I had a 71 bronco back in the day, Really missed it. Finally got the chance to get another and found a rust free 92 with just the options I wanted, Power brakes and steering. Rubber floor, manual trans and transfercase. Anyway my problem is the tinker toy axles they are putting under these trucks now days. I replaced the rear drive shaft and I still have vibration over 50 miles an hour. More from the front than rear.
Not sure where to start. spindle bearings, axle joints,Diff, or pinion bearings, front drive shaft. I am open toany ideas.
when did they quite putting 9" diffs in the Bronco?

 

Sorry, I forgot to mention . I did the prereqisite search for posts that may address my issue. Read many, many pages of posts. looking for a fresh input

 

Have the tires been balanced recently? Have you tried swapping the front wheel/tires to the rear?

 

They stop putting 9 inches in the early 80s I think or either 1979.

I just did a SAS and put a 9 inch in my 1990 Bronco. 9 inch went it like a charm. I just had to take out the flange that went to the 8.8 on the driveshaft. The U-joint went in fine with the U bolt 9 inch pinion driveshaft yoke.
I did get a 1979 Ford extended brake line too. 90 Bronco brake line worked good connecting to the 79 brake hose.

Check your tires and make sure they are balanced. If that is ok.

Check your driveshaft u-joints. If that is ok.

Disconnect the rear driveshaft from the rear axle and see if the big pinion nut inside the pinion yoke needs to be tighten. If that is ok.

See if your truck needs alignment.

 

Also look into having the drive lines balanced properly. If they are off even by a little it can cause issues. Tires are a big one as they mentioned, Make sure all the nuts and bolts are tight for the drive lines? Mine used to come loose on my 78 till I got rid of the old 12 point bolts and dropped a few hex head grade 8's in there. Worked well. Anyways, I think about 1980 was the last year for the 9 inch. I have heard mixed opinions on both the 9 inch and the 8.8, some like them some don't. Then there are the people who just go and drop a rebuilt Dana 60 in there...

I just wish I could pull a diff cover off the 9 inch for fluid changes or inspections.

 

Vibration seems to be getting worse. Hubs not locked, T-case in 2w/hi
Tires are new. Don't know if it is worth the time and money to start replacing bearings, and U-joints, or start with clean and grease with seals? and it goes from bad to worse when you put it in 4wd. Any help?

 

What kind of vibration does it feel like? Like something is rubbing and causing a fast vibration, or the kind that would rattle your teeth out?

 

before you start throwing money at this check some things first. jack up one side of front end, grab the tire top and bottom and push/pull checking for any movement. if none and hubs dont get hot while driving then bearings are fine. as for u joints i assume your talking about drive shafts. check them the same way, yank around on them and if you don't get any play then there ok. now i would guess what is wrong is alignment or tie rods, you can check these also before you spend any money. tie rods- with the truck on the ground lay under the front end and have someone turn the wheel a little back and forth while you look at each joint looking for any play. as for alignment just check it with a tape measure front and back of the wheel just make sure the points you measure from and to are the same front and back.