LLY: Pedal issue

Brassfield

New member
Jan 14, 2014
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West Plains, MO
In my zf6, I have a Valair Dual Disk Comp Clutch. At the end of the of every hook I do, when pulling, the pedal is on the floor. Clutch isn't slipping when going down the track but I kill it at the end every time because the pedal is on the floor. Usually just a pump or two and its back up and normal. I have called Valair and they had me call another shop, I tried the DOT 5 brake fluid like they said and it's still the same. Anyone else have this issue before?
The truck is a s400 2.5 truck if that makes any difference
 

ironmax

chock full of goodies
Jul 7, 2010
502
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28
Col. Ohio
So the clutch pedal is sticking during the pull. Need more info. Does it come up briefly then goes back down, or does it just stay down the whole time?
Is this the only time it does it, regular driving works fine?
 

clrussell

pro-procrastinator
Sep 23, 2013
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So the clutch pedal is sticking during the pull. Need more info. Does it come up briefly then goes back down, or does it just stay down the whole time?
Is this the only time it does it, regular driving works fine?


Strict pulling truck. At the start of the track and all the other time you drive it around the pits/ shop the clutch is normal.

After you make a pass pulling the clutch pedal goes to the floor when you try clutching it at the end and it just stays there like you have no fluid in the system for the fluid to push it back up. After you pull the pedal back to the top and pump it a couple times the pedal goes back to normal.

Almost like it's boiling the fluid or something.

I've flushed the fluid to new dot5 by pulling the line loose at the slave and having someone pour in the master while I have a mighty vac pulling fluid from the line. Ran about a quart through it to get clean fluid.

When I put the clutch in it got a new slave cyl that looked like a stock gm. It came with the clutch kit. That's the only thing we have not changed trying to remedy the problem.

It got a known good master cyl put on it when we put the clutch in it.

I know southbend had a problem a few years ago with their slave and now they are back to selling gm stockers with their kit.

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dirty_max

Member
Jan 27, 2013
815
2
18
eureka il
mine wouldn't stick when I got to the end of the track but I would be extremely soft like it was almost going to stick to the floor. which clutch do you have? when this issue was at its worse in my truck the throw out bearing blew apart because the 3 lever adjustment nuts on my pressure plate had backed off and the levers were all at different heights and I was having issues getting the clutch to disengage. and just like any other time I would call valair and ask for help they would tell me that I was not using their clutch in the proper application and they couldn't help me. I have their sintered iron dual disc, and its just a workstock truck so it saw plenty of street time as well. I did have a few times driving down the road where it would stick to the floor. if I was on the interstate for half an hour or so and then went to clutch before downshifting at a ramp, it would stick to the floor. but, since I fixed the lever adjustment and changed the slave cylinder it hasn't done it.
 

SmokeShow

Well-known member
Nov 30, 2006
6,818
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Lawrenceburg, KY
There was a guy on TDP and here for a while (totally spacing on his name but he's a mod there I think and several zf6 trucks - farms in Midwest). He found he fixed several issues w/ his ZFs once he put a trans fluid cooler on his. IIRC the ford ZF6 has a trans cooler, but like the lift pump for the cp3, GM thought it'dbe ok w/o it.


Have you determined if it's losing fluid (boiling off) or is it remaining full while this condition happens?
 

clrussell

pro-procrastinator
Sep 23, 2013
5,903
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mine wouldn't stick when I got to the end of the track but I would be extremely soft like it was almost going to stick to the floor. which clutch do you have? when this issue was at its worse in my truck the throw out bearing blew apart because the 3 lever adjustment nuts on my pressure plate had backed off and the levers were all at different heights and I was having issues getting the clutch to disengage. and just like any other time I would call valair and ask for help they would tell me that I was not using their clutch in the proper application and they couldn't help me. I have their sintered iron dual disc, and its just a workstock truck so it saw plenty of street time as well. I did have a few times driving down the road where it would stick to the floor. if I was on the interstate for half an hour or so and then went to clutch before downshifting at a ramp, it would stick to the floor. but, since I fixed the lever adjustment and changed the slave cylinder it hasn't done it.


I think his is a comp Sfi clutch. I'm not 100% sure I just installed it a year ago lol.

There was a guy on TDP and here for a while (totally spacing on his name but he's a mod there I think and several zf6 trucks - farms in Midwest). He found he fixed several issues w/ his ZFs once he put a trans fluid cooler on his. IIRC the ford ZF6 has a trans cooler, but like the lift pump for the cp3, GM thought it'dbe ok w/o it.


Have you determined if it's losing fluid (boiling off) or is it remaining full while this condition happens?


Not actually loosing fluid just acts like it has no fluid at the end of the track.

Has it been doing it since it was installed? What Did the other shop say?


Other shop suggested changing the fluid which we tried..

He has been bugging me to help him pull the trans and install a new slave and check out the clutch. We just havnt had time. It's hay season for him and I've been to busy to think about it.


