A4LD no Drive, only reverse : a rebuild thread

[johnny64]

Hello everyone,
first post in this forum that I've been monitoring since my purchase this summer of a 1993 explorer.
This car was what we call a "sortie de grange" (yeah, I'm french !) which would be a "barn discovery" in the US.
Car started right away, has a bit of rust to tackle, but the biggest issue was the no forward, in any gear, any throttle. Reverse worked fine. 250k km, so around 150K miles. on it. No history attached to the car, no idea what was done on it.
Had the car hauled to my place to start the project.
Also, the car was sold with 2 extra A4LD....

1st inspection : ATF level low, and brown.
-> drain the old fluid from the cooler line, drop the pan, change the gasket and filter, refill ATF, torque VB.
No big metal chunks in the pan, some smudge on the magnet. Noticed the pan's bolt were tightened WAY too much as the gasket's magnets were imprinted on the tranny's body.

2nd inspection : ATF level good, clean red, but still only reverse.
-> measure the pressure levels on the pressure port.
Levels was good for reverse and holding, however for all other speeds, it was spiking when I reved the engine, and dropped back to 50 psi. (I'll leave the exact measurements when I get back home).

3rd inspection : Pressure readings not correct, check VB
-> drop the pan again and check VB.
As soon as I dropped the VB i noticed a big chunk of flat metal falling in the pan (will post pictures)


I asked a transmission shop near my house, and they asked for 4000€ for a complete rebuild and I needed to bring the truck to them...... For a 1200 € car, I declined.

So there's my sign to drop the tranny and rebuild it completely !


As I am in France, it's a bit more complicated to find parts and have them delivered here at a decent cost, I'll summarize all costs in a post that I'll update whenever there's a new part bought.

I will not explain in details how I rebuilt it as Glacier's posts are extremely well documented, but I'll entertain you with my discoveries, struggles, and results !

 

[Rick]

Best of luck with your project, and welcome to the forum.

 

[johnny64]

Pressure values !

I measured the values for idle and 2000 rpm. I tried WOT for all non-functional speeds in the hopes of something...
P/N/O/D/2/1 : 50 at idle / Some movement at fast idle / WOT : spike at 200 psi, but pressure droped back to 50.
Reverse: 110 at idle , 80/90 at 200 rpm, and 200 at WOT

Vacuum modulator :
Only had a hand pump (the brake bleeding one) at the time, so my vacuum could only go as low as -13.5in Hg. 25 minutes later it was at -12.5in Hg.


My thoughts at the time : vacuum modulator seemed ok (although I have a real vacuum pump on the way, I'll test it again this w.e., now that it's separated from the unit)
Reverse is functionnal and pressure levels are ok. Pump and TC are ruled out of the problem.
However, pressure was not holding in the transmission for O/D/2/1 . Probably a problem with the VB as in my understanding it's the brain of the unit, responsible for pressure management.

That's when I took the VB out (gasket crubmled and felt like stiff cardboard), a chunk of metal fell and I decided to tear the whole unit out of the explorer.

Next up : pictures of the chunk of metal, and of the damages found during dissassembly, I hope to take pictures tonigh and post them afterwards.

 

[johnny64]

Broken stuff !

First: the metal bit that fell in the pan when I took the VB out.

Looks like a tooth from some gear, or the end of a channel from the VB or transmission. From what I can see, there are grinding / burn marks (1st pic), and shear damage (left part of 2nd picture). The up side on the second picture is perfectly flat, looks machined so I think that was not due to failure inside the unit.

Where that part is from is a mistery as I can't locate any torn piece on anything from the unit for now.

Second broken stuff : the intermediate band

Weird thing is I can't locate ANYWHERE the big missing part....

Last broken stuff : the shell itself. A part is missing from the inside of the transmission, near the gear lever (I attached a picture of a "good" transmission shell for reference)

So, there are 2 broken parts at least in this unit. the bit found does not fit anywhere broken.

There's "transmission OK " written on the outside of the trans, so my thought is, there was some things done to this unit, or at least tot the car. Keep in mind I bought 2 spare transmissions with the car.

I think the last owner tried to fix the car when it started to act weird. They probably took the pan off and removed the metal bits of the broken parts from the transmission.

Next step : complete cleaning of the parts, inside and outside. I have an overhaul kit and am waiting for a shift kit for the VB.
I'll also check the vacuum levels on the 2 VB I have now.


Question for the community : what torque converter can fit on the A4LD ? I'm debatting whether or not to get a new/refurbished one as it "worked" for reverse ?