Ok So a while ago, as stated before,my mom made me go to the local mechanic shop to fix my brakes and told me that my proportioning valve and master were out. So i just replaced the master myself with a cheapo $25 one. Problem is that ive bleed the system for like 2 hours straight and now with the new master, the car doesn't lockup tires when i slam the brakes like it used too, and i have to push down pretty far to get the brakes going and its not very good either. Should i replace the PP valve with another one or try a different master cylinder? I think the quality of the master might be bad as well..What do you guys think? I tested the booster and it checks out and no brake fluid leaks anywhere else....Please help I know this sounds weird but I have a date with the girl i like in a few days and i dont wanna crash my firebird with her in it!!
79bird
Did you bench bleed the new master cylinder? I would try gravity bleeding them and see if that will fix it. Basically, make sure the M/C is full, starting with the RR, loosen the bleeder and let the fluid drip into a pan for 15-20 minutes, tighten the bleeder. Watch the bleeder as the fluid drips for any bubbles. As long as there are bubbles, there is air in the system. Then go to the LR and do the same thing. Next, do the RF and then the LF. Keep an eye on the fluid level during the process and don't push on the pedal. Let us know if it works.79bird said:
I apologize if you covered this in your other thread...But, can you verify that the MC bore is the same size? Bore size is important with your system. Too small and you will push the pedal to the floor without fully engaging the brakes. Too big and you won't be able to press the brakes at all.
Another problem I have had in the past similar to yours was due to worn out rubber hoses, especially at the rear brake junction. Even if this doesn't fix this particular problem, it is worth replacing these parts for the safety you are looking for.
Another problem I have had in the past similar to yours was due to worn out rubber hoses, especially at the rear brake junction. Even if this doesn't fix this particular problem, it is worth replacing these parts for the safety you are looking for.
The part that I ordered said it was OEM. Ive also noticed that one of the tips on the proportioning valve doesnt go in all the way either..maybe about 1 thread is showing on the tip. Beforehand, I tried to install the my new proportioning valve (which i have yet to install) the master cylinder itself and it was having difficulty connecting...could uit be due to that? And what about the fact that its a cheap master cylinder?
http://www.rockauto.com/catalog/moreinfo.php?pk=1361637
http://www.rockauto.com/catalog/moreinfo.php?pk=1361637
I can't answer to the proportioning valve. Will need some help on that. Again, make sure you have right components. OEM doesn't mean you got one for the right application. You can do some cross referencing part numbers on most of the auto parts stores web sites to check it out if you don't trust the folks who sold you this one.
I am an advocate for good troubleshooting. But, at the same time, I am not afraid to do a full replacement on brake components. Brakes are not something we should wait to fully wear out. Especially if you don't know the maintenance history. I'd say go ahead and put on the replacement parts.
Then, follow S-10 racers advice on bleeding. It is a good way to save pumping by letting gravity bleed air out of the system. Don't let it all drain out. Keep filling the master as it gets low. Some systems will still require the standard bleed after a gravity bleed. Have someone press the pedal while you open the bleeder. If no air comes out, you'll be good.
As far as bench bleeding, I don't do it. I don't like spilling fluid on my ride. For some reason I always get it to work. Gravity bleed followed by some press and release has always gotten the job done for me.
For master cylinders, I use the cheapos myself. It could be bad, but I have only ever gotten one bad one myself. I do find the cheap ones will wear out sooner. Sometimes they leak at the bore. But for what I do, they work okay for me. You get what you pay for still applies.
I am an advocate for good troubleshooting. But, at the same time, I am not afraid to do a full replacement on brake components. Brakes are not something we should wait to fully wear out. Especially if you don't know the maintenance history. I'd say go ahead and put on the replacement parts.
Then, follow S-10 racers advice on bleeding. It is a good way to save pumping by letting gravity bleed air out of the system. Don't let it all drain out. Keep filling the master as it gets low. Some systems will still require the standard bleed after a gravity bleed. Have someone press the pedal while you open the bleeder. If no air comes out, you'll be good.
As far as bench bleeding, I don't do it. I don't like spilling fluid on my ride. For some reason I always get it to work. Gravity bleed followed by some press and release has always gotten the job done for me.
For master cylinders, I use the cheapos myself. It could be bad, but I have only ever gotten one bad one myself. I do find the cheap ones will wear out sooner. Sometimes they leak at the bore. But for what I do, they work okay for me. You get what you pay for still applies.
Bleeder Kit: Clear tubing that fits the bleeder valve and an old mason jar. And a partner to press the brakes while you open the bleeder valve.
I use a mason jar so I don't have to empty it often. The clear tubing helps you keep an eye on an air bubbles coming out of the system.
Not to insult you but for the procedure after gravity bleed: Open the bleeder valve and then have your partner push the pedal down. Close the bleeder before the partner releases the pedal. Open Valve, Press pedal, close valve, release pedal.
