C2 Clutch or M20 Rattle

[Grant M.]

Looking for some advice on where to look to solve a 'rattling' sound from either the clutch or (Muncie M20) in my '65, after re-installation following engine re-build. Had a new RAM 10.4" clutch and new throwout bearing installed, although the old clutch and throwout were working fine, but had been in the car for nearly 35 years, so I had them replaced.

The rattle seems to be engine speed related as it varies in frequency during downshifts as the engine speed increases and then slows down, or, if in neutral, engine revving. The sound resembles (slightly) the sound we made as kinds by clothes-pinning a cardboard cigarette package to the front fork of a bike so the cardboard brushed the spokes. The noise is absent with the clutch pedal to the floor.

Shifting through all gears seems normal; however, on examination, the clutch rod nut identified as "A" in the 63 Service Manual) is barely on the threads at the end of the rod and the other nut "B", is tight against the swivel on the cross shaft lever.

Any ideas on what to look at?

Thanks,

Grant

[Richard M.]

Re: C2 Clutch or M20 Rattle

Grant, Did you replace the clutch housing bolts or flywheel bolts? Possibly too long hitting something.

I forget if the 65's have a bell housing/clutch inspection plate. Something could be hitting that if equipped.

SB or BB ?

Rich

[Grant M.]

Re: C2 Clutch or M20 Rattle

If you mean the bell housing bolts, no we re-used the originals, and I was careful to instruct that the lower left position (looking forward) was the shorter bolt. No 'inspection plate' that I'm aware of, but there is the boot where the throwout arm enters the bell housing and the cover near the starter. I read something on the Corvette Forum Board about the possibility of the throwout bearing being improperly installed with the 'ears' outside the bearing groove and maybe contacting the clutch fingers...

Grant

[Edward J.]

Re: C2 Clutch or M20 Rattle

Grant, is the clutch disc possibly facing the wrong way, do you note the clutch fork moving around in neutral/with pedal fully released?

[Grant M.]

Re: C2 Clutch or M20 Rattle

I'll have to check that. I assembled the engine/clutch/transmission upon the car's restoration in 1987, but I had a local garage install the engine/transmission this time. The bell housing/clutch were installed by the rebuilder, in whom I have pretty good confidence; but.....

Thanks for the suggestion. It really seems as if something is rubbing against something while rotating; just not sure what...

Grant

[Stephen L.]

Re: C2 Clutch or M20 Rattle

Just some info on the throwout bearing installation...... right and wrong.

[Grant M.]

Re: C2 Clutch or M20 Rattle

Stephen, thanks. I saw these same images before (somewhere--CF perhaps?). What would be the result of the tangs not being properly seated in the groove? My thoughts would be that they would rub against something---the 'fingers' perhaps?

Grant

[Jack J.]

Re: C2 Clutch or M20 Rattle

Stephen, is it possible to see through the bell housing clutch fork window if your throw out bearing is installed correctly? Thanks, Jack J.

[Edward J.]

Re: C2 Clutch or M20 Rattle

Grant, there Is a shield that mounted on front of bell housing that has fingers that sit In the groove of oil pan, if not installed correctly they contact the flywheel and kind of make a flapping noise. Very easy to make this mistake. If not in grove you will have to drop starter down and remove the (4) 7/16 head bolts, the two tangs should be sitting in the oil pan groove. Also check to make sure it’s not bent, this also happens often.

[Jack J.]

[Edward J.]

Re: C2 Clutch or M20 Rattle

Jack the throw out bearing has a groove in sleeve that should have a small amount of molly grease. If dry could be binding. Also the t/o bearing retainer on trans.also can wear and cause binding, splines on disc dry also possible.

[Joe L.]

Re: C2 Clutch or M20 Rattle

Grant, there Is a shield that mounted on front of bell housing that has fingers that sit In the groove of oil pan, if not installed correctly they contact the flywheel and kind of make a flapping noise. Very easy to make this mistake. If not in grove you will have to drop starter down and remove the (4) 7/16 head bolts, the two tangs should be sitting in the oil pan groove. Also check to make sure it’s not bent, this also happens often.

Edward------


Not all lower bellhousing covers had the integral clips you are referring to. My 1969 did not originally have a cover with this feature. I'm not exactly sure when the clips were added to the 14" flywheel bellhousing because they were added without a change in part number. However, if one has a car with a cover without the clips, I strongly recommend replacing it with a cover with the clips.

The early covers for the 12-3/4" flywheel bellhousing did not have the clips. About 1973 a new part number was released which replaced the earlier cover and did have the integral clips. I recommend this cover for any cars not originally having a cover with clips.

Without the clips, the cover can be bent in enough to contact the flywheel and cause noise. Of course, the cover has to be installed so that the clips are forward of the oil pan rear seal lip, as you mention.

[Jack J.]

Re: C2 Clutch or M20 Rattle

Thanks Stephen for a picture worth a thousand words. Now I know where SOME of my problems came from!

[Grant M.]

Re: C2 Clutch or M20 Rattle

So I got the bad news today that the 'rattle' isn't a mis-installed throw out bearing or a bent/mis-installed shield on the bell housing; it's the input bearing in the transmission. As my mechanic got the car up on the hoist, engine running, and pushed in the clutch pedal (to the floor), the noise stopped, as I had noted, but only after the input shaft stopped turning; not immediately.

Out comes the transmission tomorrow...

Thanks for all of the input/insights and suggestions!

Grant

[Ken G.]

Re: C2 Clutch or M20 Rattle

Had a similar sounding rattle in the clutch pedal. Correlated with engine speed whether in gear or neutral. Gone with clutch pedal depressed. After confirming that everything was tight and lubed, noted not much play in clutch pedal or fork. Adjusted clutch rod to specs, and rattle gone! Apparently the throw out bearing was just rubbing against the clutch fingers and transfering a vibration to the upper clutch pedal.