Centerforce DF 12" shifting issues
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From: Decatur, AL
Centerforce DF 12" shifting issues I have bled the clutch 3 times and confident there is no air in the system. It drives great during normal driving. At high rpm shifts it won't go into gear and I have to granny shift it big time. The worst of it is at the end of a long 2nd or 3rd pull and I grab the clutch at 6k+ rpm it won't release. No matter how hard I mash it to the floor it won't release. I have to pull the shifter out of gear in order to coast and it has pressure on the shifter and pops when I get it out. The pressure plate fingers are obviously flexing. I have a brand new 01 slave cyl and stock 05 truck master cyl. Like I said before, it releases at the proper location and drives great normally. I have 1k miles on it and has done this from the start. Can anyone relate to similar problems?
It is entirely possible that the opposite of what you think is happening. Your theory is that the spring fingers are flexing and not allowing the clutch to release. What may be happening is that the spring is being over extended and this cause the clutch to engage. Pushing the pedal harder only makes the problem worse.
One way to check this is to jack up the truck and with the engine turned off have someone turn the driveshaft by hand. Slowly press the clutch and see at what point the driveshaft is able to be turned by hand. Note the position of the clutch pedal at the point where the driveshaft can be turned by hand. If there is several inches left in the pedal, push more and see if it gets harder to turn the driveshaft by hand again.
What is the bore of the 05 truck MC?
***edit***
Looks like the clutch MC bore on an 04 Silverado 1500 is 45/64" (.70"). Stock F-body is 3/4" bore. You may not have enough travel. Try doing the above check and see what you come up with.
Andrew
One way to check this is to jack up the truck and with the engine turned off have someone turn the driveshaft by hand. Slowly press the clutch and see at what point the driveshaft is able to be turned by hand. Note the position of the clutch pedal at the point where the driveshaft can be turned by hand. If there is several inches left in the pedal, push more and see if it gets harder to turn the driveshaft by hand again.
What is the bore of the 05 truck MC?
***edit***
Looks like the clutch MC bore on an 04 Silverado 1500 is 45/64" (.70"). Stock F-body is 3/4" bore. You may not have enough travel. Try doing the above check and see what you come up with.
Andrew
Last edited by Project GatTagO; May 22, 2006 at 10:37 AM.
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Thanks for the info. I'll try that. I know of a guy using an 02 turck master with no problems. Another thing I though about is I have a lightweight steel flywheel(ebay special). It is extremely back-cut on back side to lighten it up and it is pretty thin (17lb I think). Maybe the pressure plate is flexing but if that's the case why doesn't it flex all the time. If it is overextending like you say then at high speed & rpm it should still release when I mash it then re-engage. I think I should be able to feel it do so with that kind of load against it upon deceleraton at 6500rpm and 130mph. I'll get someone to help me with the driveshaft rotation. Thanks for the info on the MC diameters. I was currious of that.
I seriously doubt that the flywheel is flexing. What might be happening is that the flywheel was made with less offset and positions the friction surface closer to the block. This would more the fingers of the spring away from the TOB and cause the clutch not to disengage fully. Again the test I discribed will give you a good idea of what is happening.
Please post what you find. I am curious!
Andrew
Please post what you find. I am curious!
Andrew
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From: Decatur, AL
Originally Posted by Project GatTagO
What might be happening is that the flywheel was made with less offset and positions the friction surface closer to the block.
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Staging Lane
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mjhoward and tomss99,
Please give us a call (800) 932-5882 ask for tech. I am sending this link to them so that they will be aware of the problems you guys are having.
Best Regards,
Will Baty
Centerforce Clutches
Please give us a call (800) 932-5882 ask for tech. I am sending this link to them so that they will be aware of the problems you guys are having.
Best Regards,
Will Baty
Centerforce Clutches
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From: Decatur, AL
I did the rotate the driveshaft while clutch all the way in and slowly released and I could easily rotate the driveshaft while in gear and the clutch all the way on the floor and rotated smoothly until it started catching while being slowly released. The over-extending theory doesn't seem to be the case. I'm going to call Centerforce when they open. It appears i'm not the only one having this problem.
