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Discussion Starter #1
Today I bleed my brakes for the first time. The old fluid was a dark brown and I would loose braking power after a few hard stops. The pedal before the bleed was always a little low and it seemed that I should have a bit more braking power. There was about a 1.5" dead zone that did nothing. After the bleed I no longer have a problem with losing the brakes, but they still feel a bit spongy and have the dead zone. I have to press extremely hard to brake compared to all of the other cars I've driven. All of the brake pads are good and I bled until I had new fluid with no air bubbles. Any ideas on how to improve the brakes and eliminate the dead zone?
 

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Here's a thread with lots of ideas but no definate solution. Brake Pedal Travel

All I can say is I've had 'dead zone' symptoms similar to what you describe. I re-bled the system after a few days. I didn't see any big air bubbles but it was then much better. My guess is some tiny air bubbles coalesce or migrate up to the master or bleeder and the second bleed done a day or three later removes them.
 

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A lot of people make the mistake of repeatedly pumping the pedal in between each opening of the bleeder (pumping up the pedal). This causes the fluid to aerate-- lots of tiny bubbles which are next to impossible to purge without another bleeding session after the bubbles have coalesced. The best way is to push the pedal once, open the bleeder, close the bleeder, and release the pedal. Repeat until there are no more bubbles and all clean fluid.
 

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I have to press extremely hard to brake compared to all of the other cars I've driven.
As others have written, give it a few days for any small bubbles to rise up and out through the MC. If you still find that it takes a lot of pedal pressure, it could be that your booster is dead. You might try disconnecting (and plugging!) the vacuum line, and see if it makes any difference.
 

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Yeah, I'd do a quick booster test. Do a search for procedures.

Also, be careful with how far you push the pedal when bleeding, ESPECIALLY if the system has been neglected like yours! If there's rust or gunk in the MC and you push the pedal down farther than it usually goes in braking, the seals can pick up the gunk and fail. Ask me how I know...

You can also damage the booster diaphragm by pushing the pedal too far. It's a good idea to put a block or something between the pedal and the firewall so you don't overextend it.
 

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Discussion Starter #6
I think the booster is working correctly. I can feel the pedal go down when I turn the car on. The master looks like its relatively new. Is there a way to test the master? I tried not to push down too far, but I think I did pump up the pedal a few times between opening and closing the bleeder so that could have contributed to the problem. The pads look to be in good condition, but I don't know what brand they are. If a second bleed doesn't help I may replace the pads and see if that helps.
 

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replace the flex lines with braided steel lines, if that doesn't do it, get a new master, external appearance of the master means almost nothing. there is another possibility, some boosters have an adjustment on the rod coming out of the diaphragm, but it unlikely to be your problem
 

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Is there a way to test the master?
A simple test is to gently apply slow but steady pedal pressure. If the seals in the master cylinder are good the pedal will stay firm. If the seals are suspect the pedal will slowly move down over the course of a minute or two. A sharp jab on the pedal may hold firm because the sudden pressure in the fluid also pushes the thin edges of the seals tightly against the cylinder's walls. The slow movement will reveal any slight fault in sealing ability.

If a second bleed doesn't help I may replace the pads and see if that helps.
Unless the pads are far beyond their service limits changing pads would have no effect on pedal feel.
 

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Just purged the brake fluid from the system and was having problems bleeding the brakes. Even after bleeding twice, the pedal was still a little low and needed a "second pump" for the brakes to really grab.

Well considering that people in this household think that pressing on the brake pedal on command is pretty hard work and that I'm too cheap to buy a bleeder pump, I MacGyvered a self pressurized system from an old clutch reservoir cap and an air compressor.

Put the pressure on low (around 8-10 PSI) and always made sure the reservoir had plenty of fluid. Bubbles were coming out like crazy! Just had to go around the 4 wheels, twist some nipples (I'm really good at that!) and voilà! Nice hard pedal!

