4L60E - reverse drum binding
03-29-2017, 01:54 PM
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4L60E - reverse drum binding
I love the animation that suggests doing a forum search first. 
I did!
Didn't find anything though so...
Putting my trans back together and after putting in the 2-4 servo I checked to see if the output shaft still turned both ways and it didn't. So I've been tearing it down and putting it together in different ways trying to figure out what is binding.
I'm to the point that I've left out the input drum as well as the 2-4 band and servo. The second I screw the pump in that output shaft hard locks to the right.
My theories are that either the pump is too tight in the reverse drum, or that the reverse drum is pinched between the sun shell and pump.
Theory 1 - The pump is too tight in the reverse drum.
When I pull the pump out it always brings the reverse drum with it. I have to use two prybars, one on each side, to pry them apart. When they are together I can get the pump to spin inside the reverse drum, but it is really hard. Should the pump come out of the trans without the reverse drum? Should they spin more freely?
Theory 2 - The reverse drum is pinched between the sun shell and pump.
When I seat the reverse drum into the sun shell, there is about an 1/8 inch of clearance between the shelf the pump bolts into and the top of the reverse drum. Once I assemble everything I can't see or tell if the pump is touching the top of the drum or not. The inner race that the sun shell sits on at the other end sticks up about 1/4" beyond the sprag. Should the inner race be seated more fully into the sprag?
Thank you in advance!(With more thank you's for help to come!)
I did!Didn't find anything though so...
Putting my trans back together and after putting in the 2-4 servo I checked to see if the output shaft still turned both ways and it didn't. So I've been tearing it down and putting it together in different ways trying to figure out what is binding.
I'm to the point that I've left out the input drum as well as the 2-4 band and servo. The second I screw the pump in that output shaft hard locks to the right.
My theories are that either the pump is too tight in the reverse drum, or that the reverse drum is pinched between the sun shell and pump.
Theory 1 - The pump is too tight in the reverse drum.
When I pull the pump out it always brings the reverse drum with it. I have to use two prybars, one on each side, to pry them apart. When they are together I can get the pump to spin inside the reverse drum, but it is really hard. Should the pump come out of the trans without the reverse drum? Should they spin more freely?
Theory 2 - The reverse drum is pinched between the sun shell and pump.
When I seat the reverse drum into the sun shell, there is about an 1/8 inch of clearance between the shelf the pump bolts into and the top of the reverse drum. Once I assemble everything I can't see or tell if the pump is touching the top of the drum or not. The inner race that the sun shell sits on at the other end sticks up about 1/4" beyond the sprag. Should the inner race be seated more fully into the sprag?
Thank you in advance!(With more thank you's for help to come!)
03-29-2017, 08:53 PM
#2
If you leave the reverse input drum out, and seat the pump, what happens? What all is any upgrades have you done to planetaries, sunshell sprag, bearings etc? What selective shim is on the input shaft. There should be a number on it 67,68,69,70,71
As far as the reverse inout drum stivking, what youre describing sounds way too tight, did you replace the sealing rings on the stator and did you size them correctly and lube them? Also did they roll when you installed them. Is the reverse input drum a new gm unit or aftermarket?
As far as the reverse inout drum stivking, what youre describing sounds way too tight, did you replace the sealing rings on the stator and did you size them correctly and lube them? Also did they roll when you installed them. Is the reverse input drum a new gm unit or aftermarket?
03-30-2017, 12:24 PM
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Thank you Wolftrk99!
"If you leave the reverse input drum out, and seat the pump, what happens?"
-The output shaft spins freely.
"What all is any upgrades have you done to planetaries, sunshell sprag, bearings etc?"
-I have a five pinion rear planetary and a GM heat treated sunshell. The sprag is oem as far as I remember. The torrington bearings were replaced six years ago and are silk smooth. When I don't install the input drum, reverse drum, or pump, all of the rear hardware spins freely in both directions.
"What selective shim is on the input shaft."
It's either a 67 or a 69. Shouldn't matter though as I've left the input drum out completely and it still binds.
"did you replace the sealing rings on the stator and did you size them correctly and lube them?"
- I did replace and size the teflon stator seals as well as lube them. I'm a bit shaky on the "size them correctly" part though. It seems like they expand out again after sizing. I also didn't really squash them down as I was afraid of them being too loose and causing a leak.
"Also did they roll when you installed them."
I'm not sure what you mean by "roll". Do you mean when a corner of the seal catches and rolls like a rubber rolling? My first set did that and I could see that I'd shaved parts of the sealls off so I got some new ones did it again. This set didn't roll like that.
"Is the reverse input drum a new gm unit or aftermarket?"
- It's a six year old gm unit.
I played with it some more last night after work. It spins very easily without the pump installed.
I tightened the pump to case bolts a bit at a time and tested the output shaft after every 2 or 3 revolutions. I also watched the gap between the pump and the reverse drum closely.
I can say positively that the pump isn't making hard contact with the drum like I was afraid of. It got progressively harder and harder to turn the output shaft until it was all I could do to get it to turn right before the final tightening of the pump bolts.
Once I tightened the pump I couldn't get the output shaft to turn. I boogered up the splines a bit trying. It may still turn if someone with some real muscle tried but I'm nervous that it'll do damage to itself as tight as it is.
So bottom line, the stator is too tight in the reverse input drum bore. It's probably because of the teflon seals. Once I get the pump out I'll try it again without the seals.
How much squashing down should be done on those seals? Should they be flush with the mounting ridges?