I use a mason jar so I don't have to empty it often. The clear tubing helps you keep an eye on an air bubbles coming out of the system.
Not to insult you but for the procedure after gravity bleed: Open the bleeder valve and then have your partner push the pedal down. Close the bleeder before the partner releases the pedal. Open Valve, Press pedal, close valve, release pedal.
Your power brakes will not work properly without the engine running, the brake booster uses vacuum from the engine. After you gravity bleed the brakes, start the car and have a friend or family member help with the power bleeding. Here is how I power bleed.
1. Make sure the master cylinder is full
2. Start the motor
3. Pump the brakes 5-6 times and hold firmly down while the other person loosens the bleeder on the wheel. Again, start with the RR. Keep pushing on the pedal until it is as far down as it will go and hold it there while the other person tightens the bleeder back up. Repeat this as many times as it takes until you have no air coming out with the fluid, it may take 3-4 times. Top the master cylinder off and repeat this process for the LR, then the RF and last the LF.
1. Make sure the master cylinder is full
2. Start the motor
3. Pump the brakes 5-6 times and hold firmly down while the other person loosens the bleeder on the wheel. Again, start with the RR. Keep pushing on the pedal until it is as far down as it will go and hold it there while the other person tightens the bleeder back up. Repeat this as many times as it takes until you have no air coming out with the fluid, it may take 3-4 times. Top the master cylinder off and repeat this process for the LR, then the RF and last the LF.
Maybe you dont have the rear brakes adjusted up properly.Combined with trapped air that hasnt bled out, it could be the whole issue.
the prop valve evens presure from side to side on the fronts. They dont really go bad. and as long as there are no leaks. the piston should have a pintle that moves in / out when you are operating the bleed procedure. Or not.
Start the engine for power brakes
You need to bleed with a person pumping the pedal 4-5 times nipple closed. say hold down. crack and hold down. close and say up. Start at the fartherest point and work to the closest line.
No magic to brakes it is just the basics.
How old are the hydraulic rubber lines to the calipers. If they have blockages or cracks replace them . Flappers are bad and will cause pulling and failure.
Goodluck with the girl. Your are the gas , she is he brakes. that is another story.
Start the engine for power brakes
You need to bleed with a person pumping the pedal 4-5 times nipple closed. say hold down. crack and hold down. close and say up. Start at the fartherest point and work to the closest line.
No magic to brakes it is just the basics.
How old are the hydraulic rubber lines to the calipers. If they have blockages or cracks replace them . Flappers are bad and will cause pulling and failure.
Goodluck with the girl. Your are the gas , she is he brakes. that is another story.
If the rear brakes are not adjusted right you are losing quite a bit of your stopping power. Most brakes of this vintage self adjust when you brake hard when backing up, but some adjust when you apply the emergency brake. However, you need to verify that the self-adjusting mechanism is really working right.
The adjuster uses a ratcheting mechanism that moves the brake shoes closer to the drums as you apply the brakes while backing up, and the adjuster pivots and engages the next notch in the mechanism. It depends on all the parts moving freely and all the springs pulling enough to activate the mechanism. Since the entire adjuster is also surrounded by a cloud of brake dust in the drum, it can get dirty and not move freely.
Check the brake lines (as already suggested) and make sure they are not soft, since you will lose pressure if they expand.
Also take the front calipers off and look at the pistons and the slide pins and mechanism. If the front caliper does not slide you will be applying pressure from the piston only on one side, and the the pad on the other side (which should slide over and apply pressure to the other pad) is doing very little. If its not sliding you will usually see much more wear on the pad next to the piston.
Bruce
The adjuster uses a ratcheting mechanism that moves the brake shoes closer to the drums as you apply the brakes while backing up, and the adjuster pivots and engages the next notch in the mechanism. It depends on all the parts moving freely and all the springs pulling enough to activate the mechanism. Since the entire adjuster is also surrounded by a cloud of brake dust in the drum, it can get dirty and not move freely.
Check the brake lines (as already suggested) and make sure they are not soft, since you will lose pressure if they expand.
Also take the front calipers off and look at the pistons and the slide pins and mechanism. If the front caliper does not slide you will be applying pressure from the piston only on one side, and the the pad on the other side (which should slide over and apply pressure to the other pad) is doing very little. If its not sliding you will usually see much more wear on the pad next to the piston.
Bruce
From your last post, I'm not sure exactly what you are describing. If you hold your foot down on the brake pedal while stopped it may move down slightly as you press harder. However, it should not move down very far, because that would mean the master cylinder seal or your brake lines are not holding pressure.
With a bad master cylinder the pedal often immediately sinks almost to the floor as you press on it. You can sometimes pump the pedal and get it to provide some braking power. However, if the piston seal blows/tears completely you may lose all braking power.
Pushing the pedal down too far (like to the floor) when bleeding the brakes can push the seal beyond the ridge of dirt that has built up over time in the cylinder. This rough ridge may tear the edge of the seal and cause it to fail very quickly.
