4L60E forward clutch pack clearance
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From: Austin Tx
4L60E forward clutch pack clearance I am building a 2003 4L60E trans for my C10 project, and have right at .090 clearance on the forward clutch stack. I used raybestos .067 stage one frictions and .090 Kolene steels. My current pressure plate is a "C" plate, and I have had no luck in finding a "B" plate to close up the clarance. Everybody has the "C" plates, so that must have been the most common pressure plate that the general used. I checked the plates and steels that come out of the trans and they were .067/.090 as well, so it must have had a bunch of clearance in it before I pulled it apart. Are there any other options to tighten up the clearance?
Regards, John McGraw
Regards, John McGraw
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From: BERWICK PA
The .090 is fine in this pack and is typical. But if you want to tighten up get another waved cushion plate align the waves as close as possible and this will usually get you down to .020 to .040 on the pack. I actually like this pack to be pretty loose as it drags when idling in park or neutral and drag can make hot spots or distort steels due to hot spots. Optionally the very early 700r4 used thicker frictions, You can get one or two of those in the same material (Even this is not imperative just looks better if someone tears it down ever) as this set is always on in all forward gears. But as I said what you have is fine as since always on you are a not dealing with clutch overlap or shift times.
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From: Austin Tx
Thanks, The ATSG called out for a max of .063 on this pack, but this is not the first time during this rebuild that I have found the min and max specs in the ATSG to be wrong. The manual called out for the stack height on the low/reverse clutch pack to be acceptable at 2.24", but when I put mine together at that spec, the clutch was locked tight, I had to get down to 2.16" to allow any clearance at all. At 2.16, I only get about .030 of piston movement, and that is without a wave plate. I pulled the wave plate out and replaced it with an old, thinner steel from the old pack to get the clearance I needed. I had to grind some of the ears off the steel so that it would sit flat on the piston, but it works fine now. I was told that with the new wide band, getting rid of the wave would allow the pack to unlock fast enough that the band would not be fighting the clutch pack.
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From: BERWICK PA
Thanks, The ATSG called out for a max of .063 on this pack, but this is not the first time during this rebuild that I have found the min and max specs in the ATSG to be wrong. The manual called out for the stack height on the low/reverse clutch pack to be acceptable at 2.24", but when I put mine together at that spec, the clutch was locked tight, I had to get down to 2.16" to allow any clearance at all. At 2.16, I only get about .030 of piston movement, and that is without a wave plate. I pulled the wave plate out and replaced it with an old, thinner steel from the old pack to get the clearance I needed. I had to grind some of the ears off the steel so that it would sit flat on the piston, but it works fine now. I was told that with the new wide band, getting rid of the wave would allow the pack to unlock fast enough that the band would not be fighting the clutch pack.
Also note the LOW/REV set is not on ever in any gear position but manual low 1 and reverse so unless shifting manually , Band 2nd first clutch overlap is not an issue.
On the fwd set my rule is if the clearance is no more than the thickness of a fwd steel I leave it be. If more I keep a few old style thicker 700 frictions of same type to replace 1 or 2 of them, Now I would never leave the wave plate out of forward and would worry about snaping the fwd clutch snap ring lugs off in drum .
But it does sound like you may have a miss matched kits with early 700 and late 4l60e steels and or clutches. I have run into that a couple times with kits the last year or so.
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From: Austin Tx
Thanks for all the good info Frank! I did not even know about the .080 frictions until you told me. I will probably buy 2 or 3 of them just to tighten up the stack a little. I found a B pressure plate yesterday at Cobra transmission parts, but it looks like they take 7-10 days to even ship an order, and I really do not want this trans torn apart on my work bench for the next 2 weeks! The B plate will only give me about .025" decrease in clearance , and I can get almost that much with a couple of .080 frictions. I am hoping that the 3-4 clutch pack goes smooth after I get the forward done. I probably should have put the pressure plate and snap ring in and built up the 3-4 last weekend just to see if there were going to be any issues.
Regards, John McGraw
Regards, John McGraw
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From: BERWICK PA
Thanks for all the good info Frank! I did not even know about the .080 frictions until you told me. I will probably buy 2 or 3 of them just to tighten up the stack a little. I found a B pressure plate yesterday at Cobra transmission parts, but it looks like they take 7-10 days to even ship an order, and I really do not want this trans torn apart on my work bench for the next 2 weeks! The B plate will only give me about .025" decrease in clearance , and I can get almost that much with a couple of .080 frictions. I am hoping that the 3-4 clutch pack goes smooth after I get the forward done. I probably should have put the pressure plate and snap ring in and built up the 3-4 last weekend just to see if there were going to be any issues.