P.S. -
I forgot to lube anything before hand and now I can't for the life of me get the damned pump out. I took a long look at the bolt holes in the pump and was thinking of tapping them out so I could run big bolts through the pump and push against the case. I would probably only have to do it in 4 spots.
"If you leave the reverse input drum out, and seat the pump, what happens?"
-The output shaft spins freely.
"What all is any upgrades have you done to planetaries, sunshell sprag, bearings etc?"
-I have a five pinion rear planetary and a GM heat treated sunshell. The sprag is oem as far as I remember. The torrington bearings were replaced six years ago and are silk smooth. When I don't install the input drum, reverse drum, or pump, all of the rear hardware spins freely in both directions.
"What selective shim is on the input shaft."
It's either a 67 or a 69. Shouldn't matter though as I've left the input drum out completely and it still binds.
"did you replace the sealing rings on the stator and did you size them correctly and lube them?"
- I did replace and size the teflon stator seals as well as lube them. I'm a bit shaky on the "size them correctly" part though. It seems like they expand out again after sizing. I also didn't really squash them down as I was afraid of them being too loose and causing a leak.
"Also did they roll when you installed them."
I'm not sure what you mean by "roll". Do you mean when a corner of the seal catches and rolls like a rubber rolling? My first set did that and I could see that I'd shaved parts of the sealls off so I got some new ones did it again. This set didn't roll like that.
"Is the reverse input drum a new gm unit or aftermarket?"
- It's a six year old gm unit.
I played with it some more last night after work. It spins very easily without the pump installed.
I tightened the pump to case bolts a bit at a time and tested the output shaft after every 2 or 3 revolutions. I also watched the gap between the pump and the reverse drum closely.
I can say positively that the pump isn't making hard contact with the drum like I was afraid of. It got progressively harder and harder to turn the output shaft until it was all I could do to get it to turn right before the final tightening of the pump bolts.
Once I tightened the pump I couldn't get the output shaft to turn. I boogered up the splines a bit trying. It may still turn if someone with some real muscle tried but I'm nervous that it'll do damage to itself as tight as it is.
So bottom line, the stator is too tight in the reverse input drum bore. It's probably because of the teflon seals. Once I get the pump out I'll try it again without the seals.
How much squashing down should be done on those seals? Should they be flush with the mounting ridges?
P.S. -
I forgot to lube anything before hand and now I can't for the life of me get the damned pump out. I took a long look at the bolt holes in the pump and was thinking of tapping them out so I could run big bolts through the pump and push against the case. I would probably only have to do it in 4 spots.
03-30-2017, 01:23 PM
#4
Pry bar or big screwdriver between the pump and top of the reverse input drum through the case should push it back out... when i seal the rings on the stator i tighten them down as much as i can wait an hour or 12 and tighten them down again. Gonna sound ceazy but take the selective washer off the input drum and see what happens, i had the same issue with mine and had ti change the selective washer. Is the sunshell the bearing type or the plastic thrust washer type?
03-30-2017, 09:16 PM
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The input drum with the 3-4 clutches isn't involved. I left it out completely to try to narrow down what is binding.
It sounds more and more like my teflon rings are the issue. I didn't shrink/mash/squash/tighten them enough.
The sunshell has a plastic washer. It's not the beast or the sonnax smart shell, it's just a heat treated GM sunshell. So one step up from OEM.
My screwdriver isn't very big, I may need to go find a specialty prybar.
It sounds more and more like my teflon rings are the issue. I didn't shrink/mash/squash/tighten them enough.
The sunshell has a plastic washer. It's not the beast or the sonnax smart shell, it's just a heat treated GM sunshell. So one step up from OEM.
My screwdriver isn't very big, I may need to go find a specialty prybar.
03-31-2017, 12:37 PM
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Yes it is.
I pulled the stator seals off and put the pump in the reverse drum last night. It still binds up. I flipped the drum over and put the stator in the bottom of the drum. It doesn't seat all the way into the bottom reverse drum bushing but it goes in far enough to tell me it's fine. The top bushing on the other hand is horrific.
I can't believe I didn't consider the bushing as a possibility. I had a similar problem with the sun gear bushing. The bushing would fit fine on the shaft before I put it in but once I pounded the bushing in, the shaft no longer fit. I went through three of the sonnax sun gear bushings before I got it in right. What I ended up doing was sanding off 0.1mm from the outside of the bushing before I put it in. I'll probably do the same with this one. Maybe I'm bottoming them out and adding another whack or two for good measure?
I pulled the stator seals off and put the pump in the reverse drum last night. It still binds up. I flipped the drum over and put the stator in the bottom of the drum. It doesn't seat all the way into the bottom reverse drum bushing but it goes in far enough to tell me it's fine. The top bushing on the other hand is horrific.
I can't believe I didn't consider the bushing as a possibility. I had a similar problem with the sun gear bushing. The bushing would fit fine on the shaft before I put it in but once I pounded the bushing in, the shaft no longer fit. I went through three of the sonnax sun gear bushings before I got it in right. What I ended up doing was sanding off 0.1mm from the outside of the bushing before I put it in. I'll probably do the same with this one. Maybe I'm bottoming them out and adding another whack or two for good measure?
Last edited by urb0123; 03-31-2017 at 12:38 PM. Reason: wasn't supposed to be .01mm
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03-31-2017, 02:09 PM
#8
I was starting to think bushing issue, but you caught it. Honestly with the reverse input drum, i would get a new one with the bushings already installed... no chance of tearing the bushing up, plus with the band riding and clamping the drum, i like to have a new surface for it. Once you get that straightened out if the output is still binding you may need to make sure everything else is stacked properly.