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Expert
Posts: 1348
  
Location: Valley Forge, Pa. | Having poor[at best] brakes for the past 9 years and dumping thousands of $s into them with NO improvement, I am thinking when it gets warm again, I am going to go through the whole system one peice at a time until I find the problem. I am wondering where to start?
I was thinking I could plug one side of the MC. IF the pedal is hard then try the other side to make sure it is mushy. Lets say the front is solid and the rear is mushy. Do I just go to the exit side of the proportioning valve or to the right rear cyl. or maybe to the rear T and plug it then try the pedal? Will it mean bleeding the brakes every time I try anything?
Again, I/we have replaced EVERY part and inch of the system one or more times. We have bled by pushing, pulling, gravity bled several gallons through it with no difference. I'm guessing there HAS to be air somewheres[?]. Where or how would you attack this and what it the best reasonably prices device for 1 person to push or pull the fluid through? Start at the front and go back or the back and go forward? Again, will it involve constant bleeding?
This is a non-power dual [disc/drum] MC with AAJ front disc on a 1960 Plymouth Suburban. I know the Suburban is slightly longer but anyone else have any issue with Suburban brakes? All the brakes SEEM to be working when its off the ground but pedal is mushy and will not lock any of the wheels. I always drive with a safe distance but have to keep looking for somewhere to go in even mild panic stop.
Thanks again,
Karl. |
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Expert
Posts: 2002
Location: Branson, MO | If the MC is full of fluid and you push the pedal but none of the wheels lock when the car is off the ground, you have a pressure problem getting fluid to the wheel cylinders and calipers. Disonnect the line at a wheel and have someone press the pedal. You should have a strong squirt of fluid without air bubbles or intermittent flow. If you don't pass this test, disconnect one of the lines at the MC and have the pedal pushed and see if you have strong pressure as expected with no bubbles or intermittent flow. If not, it's got to be related to the MC. There is not adjustment on the disc brakes but there should be on the drums so make sure these are adjusted properly. Good luck!
"It's delightful, it's delovely, it's DeSoto"
Edited by Viper Guy 2016-01-20 3:07 PM
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Expert
Posts: 3776
Location: NorCal |
Was the car originally a non-power brake or was it power brake converted to manual? |
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Expert
Posts: 1348
Location: Valley Forge, Pa. | Always non-power.
I'm sorry if I said it wrong, the wheels will lock if it's off the ground, just not while driving. |
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Extreme Veteran
Posts: 307
Location: Newcastle Australia | Don't undo and plug the lines. All you are doing is introducing air into the system, which could cause more problems.
The first step is to clamp the flexible lines. A small pair of vice grips with soft timber on the jaws does the trick.
Clamp off the rear brakes first and test the fronts. If you can't lock up the front brakes then you don't have enough pressure in the system.
Non power assisted disc brakes are very difficult to match master cylinder to caliper. |
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Expert 5K+
Posts: 8947
Location: WHEELING,WV.>>>HOME OF WWVA | take the master cylinder off and bench bleed the hell out of it ---------------------------------------------------later |
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Elite Veteran
Posts: 610
Location: Wilmington, Delaware, USA | I know I'm late to the party but I believe your problem is in the master cylinder. You see, you need to keep a certain amount of residual pressure in the brake lines and your master cylinder doesn't have the residual pressure valve. You could either replace the master cylinder with one that is known to have the valve or plumb into the brake lines these two valves. As the amount of residual pressure is different for disc (2 lbs) and drum (10 lbs) brakes, you'll need for each side of the master cylinder.
Chris
http://www.jegs.com/i/RPC/707/R4513/10002/-1
http://www.jegs.com/i/RPC/707/R4514/10002/-1
Edited by hullinger 2016-08-10 11:06 PM
 (707-r4513.jpg)
 (707-r4514.jpg)
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 707-r4513.jpg (23KB - 186 downloads)
707-r4514.jpg (20KB - 190 downloads)
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Expert
Posts: 1730
Location: Michigan | Hullinger has a point. Do you have these in place? |
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Expert 5K+
Posts: 9654
Location: So. Cal | If he is using an OEM master that is made specifically for disc/drum, it should have those residual pressure valves already built into it.
Now you are thinking Karl. Narrow down the possibilities. First plug the rear brakes by clamping the rear hose as lozrox58 suggested. You can get clamps that are made specifically for this so that it isn't as likely to hurt the rubber. Then test your pedal to see how it feels. If it feels good, you know your problem is in the rear. If not, try clamping one or both front hoses. You can even clamp all of them, and if it still feels bad, you will know that it is a master cylinder problem.
Edited by Powerflite 2016-08-17 11:29 PM
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how would you check brake system peice by peice?
