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Discussion Starter #1 (Edited)
Car before:
M20 trans, GM pressure plate, Centerforce II disk, Centerforce TO bearing, stock bellhousing, stock linkage. Was whisper quiet.

Car now:
T56 trans with American Powertrain mechanical linkage collar, Centerforce Dual Friction plate and disk, Centerforce TO bearing (same one, it only had ~75 easy miles on it), Quicktime bellhousing, same stock linkage

I just finished my T56 swap (aside from the driveshaft) and everything seems to work together just fine. Fit is great, correct parts for the swap, didn't even have to fight the trans mount to get everything together, etc etc.

My issue is this- when I push the clutch pedal in, it is very smooth and silent during the free play phase, but when the TO bearing hits the PP to disengage the clutch I get increased resistance and a groaning/creaking noise.

Stuff I've tried/validated:

  • Pivot ball is greased, adjusted right to 4.75" from block
  • Clutch fork is 5-7* forward as Centerforce says
  • PP properly torqued in a star pattern
  • TO bearing collar on trans has a light film of grease
  • TO bearing is installed properly on the fork
  • Tried adjusting the clutch very tight with no freeplay just to see- pedal got very hard and noise was instant
  • Tried adjusting the clutch very loose- pedal was 1" below brake pedal and could self-center easy, still got noise
  • Greased the Z bar
  • Pulled and re-seated the trans completely
  • Disconnected the clutch entirely to see if the TO slides without issue- it does and is very smooth. Before I did the swap I test fit the TO on the collar and it fit perfectly with no slop but was not tight.

Has anyone ever had a similar issue with a Centerforce dual friction? It REALLY seems like the springs in the clutch itself is making the noise as everything's silent until the TO hits the fingers and applies pressure. If I adjust the clutch pedal slightly on the loose side and start the car, it makes no noise at all when the car is idling and the clutch is engaged, and if I disengage the clutch I get the groan and then silence again, until I let it out, when I get the groan followed by silence again. Everything seems to work 100% great except for when the TO and clutch fingers are in motion. It does not matter if I pump the clutch a few times, the noise is always there, but if I push it hard and fast it's very quick, and if I push the pedal in slowly I can draw a longer groan.

Any ideas? I really do not want to pull the trans again, but if I have to in order to stop a catastrophe I will. I already called Centerforce and they said to tear it all back down and check the pressure plate in a hydraulic press :bored:
 

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well, i'm thinking the T/O bearing is screaming at you... unfortunately there's no way to fix it without re-pulling the trans...
 

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Yeah if the TO moved freely on the shaft then I was thinking the pressure plate is what is making the noise. I guess testing it with a press would tell you if it was making noise, sure is alot of work though. Did centerforce say that if it was the PP making noise, what that meant and if they would replace it for you, if so I guess it has to be torn down again. Sucks, I know. Good luck
 

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once you pull it down hold the face of the bearing in one hand the collar in the other and twist/turn the bearing into the collar, as if you were smashing it together. i've seen where you can feel the bearing twist smoothly then feel like it skips the smoothness and turns free... hard to explain but it'll feel lubed then dry in a way... check it out and see what i mean... and if you need a bearing just stop in at your local reputable parts house and get a bearing... they're all pretty much the same when you're using a quality product. the bearing you bought from CF is probably just a reboxed, std, off the shelf T/o bearing...
 

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Discussion Starter #6 (Edited)
once you pull it down hold the face of the bearing in one hand the collar in the other and twist/turn the bearing into the collar, as if you were smashing it together. i've seen where you can feel the bearing twist smoothly then feel like it skips the smoothness and turns free... hard to explain but it'll feel lubed then dry in a way... check it out and see what i mean... and if you need a bearing just stop in at your local reputable parts house and get a bearing... they're all pretty much the same when you're using a quality product. the bearing you bought from CF is probably just a reboxed, std, off the shelf T/o bearing...
Thanks man!

One other thing I'm thinking and want to check:

The clutch is a Centerforce DF148552. I was given that part number to use because my "stock" setup is only a 10 spline, and I needed a 26 spline disc part number.

That number is for an 11", 1.125 x 26 spline clutch/PP for 1970+ Chevelles, Novas, Corvettes, El Caminos, etc etc. Could there be some type of wacky difference between a '68 SS and a '71 SS Nova, clutch-wise??
 

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no, no differences other than spline count. i dealt with the same thing on my '64 with the 10.5 CF clutch. i'm using their dual friction with my TKO, it's a 26 spline trans also... you're fine with that. ;)

hey, on the inside of the collar where it rides on the bearing retainer... there's a rather shallow groove, maybe 1/16" or so deep and maybe 3/8" wide or so... that groove Inside the collar is supposed to be greased... check it to see if that's dry... maybe the bearing collar is somewhat galling on the bearing retainer on trans as the bearing just touches or comes off pressure on the P/plate... just another thing to look for...
 

