Here is the link to the full size Bronco C6 rebuild thread. It does not have any captions, just lots of pictures. I found it very helpful. I had been very intimidated about tackling a trans rebuild, I found this thread before I started and was encouraged by the fact that it can be done by a regular guy in his garage

FullSizeBronco.com - 78 - 96 Ford Bronco offroad club, forums, tech, installs

I did mine with no special tools - made my own set up with a work bench, pipe clamps, some small wood blocks cut to fit for a spring compressor. If you are trying this for the first time I would highly recommend a good set of snap ring pliers as shown in the Haynes manual - the kind with flat tips that look like oversized foreceps - not the little ones with the small round tips. The larger rings on the clutches come out easily with a screw driver, the little one at the back on the tail shaft doesn't.

The Haynes manual was helpful, the ATSG manual was a waste of money.

One thing that was a real hassle that none of these really cover in detail is how to install the forward clutch piston into the drum when replacing the seal. The seal has a tapered flap that has to be fit into the drum. The Haynes manual lists a special tool to compress the seal. If you locate one of these it would be helpful. I used a large rubber band. It went in fine on the 4th try, just had to carefully slip the rubber band out as it started to seat. Everything should be well lubed, so the rubber band is very difficult to get on with just 2 hands - my wife had to help me with this one!
I am now a little nervous that this may be an issue with it not going forward.

 

OK, I checked the pressure - it is pretty much a constant 20 lbs at idle, no matter what gear- will raise to about 60 lbs at mid throttle. If I put it in reverse and rev the engine it will kick into reverse - then let off the gas to idle and it reads about 60 lbs. Just sitting at idle and putting into reverse it will not engage. Manual says 50-80 lbs drive -60-150 lbs reverse.

I took the valve body off, disassembled and cleaned. (previously noted I had not done this before) There was some crud in it. Put back together with new gasket - checked to make sure it matched. Torqued all the bolts

Put it all back together - same thing. 20 lbs

According to the manual - there are pretty much 2 things it can be - valve body or pump (after eliminating low fluid, clogged filter,loose lines, etc). Since the pump is a rebuilt unit I am trying to make sure it is not something else before I drop the tranny and tear it all apart.

Manual says a sticking regulator valve. I took that all apart and cleaned it well. It moves with a screwdriver. Also says loose valve body - I have torques all bolts to spec.

Does anyone have experience with the guts of these things to know what to look for? Can the rebuilt pump be bad? If I tear it all down, what do I look for? Could it be a blockage of crud somewhere in the case?

I tried an air test with the valve body off - the low/reverse engages, I cannot hear the forward engage. If there is something wrong with the seal on the forward piston would it cause constant low pressure? This was kind of an unplanned build, so I didn't do all the case bushings, the pump bushings are new.

I appreciate any help. Again, trying to avoid a tear down if possible, especially if I don't know what I should be looking for once it is apart.

Thanks

 

Sorry for the old thread revival...I am picking up an 88 F250 4x4 with a 7.3 and C6 that has a similar problem. I will be performing the same tests mentioned in earlier posts but was curious if anyone knew what solved the OP problem?

Also, a newbie question but I have only owned manuals so am not familiar with the C6 (or autos in general). What are the positions on the trans linkage front to rear? Park all the way forward moving the drive at the very back?

Thanks in advance!

 

On the trans positions, if you're talking about the position of the transmission arm on the side of the case, it's more up and down rather than front to back.
Park is all the way up, followed by reverse, neutral, drive, 2, low.
If your transmission has reverse but no forward chances are the forward clutch apply piston seal is bad. This is a very common C6 problem.
Usually the way it works is when the trans is cold it will have reverse but no or a very weak forward. If it goes into drive it will slip a lot. Then, as the trans warms up, the forward gets more positive with less slippage untill after its good and warm it seems to operate normally.
As time and miles go by the forward gets progressively worse untill it just stops engaging.
C6's have a forward apply clutch. That clutch has a piston in it that engages and disengages the clutch pack. This seal is notorious for getting hard and not sealing. When it's cold the seal leaks too much to seal, then as it warms up, it'll seal better and work but, eventually, it'll just stop sealing and there'll be no forward.
You can replace just the seal, but this far in just rebuild it and get a fresh start.

BTW welcome to FTE, lots of good knowledgeable people here.

 

Well said Mike, all true.........I guess the OP fixed the problem or he would still be here

 

Thanks for the welcome and response! Would it make sense that this seal would be bad if the transmission was just rebuilt? I am just going on what the PO said about the rebuild but assume it was done correctly and know it was done by a shop. I am guessing I could pull the trans and send it back to them but really would like to fix in the truck if it is possible. I also have a spare C6 with a bad reverse so if I have to rebuild one, I would probably do that one and then just swap the two...

 

If the trans was just rebuilt I'd take it back. If that's not possible, seeing as it was just worked on, there's no real way to know what's wrong . I would still strongly suspect something with the forward clutch. Maybe the o-ring was left out, maybe damaged on installation. No way to know for sure without a tear down .

 

Figured you may say that! Thanks and I will keep you guys posted