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dirty_max

Member
Jan 27, 2013
815
2
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eureka il
I would guess its the sintered iron then. it was about a year after I put mine in that is started acting up as well. I remember because when I called valair it was still under warranty and they pissed me off. did that clutch have the "adjustable" levers on it? and did you measure them when you installed it? I think that's a pretty important step and if I remember correctly they are supposed to measure .650" or 750" from the highest point on the pressure plate. I wish I was closer I would give you guys a hand, I hand my trans out so many times last year that It only took me about 2 hours the last time I did it, lol. I had read something somewhere about people fighting issues with their brake fluid in the slave cylinder boiling or something like that and they started using synthetic fluid of some sort iirc.
 

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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Lexington, Ky
I don't think your supposed to run DOT 5! That's a totally different fluid base. I have ran dot 3 in the past and just recently put in a super dot 4 (dot 5.1) with a 660 boiling point. I would suggest moving the line as far away possible from the exhaust manifold. I have had issues at the end of my pull where I'd go into reverse and it would back up by itself without engaging the clutch. I haven't got to use this new fluid yet, as I ended up breaking the pedal and didn't fix it in time last weekend.


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clrussell

pro-procrastinator
Sep 23, 2013
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I would guess its the sintered iron then. it was about a year after I put mine in that is started acting up as well. I remember because when I called valair it was still under warranty and they pissed me off. did that clutch have the "adjustable" levers on it? and did you measure them when you installed it? I think that's a pretty important step and if I remember correctly they are supposed to measure .650" or 750" from the highest point on the pressure plate. I wish I was closer I would give you guys a hand, I hand my trans out so many times last year that It only took me about 2 hours the last time I did it, lol. I had read something somewhere about people fighting issues with their brake fluid in the slave cylinder boiling or something like that and they started using synthetic fluid of some sort iirc.


I honestly can't remember on the adjustable fingers. I have a feeling it will be coming back out soon. We have a nice drive on lift and trans jack at the shop, I think last one I did I had it out in an hour.

I don't think your supposed to run DOT 5! That's a totally different fluid base. I have ran dot 3 in the past and just recently put in a super dot 4 (dot 5.1) with a 660 boiling point. I would suggest moving the line as far away possible from the exhaust manifold. I have had issues at the end of my pull where I'd go into reverse and it would back up by itself without engaging the clutch. I haven't got to use this new fluid yet, as I ended up breaking the pedal and didn't fix it in time last weekend.


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Maybe we aren't running dot5 I'll double check the bottle I put in later. Maybe it was synthetic dot4

But on a side note, are you trying to slip the clutch at the end?


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Not trying to slip the clutch. Just trying to get it out of gear at the end of the track before it dies


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zf>allison

you never had your car.
Apr 30, 2013
3,394
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elsberry mo
mine wouldn't stick when I got to the end of the track but I would be extremely soft like it was almost going to stick to the floor. which clutch do you have? when this issue was at its worse in my truck the throw out bearing blew apart because the 3 lever adjustment nuts on my pressure plate had backed off and the levers were all at different heights and I was having issues getting the clutch to disengage. and just like any other time I would call valair and ask for help they would tell me that I was not using their clutch in the proper application and they couldn't help me. I have their sintered iron dual disc, and its just a workstock truck so it saw plenty of street time as well. I did have a few times driving down the road where it would stick to the floor. if I was on the interstate for half an hour or so and then went to clutch before downshifting at a ramp, it would stick to the floor. but, since I fixed the lever adjustment and changed the slave cylinder it hasn't done it.



I had a south bend dual disc and it did the exact same thing, be on the highway for an extended period of time and I'd clutch to down shift and it would stick down at an off ramp. I know I broke my short throw in half and I was dogging the truck fairly hard. When I was on the side of the road I tried to take the short throw out and the bolts were so hot I could barely touch it. I wonder what kind of Temps they see not having the trans cooler like the fords...
 

zf>allison

you never had your car.
Apr 30, 2013
3,394
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36
elsberry mo
You almost have to be losing or boiling fluid, maybe wrap your slave line with some heat tape or something and see what happends. I don't know what would cause the pedal to suck down, never heard of an issue like this.
 

dirty_max

Member
Jan 27, 2013
815
2
18
eureka il
I had a south bend dual disc and it did the exact same thing, be on the highway for an extended period of time and I'd clutch to down shift and it would stick down at an off ramp. I know I broke my short throw in half and I was dogging the truck fairly hard. When I was on the side of the road I tried to take the short throw out and the bolts were so hot I could barely touch it. I wonder what kind of Temps they see not having the trans cooler like the fords...

I wouldn't think trans temp would have anything to do with the clutch

Mine's laying on the floor before I even touch it Jesse, and my hook may only last 10-15 seconds usually

oh so you are saying that it goes back to the floor by itself?! I call that good ol fashion witchcraft. that would make me think that your fluid is boiling and expanding, or a weak pressure plate. I had a different dual disc before that didn't have near the pressure that my pulling clutch does and I couldn't get that pedal to come off the floor at all the first time I hooked to a sled with it.