right wheel locks up

Home  \  Repairs & Maintenance  \  right wheel locks up

I have a '84 chevy citation with rear drum and front disc brakes

The emergency brake(parking brake) is foot pedal actuated. This is a left hand steering wheel car and the emergency brake foot pedal is on the left

When the emergency brake is applied the right rear wheel locks up and the brake on the left rear wheel is only partially applied(it never locks up) This is on dry pavement.

The brakes have been done a year ago with new drums, new shoes and new emerg cables(all 3 of them). There is a equalizer on the rear axle where the emerg. cable goes into it and from there it splits to either rear wheel. There are no worn parts anywhere to be found. As far as the brake drum adjusters go, they are adjusted until the drums just drag (with a loose emerg. cable of course) So as far as I can see I've done everthing right or have I ?

Got any ideas why the braking is so imbalanced??? I've tried everthing

posted by  cargrease

try tightening the cable to the left rear wheel see the pic the cable is to slack

posted by  osborste

This is pretty serious stuff so I wouldn't tweek with it without being sure of what I'm doing and if I should be doing it. I would just take it to a mechanic. If you don't want to spend the money on that, just privat message hobo. I heard he responds to PM's and he's an ASE mechanic so he'll be fine figuring this out.

posted by  Nissan_Altima

Hobo's not the only licenced tech here so go smoke a tailpipe :banghead:

posted by  osborste

osborst says

"try tightening the cable to the left rear wheel see the pic the cable is to slack"

I've tried that. The cable adjuster tightens both wheels not just one :banghead:

posted by  cargrease

So why is it you very seldom have a remotely correct answer? He even told you the e-brake cable has an equalizer and you still f*cked it up. You can't adjust them separately.



How are the service brakes? Any pulling or locking? Have you removed the drums and visually inspected the assemblies? Contaminated shoes? Proer placement of the primary and servo shoes?

posted by  vwhobo

cargrease I have the very same problem!

I own a 1986 chev cavalier and it has the same brake system as your car. I can tell from your post that you are totally exasperated by this problem.

My right wheel locks up when I push on the foot pedal but the left wheel does not. At first I thought it was bad brakes. I have a mathematical back ground so I ventured to see if I could apply some math to the problem. First I disasemmble the parking brake system and had a good look at it. I noticed something peculiar about how GM has designed this and recalled a mathematical thing called the "force vector" was the needed tool to obtain the understanding of WHY.

First the cable that comes from the foot pedal, we'll call it the "main cable"

The main cable goes from the foot pedal to a mechanism called an "equalizer" .This equalizer sits somewhat loosely near the center of the rear axle. From the equalizer there are two cables, one goes to the left wheel and the other to the right wheel. The angle that the main cable makes with the cable going to the right wheel is greater than 90 degrees, and the angle the main cable cable makes with the cable that goes to the left wheel is less than 90 degress. So the tension of the cable that goes to the right wheel is the SUM of the horizontal and vertical components of the main cable tension and the tension of the cable that goes to the left wheel is the DIFFERENCE of the horizontal and vertical components of the main cable tension.

The result is about twice as much force is applied to the right brake as compared to the left one. And there is not a thing you can do about it as GM has engineered that problem into the parking brake system. :clap:

posted by  cargrime

I must admit my car knowledge is too weak to suggest a solution to this problem but as a high school Physics student, I find your explanation very interesting. I just have one question. If I understand correctly, the main cable goes to the equalizer from the foot pedal. It is then connected to 2 different cables, one going to the right wheel, one to the left. How is it possible that the angles are different if the 2 wheels are parallel and the 2 cables go from the same point that is about equidistant between the wheels? Or am I just not picturing something correctly?

PS This freezing problem on CF is horrible...good thing I finally remembered to copy and save.

posted by  Nissan_Altima

Maybe there is a pully system. Not sure of that myself. With that kinda attitude you might ask how teh transmission is in the engine bay, and the shifter isnt right parralel to it. Its just hot its set up.

posted by  newyorker

Nissan altima says

"
How is it possible that the angles are different if the 2 wheels are parallel and the 2 cables go from the same point that is about equidistant between the wheels? Or am I just not picturing something correctly
"

It would help to see the actual GM parking brake system on these cars. The 2 different angles will be readily apparent

I'm not reffering to the angle between the right and left cable.(There is a small angle here though, but I was not reffering to it) To be more specific, it is the angle that the main cable makes with the rear axle. This is NOT a center pull type of parking brake as is found on the better systems.

I had a Toyota that had a center pull hand brake. When you pulled the lever both rear wheels would lock up everytime on dry pavement

posted by  cargrime

this is what i was trying to refer to as the center and right rear cable tighten and apply the right rear brake assembly then the left rear cable will start to tighten applying the left rear brake

posted by  osborste

Your Message