Weird / Rattlling Clutch Fork

As I noted in my "Good Day for a Drive" thead I've noticed a metallic rattling sound at idle that goes away when I push in the clutch. Well, my guess was right, while at hot idle I reached under the car and grabbed the clutch fork, it's rattling like mad, bouncing back and forth. If I push it either towards the clutch or away with my hand it goes away. Weird!

When I refreshed my engine, the cluth only had 15K miles on it and looked ok, but I did replace the throw out bearing. When the throw out bearing came from Bob at Brittek with a note saying that I might have to file a bit of the inside ears of the clutch fork to make the new bearing work, so I did and all seemed fine.

But I can think of anything that would make it rattle back and forth like that short of the flywheel being out of round and if that was the case I bet the engine would vibrate like mad. I dunno!

Bushing getting worn???

Could be the pilot bushing and/or the release arm pivot bushing. My '77 did the same thing and it was just irritating, but never caused any problem.

Hmmm, how could the pilot bush cause the problem? It's quite possible the fork bush is worn.

I wonder if the throw out bearing is working its way out of the fork. I'll go feel it again, but as I recall it did feel like it was pulsing. Between this and the oil leaks, I think the car is begging for me to pull the engine again! Geeez!

Most probably a worn bushing at the fulcrum of the fork. Unless you are just overwhelmed with the joy of pulling the power unit, for the time being I would rig a LIGHT, and I mean LIGHT spring between the clevis pin at the slave push rod and some other convenient anchor point. You would want to have the spring pulling the fork TOWARD the slave cylinder. I can't think of a perfect place right off hand, except that you might form a link OVER the cylinder and attach the link to the base of the hydraulic line with a loop or two. Neatness counts, good grief, I forgot who I was talking to here, but don't let anyone look under the car until you get around to doing the fix the right way. It might tarnish your image. LOL

I just thought of another fix. Pull the push rod and add some length to it. You can grind a small flat on the eye end and braze a 5/15" nut to it and re-drill the opening to accept the pin or you can braze a one inch 5/16" bolt to the other end, grind the brass smooth, cut the bolt off so that there is about 1/2" to 9/16" extra length and grind the end into a rounded shape to fit inside the slave piston. I have done both many times and I think that I prefer the nut routine. This will change the relative positions of the fork arm and the slave piston and just might cut the rattle out for quite a while. Probably a 30 minute fix either way.

All in all I think I would go for the lengthening of the rod rather than the spring thing.

Country boys will survive! LOL

Jack

John,

You added the above link before I came back and posted my other thoughts.

The "pulsing" can only be caused by the thrust plate part of the pressure plate being not on a perpendicular plane with the first motion shaft. I suspect that what you have here is a combination of both a worn fulcrum bushing and a failing pressure plate.

Things are most likely not going to fly apart any time real soon but I would be preparing to replace the clutch assembly and the fulcrum bushing in the future.

BTW: If you rest you foot VERY lightly on the clutch pedal and just slightly depress it, if it is a poor thrust plate you should feel a very slight pulsing just as the face of the release bearing begins to gain pressure against the thrust plate. If you don't feel it with your foot, try pushing down on the pedal with your hand with the engine at idle.

Jack

Thanks Jack,

I just cranked the car and let it idle. From underneath, with my hand I lightly pressed the fork so that the throw out bearing came in contact with the clutch and it vibrated like crazy. BUMMER!

So I guess a new clutch is in my future! Damn!

Probably got jerked around while you were pushing the transmission back up into place behind the engine. Trying to line up the first motion shaft with the pilot bushing will do that sometimes. Next time install the trans with the engine dangling from the hoist and a friend holding it steady. That way you can bear hug the transmission and have better control over its angles. You can do it with the engine sitting on the floor too, but you really ought to have it sitting with the pan on some two by fours to give you a little wiggle room with the transmission case. And don't under any circumstances allow the weight of the transmission to just dangle before you have the bell housing fully home against the engine backing plate. Doing that is a sure fire invitation to a ruined disc.

BTW: Don't trust to just "re-aligning" the plate, replace the whole shebang. Life is too short to spend it pulling B engines, besides once you have done it the first there is no more glory.

Jack

twigworker Wrote:

Damn, that sucks, John after all the work you put into the car. I feel for ya'

Brian,

Kinda like washing cats, eh?