A4LD - Reverse has gone out shortly after rebuild

[Saint Ferret]

Completed a total rebuild in August last year. This included seals, discs, clutch plates, modulator, TC, bands, valve body rebuild.... uhh.. i think thats everything?

Since then I have driven less than 10000 miles more on the vehicle. The initial failure that had prompted the rebuild was 3rd/reverse failure.

Now 2/3 shift is acting up - it wants to keep revving from 2nd and skip 3 over to 4th unless you back off the accelerator.. then it will downrev and shift in to 3rd.

Aaaaaand now reverse is gone again. It has slowly been giving warning signs of some issues the past week or so... not wanting to shift in to reverse after periods of long driving.. partial reverse engagement.. slow to engage reverse.

Just this morning went to put it in reverse - nothing. Engine revving up normally like it should to engage reverse, and it wont shift in to reverse. No 'clunk' like the reverse piston usually makes popping in to place. Sustained high revs will not force engage.

Anyone have an idea of what has happened here? Maybe some crap got stuck up in the reverse piston and wrecked a seal? (I used the recommended double lip replacement) Maybe one of the valves is sticking again? Or is there something more sinister that I am overl00king?

 

[transman304]

Was the direct clutch pack burnt originally. That pack is on in rev and 3rd gear.
Maybe bad center support, wrong sealing rings used there are 3diffrent possibilities.

 

[Saint Ferret]

Was the direct clutch pack burnt originally. That pack is on in rev and 3rd gear.
Maybe bad center support, wrong sealing rings used there are 3diffrent possibilities.

Both clutch packs as well as both bands were torched and scorched. Tranny had a main seal blowout about 5000 miles before the clutches shot. I am assuming low oil level for many miles burnt the innards all up.

Low oil has not been an issue this time.

 

[transman304]

Sounds like you will be going back through the transmission again.

 

[Saint Ferret]

Any idea why such sudden failure? Is why I was thinking this may be a stuck valve.

When 3rd/reverse went last time it was a slow failure over several months until finally 3rd wouldnt ever engage and reverse bit the clanky dust one day. Mind you this time reverse wouldnt engage on one occasion and now nothing. No signs of illness before death.

 

[transman304]

You can analyze what could it be but you know you have a problem and until you start investigating for a root cause it will keep happening. As far as why it went out all of a sudden, sometimes a light bulb will flicker sometime it worked right up to the time you turned it off to never come back on.

 

[Saint Ferret]

I could stain a deck with the transmission oil; I almost wanna cry. 2 summers now no truck only transmission troubles. If the direct cluctch pack is shot again in ~500 miles that means this a4ld is toasty mctoast right?

I followed Glacier to a T. And it worked for a while. Just dumb luck? Or are these things that finicky?

Finally a real question; what should I do now?

 

[JK080]

This is were you have to be real careful if you decide to go at it again, you will need to check everything very closely and air check each component along the way. Once things are back together you should use a pressure gauge to make sure your pressures are all in line.
Glacier did a great right up on rebuilding one of these but he did have the pump gasket on the wrong side of the plate in the pump FYI.

This is incorrect, the gasket goes between the case and pump plate.

Below is from the build thread... LINK

 

[imp]

Low oil level in an automatic transmission is VERY unlikely to cause burnt-up clutches or failed other hydraulic components, IMO.

As fluid level drops below an operational level, operating pressure drops. This causes generally incomplete/unacceptable forces needed to apply bands/clutches. Result is engine runs away, vehicle moves little, or not at all. imp