I'm happy! :D
 

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Discussion Starter #10
I also did a second bleed today and found that there was still a fair amount of air in the lines. Now The brake pedal feels much better, although I did discover that the right front brake is dragging a bit, which may explain why the car tends to drift to the right. Thanks for all of the help and suggestions.
 

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Yep, pressure bleeding is sooo much easier in many cases. Then there is the odd job where only reverse pressure bleeding is the way to go. Good Mcguyver on the bleeder!
 

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Compressor alternative

Shiraz1965,

An elegant solution and the only one I have yet to try.

How did you come by a spare reservoir cap? Suppose I could simply modify my clutch cap with a Schrader valve from a tubeless tire.

For those of us without a compressor, I have seen the same thing done with a modified garden sprayer (Big Box Hardware Store <$10).

And thanks for the photo! Some folks will take advantage of the flimsiest excuse for an opportunity to show off their attractive engine upgrades :yes:. Nice work!

Best wishes
 

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I MacGyvered a self pressurized system from an old clutch reservoir cap and an air compressor. :D
You are braver than I! A jury rigged pressure bleeder right next to all of that pretty red paint! If I tried this I'm sure it would spring a leak and spray brake fluid all over the place. But indeed, pressure bleeders rule.

As far as the OP complaint of having to press hard to stop... If the booster is well, then you might try different pads. I replaced the ones that I found on my car with the carbon-metalics from Centerline and was very pleased with this higher mu friction material. Much better decel per given pedal force, not too noisy and fairly clean with my phone dial wheels.
 

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Shiraz1965,

An elegant solution and the only one I have yet to try.

How did you come by a spare reservoir cap? Suppose I could simply modify my clutch cap with a Schrader valve from a tubeless tire.

For those of us without a compressor, I have seen the same thing done with a modified garden sprayer (Big Box Hardware Store <$10).

And thanks for the photo! Some folks will take advantage of the flimsiest excuse for an opportunity to show off their attractive engine upgrades :yes:. Nice work!

Best wishes
I know, I'm vain! I got the spare reservoir cap from my 79 Spider organ donor although I'm pretty sure a fitting cap wouldn't be too hard to find.
 

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You are braver than I! A jury rigged pressure bleeder right next to all of that pretty red paint! If I tried this I'm sure it would spring a leak and spray brake fluid all over the place. But indeed, pressure bleeders rule.

As far as the OP complaint of having to press hard to stop... If the booster is well, then you might try different pads. I replaced the ones that I found on my car with the carbon-metalics from Centerline and was very pleased with this higher mu friction material. Much better decel per given pedal force, not too noisy and fairly clean with my phone dial wheels.
PO went cheap on the brake pads and only have about 10% wear on them. Braking is good but they are really bad on the brake dust and Turbinas aren't the funnest wheels to keep clean! Can't wait to change them!
 

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Discussion Starter #16
I finally got some time to replace the master cylinder. I used a 22mm master from Centerline and also bought some speed bleeders. I bled one side at a time as suggested. After all this I had a much better pedal, but still had the free play that others suffered from so I used a small piece of hard rubber as a shim between the booster and master and made it smaller until none of the wheels dragged. Now the pedal feel is great. Its takes some force since the master is a bit bigger, but it makes it much easier to heel-toe.
 

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Hey, I thought that was my idea!

I finally got some time to replace the master cylinder. I used a 22mm master from Centerline and also bought some speed bleeders. I bled one side at a time as suggested. After all this I had a much better pedal, but still had the free play that others suffered from so I used a small piece of hard rubber as a shim between the booster and master and made it smaller until none of the wheels dragged. Now the pedal feel is great. Its takes some force since the master is a bit bigger, but it makes it much easier to heel-toe.
Despaired of ever getting a high pedal and cut and tried till a right-sized, hard rubber spacer at the end of the push rod made the situation Goldilocks.

Speed bleeders too.

And another lonely, under-used emoticon to keep it interesting. :wheelchair:

Best wishes
 
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