1996 Bronco Eddie Bauer 351 Windsor modified, REAR END?

ford
bronco

#1

I’ve had a vibration since I bought this Bronco 7 yrs ago. I have replaced everything underneath from front to rear. Tie rods, ball joints, wheel bearings, U joints, shackles, etc. As I replaced things, the vibration got better. Or at least wasn’t as violent. Now, the vibration is becoming LOUDER. It only happens during acceleration. I can get up to 65-70, let off the gas, and all I hear is the beautiful sound of the tires. If I get back in the throttle, the sound of the rumbling vibration drowns out the stereo. Also, I have recently noticed a squeaking sound in the rear, under acceleration. Ughhh
Any ideas?


#2

Assuming it happens in 2 wheel drive, it is probably u-joints, center carrier bearing, rear diff, or transmission bearings, In that order of likelyhood.


#3

U-joints? That should give you a vibration all the time and should have failed well before 7 years. Pull the driveshaft, check the U-joints first and then the driveshaft itself. Look for a shop that builds driveshafts. They can check the joints, check the shaft for straightness and balance it. Check the rearend for bearing and gear roughness by turning the pinon by hand. If there is any doubt, pull the cover and look inside. I suspect you’ll find the cause somewhere in this path. Good Luck, post later and let us know what you find.


#4

My guess is the rear end, either bearings or gears. Do like @Mustangman said, especially the turning the pinion by hand and pulling the cover to inspect (and look for shavings). If anything is wrong, I’d replace, not repair, and get a used one for it. There should be plenty.

edit - if a bearing is bad, and there’s no evidence of metal particles in the oil, and replacement is straightforward, then I’d just replace the bearing.


#5

I brought my 91 Explorer in the shop for a …’‘u joint’’… noise.
he ran some test drives and some on-the-hoist tests.

replaced the differential pinion front bearing !

No more noise.


#6

A couple years ago, I took it to a reputable drive shaft shop and told them to replace all joints and balance. That eliminated the side to side, door panel rattling, shake!
It happens in 2 or 4 wheel drive (locked in or not). Based on what I’ve already replaced and what everyone is suggesting, I’d guess it’s in the rear diff.
I’ll let you all know what happens.