4l80e reverse question
09-11-2011, 08:21 AM
#1
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4l80e reverse question I have had my 4l80e in my car now for probably 1000 miles and a couple dozen track passes. Didn't get run to hard brcause I'm having a problem with a nos solenoid. Anyhow the trans was a used gm srta I took it apart and it all lookled good but the direct clutches were discolored. I replaced the direct clutches and added Jakes valve body kit to dual feed the directs. First time driving the car reverse slipped bad getting out of my garage but then was fine? Now as of yesterday it has no reverse. All other gears seem ok. You can tell it goes in but slips One time it shuddered and then backed up but the next thing nothing. Possibly the reverse servo? Just looking for ideas before I pull it apart.
Thanks
Thanks
09-11-2011, 10:49 AM
#2
It is highly possible that the Direct clutches are compromised once again which would imply a chronic issue with that unit being as it was showing stress when you were in it last time. The Overdrive Sprag could be slipping and of course the Low/Reverse band could be inoperative or worn out.
I would suggest removing the pan for an inspection, see what sort of debris is laying there? Then remove the L/R band servo cover, remove the servo and inspect it.
Get that far and let us know what you find. I don't think I would remove it and disassemble it just yet...
One thing you might consider is to put a gauge on it and see if there is a rise or fall in line pressure when you engage reverse. You should see appx 65 psi in park and then somewhere around 120 psi in reverse.
g
I would suggest removing the pan for an inspection, see what sort of debris is laying there? Then remove the L/R band servo cover, remove the servo and inspect it.
Get that far and let us know what you find. I don't think I would remove it and disassemble it just yet...
One thing you might consider is to put a gauge on it and see if there is a rise or fall in line pressure when you engage reverse. You should see appx 65 psi in park and then somewhere around 120 psi in reverse.
g
09-11-2011, 09:37 PM
#5
Sounds like a band issue to me. Check the servo clearance when you have it apart, remove the accumulator pistons, both springs from the low servo, and push the pin, washer, and piston against the low band and see how far it goes into the case. I bet it goes in quite a ways.
If you are making good pressure and using my valve body setup, I doubt you've hurt the directs and if so, you would at least feel a difference in the 2-3 shift.
If you are making good pressure and using my valve body setup, I doubt you've hurt the directs and if so, you would at least feel a difference in the 2-3 shift.
09-21-2011, 05:58 AM
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Well I checked the rear servo pin length with the GM tool and the pin was .200"short. I ordered the longest pin from GM which is what the tool said I need. Hopefully that works. Will update when installed.
09-21-2011, 12:00 PM
#7
Sounds like a band issue to me. Check the servo clearance when you have it apart, remove the accumulator pistons, both springs from the low servo, and push the pin, washer, and piston against the low band and see how far it goes into the case. I bet it goes in quite a ways.
If you are making good pressure and using my valve body setup, I doubt you've hurt the directs and if so, you would at least feel a difference in the 2-3 shift.
If you are making good pressure and using my valve body setup, I doubt you've hurt the directs and if so, you would at least feel a difference in the 2-3 shift.
Haha yeah I missed where he said all other gears are good.
And it is firmer than ever