I have a 2015 Chevy Tahoe with a 5.3 and the 6l80 transmission. I pulled the trans because I was getting torque converter failure. I was having a shuddering under low load and when I dropped the pan the fluid was black and was covered in metal shavings but the transmission was still shifting and moving just fine. I cleaned it out completley, replaced all pistons, seals, friction disk, valves, new pump and bell housing, rebuilt pressure switches, new bushings, new upgraded cooling valve, new 3-5 Rev apply ring, new transgo tcc regulator valves, new OE valve body separator plate, and also a end plug kit for the valve body with o-rings. I have done several rebuilds on engines and manual transmission. This was my first attempt at an automatic transmission. I do have the repair manual for this specific transmission and purchased all the specials tools or made my own to do the rebuild. Now here is the problem - I reinstalled the trans and filled it full of fluid, 12 qts. I get no errors on my scan tool, I have no forward gears at all. I get a delayed engagement of reverse. I have to rev up the engine to about 1700 rpm and the reverse gear will engage and spin just fine. My scan tool shows pressure readings for all solenoids. All test are done with the car fully off the ground. My scan tool will not do the quick relearn function, but I would think it would still have movement. Any transmission guys out there that can lead me in the right direction, I am about at the limit of my ability and will have to send it in to a shop.
6L80 Transmission Rebuild - No Movement
- Thread starter zbhsmith
- Start date
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@NickTransmissions has a thread on these if you want to take a look.
www.tahoeyukonforum.com
GM 6L80 Transmission Information Thread
Hi All, Since so many of us own at least one Tahoe or Yukon equipped with a 6L80, I figured I'd start an all-encompassing transmission thread with videos, links and other information as it relates to the 6L80/90 transmissions. I'll get it going with a tear down and inspection video and go from...
www.tahoeyukonforum.com
You need to complete the fast adapt relearn process before driving it otherwise it will behave exactly how yours is currently behaving. Grab a Snap On Solis, Verus or Modis or equivalent Autel or purchase a subscription to AC Delco's tech-online diagnostic and programming suite for your vehicle...
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You will have 'false neutrals' if no adapt is performed...Other reasons for no movement in any range include installing the front planet in backwards such that the splines on the planet face away from the splines on the 3-5-R drum. Broken pump rotor due to installer error and rolled rear sprag (no forward movement in any range). If CB1 is misplaced, you'll have no forward movement; likewise for CB5 - no reverse.
Did you replace the snap rings for the 1-2-3-4, 3-5-R and 4-5-6 clutch piston/return spring assemblies as well as the snap ring for the low sprag?
Those sometimes fail after overhaul due to the stresses of being removed and reinstalled...Also the parking rod should be replaced on anything older than 2018 as well as the o-rings on the parking pawl housing otherwise they may leak after a while.
As far as the other items, I did pull this transmission back out after the no movement condition and verified the front planet faced the correct way. I test the 3-5-R drum for leaks, I inspected the pump again and the low clutch sprag. I do recall checking the sprag to see if it spun the right direct. Do you know if it has the "do not press here" on both side? I did not replace any snap rings but did check them twice to make sure there where seated all the way. Nothing on the parking pawl was replaced. Sounds like getting that fast adapt learn feature reset is where I should start. Thank you for all your help.
Think its only on the one side but would have to pull one from the drawer to confirm....The sprag should have been replaced - I never reuse those but your call...I'd replace the pkg rod also - there's a TSB on those things failing due to incorrect metallurgy on the pre-18 versions; ditto for the snap rings (they can be installed an seated correctly but fail due to metal fatigue but again, your call.
If you have to go back into it a third time I strongly recommend you spend the $50 to replace those snap rings and parking rod but your call.
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I have one more question. AS far as check balls are concerned. I am sure they are in the right place but I did add the 8th check ball. would that have anything to do with it. This is a type 2 valve body and when I pulled it apart it only have 7 check balls, but the paperwork said there was change in design and a 8th ball was added.
Please quote my posts if you would like a response from me otherwise I may not see that you have replied (I don't watch threads)....
The 8th check ball was installed to slow the release of the low reverse clutch oil so the "handshake" between it and the 1-2-3-4 clutch was smoother thus making for a less abrupt transition from reverse to drive by way of engine breaking compared to all years before the 8th check ball...The plate was redesigned to accommodate the addition of that 8th check ball and orifice in the #8 seating location was shrunk to .054" compared to the earlier 2nd design plate.
As you know, you should have had eight check balls given you have a 2015 as that change took place in 2014 for the 2014 model year and forward.
Do you remember the part number of the separator plate that you purchased for your rebuild?
Here is the link to eBay page I ordered, can't find a part number but it is for a type 2.
6L80 6L90 Transgo Valve Body Kits OE Separator Plate TORLON Check Balls 2010-up | eBay
2010-Up GM 6L80, 6L90 Valve Body Repair Kit. 8 TORLON HD Check Balls. 6L90 2010 - 2020. 6L80 2010 - 2020. Updated Valve Body Separator Spacer Plate with Bonded Gaskets For Type 2 Valve Body. A ProProven All-in-One Product from Valve Body Pro.
www.ebay.com
