VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Clutch Chatter

48 Aero has rough clutch chatter in low gear and reverse.
Second gear has some, but not as bad.

I recall burning the clutch disc some 50 yeara ago, not sure that is the correct method to handle the problem.

Will clutch adjust help or do I need to replace the disc.
Your suggestions appreciated.

Thanks

There is a long list of things that can cause clutch chatter in a Chevrolet. Could be in the clutch its self. Oil on linings, warped pressure plate or flywheel. stc.\
Could also be bad motor mounts,loosness in the drive train in general, loose rear sping U bolts or the rubber bushings in the front of the spring eyes to name a few.

Avid:

When I first got my 48, it was almost impossible to get the car moving in first gear without a bunch of surging/shuddering. I discovered that both side engine mounts(sides of bellhousing) were completely missing, and, that my transmission mount was rotted apart. After I installed the side mounts, and, replaced the transmission mount, the problem has about disappeared.

Regards:
Oldengineer
1948 Fleetmaster Town Sedan

Before spending a bunch of bucks on parts, pull the clutch housing cover. If there is oil inside it then the chatter is most likely caused by oil on the clutch disc, sourced from the rear main. Speaking of burning the clutch, ancient history now but way back when income was a buck an hour I would occasionally drive up to a utility pole, put her in low and rev the engine with the cluth partially engaged. Helped considerably for a very short time but was not a cure. Learned this from a Ford owner.

I messed around with mine for several years doing all of the things that were suggested except the one thing I dreaded doing. Finally, I bit the bullet and replaced the rear bell housing side motor mounts. Did that about three years ago. Never another problem, not even the slightest.
So, I'm gonna say, save some time and do those motor mounts. I did the front one to while I was at it. You'll find that it takes off and runs like it was supposed to - smooth! Mine is a 37 1/2 ton pickup and afterwards, I determined that the mounts I replaced were the original ones!

The pick-ups had much less of a clutch chatter problem due to their firmer motor mounts. The 1952-1954 cars had very little chatter problem as they had the big main mounts on the side of the block. They would have a little of what Chevrolet called gear rattle but not to serious. In late 1953 Chevrolet thightened up on the transmission gear tolerences to further correct the gear rattle.
Some 140 in the transmission also helps.

I now have clutch chatter on my 47 after my engine rebuild. During my engine rebuild I replaced the clutch disc, pressure plate, new motor mounts, flywheel resurfaced. I double-checked the motor mounts and tightened them down. The flywheel is dry. Any ideas?

The clutch chatter is only happening in 1st gear. Any ideas?

Worn splines on the clutch disc or input shaft?

Pilot bushing?

The pilot bushing is new. I'm not sure the condition of the input shaft?

Check your transmission mount to see if its tight, rotten, etc. It controls the fore and aft movement of the engine. After I put the revised design mount in my 48, the clutch chatter just about went away.

Regards:
Oldengineer

The redesign mount? Is that available at all the vendors, chevs of the 40's

Clutch chatter is a common problem for which there are many causes/cures. However, it can usually be greatly reduced by the way one engages the clutch (a left foot/pedal function).

Go for the motor mounts. Cheap & easy & took care of my problem chatter

You have many good ideas here. If it were my car I would make a list and check things out. I wouldn't replace anything until I knew more about the condition of all the stuff mentioned. Don

Fleetboy:

I got a NOS mount from one of the forum members. The revised one doesn't have the metal U shaped plate on top, and, mounts to the tranny with a couple of bolts. I found reference to the revised mount in the 48 service bulletins posted on the old manual site. My old mount was the original design, and, was so rotten that it fell apart in my hand when I took it out. Last time I looked, Chevys of the 40's offered a repair kit and rebuild service on your current mount, but, no replacement part of either design.

Regards:
Oldengineer

Thanks old egineer, since I've already replaced the motor mounts I'm going to try to locate a revised mount. Thanks for the info.

Does anyone happen to have a picture of the revised mount?

Anybody have one for sale?

Hi Fleetboy.

Here is a link to the transmission mount repair kit for your car. Chevrolet Transmission Mount Repair Kit $12.00 Have you replaced the rubber part to this kit? All the previous things you have done were the correct things to do. If you take the bottom cover off the flywheel is there any sign of an oil leak at the rear seal? If there is then the chatter will always be there to the extent of the leak. The clutch/flywheel/pressure plate area has to be oil free to not have some level of chatter.

Unfortunately, replacing anything on the transmission mount will require taking the transmission out of the car. Hopefully, you have replaced this rubber part and just failed to mention it in your above posts.


Good luck, Mike

P.S. I do have used transmission mounts. If you would like a picture of one let me know.

No, I haven't replaced the rubber part on the transmission. The flywheel is perfectly dry. Thanks for all the info.

I'm with you on that one...makes a big difference... :)

Mike:

I got my old tranny mount out without pulling the transmission. Someone had replaced the two studs on the tranny with bolts. I just took all the bolts out, jacked up the tranny slightly with a piece of 2X4 and a floor jack, and wiggled the old mount out. The new one slid right back in with no sweat. Since the revised design uses bolts into the tranny instead of studs - maybe one could thread the studs out without pulling the transmission.

Regards:
Oldengineer

Good info. Thanks!

I wouldn't be surprised if replacing the tranny mount helps a lot...The only chatter I get is in reverse...Let us know how it goes...