Regards, John McGraw
Regards, John McGraw
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From: Austin Tx
Frank,
I put my 3-4 pack together tonight and got clearance of about .035 with my dial indicator. Would you leave well enough alone, or open up the clearance another 10-15 thousands? The clutches are Z pack with Kolene steels. It is a 7 clutch stack with the Sonnax heavy duty backing and apply plates. The steels are .092, and I could drop to .076 on the last plate and pick up another .016 if you think it is necessary. I have read two schools of thought on this, and one side says keep it loose .050-.060 and the other says closer to .030 is better. I would be interested in your thoughts.
Regards, John McGraw
I put my 3-4 pack together tonight and got clearance of about .035 with my dial indicator. Would you leave well enough alone, or open up the clearance another 10-15 thousands? The clutches are Z pack with Kolene steels. It is a 7 clutch stack with the Sonnax heavy duty backing and apply plates. The steels are .092, and I could drop to .076 on the last plate and pick up another .016 if you think it is necessary. I have read two schools of thought on this, and one side says keep it loose .050-.060 and the other says closer to .030 is better. I would be interested in your thoughts.
Regards, John McGraw
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From: BERWICK PA
Frank,
I put my 3-4 pack together tonight and got clearance of about .035 with my dial indicator. Would you leave well enough alone, or open up the clearance another 10-15 thousands? The clutches are Z pack with Kolene steels. It is a 7 clutch stack with the Sonnax heavy duty backing and apply plates. The steels are .092, and I could drop to .076 on the last plate and pick up another .016 if you think it is necessary. I have read two schools of thought on this, and one side says keep it loose .050-.060 and the other says closer to .030 is better. I would be interested in your thoughts.
Regards, John McGraw
I put my 3-4 pack together tonight and got clearance of about .035 with my dial indicator. Would you leave well enough alone, or open up the clearance another 10-15 thousands? The clutches are Z pack with Kolene steels. It is a 7 clutch stack with the Sonnax heavy duty backing and apply plates. The steels are .092, and I could drop to .076 on the last plate and pick up another .016 if you think it is necessary. I have read two schools of thought on this, and one side says keep it loose .050-.060 and the other says closer to .030 is better. I would be interested in your thoughts.
Regards, John McGraw
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From: Austin Tx
Frank,
Thanks for all the help. Now, I have to admit that I apparently had a self-inflicted wound!
After I got it all together tonight, I figured I better make one last air test of all the clutches. Well the forward piston worked well, but the overrun and 3-4 piston both had huge air leaks! I took it all back apart and reinstalled all the pistons making sure that I had not cut any seals. When I put it back together, the clearances were entirely different on both the forward and 3-4 clutches. The forward went from .090 down to less than .030 and the 3-4 went from .035 to almost .070. Pulled out the 3 thick plates that I put in the forward today, and dropped the last steel in the 3-4 to a thicker steel that I had from the old clutch, and everything is fine! The forward is now .050 and the 3-4 is right at .040. I should have known that the dimensions could not have been that far off! The 3-4 piston must have been cocked, which pushed the 3-4 apply out too far, which made the 3-4 clearance tighter and the forward clearance way too large. Air test was good, so I can finally put that task behind me. I must have taken those clutches apart 10 times looking for a problem, but never pulled it all the way back apart to the pistons.
Regards, John McGraw
Thanks for all the help. Now, I have to admit that I apparently had a self-inflicted wound!
After I got it all together tonight, I figured I better make one last air test of all the clutches. Well the forward piston worked well, but the overrun and 3-4 piston both had huge air leaks! I took it all back apart and reinstalled all the pistons making sure that I had not cut any seals. When I put it back together, the clearances were entirely different on both the forward and 3-4 clutches. The forward went from .090 down to less than .030 and the 3-4 went from .035 to almost .070. Pulled out the 3 thick plates that I put in the forward today, and dropped the last steel in the 3-4 to a thicker steel that I had from the old clutch, and everything is fine! The forward is now .050 and the 3-4 is right at .040. I should have known that the dimensions could not have been that far off! The 3-4 piston must have been cocked, which pushed the 3-4 apply out too far, which made the 3-4 clearance tighter and the forward clearance way too large. Air test was good, so I can finally put that task behind me. I must have taken those clutches apart 10 times looking for a problem, but never pulled it all the way back apart to the pistons.
Regards, John McGraw
Last edited by J McGraw; May 20, 2025 at 10:28 AM.
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From: Poplarville, MS
I thought the Z pack clutches had friction material on one side a bear steal on the other. The reason I am asking is because if that's the case be careful where/how you are placing the extra steels.
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From: BERWICK PA
Yes , I assumed he misspoke and is actually using GPZ frictions, If indeed using a z pack that changes everything, Extra steels can only be added at top of pack.
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