Hello everyone, I've got some issues with my transmission. Any help would be greatly appreciated. There were two things that were not working on my C4 transmission (from 81 F100) that caused me to take it down and begin an overhaul. I wanted to ask whether anyone might have any ideas as to what to look for during this process to help identify the causes. Below are the issues.

1. The transmission would not upshift from 1st to 2nd. It would though shift down from 2nd to 1st. I hate to say this but this may have been caused by negligence. I had had the truck for about three days and had to take it to a mechanic. The dashboard display indicating which drive it's in doesn't work so I was going by feel. In any case I think the transmission may have been in drive when it was towed. After this point is when the 1st to 2nd gear stopped working. My question is can these two events be related and if so what should I look for while overhauling.

2. I drove the truck for a few years like that (would start from a stop in drive 2) but eventually the reverse went out. I have to admit it happened after an incident where I was making a 3 point turn on a slight hill. Rather than wait for the truck to fully stop I did the ole engage reverse a bit early (learned my lesson). After this I made the decision to overhaul the transmission. While removing the extension housing I found half a snap ring laying in the housing. I've come to realize this is the snap ring that holds the governor distributor body (and i.e. the governor) in place. With this snap ring gone the distributor body slides back and forth about an inch or more. Could this broken snap ring be the cause for the lack of reverse? If not what else could be causes for such a sudden stopping of the reverse function.

Thanks again for any assistance.

 

There's no rear pump on a c-4, so you didn't do any damage towing it. Most trans issues are from the seals getting old & hard, or of lack of service. Just go thru it & put in a master kit, replacing clutches and any worn bands, seals & governor rings, and you should be fine. Make sure the valve body is very clean, c-4's seem especially prone to valves sticking if any dirt gets in them while trans is apart. You can air check the clutch & band functions on the bench with a blow gun before & after overhaul.

 

Thanks for the reply. As much as possible I was hoping to identify obvious issues prior to reinstalling. So far I have a broken snap ring on the output shaft (governor side), worn down and damaged seal on the intermediate servo piston, bad inside seals on the clutches, and a few sticky/nearly stuck valves in the valve body. Considering one of the main issues was losing reverse, do you think I should replace that low-reverse band? It seems ok and doesn't have a lot of wear.

 

If it doesn't show wear, there's no need to replace it. It wasn't slipping in low or reverse, right? If it was, I'd put a new one in for insurance.

 

No, it just happened. Prior to it going out it was clunking into reverse. But as far as how it happened, pulled out of my house in reverse fine...parked in town, and then tried reverse again and nothing. If the reverse going out was associated with me putting the truck into reverse while it was still rolling a little down hill, what would that damage. Clearly your not supposed to do that, and so I guess the question is what happens to the transmission when you do?