Hey everyone,
I figured instead of continuing in my thread about no power anywhere, I should just make a new thread. The electronics in the Mallory Unilite distributor on my '79 F-100 were completely shot, so instead of spending $100 to replace the module and waiting a week, I spent $80 and replaced the whole distributor immediately. A quick timing and wiring job later, and the truck finally runs, and it sounds great. After searching everywhere, I was only seeing posts about having reverse but no forward gears, which is the complete opposite of my problem.

After running it for a few minutes, I decided it was time to check the transmission. I started by putting it in drive, and it goes forward without a problem. I then tried putting it in reverse, and it acted like it was in neutral. I pulled the shifter to and from drive and reverse several times, and only once did it go into reverse, but only for about a second. I'm not even sure that it actually went into reverse, I just think the momentum of shifting rolled it back a bit. Anybody know what could be causing this? I don't have any reverse lights either, could that somehow be connected to the problem? The transmission fluid is full, I topped it off before trying to shift. Any help would be great

Thanks,
Sean

Edit: The truck has a 302 in it, and the transmission either a C4 or a C6. I'm not entirely sure, as I haven't spent much time under the truck, but I do believe it has a C4

 

The first thing to do is make sure your linkage is adjusted correctly and it's actually selecting the gear you think it is.

The reverse lights have nothing to do with the transmission itself but the fact they aren't working could indicate your not going into reverse. but it certainly isn't the only or most likely explanation for them not working.

 

When I work on it tomorrow, first thing I'll do is get under the truck and check the linkage. It goes into park, neutral, drive, 2, and 1 without a problem, could the linkage be off enough where it doesn't grab only reverse?

 

Obviously check the fluid level.

 

Checked while cool, warm, and running once it was warmed up, fluid level is full

 

And make sure you have your vacuum line connected to the transmission, at the modulator valve I believe. The other end should go to manifold vacuum.

Have you driven it forward at all? When I forgot and left the vacuum line off of my C4 in my old '68 Cougar, I believe it didn't have reverse, and also I remember it had trouble shifting to second gear, and in either first or second gear, there was no engine braking. Boy was I relieved when I found that vacuum line...

 

if it's shifting into park and the other gears properly then it's not the linkage.

Unfortunately the odds are there's not going to be an easy fix.

 

So the hose connecting into the vacuum modulator on the back of the C4 could just very easily fall out, I touched it with a set of pliers and it was already ready to come out. I got some new vacuum tubing and ordered a new vacuum modulator that should come in tomorrow. Would that be the cause of having no reverse? I also noticed that it going into drive is somewhat rough, not hard, but you can definitely notice it.

 

I don't think that would cause it but I can't say for sure. a broken reverse band is the most common cause for no reverse but there are other possibilities as well.

 

You're probably right. Next step is to get the new vacuum modulator and line put on, and if that doesn't fix the problem, then it looks like I'm going to have to rebuild the transmission. A C4 rebuild kit costs about $100 to $150 if I remember right. And from what I've heard, the C4 is very easy to rebuild, especially for a guy like me who has never rebuilt or even taken apart a transmission.

 

The older automatics aren't that hard to work on the biggest problem is not having the experience to see hard parts that need replaced . getting it to work is one thing, getting it to last is another, there's a reason most accomplished mechanics send their transmissions out of house to be rebuilt .

You can give it a whirl if you want to but don't be surprised if it doesn't go as well as you hoped.

 

So yesterday, I lifted the rear end up, adjusted the reverse band adjustment bolt to 2 turns, then 1 and a half turns, and disconnected the linkage to put it in reverse by hand, and still got no reverse. Occasionally, when in reverse, the wheels would move forward, but never backwards. I went ahead and ordered a complete rebuild kit that will be in tomorrow, but do you guys think I should go ahead and replace the reverse servo too?
Thanks,
Sean

 

I went ahead and started taking the transmission out of the truck tonight, everything is disconnected and the transmission is free from the engine, but I can't seem to fit the bellhousing through the transmission tunnel in the firewall. Any tips for removing it?