shorts/eLKnJnMbAJ4?feature=share

That said, my LUK kit came with a throwout bearing but I never used them this time or last time due to the composite (or whatever kind of material it is) construction. Do you guys use them or steer clear of them? (Unused LUK throwout bearing is the last pic.)

I’m planning on replacing the pilot bushing as suggested also. I can’t detect any significant wear but once I decide if I’m going to buy a puller or try the grease method I’m just going to change it.

Appreciate any input.

*tap tap tap* is this thing on? :D

Hard to tell for sure from the pix, but the pressure plate and flywheel surfaces look kinda rough. Also looks like uneven discoloration. When you replaced the clutch, did you just replace the disk or did you also replace the pressure plate and resurface the flywheel?

Also, did you verify that the disk was installed the correct direction?

Eric

Flywheel, disc and pressure plate were all new. Disc was installed in the correct direction.

Post a picture of the input shaft of the transmission. I agree with Tom S. I replace the pilot and throwout bearings every time.
I have had the best luck with the centerforce PN: N1716 throwout bearing. I always look at the front bearing retainer that the throwout rides on. This should be perfectly smooth. If not, replace it. Next slide the throwout bearing over the top and you should have very minimal 'rock'. Most clutch chatter I have encountered is from excessive bearing to retainer clearance. Next wiggle the input shaft. I have seen excessive play in this as which is either a bad input shaft bearing or the case itself is bad. Next, go to the bellhousing and make sure the pivot ball is 4.75" down from the mounting flange. Make sure the pivot ball doesn't have excessive wear. It's too late now to see how it was installed but I have also seen throwout bearings install on the clutch fork wrong.

I appreciate the tips. The two pictures I posted below are the best I have of the input shaft back from July of last year when I had the trans out last.

I have everything back together now with a new T/O bearing and pilot bushing installed. I was careful to install the fork correctly. As for the other suggestions you made I’ll have to check another time.

The chatter seems improved but not fixed. I wonder if part of that is due to the surface of the flywheel and pressure plate being “altered” from the previous chattering condition. I considered replacing the clutch kit but since I found my T/O bearing to be suspect I decided to try replacing that first. Pulling everything wasn’t hard so if the remaining chatter doesn’t improve (which it probably won’t) I’ll pull it all again, check the things mentioned, have the flywheel turned and replace the clutch kit.

Back in post #7 I asked if input shaft play could be measured to be within an acceptable tolerance or if it was “by feel”.

I am no expert but looking at the pictures the flywheel has obvious signs of slippage about the 7 o'clock position of your picture. Also the pressure plate shows rings like when you chop down a tree demonstrating to me uneven pressure applied to the disc. It might just be a trick of light but the clutch disc looks like it got really hot with the purple and blue metal that holds the clutch disc material to the center hub. I would defiantly resurface the flywheel and change out clutch disc and pressure plate next time you have it apart. I have changed out my fair share of clutch discs being young and dumb and dumping the clutch on my Nova. Good luck

I would have to agree with you. I wondered about the discoloration on the disc tabs. Not a trick of the light. Perhaps the old throwout bearing was the cause of uneven pressure. If things don’t improve (not that I necessarily expect them to) a resurface along with a new clutch kit are my plan.

Thanks.

Is it possible the surfaces weren't cleaned before going back together. Wouldn't a greasy surface cause this. Just like brakes when they get grease on them they lock up. A greasy surface could be causing it to grab and chatter.

Just a thought

Mark

I would’ve thought it could be possible the first time I had things together, though I was pretty sure I cleaned everything thoroughly. But I was very deliberate in cleaning everything this second time around.