Mystery sound is back

My earlier post was titled "Knocking/Thunmping in front end"

Well, I thought I had this problem fixed. After a brake job and snugging up some bushings, it seemd to go away but it's back. There is an unnerving "knuckling" or binding sound at low speeds, mostly when I'm braking. I actually crawled beside it today while a buddy drove it slowly forward and back and have determined it to be coming from the vicinity of the transmission mount area or the front of the driveshaft...I think. This only seems to occur after the truck has been driven at any decent speed for a little while, never just around the block or short slow speed trips. Our guess is u-joints? We can not find anything at all that is loose or has any play in it. We've checked every bolt, bracket, etc....nothing, and there is no play in the driveshaft at least that we can tell. Would it be a good idea to change the ujoints as a good guess that's the culprit? The Bronco is a 92 and is all original, 113K miles. This really has me baffled, not to mention concerned.

The front driveshaft u-joints would be my first suspicion as to the cause of your problem, especially if they're still the factory items. The u-joint may look O.K., but if the grease is gone or dried up it will rattle and bind. If you still have this problem after changing these out, then it's a guess that one or more of the axle u-joints are going out. When you changed the brake rotors, did you also get new wheel bearings? It sounds to me from what you describe as more of a driveline problem than a suspension one, (like balljoints, radius arm or axle pivot bushings). Those generally have a popping sound as they relieve tension. Good Luck!

Well, it's not the ujoints. The search continues. I'm just going to work my way forward. Nothing has ever had me this baffled.

I'm throwing out a few more suggestions as if I was looking at my own Bronco. DO you have a manual transmission? The pilot (throwout) bearing may be going bad. Re-check the hubs and wheel bearings for fresh grease and no broken parts. WHen I installed new brake pads AND new rotors at the same time, I had to remove the shims on the pads to get enough clearance so that my old, wornout calipers would not bind. The old pads were worn down to the metal, and the old rotors were beyond repair. If your brake calipers are hanging up and not functioning properly, that might cause some weird noises. BTW, it took me and a mechanic friend 4-5 months to find a mystery oil leak on my rebuilt motor, so I know how frustrating the Bronco can be at times!!!

check all your bolts and tranny mount just to make sure they are tight

Quote:

My earlier post was titled "Knocking/Thunmping in front end" Well, I thought I had this problem fixed. After a brake job and snugging up some bushings, it seemd to go away but it's back. There is an unnerving "knuckling" or binding sound at low speeds, mostly when I'm braking. I actually crawled beside it today while a buddy drove it slowly forward and back and have determined it to be coming from the vicinity of the transmission mount area or the front of the driveshaft...I think. This only seems to occur after the truck has been driven at any decent speed for a little while, never just around the block or short slow speed trips. Our guess is u-joints? We can not find anything at all that is loose or has any play in it. We've checked every bolt, bracket, etc....nothing, and there is no play in the driveshaft at least that we can tell. Would it be a good idea to change the ujoints as a good guess that's the culprit? The Bronco is a 92 and is all original, 113K miles. This really has me baffled, not to mention concerned.

By any chance did you change the UJoints too ?.

If not it does not cost much, Do so.

Also in checking the U-Joints, put the vehicle in park and then into reverse and then to drive, if the knock sound is there, that is what it is (U-Joints), there is a pin noise that you will hear too, most of the time it is the driveshaft but it could be the frontend Joints too.

Note :
A kid locally is having to same problem, well he found out that it was the axles (Rear & front) as he rounded the corner by the house and pulled up in my drive way, the rear axles both came out and a big hole in the back pan, This means the C-Clips gave out letting both axles come out from the axle housing, the front need the joint changed too, he mud runs all the time.

I hope this is not what is wrong with yours.