Touchy brakes
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Cargo Master
Joined: Apr 2001
Posts: 2,364
Likes: 3
From: Eustis FL
Touchy brakes
I just replaced a brake booster because the pedal was dangerously hard to press and stop.
With the new booster, the pedal effort is now easy like it should be.
Problem now is that the brakes are real grabby, especially at low speeds. I would amlost say a front end dive would indicate the back brakes aren't pulling as soon as the front brakes. I adjusted the new booster's rod so that I have a good 2" of travel before brake force comes on, as recommended.
The pads and shoes are all clean and in good shape, with no leaks detected anywhere. I bled the whole system big time. Any idea of what this might be? I fixed it for my sister in law, and while I can adjust to driving it no problem, I don't want her to drive it like that. It can stop on a dime. Funny thing is, it seems that when you hold the pedal in one spot, it feels like the brakes are progressively being applied... Does that give enough description?
With the new booster, the pedal effort is now easy like it should be.
Problem now is that the brakes are real grabby, especially at low speeds. I would amlost say a front end dive would indicate the back brakes aren't pulling as soon as the front brakes. I adjusted the new booster's rod so that I have a good 2" of travel before brake force comes on, as recommended.
The pads and shoes are all clean and in good shape, with no leaks detected anywhere. I bled the whole system big time. Any idea of what this might be? I fixed it for my sister in law, and while I can adjust to driving it no problem, I don't want her to drive it like that. It can stop on a dime. Funny thing is, it seems that when you hold the pedal in one spot, it feels like the brakes are progressively being applied... Does that give enough description?
Thread Starter
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Cargo Master
Joined: Apr 2001
Posts: 2,364
Likes: 3
From: Eustis FL
Yes, I adjusted the rear shoes out all the way, can barely slip the drums on (but still spin by hand).
The vehicle?? Um... Er....
It is a 1981 Dodge Mirada CMX. Heh heh! Only about 5000 made of these cars. But, same as Cordoba from 80-83.
The brakes have actually gotten worse since my brother in law drove it a few times. Same symptoms, only much worse. I confirmed that by trying to brake just in the driveway. In reverse, then braking, not an issue. Maybe the rear shoes got contaminated deeply by an old axle seal leak? Or, maybe they somehow degraded with time? (it hasn't been driven for a while)
Thanks for the reply! I was wondering if anyone would give it a go!
Mark
The vehicle?? Um... Er....
It is a 1981 Dodge Mirada CMX. Heh heh! Only about 5000 made of these cars. But, same as Cordoba from 80-83.
The brakes have actually gotten worse since my brother in law drove it a few times. Same symptoms, only much worse. I confirmed that by trying to brake just in the driveway. In reverse, then braking, not an issue. Maybe the rear shoes got contaminated deeply by an old axle seal leak? Or, maybe they somehow degraded with time? (it hasn't been driven for a while)
Thanks for the reply! I was wondering if anyone would give it a go!
Mark
Postmaster
Joined: Jul 2005
Posts: 3,248
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When inspecting the rear brakes, where the the brake shoes istalled properly, Primary shoe (brake shoe with longest pad to the back of car) and secondary brake shoe (brake shoe with shortest pad toward front of car).
It was my understanding that the shoes were inpected and clean of oil. Oil would cause a grabbing brake.
With front tires jack up in the air, wheel and tires off. Have some one, press brake and verify that the front brake are functioning properly, brake should engage the release once brake pedal is released. And should be noticeable at the brake caliper, should move inward then outward. Maybe the caliper is sticking.
It was my understanding that the shoes were inpected and clean of oil. Oil would cause a grabbing brake.
With front tires jack up in the air, wheel and tires off. Have some one, press brake and verify that the front brake are functioning properly, brake should engage the release once brake pedal is released. And should be noticeable at the brake caliper, should move inward then outward. Maybe the caliper is sticking.
Thread Starter
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Cargo Master
Joined: Apr 2001
Posts: 2,364
Likes: 3
From: Eustis FL
The problem isn't in the front brakes, as far as I can tell. They brake and release like they should, but the rear brakes seem to be coming on way too late. I know they work, because with the car blocked up on stands, I can stop the wheels from spinning when in drive. It seems maybe effort is a little much on them, so maybe the linings were contaminated at some point? Won't grab very good at all.
Mark
Mark
Postmaster
Joined: Jul 2005
Posts: 3,248
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It could also be proportioning valve and is installed in the drum-brake hydraulic line on vehicles equipped with disc brakes in the front and drum brakes in the rear. In a dual hydraulic brake system, it is installed below the pressure differential valve. The function of this valve is to prevent premature rear brake lockup and skidding. Line pressure is allowed to increase normally up to a certain point (determined by vehicle weight and braking distribution). When this predetermined pressure point is reached, the valve begins to limit the amount of increase in hydraulic pressure delivered to the rear drum brakes. This limiting action prevents the rear brakes from backing up before the full, effective braking effort is produced by the front disc brakes. This valve is also known as a pressure-control valve, a pressure-ratio valve, or a pressure-regulating valve.
How is the fluid pressure at all brake bleeder valves in the front and the rear of your car? Does it have good fluid pressure?
How is the fluid pressure at all brake bleeder valves in the front and the rear of your car? Does it have good fluid pressure?
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