1991 Ranger Tranny Rebuild

[Ramblinwilly]

Glad to be Here!
Had to give my 93 F150 5.0 last rites last Friday. Got extremey lucky and found a 1991 Ranger 4X4 with an automatic with 67,000 original miles. Yes, all original. Truck is in great shape inside and out. However, I've got one small issue that may need to be remediated by a tranny rebuild and that is the nature of my question.

There is a slight hesitation/slip between 1st and 2nd gear. Truck runs great in all other gears and goes down the road just fine. I checked the tranny fluid and it's full but is a bit dirty. Not burnt smelling just dirty. Tomorrow I am going to change tranny fluid, filter and do the flush to see where that gets me.

1. Are there any adjustments external to the tranny that would cause this issue? I know that my F150 would not shift properly if one or more of the electronic components were causing a poor running condition. This vehicle runs perfect but just though I'd ask.

2. In the event that a tranny rebuild is in order, I was going to get one from a bone yard and rebuild it while the original is in the truck. I found this site by searching for transmission issues. My question is where can I find a decent how to guide on a rebuild? I don't need to be spoon fed. I kept my
F150 going for quite a few years and have done some relatively ambitous projects by having good reference material. Any guidance would be greatly appreciated.
Thanks
Willy

 

[arco777]

Welcome to the forum!

If all you have is a 1-2 shift issue, you probably won't need a rebuild.

There are two things that are (relatively) easily fixed from outside the transmission that affect the 1-2 shift.

#1 is the vacuum modulator. This modulator sticks into the passenger side of the transmission. A vacuum hose running through a combination of metal and rubber tubing to the intake manifold provides vacuum, which operates a diaphragm inside the modulator and pushes a pin in and out that pokes important bits inside the trans. Failure of the modulator usually involves a ruptured diaphragm (this will cause the vac line to carry trans fluid up into the intake) or general failure causing delayed 1-2 shift. Also, the vac line sometimes comes off or gets damaged. Replacement of the modulator is pretty easy, just go through the access panel in the floor. A new modulator is inexpensive. Research the subject on this forum (do a search) and you should find a how-to thread about it, along with more info.

#2 is the governor. The governor is in the tail housing extension on your transmission. The governor has a valve controlled by a sliding weight. This weight rides on a "stalk" and is spring loaded. Gunk in the transmission fluid causes the valve to bind up. Usually a sticky governor causes delayed 1-2 shifts when fluid is cold, but when fluid warms up and it cycles a few times it will shift smoothly until you shut the truck off and let it cool again. Research it on the forum for more info. Accessing the governor on a 4WD requires dropping the transfer case (pretty easy) and reaching into the tail housing extension, undoing the two bolts and just pull it out. There are no new governors available for sale, but you can clean your existing governor easily once you remove it. At 67k miles it is likely in good shape, even if dirty, so cleaning it and changing the trans fluid should do the trick if it is sticking. For high mileage governors or as added insurance you can replace the stock governor weight with an upgraded weight made by Sonnax (~$8), which will also make the 1-2 shift come a bit earlier.

 

[jd4242]

Also check your band adjustments on the outside of the trans.

 

[Ramblinwilly]

Sincere thanks. When changing tranny fluid and filter, I checked the modulator and found that hose needed to be replaced. Shifting problem solved!!!!!!!!!!!!!!!!!!!

 

[arco777]

Glad it's sorted