My Buick's brakes JUST WONT STOP like they used to!!

[Guest janusjwilde]

I have a 1964 Buick Lesabre, drums all the way round. My car used to stop on a dime, but now it brakes ever so slowly. I took it to the shop today and had the shoes changed. That didnt make much of a difference. The wheel cylinders are fine, the brake lines are fine, the master cylinder is fine and it seems the brakes dont need bleeding. What could be causing this problem? The only thing I HAVENT done is turn the drums. Could that be it? If anyone has an idea of what could be causing this my brake troubles, please let me know.

[special55]

Poor finish on the drums would definately effect the overall performance of the braking.

I am curious though why you(or the repair shop) feels the brakes don't need bleeding. I have seen many an instances where a brake hose collapses and shows no evidence externally that there is a blockage. If this were to happen up front you would most likely have a "pulling" condition on braking but not necessarily if it where the back.

If the shop isn't completely familiar with four wheel drum barakes they may not have the shoes adjusted properly. These can be a bit tempermental and the service manual procedure should be followed to a "T".

Just a couple suggestions. I am no expert on 64 LeSabres by any means.

Keep us posted on what you find out though so others can benifit from your resolution.

Rich

[Guest janusjwilde]

I have been spending tons of money trying to figure this out, and I guess it IS as simple as the brake drum refinishing. It got worse after they put the new shoes on, so I am going to tell them to resurface the drums.

[Guest Trunk Rack]

sad fact is you may not be able to get the kind of brake linings your car had on it when it was new. Modern lining material may not be as "grabby" as earlier materials. Hopefully, someone in here who knows about this stuff can refer you to a supplier who can provide you with brake linings that have the proper "co-efficient of friction' to make your brake system behave like it was designed to do.

A well equipped DRUM brake shop SHOULD have the tools to not only "turn" your drums, but also to make sure, either by adjustment of the ecentrics (I cant recall whether your era Buick has "ecentric" pins that are adjustable) or by attaching a power tool that "centers on the axle, and makes sure your brake lining surfaces are actually "round" in terms of their relationship to the drums.

good luck. Good brakes are nice !.......!

[special55]

Trunk Rack just jogged my memory.

Friction material that is too hard can be a problem.

Check out this thread:

http://forums.aaca.org/f162/brakes-ii-227946.html

There is some good info on poor functioning brake shoes that are brand new.

Good luck,

Rich

[Guest janusjwilde]

the problem wasnt with brand new brakes. The problem exists with new AND old brake shoes.

[jrbartlett]

There are lots of things to check. First, is this a power brake car? If so, the booster may be going bad. Or if the master cylinder or booster was replaced recently, the actuator rod going into the MC may need adjustment. Too far one way, and the pedal is too hard from insufficient power boost. Too far the other way, and you get too much boost and you can't avoid locking up the brakes.

Others have already mentioned bleeding the system and checking the hoses and lines.

As for the drums, there are two possible problems -- are they now oversized from wear and previous refinishings? Are they out of round? If so, that will hamper performance -- and could be dangerous. If they are grooved from wear, the new brake shoes would not work as well as the old ones, because they do not conform to the grooves like the old ones did. Also, it is rare to find anyone who correctly sizes brake shoes (by grinding them on a special machine) in order to fit the drums. Eventually the shoes would wear in, maybe, but in the meantime performance suffers. Further, your drums could be "glazed," meaning the surface is too smooth. That's another reason that drums require turning. A qualified brake shop will have the specs and equipment to measure your drums and determine what they might need.

The brake shoes themselves could be a factor. I have a '66 Riviera with drum brakes, and I took it to an old-time brake shop for a rebuild. The "old man" there -- by far the most experienced employee -- insisted on ordering specific Raybestos shoes from an out-of-town source, rather than getting something from the local parts stores. He said these shoes would make a tremendous difference in performance. Others in the shop questioned this, saying "Why wait." Well, the shoes did come in, and the brakes now work superbly -- with strong, straight stops.

Buicks of that era were known for having good brakes compared to other cars (though nothing like what we have today). Just keep working at it.

[Guest janusjwilde]

You said: There are lots of things to check. First, is this a power brake car? If so, the booster may be going bad.

How can I tell if the Power Booster is going bad?

You said: Others have already mentioned bleeding the system and checking the hoses and lines.

The Hoses and lines have been checked.

You said: As for the drums, there are two possible problems -- are they now oversized from wear and previous refinishings? Are they out of round?

The havent been turned in years, but the mechanic did say they have grooves in them. He didnt turn them though. How can you tell if they are out of round? And how is that dangerous?

You said: If they are grooved from wear, the new brake shoes would not work as well as the old ones, because they do not conform to the grooves like the old ones did. Also, it is rare to find anyone who correctly sizes brake shoes (by grinding them on a special machine) in order to fit the drums. Eventually the shoes would wear in, maybe, but in the meantime performance suffers. Further, your drums could be "glazed," meaning the surface is too smooth. That's another reason that drums require turning. A qualified brake shop will have the specs and equipment to measure your drums and determine what they might need.

So if the drums are smooth and they are later "turned" will everything be ok?

Edited July 24, 2009 by janusjwilde (see edit history)

[jrbartlett]

In response to your questions, I think I would start with the drums. They were manufactured to a certain specified diameter, and can simply wear out over the years. A good brake shop will have a measuring tool that can determine whether they are worn too much to be turned. The same tool can determine if the drums are out of round due to wear. Extreme wear becomes dangerous because a too-thin drum can shatter, locking up the wheel or even worse, causing total loss of braking. I think there are federal regulations governing how much drums can be turned -- I know there are for rotors on disc brakes.

