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Old 09-29-2007, 05:02 PM
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I have a 67 camaro with 4 wheel power drum brakes......since I bought the car a year ago the brakes have been very touchy, if you step a little hard on the pedal, you'll go through the windshield ! I don't drive the car very often and when I get out of my jeep and jump in the camaro, the first few times I hit the brakes I'm screeching the tires until I get use to it. If I let anyone else drive the car, the first thing they do is lock up the brakes when they stop. I've installed a new brake booster and master cyl. ( not to correct the problem, I wanted a correct looking booster and then discovered the master cyl. was leaking so I replaced that as well) I've bled the brakes thinking there was possibly air in the system but that didn't help. Could it possibly be a faulty pressure balance valve ??

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Old 09-29-2007, 05:57 PM
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Brake grabbing is what comes to my mind........Have you pulled the drums and inspected for leaks? A wheel cylinder seeping a little and it gets on the brake shoes...it will cause this. Another thing that can cause it..is grease...while you have the drums off look and see if a rear axle seal is leaking grease...also check and be sure that the front wheel bearing seals are not leaking bearing grease. It does not take much brake fluid or grease on brake shoes to make them grab.
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Old 09-29-2007, 06:13 PM
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I've had the drums off and haven't seen any leaks. The rear end was recently rebuilt with all new seals as well.
It almost feels like the front brakes are doing all the work.
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Old 09-29-2007, 06:42 PM
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[ It almost feels like the front brakes are doing all the work.[/QUOTE]
What about your shoe adjustment? Could be the front ones are tighter than the rear.
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Old 09-29-2007, 07:20 PM
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Also could be to agressive friction material if the brakes have been redone,The stock asbestos shoes are no longer available and many aftermarket compounds can do this.Something to check if all is well mechanicaly.
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Old 09-29-2007, 10:34 PM
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I would run it on some gravel 5 or 10 mph should be plenty of speed and hit them so they lock up ..once stopped get out to see which wheel/ wheels locked up and go from there..
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Old 09-29-2007, 11:52 PM
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1.check and make positively sure that the Master cylinder that you have on the car is the correct one for the car.
It sounds like you may have a non power cylinder on the car with the booster.

2. Make sure that you have the correct booster for the application.

With both of these items, just because they bolt on doesn't necessarily mean that they are correct for the application.

3. Make sure that your brake shoes are installed correctly. The one with the least lining is always the front shoe and the one with the most lining area is always the back shoe in a set for one wheel. Back 35 years ago when I was doing several brake jobs daily I often had to follow behind home mechanics who got things mixed up.

4. Make sure that all of the brake springs and hardware are installed correctly and in good shape. Springs attached wrong or in the wrong location or missing will cause problems.

5. As mentioned by someone else Make sure that there is no foreign material on the linings or drums. = grease including finger prints, brake fluid or oil.

6. As at least one person previously mentioned, make sure that all four wheels have the shoes adjusted correctly.

As a side note, when I was working in a national brand tire store as the brake and front end mechanic I found that the "Joe Cheap" discount auto store shoes often had a better feel, stopped smother and quieter than the top of the line shoes. They didn't stop as well, didn't last near as long and faded quicker with repeated high speed stops but I had less complaints from the average drive it to work guy. I'm not even suggesting that you switch to lesser shoes but saying that some of the top of the line stuff can be a bit touchy unless everything is perfect.
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Old 09-30-2007, 12:06 AM
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Another thing to consider is this. Having driven many GM cars of this era back when they were new, overly sensitive power brakes, just as you describe, was not unusual. They were definitely different than other cars and simply required a much lighter touch.
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Old 09-30-2007, 09:21 AM
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Thanks to everyone for posting all the helpful suggestions.
I never thought to check the brake shoes, I had a 68 camaro that had the shoes put on backwards. I will go over the system again and post any findings. Many Thanks !
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