Lose reverse when Trans is warmed to normal Temp

[lundrv92]

This is a first for me but I have been reading a lot of good infomation on this site. I have a BIG problem with one of my Explorers Transmissions. My A4LD has been rebuilt more than I should amitt to, 3 times.
The shop that did the work the last time is long gone. I had a problem with the unit up shifting from 1st to 2nd when it was cold. After that the unit would not go into any gear unless it was cold.
I adjusted the bands as Glacier991 out lined and the trans started working great!
Bad news was after the test run for 10 miles. The unit now has NO reverse when it is warm.
Does anyone have any ideas?
Is it in the valve body?
Is there any way to adjust the 1st reverse band?

 

[BrooklynBay]

Welcome to this forum! The delayed 1-2 shift when cold is most likely the governor. The hot no reverse issue is probably related to the valve body gaskets. Do you still have manual 1st without reverse?

 

[lundrv92]

Yes, I have all of the forward gears.

 

[BrooklynBay]

The low/reverse servo engages the rear low/reverse band. Check the valve body, and gaskets first to rule out the possibility of internal damage from ripped center support seals, and clutch pack piston lip seals.

 

[lundrv92]

BrooklynBay,
If I purchased a Trans oil pressure gauge would it tell me if the servo is engaging correctly? Or if it is leaking?
I just hate to have to drop the pan and find that I should have taken't some pressure test first.
Besides I have an inch of Utah clay mountain mud "concrete" on the whole undercarriege from last years Hunts. Yes I have pressured washed the Explorer 3 or 4 times. It takes a year on dry, dirt, washboarding roads to get the mud shook off.

 

[Glacier991]

You *might* see a low pressure issue in reverse on a pressure test.... If you have access to a gauge, no harm in trying that first. The reverse spool could be hanging up though and that would not show up as a pressure loss.

 

[lundrv92]

Glacier991,
The pressure gauge worked great! I found that if I was patience and waited for the linkage to find reverse only if I came from drive to reverse then the pressure would go up and like magic there was reverse. If I went from Park to reverse very seldom did reverse work.
I guess that I must have a valve hanging up or one of those balls is out of round or sticky. What do you think?
I'm planning on dropping the pan and then removing the valve body this week. Like I have any choice at this point.

 

[BrooklynBay]

It could be an irregularity in the manual slide valve or the valve body's bore. There is a small amount of wear as it gets older. A visual inspection might not always be obvious. The aluminum valve body expands when it warms up so it might not make a close fit with the slide valve (although the slide valve also expands when it warms up). They sell thicker valve body gaskets for old, slightly warped valve bodies. They cost a little more, and not everybody sells it.

 

[Glacier991]

I'd rebuild the VB

 

[lundrv92]

BrooklynBay OR Glacier991:
Hey Guys,
Do any of you have a picture of the selector shafts on how they are put together and as to the way they pass thru the transmission casing. I believe this could be the problem. I can wiggle I mean WIGGLE the shaft in the casing. I believe this is moving they select rod back and fourth in the valve body.
Yes I have the pan off and was going to take the vale body out until I ran into the Shaft problem.

 

[Glacier991]

Do you mean the bore is terribly worn (wobbles)? Or that the shaft moves easily in and out ?

That bore can be sleeved. And although I have never done it in place, I believe it could be done in place (e.g. trans still in car)

In addition the bore in the manual valve tends to oval out over time. Sonnax makes a sleeve that corrects that as well.

 

[lundrv92]

Hey Glacier,
It is doing both after I removed the kick down nut. The question is is this a press in fit with a dowl pin holing it in??
Does the internal nut tighten the unit to the casing?
If I new how to remove the shafts from the casing unit I can find away to repair it.
Any pictures or articles?
It's late here and I'm probaly not making any friends this late.

 

[BrooklynBay]

Check the photo gallery, and the A4LD rebuild diary.

 

[lundrv92]

BrooklynBay,
I have checked the Photo Gallery with no luck. I find pitctures with the case bare and with the unit installed. no pcitures iwth the unit by its self.
Help!

 

[lundrv92]

Hey Brooklynbay or Glacier991,
How on earth do you get the pin out of the casing that is holding in the selector shaft???

 

[BrooklynBay]

That pin is hard to pull out. Grab it with the end of a Vice Grip, and carefully try to twist, and pull. The rebuild manual recommends grabbing it with the end of a wire cutter, and prying it out. I once tried this, and cut the pin off! I tried to drill it out, and tapped it with a center punch first. The case cracked, and I had to replace the case. I use nails, and bend them to get a grip on them instead of using a pin. I had an idea, but I've never tried it as of yet. Heat that area with a blow torch, and then grab the pin. It should expand, and make it easier to pop out. I take no responsibility, and repeat that I've never tried that yet.

 

[lundrv92]

Hey BrooklynBay,
I found the fast and easy way to remove the pin.
Purchase a Stud Gun at Habor Freight and shut a stud on.
We did already have the stud gun and with two pulls on the slide hammer out it came.:
Now what size of nail do you use to replace the stud?

 

[BrooklynBay]

Get a nail the same diameter, but longer of course. It has to bend into the groove in the bottom of the case. Could you post a link to that Harbor Freight tool? I'm not sure what tool you are referring to. Is it the thing they use to weld a stud onto a fender to pull out a dent?

 

[lundrv92]

Hey BrooklynBay,
It is the same tool that is used for pulling out fenders!
Now on to the Valve Body.
The reason the shaft was wobbling is that when I was hunting the shifting arm hit something and it bent through the grooved area for the hold-in pin. I would have never believed it unless I were holding it in my own hand. Straight edges never lie. Oh for your info, the case meassured round.

 

[BrooklynBay]

Could you post any pictures of what happened? Did the inside of the case get damaged? There is a repair kit for this part of the case which requires a special tool. Thanks for the tip about using a stud gun!