Assuming the drums can be turned, that will take care of both the grooves and any out-of-roundness. If the drums are too worn to allow another turning, you need to find some replacements.

Another issue with worn drums is that brake shoes are manufactured to fit factory-spec drums. Back in the '60s, replacement shoes could be re-radiused by good brake shops to more precisely fit worn drums. This has become a lost art due to regulations over brake dust and the rise of disc brakes. If you can find someone who can do this, it will also help.

I have a '64 Lincoln with a quarter-million miles on it that has excessively worn drums (they measure out-of-spec and can no longer be turned). The brakes don't work as well as they once did, despite new shoes, and they tend to lock up easily or shudder from high-speed stops. I've found rear drums from a lower-mileage car, and plan to swp them out shortly. As for the fronts, I'm going to install disc brakes from a '65 Lincoln, as good front drums are extremely hard to find.

While I hope this has been educational, it sounds like you should identify a really crackjack brake shop in your area that has experience with older drum-brake cars -- or best yet, that also has some older employees. This stuff will be right up their alley.

[Guest janusjwilde]

In response to your questions, I think I would start with the drums. They were manufactured to a certain specified diameter, and can simply wear out over the years. A good brake shop will have a measuring tool that can determine whether they are worn too much to be turned. The same tool can determine if the drums are out of round due to wear. Extreme wear becomes dangerous because a too-thin drum can shatter, locking up the wheel or even worse, causing total loss of braking. I think there are federal regulations governing how much drums can be turned -- I know there are for rotors on disc brakes.

Assuming the drums can be turned, that will take care of both the grooves and any out-of-roundness. If the drums are too worn to allow another turning, you need to find some replacements.

Another issue with worn drums is that brake shoes are manufactured to fit factory-spec drums. Back in the '60s, replacement shoes could be re-radiused by good brake shops to more precisely fit worn drums. This has become a lost art due to regulations over brake dust and the rise of disc brakes. If you can find someone who can do this, it will also help.

I have a '64 Lincoln with a quarter-million miles on it that has excessively worn drums (they measure out-of-spec and can no longer be turned). The brakes don't work as well as they once did, despite new shoes, and they tend to lock up easily or shudder from high-speed stops. I've found rear drums from a lower-mileage car, and plan to swp them out shortly. As for the fronts, I'm going to install disc brakes from a '65 Lincoln, as good front drums are extremely hard to find.

While I hope this has been educational, it sounds like you should identify a really crackjack brake shop in your area that has experience with older drum-brake cars -- or best yet, that also has some older employees. This stuff will be right up their alley.

Its not the drums, or the shoes or. It seems like its the master cylinder. The pedal is all the way to the floor and it barely stops the car. I recalled yesterday that many years ago I hav ethe very same problem. I hope when the MC is changed (I had to order it, they had none at my local parts store) the problem will be solved.

Edited July 24, 2009 by janusjwilde (see edit history)

[Steve Braverman]

If the front drums are the aluminum finned drums that Buick used, try not to turn them. They will warp terribly if they get too thin. I had a '63 LeSabre that had these drums and it is a problem.

[RansomEli]

Don't know if this is your problem, but something similar happened to me.

I changed brake shoes and the car just didn't stop as well. Replaced with a new set and the problem went away. Upon retrospect, I did not carefully break in the old set properly and accidentally glazed them. Replacing new shoes and cleaning up the brake drums did wonders.

I have never had this happen before, but now I religiously take the time to wear in the new shoes/pads.

[joe_padavano]

Don't know if this is your problem, but something similar happened to me.

I changed brake shoes and the car just didn't stop as well. Replaced with a new set and the problem went away. Upon retrospect, I did not carefully break in the old set properly and accidentally glazed them. Replacing new shoes and cleaning up the brake drums did wonders.

I have never had this happen before, but now I religiously take the time to wear in the new shoes/pads.

There are many, many variables in this problem. First, brake lining material is different today due to EPA requirements (asbestos). Second, you can get metallic drum brake shoes, but keep in mind that metallic linings need to be hot to work properly. Cold metallic linings have a lower coefficient of friction and won't stop as well. Third, verify that you have the correct master cylinder and that it is not leaking internally. Many replacement MCs have consolidated part numbers and yours may not have the correct bore diameter. Fourth, have you replaced all the rubber hoses in the system? These hoses can (and do) break down internally and small flaps of the lining can block the passage. Fifth, have you checked all the hard lines? I had a situation where a rust-weakened hard line was expanding, reducing brake effectiveness, until it ultimately started leaking. Sixth, if the drums have been turned, were the shoes re-arched to match? If not, only a small portion of the lining will make contact with the drum.

[Guest janusjwilde]

There are many, many variables in this problem. First, brake lining material is different today due to EPA requirements (asbestos). Second, you can get metallic drum brake shoes, but keep in mind that metallic linings need to be hot to work properly. Cold metallic linings have a lower coefficient of friction and won't stop as well. Third, verify that you have the correct master cylinder and that it is not leaking internally. Many replacement MCs have consolidated part numbers and yours may not have the correct bore diameter. Fourth, have you replaced all the rubber hoses in the system? These hoses can (and do) break down internally and small flaps of the lining can block the passage. Fifth, have you checked all the hard lines? I had a situation where a rust-weakened hard line was expanding, reducing brake effectiveness, until it ultimately started leaking. Sixth, if the drums have been turned, were the shoes re-arched to match? If not, only a small portion of the lining will make contact with the drum.

The problem is the master cylinder. It will be changed this week.