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Did you get the TO bearing installed correctly on the fork. Ive seen some people put that little spring clip in the groove on the bearing instead of behind it.
 

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Pulling what remains of my hair out
Look at the bright side Bill.....

With the money you'll save on hair cuts you'll have more money to spend on the car. :D
 

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Got under there tonight and noticed that one of the two 'tangs' that keep the clutch fork on the pivot ball is splayed outward and bent. Don't know how I missed that before.

D'OH


New clutch fork on the way.
That same thing just happened to my brothers Chevelle. He pulled his T-56 out last weekend and found it. His wore some spot's on the bearing collar on opposite side's as if the TO bearing was riding on it cocked. We think when the clutch fork came off the pivot ball, it was at a angle down and was forcing pressure down on the TO bearing, putting it in a bind.Kinda hard to explain unless you see the parts in hand. You might want to check your bearing collar and the inside of your TO bearing for some wear marks. His collar seems to be OK no grooves in it just discolored but he's replacing his TO bearing. He was using a fork from Jegs but it had a GM part # stamped on it.
 

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Discussion Starter #13 (Edited)
Look at the bright side Bill.....

With the money you'll save on hair cuts you'll have more money to spend on the car. :D
LOL. Going bald is weight reduction and better aero.

That same thing just happened to my brothers Chevelle. He pulled his T-56 out last weekend and found it. His wore some spot's on the bearing collar on opposite side's as if the TO bearing was riding on it cocked. We think when the clutch fork came off the pivot ball, it was at a angle down and was forcing pressure down on the TO bearing, putting it in a bind.Kinda hard to explain unless you see the parts in hand. You might want to check your bearing collar and the inside of your TO bearing for some wear marks. His collar seems to be OK no grooves in it just discolored but he's replacing his TO bearing. He was using a fork from Jegs but it had a GM part # stamped on it.
Did a new fork fix it? I didn't really run my engine yet but I'll check for grooves.

I know that Jeg's and Summit's HD forks aren't correct. I bought GM #3892632.
 

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unfortunately the only way to repair/replace the fork is to pull the trans... but while you're at it make sure the inner diameter groove of the T/O bearing is lubed. other than the labor to pull the trans, glad it's an easy fix for ya. i bet that'll never happen again, so it may have been a good thing to have happen, huh? ;)
 

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Discussion Starter #15
unfortunately the only way to repair/replace the fork is to pull the trans... but while you're at it make sure the inner diameter groove of the T/O bearing is lubed. other than the labor to pull the trans, glad it's an easy fix for ya. i bet that'll never happen again, so it may have been a good thing to have happen, huh? ;)
Yup, gonna pull it all out again. Worth it to do it right. I think it's two things- 1, the clutch fork 'tines' are messed up, and 2, the clutch fork angle is probably off, too.

On a positive note, I cut the heads off of some long 3/8" bolts to use as "alignment pins" for reinstallation. Should make it even less of a big deal.
 

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i too have studs that are for that purpose... take a hack saw/cutoff wheel and slice/groove the ends so a screwdriver will turn them if/when they get tight. having weight on them, they may not finger spin out...

i doubt you have any severe damage, if i read everything right there wasn't enough run/drive time involved... just take a look at everything. it may very well be possible there's nothing wrong with the fork either and it just needs removal/proper re-installation...
 

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LOL. Going bald is weight reduction and better aero.



Did a new fork fix it? I didn't really run my engine yet but I'll check for grooves.

I know that Jeg's and Summit's HD forks aren't correct. I bought GM #3892632.
He doesn't have his trans back in yet. He was going to buy another fork from Jegs. I don't think his was making any noise like yours. He said it worked fine when cold but when it heated up it wasn't smooth and had a ratcheting feel to it. This is the fork that he has, http://www.jegs.com/webapp/wcs/stor...ar=0&Ne=1+2+3+13+1147708&searchTerm=555-60101 The GM part # that starts with 140 was stamped on his old one.
 

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Discussion Starter #18 (Edited)
Well, I got my trans back in with a new throwout bearing and new clutch fork. It still makes a noise but it's much more faint, and is a sliding noise vs. a creak now.

Talked to American Powertrain about it and after explaining what I've done to diagnose it they said that nothing seems to be really out of order so I should put a few miles on it and see what happens since everything is still brand new. Could be that I'm just being too critical over something that's totally normal.

At this point I really just think that the TO bearing to bearing collar clearance is a bit tight since everything has no runtime on it.
 
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