1991 4-speed auto shutter/vibration

[Golfball]

So I have a 1991 Ranger, 4.0 with 4 speed auto transmission. It has developed a vibration that really kicks in after shifting into overdrive. It didn't do this until a few weeks ago and nothing else changed on the truck. I searched through this forum and can't find much that relates. So does anyone have any ideas on this? I have checked the driveshaft and u-joints and they are good and tight, no worn parts. Changed fluid and filter but still have the same vibration/studder. And it isn't a tire issue either. This seems to start some in 3rd gear and really vibrates in O/D.

Couple of pics of the truck. Really clean 2 owner.

 

[franklin2]

I would investigate the engine. Could be a misfire on a cylinder? Only does it when you press on the gas pedal correct? Find a steep hill and start off on that and see if it does it in the lower gears also.

 

[rumblecloud]

Looking at the images you posted, the problem is obvious to me -- it's the rearview mirror -- you need to get that back on the windshield where God intended it.

 

[Golfball]

Looking at the images you posted, the problem is obvious to me -- it's the rearview mirror -- you need to get that back on the windshield where God intended it.

Haha. I did and it didn't fix it. I was actually waiting on the new windshield to be installed. But good catch.

 

[lil_Blue_Ford]

So I know you said you checked the driveshaft/u-joints, but heres a couple things I’ve run into. If the joints are just starting to go bad, sometimes you have to block the wheels and put it in neutral to find it. Sometimes the little bit of tension from being in gear (manual) or park (auto) can be enough to hide this. Also, if it has a two piece driveshaft with a pillow block bearing on a crossmember, that can go bad and cause vibration. I went to a single piece rear shaft in my 92 because of this. Source from a newer Ranger with the same options.

Check motor mounts and transmission mount, if they are worn/broken you can get a vibration.

Front end. My 92 was tearing up front tires and had a vibration that kept getting worse but I couldn’t find anything loose. I took it to a repair shop (Monroe Muffler in my case) and explained the problem and asked if they could check it. Took three techs before one found a little play in the one tie rod end. It was one of those things where you couldn’t move the tire too hard or you would miss it. I took it home, pulled the spare new one off the shelf (I often pick up spare new parts if they fit multiple vehicles I own or I know it will need replaced and get a deal on it) and swapped it over and it cured the problem. Sometimes it just takes someone else to look at it.