Possibly causes for forward clutch failure.
08-27-2015, 10:17 AM
#1
Possibly causes for forward clutch failure.
Bought a truck with bad motor. Rebuilt motor, found out the tranny was toast...forward clutch was metal,no friction material at all.
So I rebuilt it myself with all new seals, clutches, bushings etc. Wasn't quite acting right so I pulled it again, and front clutch is toast again (though not as bad; I only drove it 2 weeks though).
What are any possibly causes to make the forward clutch go out? I'm going to focus on those things. I already have a new torque converter, new solenoids, and will be buying a new valve body. What about all those accumulators and pistons at the bottom near the valve body?
Background: when I first rebuilt and started filling the transmission with mercon V, I put about 6 or 7 quarts in....then started it and shifted through all the gears, total time of about 3-4 min, then cut off truck. Pulled the dipstick to check and white smoke came out. I knew something was burned but wasn't sure how bad. I filled up to about 10quarts and it read that it was full. I started the truck and ran through the gears....this time, there was NO smoke.
I did drain the torque converter, but didn't fill it up prior to install, how bad is that?
Problem I had with tranny after rebuild was it not downshifting, and some slipping (chugging) at higher RPM's. It also sometimes wouldn't rev higher than 2k, but would continue to accelerate.
I could manually shift into "1" and it would run hard and strong, then I would have to shift into "D" and things didn't perform so well.
Any ideas? I've heard from mighty possibly a valve body, which is why I have one on the way.
So I rebuilt it myself with all new seals, clutches, bushings etc. Wasn't quite acting right so I pulled it again, and front clutch is toast again (though not as bad; I only drove it 2 weeks though).
What are any possibly causes to make the forward clutch go out? I'm going to focus on those things. I already have a new torque converter, new solenoids, and will be buying a new valve body. What about all those accumulators and pistons at the bottom near the valve body?
Background: when I first rebuilt and started filling the transmission with mercon V, I put about 6 or 7 quarts in....then started it and shifted through all the gears, total time of about 3-4 min, then cut off truck. Pulled the dipstick to check and white smoke came out. I knew something was burned but wasn't sure how bad. I filled up to about 10quarts and it read that it was full. I started the truck and ran through the gears....this time, there was NO smoke.
I did drain the torque converter, but didn't fill it up prior to install, how bad is that?
Problem I had with tranny after rebuild was it not downshifting, and some slipping (chugging) at higher RPM's. It also sometimes wouldn't rev higher than 2k, but would continue to accelerate.
I could manually shift into "1" and it would run hard and strong, then I would have to shift into "D" and things didn't perform so well.
Any ideas? I've heard from mighty possibly a valve body, which is why I have one on the way.
08-27-2015, 10:20 AM
#2
To add, the fluid was obviously filled with material. I never flushed the lines before reinstall. Could some of the old fluid coming back in caused this? How should I prep for reinstall?
08-28-2015, 10:45 AM
#3
Senior Member
Bought a truck with bad motor. Rebuilt motor, found out the tranny was toast...forward clutch was metal,no friction material at all.
So I rebuilt it myself with all new seals, clutches, bushings etc. Wasn't quite acting right so I pulled it again, and front clutch is toast again (though not as bad; I only drove it 2 weeks though).
What are any possibly causes to make the forward clutch go out? I'm going to focus on those things. I already have a new torque converter, new solenoids, and will be buying a new valve body. What about all those accumulators and pistons at the bottom near the valve body?
Background: when I first rebuilt and started filling the transmission with mercon V, I put about 6 or 7 quarts in....then started it and shifted through all the gears, total time of about 3-4 min, then cut off truck. Pulled the dipstick to check and white smoke came out. I knew something was burned but wasn't sure how bad. I filled up to about 10quarts and it read that it was full. I started the truck and ran through the gears....this time, there was NO smoke.
I did drain the torque converter, but didn't fill it up prior to install, how bad is that?
Problem I had with tranny after rebuild was it not downshifting, and some slipping (chugging) at higher RPM's. It also sometimes wouldn't rev higher than 2k, but would continue to accelerate.
I could manually shift into "1" and it would run hard and strong, then I would have to shift into "D" and things didn't perform so well.
Any ideas? I've heard from mighty possibly a valve body, which is why I have one on the way.
So I rebuilt it myself with all new seals, clutches, bushings etc. Wasn't quite acting right so I pulled it again, and front clutch is toast again (though not as bad; I only drove it 2 weeks though).
What are any possibly causes to make the forward clutch go out? I'm going to focus on those things. I already have a new torque converter, new solenoids, and will be buying a new valve body. What about all those accumulators and pistons at the bottom near the valve body?
