Brake pull in 2wd but not 4wd

[jman11788]

So I’ve been chasing a brake pull for 2 years now which is absurd. Anyway, today I just noticed if it put the truck in 4hi the brakes don’t pull at all as it should. I realize this is because both driveshafts are locked to together so there is equal stopping power from the front brakes to the rears.

I think this would eliminate all the suspension components being a culprit and narrow the problem to the brake system. Last week I bled the master cylinder and the brakes of course. It took 180 pumps to finally get the bubbles out of the MC and honestly I still don’t think all is out. After doing that it felt like the pull was gone but it was still there. I do however think it helped.

I jacked the truck up on all 4s and put it in drive to see if the brakes would slow all wheels down evenly and it did. I don’t think I have a collapsed brake hose but something is definitely wrong with the brake system

It likes to pull at higher speeds, going down hill, rain, and imperfections in the road. Any clue?

 

[nc-grayson]

how are your rear drums? are either of them hot after a normal drive? I'm guessing one of them is dragging slightly.

I would recommend getting a vacuum bleeder and bleed the shit out of the rears. try a mityvac

 

[fourwd1]

After 2 yrs chasing this its time to get serious.
I would pull each caliper off and check for a seized piston,
And then pull the drums and check for proper operation of Everything there.
Fix what you find and see how it goes.
Then move on to the MC if necessary.

 

[3bears]

I had a break pull, but not continuous.
Finally one day it pulled hard right by a tire shop. It was a caliper piston that sometimes would stick.. My fix TBU.


I had another car years back, pulled to one side, Looked at everything, did everything I could think of , finally replaced the hoses. Problem solved. Hoses don't have to look bad form the outside to be bad. Sure enough , disconnected hoses, stepped on master cylinder and one was barely pissing. Bu that was a car from the 60's and IM sure brake hose technology has changed.

If your shocks and suspension are right on, then it has to be realted to the brake system, and I would think calipers

 

[Mudeprived]

Have you thought about disconnecting the lower strut and testing your control arm bushings?