I recently bought a 76 F250 with 76,000 original miles. The guy I bought it from said the front seal in the trans (C6) went out about 4 years ago. He said when he parked it the trans shifted/ worked fine other than pouring fluid out of the front seal. It's been sitting for 4 years. I got it home and dropped the trans and replaced the front and rear seals, and changed the filter, fluid and pan gasket. When I re-installed it, it won't move in forward gears, but reverse works fine. The shift linkage is not the problem. It has plenty of fluid in it. It doesn't do anything in any forward gear. I mean nothing!! It doesn't even try to creep forward, jerk or anything. It's like it's in neutral. I only paid $400 for the truck and it's in excellent condition so I'm not opposed to rebuilding it, but I really don't want to flat back that trans again in the driveway if I don't absolutely have to. Any information is appreciated. Also if there's anyone in my area (charlotte, nc) that is interested in rebuilding it if it comes to that, or any suggestions of a good trans rebuilder is welcomed. Thanks Dan.

 

The forward clutch is probably causing the problem. Usually the clutch apply piston seal goes bad, becomes hard with age and no longer seals. This will prevent the clutch from applying.
The only way to repair it is to teardown the transmission. While you're there, you may as well rebuild it.

 

thanks Mike. That's kind of what I figured. A $1 seal gone bad and the trans is crapped out!! Lol. Looks like me and my son are gonna spend another weekend on our backs in the driveway.

 

Yeah, this is a common C6 problem. It's the seal that goes around the clutch apply piston. It gets hard and doesn't seal the pressure in.
Usually when it goes, it's gradual. First, when it's cold, you'll notice it takes a little longer for the trans to engage. Then you'll notice that it takes longer. Then eventually it just doesn't engage.
In the beginning, warming up the truck helps because heat makes the seal more pliable but you're on borrowed time.
BTW, welcome to FTE. Lots of good knowledgeable people here.

 

The C6 on my 73 F-250 is currently experiencing the same problem but I still have the forward gears when the tranny warms up. I think I'm gonna drop it and rebuild it myself. I've do a lot of research on it and it seems pretty doable for the someone mechanically inclined. I'm actually more concerned with being able to drop it by myself than rebuilding it. My decision is also based on other maintenance items that need to be addressed. My differential is leaking around the pinion seal and I want to replace the U-joints on the drive shaft.

 

I've rebuilt many C6's back in my day but it's been 20 years since I did one.
Many people including mechanics are afraid of working on automatic trannys because they simply don't understand how they work, the answer is easy, it's magic
Actually all they are is a system of hydraulic clutch packs and are in many ways easier to rebuild than a engine. The main difference being a lot more small parts. The best advice I can give to anyone who wants to learn this magic is to make sure you replace each and every seal, double check everything you do and keep things operating room clean.
I've made a U shaped piece of metal to use in depressing the clutch pack piston and a small rounded piece of wire to help install the clutch pack piston, use some type of lubricant when doing this on the seal.
There's two things I've learned in my career as a mechanic and that is most mechanics are lazy and will do short cuts where and when they can and that I can screw up something just as bad as they can without paying for it so I just as well do it myself and maybe learn something in the process.
Welcome to the world of magic, you will see what I mean when you tell people that you rebuilt your own transmission!

 

A guestion for Mike; as I said above its been 20 years since I have done a tranny but isnt the low forward clutch pack the same one that operates the reverse gear? My memory isn't what it used to be or at least I think it isn't.

 

No, the C6 has three clutch packs. The one located towards the front of the transmission is the 'reverse-high' clutch, the next one is the one that's probably causing the problem, the 'forward' clutch. The last one is the 'low-reverse' clutch.

 

dreed, if you do the work yourself, I would recommend getting a good manual or self help video.
The C6 is a relatively simple trans to rebuild. The key is cleanliness, knowledge and patience.
It's been a while since I rebuilt a C6, but as I recall, you're supposed to use a special tool on the last clutch pack (low-reverse) to depress the assy. I just cobbled something together.

 

Thanks for the refresher Mike, the last tranny I rebuilt would have been a C6 back in the late 90's. It's amazing where the time goes!
I also appreciate your time and effort helping all the all the folks on here, sharing and passing along your knowledge is a good thing, even after over 30 years of working as a mechanic I am amazed at what I have learned on here.

 

Thanks OldMetal, I know what you mean about time slipping away.
Even at my age, I still learn something pretty much every day.

 

To the OP, here's a link to Bad Shoe Productions how to video. I've heard that it's a pretty good video but have never seen it myself.
There are also quite a few videos on YouTube.
Bad Shoe Productions How To Video Series - Ford Transmissions & Rears

 

i was out hooning my truck this afternoon, rounding a turn in 1st lighting the tires up and then BAM! thruck goes limp and so do I. I coasted it to the nearest curb and 20 minutes later I'm hooked up on a AAA truck.

Here's the deal. the c6 was rebuilt and has less than 100 miles on it. it was pulling hard in every gear before this happened. so what is it?same thing?seal on the band apply piston in forward clutch. that was replaced when i rebuilt it. and it was working. it makes sense if it were something in the valve body. like a blown gasket and pressure is diverting somewhere.

but now i got the same thing, no forward gears. but reverse is nice and strong.