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Discussion Starter · #1 ·
I was headed out today on a beautiful morning to go to the local cars and coffee in Oklahoma City.

Made a stop a couple miles from the house to fill up. Fires up just fine, I depress the clutch pedal, and it went all the way to the floor with no resistance at all. AAA time.

I do see that break fluid is leaking around the slave cylinder area when pushing the clutch pedal.

My thoughts are that the slave cylinder is the problem. What does not make sense to me is that the clutch is in the fully engaged position. I know this and was surprised by it when it was coming off of the flat bed at home, I put it in gear when it got on the ground, and it rolled as if it was in neutral.

Reaching out here to see if anyone has any ideas or thoughts. I did get the hydraulic clutch components from Mike Forte - and that is no complaint at all - things happen with these race cars with a license plate. Got the car home on a flat bed, and getting ready to get it up in the air on jack stands to see what I can figure out.

Thanks in advance for your thoughts.

David Peck
 

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Did you go with the external slave? If so, the actuator rod length is critical. I made mine too short and the piston popped out and earned me a flatbed ride home. Good luck and keep us posted with what you find.
 

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If it is a too-short actuator rod, you can easily make one from the appropriate diameter bolt. Just cut the head off & round the tip with a Dremel, and you’re back in business.

John
 

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Discussion Starter · #4 ·
sdonnel - I'm very curious. When that happened to you, was your clutch stuck in the disengaged position?

phileas - Thanks for your response. I fear the external slave is damaged with the fluid coming out of the rubber boot that covers the cylinder to the threaded rod.

I've got it in the air on jack stands, crawled underneath, and peeled back the rubber boot from the slave cylinder, fluid ran out immediately.

My plan right now is to wait till Monday / Tuesday next week and give Mike Forte a call. Thinking I'll likely need a new external slave. The rod may have been trimmed too much which perhaps got this whole thing set in motion.

Thanks guys ... and if anyone else can weigh in with additional thoughts I'd be glad to have them.

David Peck
 

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Match the bore on your slave cylinder. Sounds like the piston pushed out of the cylinder, cocking and holding the clutch fork in the release position. Your slave may be rebuildable if a replacement is not available.
 

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sdonnel - I'm very curious. When that happened to you, was your clutch stuck in the disengaged position?

phileas - Thanks for your response. I fear the external slave is damaged with the fluid coming out of the rubber boot that covers the cylinder to the threaded rod.

I've got it in the air on jack stands, crawled underneath, and peeled back the rubber boot from the slave cylinder, fluid ran out immediately.

My plan right now is to wait till Monday / Tuesday next week and give Mike Forte a call. Thinking I'll likely need a new external slave. The rod may have been trimmed too much which perhaps got this whole thing set in motion.

Thanks guys ... and if anyone else can weigh in with additional thoughts I'd be glad to have them.

David Peck
sdonnel - I'm very curious. When that happened to you, was your clutch stuck in the disengaged position?

phileas - Thanks for your response. I fear the external slave is damaged with the fluid coming out of the rubber boot that covers the cylinder to the threaded rod.

I've got it in the air on jack stands, crawled underneath, and peeled back the rubber boot from the slave cylinder, fluid ran out immediately.

My plan right now is to wait till Monday / Tuesday next week and give Mike Forte a call. Thinking I'll likely need a new external slave. The rod may have been trimmed too much which perhaps got this whole thing set in motion.

Thanks guys ... and if anyone else can weigh in with additional thoughts I'd be glad to have them.

David Peck
Dave,
My clutch did fail in the disengaged position. I literally just cleaned the pics and videos off my phone or I would post what the piston looks like when it comes out of the slave body. You likely do not need a new slave, rather you may need to fabricate a longer activation rod. Don’t lose the bullet shaped tip that seats on the piston.
Scott
 

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If the rod was too short and the piston pushed out, just push it back in an make a new rod as Phileas suggested. The piston may not have come fully out of the bore but if it got far enough that the seal leaked it has the same effect. There have been several instances of this happening over the years. Also be sure the MC push rod has a slight bit of free play when the clutch pedal is fully up. BTW, before trying to push it back in, lube both the seal and the bore w/ brake fluid.
 

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Is there a way to make the rod adjustable? I have an external slave that pushes into the fork. The shaft is threaded, with a rounded washer that sits in the fork "dimple", and the shaft extends through the hole in the base of the dimple. Double nut behind to adjust and lock in. So I am able to adjust the clutch engagement point.
 

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Discussion Starter · #9 ·
Talked to MIke Forte today and explained what happened. He told me that the slave is likely damaged - so I ordered a fresh one from him today, along with a new threaded rod. I asked for guidance around the length of the threaded rod knowing it must be trimmed with my first cut at this being too short obviously, and he told me it needed to extend about 3/16" beyond the clutch fork where it mounts, with the slave piston pushed all the way into the cylinder with no fluid in it.

I'll keep the old one as a back up, but I've got enough small leaks in this outfit already without potentially adding a new one (leak that is).

Thanks for all the feedback guys.

David Peck
 

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If your slave cyl is a 1" bore and you can part with it, I would be interested in buying it. I bought my hyd clutch kit from Mike, but got a 7/8" slave. It makes the clutch pedal heavier than I like, hence my search for a 1" slave.
Thanks,
 

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Hey Cowboy, just a thought. Double check that you don't have too much pedal travel and pushing the slave out of the bore. I think it's pretty common to need to add a pedal stop. I know I needed one with my Forte set-up.
 

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Discussion Starter · #13 ·
Tony_G - thanks for that thought.

I've got it back in operation now. With the new set up, it does feel as is the clutch is fully disengaged well before it gets to the floor. Thinking about this, in shifting, with the deceleration that comes with it, it's sort of hard to not push the pedal to the floor. A pedal stop would make a heck of a lot of sense. I will investigate further.

David Peck
 

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From my build log, post #394 & 398.


John

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A late add for my build was a clutch stop. Now that I’ve got my pedals set where I want them (for now anyway), I realized that at max extension the clutch arm is roughly 2 1/2” away from the forward foot box wall. That means the only thing stopping my clutch was whatever retaining ring or jam nut was inside the Wilwood clutch master cylinder.

I don’t weld, so I decided to beef up the forward foot box wall with a backing plate. Then I’d use some 1/2”-13 bolts and a coupler to make the stop.

I made the backing plate out of 16 gauge steel.

IMG_4410 by jhsitton, on Flickr

I used a generous amount of JB Weld and some rivets to secure it in place. Note that the backing plate goes inside the foot box, not outside as shown in the picture below.

IMG_4410 by jhsitton, on Flickr

I placed my stop fairly high off the floor to take advantage of the slight bend in the foot box aluminum. The bend adds stiffness, and I want as much as I can get.

With the carpet in place, I was able to mock up the post for the clutch stop. It took a couple of tries, but I found a combination of bolts and washers that will work.

IMG_4445 by jhsitton, on Flickr

For those interested, I used two 1/2”-13 x 3/4” bolts with a a 3/4” coupler. I used two SAE washers (on the outside of the foot box panel and on the inside next to the backing plate) and two USS washers under the inside bolt. I may have to add or subtract a USS washer depending on a drive test.


John
 
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