Clutch Slave pushrod length
Thread Starter
4th Gear
Joined: Jul 2004
Posts: 4
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Clutch Slave pushrod length
On my 84 I replaced the clutch with an Zoom kelvar clutch when I had the od unit out for repair (by Darrell 4 Speeds - does great work.) My problem is this, the clutch won't disengage till the pedal hits the floor boards. I bleed the system till I'm blue in the face with no improvement. Tore it down a second time to make sure everything was installed right ( Throwout bearing, disk and pilot bearing, everything is perfect.)
Zoom thinks its because to much was removed from the flywheel when it was resurfaced. From searching the posts I think I can cure it by making the slave push rod longer. My question is how much longer should I make it and will it shorten the pedal travel? Any help or insight will be greatly appreciated.
Lowell
84 -Z51
Zoom thinks its because to much was removed from the flywheel when it was resurfaced. From searching the posts I think I can cure it by making the slave push rod longer. My question is how much longer should I make it and will it shorten the pedal travel? Any help or insight will be greatly appreciated.
Lowell
84 -Z51
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You will have to adjust the length of the rod. The clutch pedal has a large mechanical advantage to allow for reasonable pedal forces, so along with this large (around 10- 15 times) advantage comes a reduction of 10/15 in the stroke at the clutch spring which makes the length of the rod very sensitive to the clutch pedal position when the clutch disengages. .005 was removed from my flywheel and a new clutch disc installed and the clutch would not disengage so we made a longer rod.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
I think I need to do this as well. I converted my '87 4+3 to a ZF 6 speed. Used the 5 7/8" bellhousing, Fidanza aluminum flywheel, ZF hydraulics, and ZF clutch/pressure plate/t.o. bearing set up.
My clutch grabs VERY low to the floor. I even had my mechanic take a look. He went over everything and still couldn't get the pedal up. The only thing I can think of at this point is to try a longer slave push rod.
LD85 - I've read a lot of your posts regarding this issue. Do you think the longer slave push rod will help me? What other options do I have?
Thanks!
My clutch grabs VERY low to the floor. I even had my mechanic take a look. He went over everything and still couldn't get the pedal up. The only thing I can think of at this point is to try a longer slave push rod.
LD85 - I've read a lot of your posts regarding this issue. Do you think the longer slave push rod will help me? What other options do I have?
Thanks!
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Originally Posted by byebyeL98
I think I need to do this as well. I converted my '87 4+3 to a ZF 6 speed. Used the 5 7/8" bellhousing, Fidanza aluminum flywheel, ZF hydraulics, and ZF clutch/pressure plate/t.o. bearing set up.
My clutch grabs VERY low to the floor. I even had my mechanic take a look. He went over everything and still couldn't get the pedal up. The only thing I can think of at this point is to try a longer slave push rod.
LD85 - I've read a lot of your posts regarding this issue. Do you think the longer slave push rod will help me? What other options do I have?
Thanks!
My clutch grabs VERY low to the floor. I even had my mechanic take a look. He went over everything and still couldn't get the pedal up. The only thing I can think of at this point is to try a longer slave push rod.
LD85 - I've read a lot of your posts regarding this issue. Do you think the longer slave push rod will help me? What other options do I have?
Thanks!
The 4+3 has a loose steel rod with abullet nose end that could be taken out, so on the 4+3 you could replace the rod with an adjustable rod.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Originally Posted by LD85
The ZF slave has a piston with a seal on the hyd-end of it if I remember correctly. If yo ucan push the rod back into the slave bore and have a gap between it and the clutch fork, then you could add that much to the rod and it would chaneg your pedal
The 4+3 has a loose steel rod with abullet nose end that could be taken out, so on the 4+3 you could replace the rod with an adjustable rod.
The 4+3 has a loose steel rod with abullet nose end that could be taken out, so on the 4+3 you could replace the rod with an adjustable rod.
Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Originally Posted by byebyeL98
Does that mean I can't take that push rod out of the ZF slave? If not, how would I increase the rod length?
Then I would measure from the bell housing mount surface to the fork depression while pushing on the clutch fork towards the front of the car.
Then I would make a cap to slip over the rod, that would be the difference between the two dimensions and add @ 1/8" .
A cap could be a piece of round steel @ 3/8" or 1/2" OD with a hole inside large enough for the slave rod to go into.
A little trial and error and your engagement height would be higher instead of all the way at the floor because the slop in the fork and slave would be reduced to a minimum. Not a big deal if you have access to a piece if steel. You coudl dril lthe hole on a drill press.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Great - thanks for the idea!
My only concern is that the clutch fork might rub against the pressure plate. I've also read where guys have relieved about 1/8" to 1/4" of material from the back of the fork to avoid this. Will that significantly lower the strength of the fork?
If none of this works, what other options do I have? (Other than setting the car on fire or letting it roll into my neighbor's rock wall).
My only concern is that the clutch fork might rub against the pressure plate. I've also read where guys have relieved about 1/8" to 1/4" of material from the back of the fork to avoid this. Will that significantly lower the strength of the fork?
If none of this works, what other options do I have? (Other than setting the car on fire or letting it roll into my neighbor's rock wall).
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Race Director
Joined: Feb 1999
Posts: 12,772
Likes: 17
From: Indianapolis IN
Originally Posted by byebyeL98
Great - thanks for the idea!
My only concern is that the clutch fork might rub against the pressure plate. I've also read where guys have relieved about 1/8" to 1/4" of material from the back of the fork to avoid this. Will that significantly lower the strength of the fork?
If none of this works, what other options do I have? (Other than setting the car on fire or letting it roll into my neighbor's rock wall).
My only concern is that the clutch fork might rub against the pressure plate. I've also read where guys have relieved about 1/8" to 1/4" of material from the back of the fork to avoid this. Will that significantly lower the strength of the fork?
If none of this works, what other options do I have? (Other than setting the car on fire or letting it roll into my neighbor's rock wall).
Your other option is to go to the McLeod TOB and the 84-88 clutch or,
leave some wire loom close to your headers, then start the car, let it idle and go into the house for @ 5-minutes, then call the fire department,,, dont ask me how I know this either.
Safety Car
Joined: Sep 2003
Posts: 3,598
Likes: 23
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
I'll start by extending the slave push rod length. If it works, but the fork hits the pressure plate, I'll shave a little off the fork.
If nothing works, I'll throw all the wire looms I can find onto my headers, start the car, put a brick on the gas pedal, call the fire department, and drink lots of beer. After 15 minutes, I'll roll the whole flaming mess into a dumpster!!!
If nothing works, I'll throw all the wire looms I can find onto my headers, start the car, put a brick on the gas pedal, call the fire department, and drink lots of beer. After 15 minutes, I'll roll the whole flaming mess into a dumpster!!!
Team Owner
Joined: Oct 2004
Posts: 81,241
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From: altered state
St. Jude Donor '05
Always a way!
Better to add a little to the ball end on the rod going into the fork then forcing the slave to overextend itself.
Just went through that chewed up some synchros.
Sometimes aftermarket clutches can sit a little higher than the stock one creating a situation like yours. Cutting fw etc. Measure everything once you stray from stock.
Better to add a little to the ball end on the rod going into the fork then forcing the slave to overextend itself.
Just went through that chewed up some synchros.
Sometimes aftermarket clutches can sit a little higher than the stock one creating a situation like yours. Cutting fw etc. Measure everything once you stray from stock.
