Pass rear brake locks up

[BigRedWeather]

Over the past year my passenger rear brake has been getting too much of the hydrolic pressure causing the wheel to grab hard or even lock up sometimes when I brake. The first time I tap the brakes the ABS and E-Brake light come on, and stay on until I shut the engine off. Over time the grabbing or lock up has gotten worse. If I use the brakes lightly, it will not lock up. If I am going down a hill to the right, and apply the brakes moderately it will always lock up.

When I come to a stop and the rear brake has gotten too much hydrolic pressure after 5 - 15 seconds the brakes will have released.

I have taken the truck to two brake shops. The last one said I have an electrical short somewhere in the truck. They told me to eliminate the short and bring it back to them.

Anyone seen anything like this? My factory manual tells me next to perform the "Wiggle Test" on all connectors associated with brake wiring. Does anyone know of some ways to eliminate portions of the wiring harness so I don't have to troubleshoot every inch of it?


BigRedWeather

 

[aaklingler]

Are you loosing brake fluid?

 

[OLDBULL8]

First thing I would do is replace both sides brake hoses. Drivers side may have collapsed.

 

[BigRedWeather]

No, I am not loosing brake fluid.

By "replace both side brake hoses" do you mean:

-replace all flexible brake hoses on the truck
-replace all flexible hoses and hard brake lines on the truck

I'm pretty sure the Wheel and Brake shop would have ruled all brake lines out. They went over it very carefully.

Not to disregard this input... has anyone had experience with electrical connectors or wires causing brake problems (expecially like this?)


Thanks for your posts,


BigRedWeather

 

[u2slow]

Are the self-adjusters actually working? Are they adjusted evenly?

I had a seized brake cable one side, and a seized adjuster on the other. Made for some interesting on-tire skids.

 

[Goofyexponent]

Are the self-adjusters actually working? Are they adjusted evenly?

I had a seized brake cable one side, and a seized adjuster on the other. Made for some interesting on-tire skids.

Agreed. I had the same issue until I removed all the hardware from the Driverside rear tire, hauled back on the E brake cable (which was seized up solid) and then re-adjusted the brakes. No issues since and the pedal is right there...you litterally just lay your foot on the pedal and the truck is stopping FAST!

 

[BigRedWeather]

Hard Pedal goes soft on start up.

I did not include one part of this because it only happens 1 out of 4 times, when it has been sitting overnight, when I start the truck. I put my foot on the brake and it is firm- I can depress it only 1/2". Then I start it with light pressure on the brake and as soon as it starts, the pedal goes down easily about 2 more inches and then becomes firm again.

Does this point to some other problem/cause?


BigRedWeather

 

[Goofyexponent]

When my emergency brake cable seized on the driver side, my pedal didn't have any effect until it was almost 3/4 of the way down to the floor. If I let off it and pumped it again it would be a LOT better.

When I tore apart the rear drums and reefed teh cable back (as a temporary fix) and then lubed everything up and adjusted both brakes, my pedal moves 3/4 of an inch and the brakes are RIGHT there.

I am willing to bet you have a seized adjuster, seized Ebrake cable or pivot. It might seem a bit confusing once you take'r apart, but it's really not too bad. You can take the adjuster out without disturbing anything.

If that little cable that holds the adjustment mechanism is broke or off it's retainer you will lose your adjustment in the matter of a day or so while driving around.

 

[Freight_Train]

I had an issue several years ago where my rear brakes would lock up and not release.The ABS valve on these trucks are bad about going bad if you don't exercise them from time to time(By that I mean get on a gravel/Dirt parking lot or road and just HAMMER the brakes a couple times so the ABS pulses.The valve doesn't move unless the ABS is used and will stick.As for the brake lines,THey are talking about all rubber lines as the lines will swell from the inside out.Sometimes letting fluid in but not out or not out fast.Also heard of some hoses comming apart internally and a lil flap of rubber acting like a check valve not letting fluid pass in only one direction.BUT....being as your rears are getting more pressure I will say the master cylinder or booster is going bad.I had a Chevy that didn't have ABS(1981 model) and it would lock the rears up with little pressure applied to the pedal.Was real fun.Got some funny looks when you would slide sideways to a redlight.The front brakes and REar brakes are different on out trucks so the fronts have a residual pressure valve that holds pressure at 2PSI and the rear has drums so it stays at 10PSI.THe valving might be messing up and not sending any to the front.So I would start with the Master Cylinder.

 

[BigRedWeather]

I replaced my Master Cylinder and Booster three months ago... I'm gonna go into the breaks and see what i find.

 

[BigRedWeather]

When my emergency brake cable seized on the driver side, my pedal didn't have any effect until it was almost 3/4 of the way down to the floor. If I let off it and pumped it again it would be a LOT better.

When I tore apart the rear drums and reefed teh cable back (as a temporary fix) and then lubed everything up and adjusted both brakes, my pedal moves 3/4 of an inch and the brakes are RIGHT there.

I am willing to bet you have a seized adjuster, seized Ebrake cable or pivot. It might seem a bit confusing once you take'r apart, but it's really not too bad. You can take the adjuster out without disturbing anything.

If that little cable that holds the adjustment mechanism is broke or off it's retainer you will lose your adjustment in the matter of a day or so while driving around.

Sounds like you had the same problem I am having. I will look the adjuster over, but I have been told by a professional brake man that the adjusters actually work on a very few cars. They are to work on my truck if I press the brakes pretty hard after going about 20 in reverse. They don't provide any adjustment though.


BigRedWeather

 

[Goofyexponent]

Sounds like you had the same problem I am having. I will look the adjuster over, but I have been told by a professional brake man that the adjusters actually work on a very few cars. They are to work on my truck if I press the brakes pretty hard after going about 20 in reverse. They don't provide any adjustment though.


BigRedWeather

I think that everyone recomends doing a manual adjustment on the brakes, but if your ebrake cable is seized or the pivot is seized, the little cable is not allowed to do it's job and hold the adjuster where it should be. You can litterally reach in there with your fingertip and turn the adjuster back and forth. If anything is seized up and not letting that cable do it's job, the pass side brake will take all the load (if the driver side is out of adjustment, or vice versa) and lock that wheel up.

I am going to say either an adjustment cable broke, something is seized iun the cable itself ot the pivot is seized or gummed up. Maybe eveb a spring broke, but you didn't mention any rattling.

 

[Popeye2347]

The brake hardware is probably the problem, but are both drums dry? Maybe a bad seal allowing diff lube onto the brakes causing it to grab?
I had a similar problem, turns out it was a bad seal and hardware that failed.

 

[u2slow]

Take the wheel and drum off already and have a look!

Speculate all you want, but really... you need to get in there and look.

 

[sassyrel]

I did not include one part of this because it only happens 1 out of 4 times, when it has been sitting overnight, when I start the truck. I put my foot on the brake and it is firm- I can depress it only 1/2". Then I start it with light pressure on the brake and as soon as it starts, the pedal goes down easily about 2 more inches and then becomes firm again.

Does this point to some other problem/cause?


BigRedWeather

no vac at no start--when you start--vac lets pedal go down more--but shouldnt be that far--