Rear brake shoes worn. New cylinders as well?

[Julien Abrahams]

Hey gyus,
Wanted to have your thoughts on this. The other day I rotated the tires (to see if a slight pull to the right was caused by the tires) and I decided to check the rear brake shoes to see in which state they were in. Last year I changed the front shoes, cylinders and hoses. I saw that on the left hand side, the brake shoes were almost completely worn. If I had to guess I would say that there was about 1/10th mm lining left. The right hand side was not worn.
I still had new brake shoes lying around, so last week I put them on. Now everything is back together I'm thinking if it is a good idea to change both brake cylinders and the rear hose as well. What do you think? Better safe than sorry?
Normally, the cylinders start to leak before the lining is worn down, so I was a bit surprised about this .

[Bobby B]

J,
  Hi. Either the cylinder is hanging up hydraulically (or not retuning), or they weren't adjusted evenly from the get-go. The wear factor of linings really depends on the composition of the material that they're made of. The fact that one side is worn way more than the other is a red flag, and you need to look a little further into this. I'm surprised the car wasn't pulling noticeably to one side when braking.  Brakes are something you need to address properly for your own safety. Putting new shoes on is a band-aid for now. Try and get to the bottom of this before you get stuck somewhere on the side of the road with a locked up cylinder or something worse. Good Luck!
                                                                                                  Bobby

[Jay Friedman]

I agree with Bobby B.  It's not a good idea to change the front shoes, cylinders and hoses and not do the rear wheels at the same time, and cylinders can leak at any time.  What year car do you have?

I would like to add that pulling to one side can be caused by a bad wheel cylinder, a bad hose, shoes out of adjustment or worn unevenly and even wheels out of alignment.  I even once had it caused by nothing that professionals could figure out, but which was cured by driving at 50 mph on a quiet road, holding the steering wheel tightly in the straight ahead position and slamming on the brakes several times until they no longer pulled.  (Had to show 'em who is the boss!)

I would also like to add that once you finish, if you haven't done so already, it's also a good idea to do what Cadillac called a "major" brake adjustment.  This involves adjusting the "anchor pin", which the top of the 2 shoes rests against and that the 2 upper springs are attached to.  It is explained in the shop manual and also involves measuring the brake shoe to drum clearance through a slot in the drum using a feeler gauge. 

[savemy67]

Hello Julien,

I recently completed refreshing the brakes on my '67 Sedan DeVille (see High School Reunion with 1967 Sedan DeVille in the Restoration Corner section of this forum).  This task included installing new hoses in the front and rear, new front wheel cylinders, and dis-assembling and cleaning the rear wheel cylinders.  My linings had even wear, and plenty of material remaining, so I cleaned and reused the shoes/linings.  My car did not pull before refreshing the brakes, and it does not pull after refreshing the brakes.

I had to bleed and adjust the brakes a couple of times before I was satisfied with the pedal feel and performance of the brakes so be sure you take the time to bleed and adjust the brakes properly.  The shop manual calls for the use of a two foot (61 cm) bar when adjusting the brakes.  I used a bar like this, however I did not back off the star wheel as many notches as the shop manual states (40 notches).  On my car, this would have made the adjustment too loose.  You will have to experiment.  When I bled the brakes, I used a hand vacuum pump first, and then I had my neighbor apply the brake pedal several times while I bled the brakes again.  Ideally, a power bleeder would be best, but I do not have that equipment.

The point of doing a brake job on all four wheels at the same time is to eliminate the possibility that the brakes are the cause of uneven lining wear or pulling.  By all means, clean, rebuild, or replace both rear wheel cylinders and the rear hose.  You should also consider refreshing all the rear brake components so that you are confident the springs, star adjusters, and parking brake mechanisms work correctly.  A defective parking brake mechanism in the wheel that had the worn linings is something you should examine thoroughly.

The rear brakes may or may not have been the cause of the car pulling.  In general, most of the braking force (75% or more) is on the front wheels.  Half of the remaining force at one of the rear wheels - about 12% in this example - is probably not enough to cause the car to pull.  Once you have corrected the defects in the hydraulic and mechanical portions of the rear brakes, bleed and adjust them properly, double check that the front brakes are adjusted properly (and that the self adjusters are OK), then you should be able to diagnose the pulling issue without considering the brakes as a contributing factor.  Good luck.

