Parking brake problems

I am going round the bend . Finally finished my CJ5 and took it to get a road test certificate (MoT required in UK) .

It failed as emergency parking brake not holding the vehicle sufficiently when applied with foot . They have replaced the linings, spings, mechanisms, cables (all three and equaliser) and still it does not hold the vehicle well enough to pass. Anyone know of any obvious or commom problems ? The vehicle is 1974 CJ5 with drum brakes all round.

Thanks, Jas

 

Try adjusting the brakes.

With automatic adjusters, the brakes will adjust when you back up (5-10 mph) and apply the brakes firmly. The pedal feel should improve as the brakes are adjusting. If the pedal feel does not improve, then the adjusters may have been assembled wrong or backwards.

With a lot of slack in the adjustment, the parking brake pedal may not travel far enough to fully tighten the shoes against the drum. The p-brake pedal should only travel about half its full distance before you cannot drive it down any more.

Typically a foot-pedal design like this will give you plenty of leverage to lock up the rear wheels on a dry surface.

 

Thanks, I'll try reversing and applying brake to adjust ? Secondly it is possible that the parts supplier gave me later cables as one side the cable is longer than the other. Should they be the same length both sides?

 

Possible. But it should still work if you can remove the slack using the threaded adjuster.

I will check the PNs when I get home later.

 

Appreciate it.

 

I'm not really impressed with my 74's parking brake's holding power.
Mine, too, is all new everything (except the backing plates, and the pedal assy.)
My cables were the same P/N and length on the rear.

I can crank down on that pedal till it starts to bend, and it will barely hold on my ever-so-slightly sloped driveway.It works OK from going forward, naturally, but it is dreadful for offroad use.

I've done scores of brake jobs professionally and never had such a miserable parking brake.

 

Both cables to the wheels are the same - Jeep PN 999980.

The overall length of the two cables can be different, but the amount the cable protrudes from the sheath must be the same for both sides.

I've owned three of these CJs now (plus my trucks) and I have not noticed that the p-brakes are so terrible. Back in the day, the pedal was troublesome. The frame of the pedal would bend and the ratchet would not work right - you'd press the pedal but the ratchet would not catch. But this wasn't a problem with the strength of the brakes - instead it was a problem with the location of the pedal assembly. Becasue it's off to the side of the driver, pedal force was not always straight-on to the pedal. The lateral push would bend the frame of the pedal.

 

On my '74 CJ5 the rear parking brake cables are the same length for both sides.

You can also adjust the shoes by pulling the rubber plug from the backside of the backing plate and using a screw driver (or brake adjusting tool) to manually turn the adjusters. With the wheels off the ground just adjust until there is a very slight "drag" when turning the wheel by hand. You should be able to feel it, but don't over tension them either. If a significant adjustment is needed, this may be faster / easier than doing it by backing up and applying the brakes. Just remember that the passenger side adjuster is reverse threads.

-Chris

 

Oh, another thing you can do is to pre-load the rear brakes with the brake pedal. Stomp on the hydraulic brakes at the same time that you push on the p-brake pedal. This way you're only taking up the slack in the cable on the already-seated brakes.

I would also lube the cables well. The mechanics at the Jeep dealer kept a pump oiler full of motor oil thinned with solvent. They'd use that on the springs and the cables - it soaks in, and the solvent evaporates. Or you could use the home-made penetrating oil recipe of half ATF and half acetone, again in a pump oiler.

It helps to put a little dab of white grease on the bearing points and pivots in the rear brakes. Anything you can do to reduce friction in the mechanical linkage will help. Beyond that, the mechanical advantage is what it is.

And make sure that the cable adjuster does not have so much slack that you can't properly seat the p-brake.

 

I had the same problem with my 72. I replaced the cables when I first got it because the originals would not move at all, after that the parking brake would just barely work and it would not hold the vehicle on a hill at all. After removing the drums and applying the park brake I noticed that the springs that are on the ends of the cables that are supposed to return the park brake actuator lever when the park brake is released where too long and would coil bind before the brake shoes could apply enough force to the drums, that explained why the park brake pedal would go down about 2 inches and get firm all at once. I cut about 4 coils off each cable spring and now my park brake works great. Hope that helps.

 

I think I will get the right cables first, ie both the same length, then try the adjustments you mentioned. Thanks.

 

new brake, Make sure they been ached and fit the drum correctly. And the drums have been turned .