Background: when I first rebuilt and started filling the transmission with mercon V, I put about 6 or 7 quarts in....then started it and shifted through all the gears, total time of about 3-4 min, then cut off truck. Pulled the dipstick to check and white smoke came out. I knew something was burned but wasn't sure how bad. I filled up to about 10quarts and it read that it was full. I started the truck and ran through the gears....this time, there was NO smoke.
I did drain the torque converter, but didn't fill it up prior to install, how bad is that?
Problem I had with tranny after rebuild was it not downshifting, and some slipping (chugging) at higher RPM's. It also sometimes wouldn't rev higher than 2k, but would continue to accelerate.
I could manually shift into "1" and it would run hard and strong, then I would have to shift into "D" and things didn't perform so well.
Any ideas? I've heard from mighty possibly a valve body, which is why I have one on the way.
when you did the rebuild, did you replace the forward clutch piston seal? if so, did you use the correct lip seal protector when you assembled it? did you check to make sure you had the correct clutch pack end clearance? did you air check the clutch pack before assembly?
check the grooves on inside of the clutch drum for smoothness, if there is excessive wear, the clutch plates will hang and not release properly.
If you are working on a 4R70/4R75 transmission, check the teflon seals on the input shaft, if these are worn or torn it will leak pressure.
Also check the stator grooves and metal sealing rings on the stator. if those are worn, it will leak pressure.
on the 4R70/4R75 its common for the forward clutch drum to split at the snap ring groove. check it closely, pry on the groove slightly with a screw drive and see if it moves.
08-28-2015, 11:26 AM
#4
2003 f150 lariat 5.4 supercrew, 4r70w
Endplay in the clutch pack was good. I air checked it: responded very nicely with extremely minimum leaking (I wasn't using a rubber tip nozzle).
I used the lip seal installer thing that came in the kit. It was the circular plastic that you kinda roll around the seal to get it to sit. Even though I was getting frustrated, I took my time to not force it. Took me about 2hours off/on from walking away to get it to sit.
Checked the snap ring groove, was still solid. The drum may have been an issue as the clutch was previously burned, but I cleaned it very well and it wasn't discolored. The whole clutch pack went in/out very freely. I'm buying a new one though because this one now is in pretty bad shape.
Gave the entire pump assemply a once over and looked well. I'll check the stator more specifically.
It had all new teflin seals and the metal clad seals installed (those metal ones were a B**tch to get to hook together.
I did check the piston seal in forward drum, it was in good health but there was a very small nic on the seal...talking a millimeter or probably less. That enough to cause all this?
Endplay in the clutch pack was good. I air checked it: responded very nicely with extremely minimum leaking (I wasn't using a rubber tip nozzle).
I used the lip seal installer thing that came in the kit. It was the circular plastic that you kinda roll around the seal to get it to sit. Even though I was getting frustrated, I took my time to not force it. Took me about 2hours off/on from walking away to get it to sit.
Checked the snap ring groove, was still solid. The drum may have been an issue as the clutch was previously burned, but I cleaned it very well and it wasn't discolored. The whole clutch pack went in/out very freely. I'm buying a new one though because this one now is in pretty bad shape.
Gave the entire pump assemply a once over and looked well. I'll check the stator more specifically.
It had all new teflin seals and the metal clad seals installed (those metal ones were a B**tch to get to hook together.
I did check the piston seal in forward drum, it was in good health but there was a very small nic on the seal...talking a millimeter or probably less. That enough to cause all this?
08-30-2015, 10:03 AM
#5
Senior Member
so you didnt replace the forward clutch piston seal?
even the smallest nick and cause a pressure leak. This means the clutch will apply, but may leak pressure slowly and cause the clutch to burn.
Understand that the forward clutch is applied once you put the gear selector in Drive and it stays applied in 1st, 2nd and 3rd gear, so it has to keep fluid pressure otherwise it starts to slip.
I would also check the pressure regulator valve in the valve body, these like to wear and get scored, which causes a pressure leak.
It is also common for the separator plate to bend and crack where the 2-3 servo cover pushes on the plate. If the dimple becomes severe enough, Forward clutch pressure can bleed over to the direct clutch passage. I replace the separator plate with the Superior Tuff plate part # K092
even the smallest nick and cause a pressure leak. This means the clutch will apply, but may leak pressure slowly and cause the clutch to burn.
Understand that the forward clutch is applied once you put the gear selector in Drive and it stays applied in 1st, 2nd and 3rd gear, so it has to keep fluid pressure otherwise it starts to slip.
I would also check the pressure regulator valve in the valve body, these like to wear and get scored, which causes a pressure leak.
It is also common for the separator plate to bend and crack where the 2-3 servo cover pushes on the plate. If the dimple becomes severe enough, Forward clutch pressure can bleed over to the direct clutch passage. I replace the separator plate with the Superior Tuff plate part # K092