Christopher Winter

[curly]

The fact that one side was worn more than the other may have been caused by a worn backing plate.  When I first got my 59, the backing plates had grooves worn in them from the movement of the shoes, bad enough that I removed the plates ( I had to install axle bearings and seals anyway) and had them welded up.  The shoes were hanging up in the grooves.
I used to have a can of Bendix grease specially make for backing plates. Ran out, haven't been able to find a replacement. I just use a dab of high temperature grease now.

T Lewis

[bcroe]

I replace all brake hoses about every 15 years.  If the car isn't driven regularly, I would be doing all the
cylinders as well.  And check for rusty lines (mine are stainless steel).  If you don't have a dual circuit
master cylinder, keeping everything in top shape is extremely important.  Bruce Roe

[Julien Abrahams]

It's a '67 Deville btw.

I have ordered the rear brake cylinders and rear hose, so they should be here and ready to go on early next week.

Well, I checked the shoes again, and it seems that the secondary shoe of the left rear wheel was almost completely worn, while the primary shoe showed the same amount of wear as the shoes on the right rear wheel. Not sure what has caused this. Especially with regard to the results from the brake analyzer/brake roller test stand as it showed that the brake force was very similar between left and right (front and rear).

I looked at the backing plates, and they look good. Good also be the brake cylinder not working properly?

When I put the cylinders and new hose on, I will adjust the brakes by the shop manual, then bleed the brakes, then adjust the parking brake and lubricate the parking brake cables. Should be good to go then.
When I check the last time (on the brake roller test stand) also the parking brake was working properly on both rear wheels. To make sure that the parking brake doesn't freeze, I operate it once in a while (say about once a month).

With regard to the pull: to cut a long story short, here are the facts point by point:
- when I first got the car, it pulled slightly to the right while braking
- at the first inspection (about 4 years ago) , front and rear brakes were tested on a roller brake tester and brake force (especially on the front ) was equal between left and right, so I kind of ruled out the (front) brakes as a possible cause for the pull
- the steering box was changed (old one had to be rebuild), still pulled when braking
- after a brake cylinder leak the front, replaced brake hoses, shoes and cylinders of the front brakes. Tested them at the brake roller test stand, brake force was equal between left and right. About a year ago the car has gradually started pulling to the right while driving
- had the car aligned, pulled less, especially when applying the brakes.
- adjusted the tire pressure: pull was gone, but now steering wheel was off center while going straight down the road.

Somebody here on the forum suggested to rotate the tires, so that is what I did last week (put the rear left tire on front  right, and left front on the rear right.
That is also how I discovered the rear brake issue.

I think that the pull is caused by one of the front spherical joints. But not sure.

[savemy67]

Hello Julien,

It probably would have been more effective if you had moved the left front tire to the right front, and the right front tire to the left front, and kept the rear tires in place.  When trying to isolate a pulling condition and you suspect the cause is the tires, it is more effective to change one variable at a time, and then assess the results of the change.

Since you have new rear cylinders and a hose on order, put the tires back to where they were located before you rotated them, install the new parts, and check for pulling.  If the new parts do not correct the pulling problem, swap the front tires side to side and see if the pulling follows the tires.  If the front tire swap does not change the condition, and pulling persists when the brakes are applied, it is possible you have a suspension problem.

Consider what happens when the brakes are applied.  Both front tires (as well as the rear tires) rotate at the same speed before the brakes are applied.  When the brakes are applied, the rotational speed of both front tires should decrease at the same rate if the brakes apply evenly.  If the braking force is uneven, one tire will slow down faster than the other, and this may cause a pull.  If braking forces are even, but you have a defective suspension component, the shift in the car's mass due to deceleration may alter the relationship of the alignment geometry on the side of the car with a defective component.  This might cause a pull.

Your post indicated that a change in tire pressure and an alignment affected the pulling condition.  This seems like a good place to start.  Do all four tires have the same tread pattern?  Are you inflating the tires to the same pressure when the tires are cold?  Are any tires worn excessively?  There are many spherical (ball) joints on the car.  Check all of them for lateral looseness, and check the upper and lower control arm ball joints for axial play.  Also, check the control arm bushings where the control arms mount to the frame, and the strut rod bushings at the front crossmember, and the sway bar links.  Good luck.

Christopher Winter