Okay, I have drum brakes in my 1969 Oldsmobile Cutlass 5.7L 2bl. Ever since we got that car the brakes have been real iffy. Most recently, I decided to work on them. We changed one rear wheel cylinder about two months ago and two days ago I changed the other rear wheel cylinder. I'm still waiting to get the new spring set (that comes tomorrow) to put both sides back together. It has always been the rear drum brakes that seem to give the problems. We have taken the brakes to the shop many times and the longest any work has lasted has probably been 2 months until they went back to how they were. I believe the new wheel cylinder I just replaced was leaking but I'm not sure. We have also had a new master cylinder put in on one of the trips to the shop. What I'm wondering is how much more could be left to check out? The only thing left I can think of would be rear brake lines or power booster, but if the power booster went out I wouldn't have any brakes right? The front brakes seem to work fine, it's the rear drum brakes that don't seem to do much. What else could be left? Any tests I could perform? Here is a link to my photo album: http://photobucket.com/69olds
P.s.- Along with putting in new wheel cylinders, I'm putting in new springs on both sides and new self adjusters.Where could air be getting into brake system? Hardly, if any, rear braking.?Another 40 year old vehicle with the same old problem. Either the workmanship is defective and air hasn't been removed from the lines correctly or your brakes are boiling the fluid thus causing air pockets to form in the line/s. Since air is compressible, this is why the rear brakes feel spongy (the vague feeling). Save some cash and invest in a disc braked rear end. problem solved.
Can you post a pic of the whole car?Where could air be getting into brake system? Hardly, if any, rear braking.?Theres a couple things I can see immediately off the start. I own a 2007 Cobalt LS and it has rear drums, and I agree I haven't seen them do much of anything since I got the car, but as the commercial says, the front does about 70% of the work. If your front brakes work fine, chances are its something in the rear lines, air is a big thing especially with older systems, bleeding them the right way and the right order is critical to getting the air out.
Another thing could be the actual drum cover, where the pads rub against. If the drum cover is under spec minimums, the pads won't even touch the walls. You need a shop or a micromoter to tell you whether this is true or not though. I wouldn't be surprised though if they were too thin, it'd explain the lack of control in them since the beginning and consider the age of the car, it is a likely possibility.Where could air be getting into brake system? Hardly, if any, rear braking.?I would make sure the rears are adjusted properly. If the star adjusters are not set right after a brake job the shoes will not touch the drums.
Also ask the shop if they bench bled the master cylinder properly before they installed it. If the all of the air is not purged out of the master before the lines are attached, you will not be able to get all of the air out.
Good LuckWhere could air be getting into brake system? Hardly, if any, rear braking.?try bleeding your rear brake lines! and you do have brakes if the booster is out ,when the engine is running and you press the brake paddle if you hear a hissing sound could be booster!when ever you change cylinders you must bleed the system!Where could air be getting into brake system? Hardly, if any, rear braking.?It sounds like your adjusters are backing off ,change out the arm and auto adjuster cable and be sure when you adjust the shoes up that the arm catches the teeth on the adjuster .If not the shoes are backing off on you .