Last edited by mjhoward; May 24, 2006 at 09:23 AM.
Originally Posted by mjhoward
I did the rotate the driveshaft while clutch all the way in and slowly released and I could easily rotate the driveshaft while in gear and the clutch all the way on the floor and rotated smoothly until it started catching while being slowly released. The over-extending theory doesn't seem to be the case. I'm going to call Centerforce when they open. It appears i'm not the only one having this problem.
Andrew
If you have that clutch in a turboed 6.0 you undoubtedly make to much power for that disc. At 500rwhp in a 3500# corvette, the first centerforce dual friction disc actually cracked the friction material around the disc near each hub spring. The second one went up in smoke in 4th gear and had pieces of the friction surface broken off the disc gouging into the pp. You are trying to use the same clutch in a heavier vehicle that I'm guessing is making more power.
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Don't know about power yet but I'm sure it's more that 500rwhp. My shifting problems have nothing to do with hp though. I haven't even launched it on radials yet much less slicks. I just got this clutch until I could afford something better. As long as i'm not rough on it it should last a while.
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Update. Finally got around to installing a .160" shim behind the slave. The release point is a little higher, as it should, but the problem still exist. As I said before, driving around normal is fine but trying to shift at 6000-6500 and the trans is still undr load when coming out of gear. It pops when shifter goes to neutral and won't go into the next gear until 4k rpms or less(basically when the rpms drop to sychonization point of the next gear). I personally feel that the weights on the fingers are doing too good of a job and flexing the fingers do to excessive centrifugal force. This bowing of the fingers is closing the gap on the disc at high rpm. Anyone have anything else to add. Centerforce's tech dept consist of voice mail and the 1 message I left a couple of weeks ago went unreturned. Never get anything other than voicemail when I call 
Not impressed by their customer service or product so far.
Not impressed by their customer service or product so far. 
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From: Decatur, AL
Originally Posted by 02SOMWS6
man I thought a shim would have fixed it for sure. Might be time for a adjustable master
I'm not saying that an adjustable master won't fix the problem but do I want to risk that expense? Also, they don't make an adjustable master for a truck and the mount is very different than the f-body. I have bled it 4 times and probably used an entire qt of dot3 fluid, that is how much i've pumped through there. Not to mention 2k miles of driving for air to work itself out to the resivoir.
As I said to you in a PM I had a similar problem while I went to the track with mine, hence the low mph. Anyway, I just bled the crap out of it several times and no issues, no shims. I am running SPEC's billet steel flywheel though. I'm running an 04 master and a modified f-body line. I don't know if we discussed this, but does the truck line have any type of restrictor in it? It might need a drill mod. The little restrictor plate could be burried in there aways too. Just a thought.
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From: Decatur, AL
I have not done the drill mod nor do I know if the truck line has a restrictor. The drill mod eliminates the orfice restriction which slows down the release rate. @6500 in the top of 2nd or third gear I grab the clutch to coast and it won't release. As much as 2-3 seconds have elapsed before I got the shifter yanked out of gear, and I mean yanked out! That pretty much rules out a restriction in the line causing it wouldn't you think? Thank for the input.
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mjhoward,
Please call me, (800) 932-5882 dial "0" and ask for me. I will only be here another 35 minutes so if I miss your call please ask for K.C. Payne. I am going to let him know that incase I miss your call to expect your call. I am sorry that you never got a returned phone call, do you know who you left a message with??
The Orfice also limits the amount of travel the TOB will move depending on how fast you depress the clutch pedal? I will explain this in more detail when you call.
Best Regards,
Will Baty
Centerforce Clutches
Please call me, (800) 932-5882 dial "0" and ask for me. I will only be here another 35 minutes so if I miss your call please ask for K.C. Payne. I am going to let him know that incase I miss your call to expect your call. I am sorry that you never got a returned phone call, do you know who you left a message with??
The Orfice also limits the amount of travel the TOB will move depending on how fast you depress the clutch pedal? I will explain this in more detail when you call.
Best Regards,
Will Baty
Centerforce Clutches
