Throwout fork hitting pressure plate

[dho]

I'm nearing the end of the restoration of my '71T. The engine is installed and running, but I have an issue with the clutch release. According to the factory manual, the throwout fork must move 15mm to release the clutch. I can only get 7-8mm before the fork hits the pressure plate. I've tried adjusting the pedal freeplay, the pedal stop and the cable length.

New clutch disk; new throwout bearing; new pivot ball, thick cone washer, spring and shim; original pressure plate; original flywheel, surfaced.

It looks like the throwout fork needs to move forward (toward the front of the vehicle) to give it more room to release, but I don't see how that can be done.

Any tips or suggestions are appreciated. Thank you.

dho

[Scott A]

With no cable on it.
Then you can see how far it goes from stop to stop.
And you can use a long screwdriver or crowbar to lever the fork…to see how much travel you have.

See if you get your full travel.

That should give you some clues as to where it is hanging up.

[dho]

Update: I spent time this afternoon under the car and talking with Scott A, who had good suggestions. As best I can tell, everything is mounted as depicted in the diagram Scott posted above. It appears that the pivot point of the fork (where the bolt goes through) needs to move toward the bell housing, so that the arm will have enough room to move toward the rear, to release the clutch, without hitting the pressure plate. However, I don't see how to accomplish this with the existing hardware. (I'm using JimmyT's pivot bolt, which I assume has the same dimensions as the stock bolt.)
I appreciate any thoughts or suggestions!

dho

[edmayo]

You need to shim the pivot bolt. Usually a valve cover washer will work.

[dho]

Ed, where would the shim (washer) go? If I put it between the bolt and the bell housing, won't that move the fork towards the engine (to the rear) and make the problem worse? It appears that the fork needs to move toward the bellhousing, so that the fork arm has room to move rearward when the clutch pedal is pressed. Would a thinner cone washer accomplish this?

Thank you for your thoughts and suggestions.

dho

[Scott A]

I also think the spacers need to be thinner.
(In its current state, assuming things are right in there)

It really must be that we both have pressure plates that are thicker than normal.
And it causes us a need to modify the spacers to ‘thinner’.

[Jon B]

I'm using JimmyT's pivot bolt, which I assume has the same dimensions as the stock bolt.

Given your issue, you should confirm that and not assume it.
The original '70-'71 multi-piece pivot bolt and the factory replacement 1-piece pivot bolt have different dimensions.

If Jimmy T produced his part as a direct replacement for the original multi-piece part, then it doesn't use the thick conical washer that you're using
He doesn't mention or offer the conical washer anywhere in his classified ad or his follow-up posts... https://www.early911sregistry.org/fo...911-116-772-11

Jon B.
Vista, CA

[dho]

Jon, you are correct. (I know what you do when you “assume”.) Scott was gracious enough to come down this evening and we were able to: compare a stock pivot bolt with Jimmy’s bolt, and they are substantially the same; and, look inside the bell housing with his scope and confirm everything was installed correctly. At this point, the engine needs to come out to inspect and identify a solution. Because of my schedule, this will probably happen in mid July. I appreciate everyone’s suggestions and assistance, including Jimmy, who promptly responded to my emails; and particularly, Scott, who took the time to drive down from Gainesville this evening to help sort things out.
dho

[Scott A]

A couple things I thought about on the drive home.
1. The more worn the fork points/bumps are, the closer your fork gets to the pressure plate.

2. If the fork points are off the throw-out wings, like they slipped off, then the fork gets closer to the pressure plate.
( this seems most likely the cause) the distance between the forks can wear too big and the throw out wings can get out of place.

3. Maybe , before you take out the engine, you buy a spare (new or used) fork. So you are ready to install if needed.



Above: This image shows a lot, pizza slice spring plate, holding the throw out bearing, the ball-joint bolt & even some side of the fork’s tong. Shows bevel washer & tongue spring. I wish it showed if the bearing was slightly turned. And the flats, if out of place.



Above: the orange is the top of the fork, but is it the bump? Or did the bearing rotate away from the bump?

4. You know how you have to rotate the throw-out bearing to separate the transmission.
Then you have to rotate the bearing back 90, when you have it back together, are you 100 percent certain that you rotated the wings on the bearing back the 90 degrees?

[edmayo]

Assuming all other factors correct, when a flywheel is machined the pressure plate moves away from the pivot. The shim moves the pivot back closer to the pressure plate plate.