2001 Ram 2500, Cummins, 4wd at almost 350k miles. Disc front and shoe rear. Brake calipers/pads/shoes always have been well maintained and zero problems to date.

Recent event - after stopping and when starting to accelerate, mild inertial resistance, vibration and groaning sound which stops once truck begins rolling. At that point, problem seems gone. This does not occur with every braking stop, and has happened more than once when coasting to stop. (Yes, drove around a big parking lot and tried every conceivable variable.) From driver position, it seems to be coming from the front. Never occurred when starting out in reverse.

Removed both front wheels, inspected calipers/pads/etc. - both turn by hand but with resistance (will not continue rolling) , which I expected with 4wd. Opened driver side bleed valve and a little bit of fluid ran out - maybe 10 ml.

Put all wheels up, ran drive train in 2wd and 4wd - of course, no noise or vibration anywhere after several applications of brakes. Will further attack diagnosis today - but do need experienced suggestions.
Thanks for any insights.

 

Check your u-joints and carrier bearing if you have one.

 

Thanks - while it is up on stands, just did this. Lube good, no binding, no play, no noise. Replaced carrier bearing at about 200k.

 

If the brake hoses are old, I would change them. They could be failing internally. Check rear brakes for wheel cylinder or axle shaft seal leaking.

 

Thanks for your reply. Today removed rear wheels etc. - shoes good at about 75% and nothing binding - no leaks from wheel cylinders or axle seals. Shoes engage and retract smoothly.

Yes, the fluid lines are now almost 22 years old, but seem undamaged by corrosion or abuse - always has been in a dry climate and rarely driven on salted roads.
I opened both ends of the front lines today and blew air through from both directions - flow seemed normal. Then, bled those lines.

Put some lube on the clip surfaces on which the front pads move - they seem to be moving laterally with freedom. Maybe that was the problem.

Will take it off the jacks and do a test run.

Thanks for the reply.

 

Vac boost or hydro?

 

It's the soft lines that can cause the brakes to not completely release. They may look perfectly fine, however, they break down internally, and begin to act as one-way valves...... With the truck up on jack stands, spin the wheels to get an idea of how much effort it requires. Then, hit the brakes a couple times, and try and spin the wheels again. If they are stiffer now, crack open the bleeder valve, if they get easier to turn, the soft lines are bad, and need replace. If you change one, change ALL of them. They all live in the same environment, and are all the same age.... so, if one is bad, you can bet the others aren't far behind.