1985 Ford Ranger -Transmission slippage

Good day all!

I own a 1985 Ford Ranger, 2wd, 2.8l automatic.

a couple weeks back i noticed my transmission slips out of first gear right around the time when it should shift into second. I brought it in to my mechanic and they suspected the modulator valve. They wanted to do it Wednesday when it was Friday, but me being impatient i did it myself that weekend.

So once i installed the modulator valve it went from slipping 1-3 times a WEEK to 3-5 times a DAY. It slipped so much more often. transmission fluid was great, right in the cross hairs. I took it in again and they wanted to rebuild the transmission as they thought it was something internal. I made a bit of a fuss and told them it must have something to do with the modulator valve since that’s the only thing i touched. Sure enough they took my modulator valve out and figured the pin was way too small. They put in a new adjustable modulator valve with the correct size pin.

Now this is where it gets interesting, but first let me elaborate. lets jump back to after i messed with my modulator valve the first time which resulted in it slipping more often. I had to just barely push on the gas and it would clunk into 2nd, around it’s proper timing. I cant go too fast or too slow. otherwise it would slip.

Jump back to now, i can stomp on the gas, go light, do whatever i can to try and make it slip like it once did but it wont. That sounds good right? But now it won’t shift automatically. I can get it to manually shift if i take her off of drive and put it to 2nd you can clearly hear it shifting. My question is is obviously to get a ball park idea of what it could be. I’m a amateur when it comes to vehicles, and a complete newbie to transmissions. But i suspect it has something to do with the computer telling my transmission when to shift. What do you guys got for ideas? Thanks!

If the modulator is vacuum operated, it could be the vacuum line needs replacing.

1 Like


Yesterday i took it to a backyard mechanic I’ve heard great things from. He took out the modulator valve and said the pin was .070 too long and that it was basically telling my engine to shift super late that wasnt feasible, Put in a smaller pin and slapped the modulator valve in there. Went to drive it and it finally shifted, but very late. before i would have to press very lightly on the gas until i shift to 2nd gear then i can go full throttle. Now it shifts and i can go a bit harder on the gas before it slips. That was yesterday. I went to drive to work today and it kept slipping in and out way worse then i’ve ever seen. It was making a weird sound when downshifting from first and shifting late. Here is a quote from a website listing common problems with the a4ld transmission " [The governor is yet another common area where problems may arise. Over time, dirt build up can cause the governor to stick, especially when it’s cold. Common symptoms of this problem include a delayed 1 – 2 shift" So yesterday my truck was fine, it was warm. I drove it this morning and it was acting just so weird. Maybe its cause it was cold?

Anyway, that’s my update. Now to answer you Purebred. I’m not sure if i did it right but yesterday when i woke up i started my truck quick let it run for like a minute shut it off. Went under my truck and pulled the vacuum line off the modulator. No transmission fluid came out (which none should since its a brand new modulator) and i tried sucking air out of the tube and i couldn’t get anything.

With my transmission getting gradually worse i’m honestly thinking of tossing in the towel and buying a new transmission and installing it, rebuilding mine, or getting one from scrap and throw it in. My truck is low kilometers so i’d like to get a scrap a4ld tranny that is low km too.

My truck is at the shop right now and getting looked at tomorrow. You guys think my transmission is screwed?

I think it’s going to be in the shop for a rebuild within a week or two. I own a 70’s Ford truck, and when this sort of thing started to occur I didn’t mess around. Into the shop, and the rebuild fixed the problem 100%. The modulator valve doesn’t do that much btw. I think you are on the wrong track there. The modulator improves the trans shift when accelerating or under heavy load. But it will still work pretty good even without the modulator even connected for just putting about town, as long as the disconnected modulator doesn’t create an engine vacuum leak. As long as your truck has been well maintained and reasonably driven a rebuild is the best option imo.