Help,my son just called,he has an 07 f150 4x4. he says the rear wheels lock up In reverse but drives forward fine. he's in tn. i'm in Utah. told him to pull the back wheels and check the brakes etc. says brakes shot. he did a brake job new pads and rotors. still locking up. had him check the e=brakes he says there fine????. he says now it may lock up forward or back. any thoughts appreciated. is it possible the rearend. once it goes he says it drives fine. hard to trouble shoot over the phone

 

It's just as hard to T/S over the Internet........

 

not looking for a trouble shoot,just if anyone has had a similar problem and possible cause. thanks

 

Kinda sounds like a diff or transfer case problem.

 

Something I'd do to try and determine which component would be at fault....

Jack the rear up

Put on jack stand make sure to block front wheels

Remove rear wheels, calipers, rotors

Make sure calipers are tied back and clear of hubs

Disconnect drive shaft from yolk and tie up out of the way

Get a large adjustable pliers and turn the yolk

First in the forward direction then in the reverse direction

If it locks up in reverse then it's the differential

If it operates ok then look at the brake system next...especially the E brake system...cable and shoes

Now if everything checks out ok on the rear axel then move the attention to the front differential
In some cases the front differential will be the cause

 

I doubt that this problem is a brake issue. Brakes, especially the e-brake, can usually be overpowered by the engine so it wouldn't "lock". Much more likely to be a problem with gears somewhere in the driveline.

I would follow 88racing's suggestion to troubleshoot the driveline