I have a 1995 F350 Powerstroke 4x4 that I tow my 26' boat with. Last year the problem started when I went to back the boat down the ramp and touched my brakes at all the truck shakes, makes one hell of a racket, and feels like the entire rear end is going to twist out of the truck? I let off the brakes, the popping shaking and chattering stop. Things I have done since then is to put new brakes, springs, and drums on the rear axle, drained all the fluid out of the rear end and replaced it with new fluid and friction modifier. I go to launch the boat for the first time this year on Friday and absolutely smooth, not a hiccup. I go back today and touch my brakes going down the ramp and once again it feels as if the whole rear end is going to twist out of the truck, terrible chattering and clunking every time I touch my brakes when backing down a hill. Will never have anything like this going forward and when backing with out the boat loaded on the trailer. It is only when there is a load on the boat trailer. Before you ask, it is definitely NOT the boat trailer as when it started with my truck we started towing it with my buddies rig and NO ISSUES at all. I also have checked my u-joints, they are tight. My biggest fear is that my rear end will fall out on the boat ramp some day. Does anybody have any ideas? It is driving me crazy!

 

Have you looked at the front brakes? Noise while backing can happen when pads get too low. Also, did you check the spider and ring gear alignment when you had the diff cover off?

 

Thanks for the response. It is definitely coming from the rear not the front, I also had a friend watch the rear end while I backed and applied the brakes. He said it looked like the rear end was going to roll off of the springs. It is not pad too low kind of noise, it is a LOUD Popping, Shuddering type noise that shakes the whole rear end. The gear all looked brand new when I changed the fluid. No metal on the magnetic drain plug, no shavings in the bottom of the housing, everything looked perfect. Let me put it this way, when it makes the noise people from 75 yards away turn around to see what is making all the racket.... I have checked every bolt on the rear end, spring mounts, shock mounts, etc.... I can find nothing loose, nothing broken!