Clutch Fork Play - Root Cause?

Reply Subscribe

Thread Tools

Search this Thread

Feb 17, 2017 | 10:32 AM

Matt81

Thread Starter

Racer

Joined: Sep 2001

Posts: 352

Likes: 51

From: Austin TX

Clutch Fork Play - Root Cause?

This morning, I removed the fork boot and took a good peek inside. The TOB sits right where I think it should, not in contact with the clutch but about 0.25" away. I pressed the clutch pedal down until I met resistance with the clutch and was surprised by how much the fork moved. The fork seemed to move an excessive amount before making firm contact with the clutch, even shifting upwards a bit at the end of its stroke.

Here is a video:

The TOB makes initial contact with the clutch very early in the pedal travel, then the rest of the movement is the clutch fork moving until it finally starts to put pressure on the clutch to disengage.

I confirmed deck height with the Fidanza is right within spec with OEM at 0.965", so the stock pivot ball height should be correct.

However, does the clutch fork movement indicate a worn out clutch fork?

Thanks guys for the help so far!

Last edited by Matt81; Feb 17, 2017 at 10:34 AM.

Feb 17, 2017 | 10:43 AM

gkull

Team Owner

Joined: Apr 1999

Posts: 21,953

Likes: 1,445

From: Reno Nevada

2024 C3 of the Year Finalist- Modified

Imo, you need a longer pivot ball. I use the GM longer. When I do engine or tranny R&R I setup the throwout baring to fingers to 060. Your. 250 is wrong. I've also used adjustable pb

Feb 17, 2017 | 10:54 AM

Matt81

Thread Starter

Racer

Joined: Sep 2001

Posts: 352

Likes: 51

From: Austin TX

Quote:

Originally Posted by gkull

Imo, you need a longer pivot ball. I use the GM longer. When I do engine or tranny R&R I setup the throwout baring to fingers to 060. Your. 250 is wrong. I've also used adjustable pb

Increasing the pivot ball height should reduce the clutch fork travel.

Did the amount of movement in the fork look normal, or should that be replaced as well, as long as I have it apart again?

Thanks for the tip on bearing to fingers distance. Are you able to measure that thru the clutch fork hole in the bellhousing?

Feb 17, 2017 | 05:36 PM

Matt81

Thread Starter

Racer

Joined: Sep 2001

Posts: 352

Likes: 51

From: Austin TX

I'm leaning towards buying both a new clutch fork and pivot ball as the best option. That at, everything from crank hub to rear differential is new. Pull the trans one more time and be done with it. Hindsight being the perfect 20/20...

Parts:
Lakewood 15501 adjustable pivot ball
GMPP 3887177 clutch fork

Going to shop on Summit now.

Feb 17, 2017 | 05:58 PM

540 vette

Race Director

Joined: Jan 2002

Posts: 11,619

Likes: 350

From: No Where USA

I had the same problem in my 80. I was going to put in an adjustable pivot ball but came across the clutch linkage setup that Corvette central offers. It has heim joints at the ends of the rod and the rod that goes from the z bar to the clutch fork is adjustable and I solved the problem with adjusting that rod.

http://www.parts123.com/corvettecent...50g&ukey=17086

Feb 17, 2017 | 07:01 PM

Matt81

Thread Starter

Racer

Joined: Sep 2001

Posts: 352

Likes: 51

From: Austin TX

Quote:

Originally Posted by 540 vette

That is definitely my next step. Based off my current setup with the clutch barely disengaging at the end of the pedal travel with the clutch adjustment rod backed all the way out, I'm concerned there is something going wrong internally. That improved linkage might fix the problem, but could put too much side load on the TOB. At least with a new clutch fork and pivo ball, I shouldn't need to pull the trans again and can add the clutch linkage you mention pretty easily.