4l80e no reverse.

[bluchev]

ok this is weird, its a 2000 chevy 3500.
1-2-3-4 all work great.
no reverse, it went from a shudder while backing up(a couple weeks ago) to nothing(today). absolutely no reverse.

so im thinking, broken band or broken servo, i drop the valve body, drop the servo cover- its fine. the fluid is brownish with a decent amount of metal on the magnet, but definitely not really bad.(truck has 92k on it)

so i decide to pull the unit.

i tear it down tonight and the reverse band is intact and the case lugs are fine and most everything looks decent in the trans, the clutches all show some wear but nothing smoked or burnt at all. bushings all look good and center support seals and teflon shaft rings are all intact and not damaged.
i havent pulled the pistons out of the drums yet(they are the molded steel), but i would think that if the direct was leaking they would all be burnt???


Im stumped.

any ideas on what i should look closer at???

 

[jakeshoe]

Your band clearance is too loose.
Wear on the band, wear on the reaction carrier, maybe a little bit less pressure, and now you have a band that can't hold.

You could have added .100" to the pin and went on about your business for awhile.

Check the servo piston closely for cracks.

Install a new band, and be prepared to build it with a longer pin.

 

[bluchev]

yea its crazy, the band shows some wear and a bit of glazing but is by no means destroyed.

thanks for the reply jake

 

[Not Avg 6]

I have a good one in the parts for sale section. Must go, make an offer with local pick up south of Chgo.

 

[TATTYPE]

ck your pistons - look for crack - new pistons are steel

 

[bluchev]

Sorry I should have updated this long ago but the problem ended up being the new reverse band was part of a bad run of bands and when i tore the unit down the entire lining of the band was delaminated from the steel part of the band. Talk about shit luck