Why are my front brakes dragging??(1980 GMC Vandura 35 class c)

The front brakes on my 1980 GMC Vandura 35 class c motorhome are dragging and I am not sure why.Once the brakes cool off they work fine but once they heat up the front brakes are dragging again.

I took the unit out for a test drive and when I got back home I jacked the front end up off the ground but I could not make either wheel move at all.I left it for 1 hour and they moved fine.

Any help would be great.

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Comment by David Larry Smith on September 9, 2014 at 3:01pm

If your brakes are hanging up then this is the inexpensive fix---follow your flex hose to the bracket that holds it to the frame--what happens is the bracket rusts on the inside and pinches the flex line to restrict the release of brake fluid from your brakes---I took a small die grinder with  a cut off blade and carefully cut the small bracket without cutting the flex hose---so I could relieve the pinching pressure on the hose --I never had anymore problems and the flex hose never had to be replaced-----a small dremmel type tool with a thin cutoff blade worked great---just be carefull not to cut deep enough to hit the flex line--cut just deep enough so you can use a screwdriver to pry the clamp apart-----a loose twist tie or tape can be used to resecure  the flex line to the frame-----I had bought a new flex line but never had to use it after cutting the pinched rusted clamp bracket-----Dave

Comment by Lakota Wolf on August 28, 2014 at 2:56pm

Bill is absolutly right,,,, I totally forgot about THAT rubber line. (and I had just replaced complete brake system on my One ton.). I totally forgot that the Brake Block (splitter had a pressure switch to it) which was connected with a flex line for movement of the rear axle. 

Comment by Bill Ford on August 28, 2014 at 11:46am

Shawn, there actually is a flex line on the rear, it runs from the frame, usually the cross member, to the distribution block on the rear axle, from there it is solid steel line to the wheels. Visually inspect this and check for cracks in the outer shell.

Comment by Lakota Wolf on August 26, 2014 at 9:09pm

Rear brakes RARELY have flex lines, its usually a hard brake line from the spitter/equalizing block to each wheel cylinder. Its always a good idea to check those yearly,if not more often for corrosion and rust, especially where the clamps hold the brake line to the rear axle. A tell tale sign of a failed wheel brake cylinder is wetness around the drum and dust plate, (on the inside of the wheel).

Comment by Shawn Kane on August 26, 2014 at 8:58pm
I was able to fix my dragging brakes issue by replacing the old flex hoses and running running new brake fluid completly through the brake system until the lines ran clear.
Also just wondering if I have flex hoses on the rear brakes???
Thanks for all of the great help.
Comment by Kevin Crowley on August 26, 2014 at 8:34am

I'd be checking calipers if it was mine. We had similar issues with our G35 a wile back and it turned out to be sticking calipers as suggested by John T below. Easy to fix. Remove calipers, clean moving faces and apply the smallest amount of copper grease to the critical sliding surfaces only, circled in red on the attached photo. No more sticking brakes for us.

Comment by John "T" Nordhoff on August 24, 2014 at 5:06pm

  I like Wolf Man and Bills comments, I have had that happen but also on a truck that sets a lot the calipers tend to stick and hang. You can start with new lines as that's not too expensive HOWEVER those fittings are bad to corrode and are hard to loosen and you may bite off more then you can chew. I take a hammer to beat n shock the fittings and ALWAYS use flare nut line wrenches. Similar the teeny bleeder plugs on the calipers can be tough to loosen so do likewise on them. NOTE unfortunately there's a good chance your rotors are now warped so you may need new lines,,,,,,,,,new calipers,,,,,,,,,,,,new rotors (or at least turned down true)!!!!!!!!! Grrrrrrrrrrrrrrrrr

 John T

Comment by Lakota Wolf on August 24, 2014 at 4:49pm

As Bill Ford Mentioned,,,,,, It is a common problem for the rubber (flex) brake hose to deteriate and calapse inside the housing, Brake fluid heats up when applying the brakes and which in turn causes the rubber to become pliable,, hence  colapsing.. That has been the MOST common problem I have come across on brake lock up after driving,, even a short distance. Replacing the rubber lines to the caliper usually does the trick. Just be sure to colapse the caliper piston completely and add fresh brake fluid.  Bleeding out the old while adding NEW fluid into the resivoir, (to avoid filling the lines with air.) Checking the movement of the brake caliper piston is always a plus,, to check if its *retracting AFTER the brake pedal is released.

If the piston in the caliper is working properly then you shouldnt have any issues.

* NOTE**  Even if the Rubber brake/flex line LOOKS good,, interior deteriation does happen.

Rubber brake/flex line is actually a heavy brake hose inside a protective sleeve.

Hope this helps.

As always,, If your not confident in performing brake work, have a knowledgable friend or Mechanic do the work,, Just for safety.

Nothing is worse the trying to stop on a dime and ending up stopping on a buck fifty.

Comment by Bill Ford on August 24, 2014 at 3:44pm

Chances are that on a system this old the inner liner of the rubber hoses that run from the frame to the caliper has collapsed causing a check valve type of phenomenon where the liner restricts the flow of fluid out of the caliper. a way to check this is (if you are familiar on how to bleed the front brakes) to loosen the line at the caliper and bleed the pressure off, and see if the caliper releases. if it does not, then chances are that the piston may be beginning to seize within the cylinder bore of the caliper. after performing this test it is essential to bleed whichever caliper that that you loosened up to remove any air that may have entered while it was loose. Hope this helps.

Comment by Russell E Johnson on August 24, 2014 at 1:27pm

Maybe they were tired>? LOL Sorry, could not resist.  Do you have disc or drum branks up front




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