Once a master cylinder starts to go bad you may lose braking power very quickly. It does not give you a lot of time to get to the mechanic. I've had one go from "poor stopping power" to "zero stopping power" during a 10-12 mile drive to a repair shop.
Bruce
With a bad master cylinder the pedal often immediately sinks almost to the floor as you press on it. You can sometimes pump the pedal and get it to provide some braking power. However, if the piston seal blows/tears completely you may lose all braking power.
Pushing the pedal down too far (like to the floor) when bleeding the brakes can push the seal beyond the ridge of dirt that has built up over time in the cylinder. This rough ridge may tear the edge of the seal and cause it to fail very quickly.
Once a master cylinder starts to go bad you may lose braking power very quickly. It does not give you a lot of time to get to the mechanic. I've had one go from "poor stopping power" to "zero stopping power" during a 10-12 mile drive to a repair shop.
Bruce
Alright thanks heaps Bruce, and I should use a 1/4inch OD tuning right? I still went on the date with the Girl with the brakes and she loved the car 
. But anyways, im gunna have to bleed it Wednesday since I had something come up, just want to make sure, but should i use s 1/4inch Outside Diameter tuning or 3/8?
. But anyways, im gunna have to bleed it Wednesday since I had something come up, just want to make sure, but should i use s 1/4inch Outside Diameter tuning or 3/8?
I assume you are talking about the tubing you use when bleeding. You want a flexible line with a tight fit on the bleeder valve, so 1/4" should work better. It should also be as short as you can reasonably make it, since that reduces the volume of air in the tube.
Buy/borrow the right flare nut wrench to turn the bleeders. The bleeders are small and fragile, and you need to have the flare nut wrench that wraps around them. They are nearly impossible to remove with a standard open end wrench, since it just rounds off the bleeder screw edges without moving it. I would also spray the fitting with penetrating lubricant ahead of time to make it easier to break loose. Even if you are careful, you may screw up a bleeder and have to extract and replace it. Make sure the car is parked somewhere that it can sit for a while if the job goes bad.
Fill the master cylinder reservoir almost the top with brake fluid, and leave the cap off. Start at the wheel that is farthest from the master cylinder.
With the tube end in a jar of brake fluid (use clear tubing and a clear jar) you will have an assistant pump the pedal and then hold it down. As you release the bleeder screw you will see brake fluid coming into the tubing. Keep pressure on the pedal, and allow the tubing to fill with fluid until it reaches the jar and there are no bubbles showing in the jar. Close the bleeder valve and leave the tube in the jar of fluid. Now have your assistant pump up the pedal again and you repeat the bleeding process. You must repeat the process until you get no more air. Then do the other three wheels. Go through the complete cycle of bleeding each wheel at least twice. Ensure the master cylinder reservoir always has fluid.
If the brake fluid you are bleeding out looks extremely dark you may want to buy additional fluid and try to flush the system completely as part of your bleeding. In that case you would keep bleeding each wheel until you get very clear (new) fluid coming out of the bleeder. I'm not sure how much fluid you would need to buy to replace what is in the system.
There are also one-man brake bleeders that pressurize the system for you, and you might be able to borrow one from Autozone or another retailer. However, I've never used one so I can't tell you how well they work.
Bruce
Buy/borrow the right flare nut wrench to turn the bleeders. The bleeders are small and fragile, and you need to have the flare nut wrench that wraps around them. They are nearly impossible to remove with a standard open end wrench, since it just rounds off the bleeder screw edges without moving it. I would also spray the fitting with penetrating lubricant ahead of time to make it easier to break loose. Even if you are careful, you may screw up a bleeder and have to extract and replace it. Make sure the car is parked somewhere that it can sit for a while if the job goes bad.
Fill the master cylinder reservoir almost the top with brake fluid, and leave the cap off. Start at the wheel that is farthest from the master cylinder.
With the tube end in a jar of brake fluid (use clear tubing and a clear jar) you will have an assistant pump the pedal and then hold it down. As you release the bleeder screw you will see brake fluid coming into the tubing. Keep pressure on the pedal, and allow the tubing to fill with fluid until it reaches the jar and there are no bubbles showing in the jar. Close the bleeder valve and leave the tube in the jar of fluid. Now have your assistant pump up the pedal again and you repeat the bleeding process. You must repeat the process until you get no more air. Then do the other three wheels. Go through the complete cycle of bleeding each wheel at least twice. Ensure the master cylinder reservoir always has fluid.
If the brake fluid you are bleeding out looks extremely dark you may want to buy additional fluid and try to flush the system completely as part of your bleeding. In that case you would keep bleeding each wheel until you get very clear (new) fluid coming out of the bleeder. I'm not sure how much fluid you would need to buy to replace what is in the system.
There are also one-man brake bleeders that pressurize the system for you, and you might be able to borrow one from Autozone or another retailer. However, I've never used one so I can't tell you how well they work.
Bruce
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