Will higher line pressure wear out clutches faster?
09-12-2005, 10:07 PM
#1
Will higher line pressure wear out clutches faster? A buddy of mine and I were messing around with some tuning. We raised the line pressure on the 1-2 shift a little because it was rather soft. It shifts much harder than it did before (no kick to it before, now theres a noticable kick). Will upping the line pressure cause more wear or less wear on my clutches? 
09-13-2005, 05:41 AM
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It seems to me that more pressure holding the clutches would be better. It wouldnt allow them to slip and wear out under high power. I thought that was part of the reason for going vacuum modulated. The stock setttings in the trans tables dont apply full pressure in third gear for sure.
09-14-2005, 09:13 AM
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Just from my own experience I never toasted a tranny until I messed with the line pressure and then it was one after another. I'm not against upping the line pressure just do it in moderation
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09-14-2005, 06:45 PM
#8
I think theres (more) misunderstanding automatic transmission operation here.
There is no way more pressure burns the clutches up.
This is basically how it works. The clutch apply pistons and the drums they're in create a chamber that fills with fluid that applies the clutch. The more pressure the more clamping force.
The problem is misdiagnosis. High pressure can among other things blow out clutch apply piston seals. Then guess what that does, it burns the clutch up because the apply pressure is leaking out of the blown seal.
Then some people actually take the trans apart, see a burnt clutch pack, replaces it and it burns up again because they never checked the seals. What do you have then? Another piece of **** 4L60E, or so is thought. The actual problem was not fixed and was caused but bumping the pressure up way too high.
But thats just my opinion, I'm just a dumbass doing this for free, not trying to get a sale.
There is no way more pressure burns the clutches up.
This is basically how it works. The clutch apply pistons and the drums they're in create a chamber that fills with fluid that applies the clutch. The more pressure the more clamping force.
The problem is misdiagnosis. High pressure can among other things blow out clutch apply piston seals. Then guess what that does, it burns the clutch up because the apply pressure is leaking out of the blown seal.
Then some people actually take the trans apart, see a burnt clutch pack, replaces it and it burns up again because they never checked the seals. What do you have then? Another piece of **** 4L60E, or so is thought. The actual problem was not fixed and was caused but bumping the pressure up way too high.
But thats just my opinion, I'm just a dumbass doing this for free, not trying to get a sale.
09-14-2005, 07:56 PM
#9
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line pressure: craig clutches actually last longer with hi line because they engage quicker- less slippage during the application- slippage is really the only wear factor when it comes to clutches.
however- (seems there's always a however)- if line gets too hi- it puts more pressure on the sides of the sealing rings-(very important)- than they can handle- and wears them out prematurely- this is just one risk of installing a full race kit- they are designed to operate at the extreme borderline of street safety (safety of the trans) full race shift kits if installed properly will not last long at all on the street- also wear actually occurs on some of these parts while running in neutral and park. Craig
however- (seems there's always a however)- if line gets too hi- it puts more pressure on the sides of the sealing rings-(very important)- than they can handle- and wears them out prematurely- this is just one risk of installing a full race kit- they are designed to operate at the extreme borderline of street safety (safety of the trans) full race shift kits if installed properly will not last long at all on the street- also wear actually occurs on some of these parts while running in neutral and park. Craig
09-14-2005, 11:34 PM
#11
Originally Posted by s346k
would the addition of an aftermarket stall converter extend the life of the transmission with a full race shift kit installed?
So the line pressure is still there, in fact it's there more often with a higher stall converter.
09-15-2005, 12:54 PM
#12
I would not mess with the PCM commanded pressure on a built tranny unless told to do so by your tranny builder. Most install a shift kit and make other changes to the fluid flow and I believe that the upgrades are designed to work with stock pressure.
