1995 GM Cadillac STS 4T80E trani 94 shift ratio A 76 force motor malfunction problems
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Member
Joined: Sep 2009
Posts: 45
From: FRANCE
Work of today :
More photos :
http://cadillac-sts.skyrock.com/25.html
Senior Member
Joined: Apr 2009
Posts: 108
From: Seattle Area
Thanks for the photos confirming the problem. Was the debris present when you changed the scavenger filters?
You probably already know, but just in case... In addition to the scavenger filters, the main filter is under the side cover.
You probably already know, but just in case... In addition to the scavenger filters, the main filter is under the side cover.
Thread Starter
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Member
Joined: Sep 2009
Posts: 45
From: FRANCE
Thread Starter
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Member
Joined: Sep 2009
Posts: 45
From: FRANCE
I went back and re-read all of the posts. You say that originally, the transmission was working fine, and then the problems started after a few thousand miles. This tells me that the ratio is probably correct...which is good. The bad news is, the trans has probably burnt the band for overdrive
Adam's apple : you are the best !
Last edited by memez; Jun 6, 2010 at 08:15 AM.
Thread Starter
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Member
Joined: Sep 2009
Posts: 45
From: FRANCE
Be careful handling this trans. It weighs almost 300 pounds!
If you decide to pull it out, be sure to replace the seals in the channel plate for the input sprocket, as these are the #1 problem with this trans. Another problem is the forward clutches(#s 816 & 817 in your diagram). In every single 4T80E I have done, there has been at least one of the clutches with the friction material flaked off of it.
It would be advisable to get an overhaul kit, and just do the entire trans while it is out. Just replacing the band(if that's what it needs) isn't worth the trouble of pulling the trans out of the car, imo.
Also, depending on how bad the band is burned, it may have damaged the reverse clutch drum (# 500 in your diagram). I've seen many of those drums turn blue from the heat of the band slipping, which causes them to no longer be round.
The low/reverse band(# 13) also has issues with the friction lining flaking off, so inspect it carefully.
The rest of the trans is pretty solid, and we don't see many problems from any of the other parts, unless there has been some abuse, or major neglect.
You should be able to see part of the reverse drum with the lower pan off. You might be able to see if there is evidence of the band burning from there. There is an opening in the case there shift linkage is, and part of the drum is visible.
Another note....on the shift linkage wire that connects the case linkage to the valve body, there is a plastic clip that holds the wire to the case linkage...be VERY careful removing that wire linkage, as the plastic clip will break very easily.
If you decide to pull it out, be sure to replace the seals in the channel plate for the input sprocket, as these are the #1 problem with this trans. Another problem is the forward clutches(#s 816 & 817 in your diagram). In every single 4T80E I have done, there has been at least one of the clutches with the friction material flaked off of it.
It would be advisable to get an overhaul kit, and just do the entire trans while it is out. Just replacing the band(if that's what it needs) isn't worth the trouble of pulling the trans out of the car, imo.
Also, depending on how bad the band is burned, it may have damaged the reverse clutch drum (# 500 in your diagram). I've seen many of those drums turn blue from the heat of the band slipping, which causes them to no longer be round.
The low/reverse band(# 13) also has issues with the friction lining flaking off, so inspect it carefully.
The rest of the trans is pretty solid, and we don't see many problems from any of the other parts, unless there has been some abuse, or major neglect.
You should be able to see part of the reverse drum with the lower pan off. You might be able to see if there is evidence of the band burning from there. There is an opening in the case there shift linkage is, and part of the drum is visible.
Another note....on the shift linkage wire that connects the case linkage to the valve body, there is a plastic clip that holds the wire to the case linkage...be VERY careful removing that wire linkage, as the plastic clip will break very easily.
Senior Member
Joined: Apr 2009
Posts: 108
From: Seattle Area
The rear cover is called a Transmission Case Extension. To remove it, first remove the speed sensor and ground wire, unbolt the cover, then there is a roller thrust bearing and scavenge tube.
The differential carrier is next. It is important to first rotate the manual shaft counterclockwise to place the transmission in park and prevent the differential from rotating. Then unbolt the differential carrier.
The final drive carrier is next. Push on the output shaft in order to expose the left side gear snap ring and remove the side gear and thrust washer. Remove the final drive carrier, thrust bearing, and sun gear. The final drive internal gear comes out with an internal snap ring. The output shaft come out the left side of the case.
Adams Apple was right on and he knows more about these transaxles than me. Hopefully he will come back to help you.
