Brakes barely working
Thread Starter
Pro
Joined: Oct 2007
Posts: 587
Likes: 0
From: Overland Park Kansas
Brakes barely working
Alright. Well initially when I got the car, the front left caliper was locked on the rotor. I replaced both front calipers and bled the ENTIRE car, 3 times. The pedal is still mushy, and even when standing on the brakes it takes forever to slow down. They just aren't working well at all.
I know these cars didn't stop well stock, but this is crazy. I'm afraid to drive it honestly.
Any ideas? I know the master was replaced not that long ago (not that that means its not bad), I'm just at a total loss as to what could cause this. I'm thinking about taking it somewhere and having them look at it, but that's $$$$$.
Thanks!
-Josh
I know these cars didn't stop well stock, but this is crazy. I'm afraid to drive it honestly.
Any ideas? I know the master was replaced not that long ago (not that that means its not bad), I'm just at a total loss as to what could cause this. I'm thinking about taking it somewhere and having them look at it, but that's $$$$$.
Thanks!
-Josh
Burning Brakes
Joined: Oct 2007
Posts: 946
Likes: 0
From: Lake Geneva WI
I have a similar issue, but it is a 1979 and it is the driver rear that is problematic.. The guy I bought it from swears up and down they had the brakes re-done 6 months ago.. Whoever did it was either an idiot, or did not do a very good job.
From what I can tell the rotors were turned and do seem to be in great shape..
Looking forward to replies on this topic.
From what I can tell the rotors were turned and do seem to be in great shape..
Looking forward to replies on this topic.
Burning Brakes
Joined: Jun 2004
Posts: 872
Likes: 3
From: Cortlandt Manor New York
If your pedal is mushy you have air in the system and you have to bleed the brakes properly. You can search here for brake bleeding and you will find hundreds of posts and many methods. This is one of the most important things you can do on a Corvette and one of the toughest to get right. You will see from the posts the frustration this can cause.
I have tried many methods and had some success with most of them and lots of patience. What I have found was that the easiest and best way I have used to bleed Corvette brakes is with speed bleeders. I bought a set of bleeders for each caliper and I was able to bleed to system in about 20 minutes. That was in the spring and everything has worked fine since then. I will never go back to other methods.
I have tried many methods and had some success with most of them and lots of patience. What I have found was that the easiest and best way I have used to bleed Corvette brakes is with speed bleeders. I bought a set of bleeders for each caliper and I was able to bleed to system in about 20 minutes. That was in the spring and everything has worked fine since then. I will never go back to other methods.
Instructor
Joined: Feb 2007
Posts: 223
Likes: 0
From: Palmer Ma
presure bleeder
this power bleeder was a god send I tryed to get all the air out of mine for weeks I bought this and was done in 10 mins!!!!!
http://www.hrpworld.com/index.cfm?fo...action=product
http://www.hrpworld.com/index.cfm?fo...action=product
Burning Brakes
Joined: Mar 1999
Posts: 1,047
Likes: 3
From: CA
this power bleeder was a god send I tryed to get all the air out of mine for weeks I bought this and was done in 10 mins!!!!!
http://www.hrpworld.com/index.cfm?fo...action=product
http://www.hrpworld.com/index.cfm?fo...action=product
Drifting
Joined: Jul 2002
Posts: 1,944
Likes: 20
From: The only Corvettes in Highett Victoria
You're kidding?!?!?!?!
defsegx,
You have to be kidding, don't you? The C2 and C3 disc brakes were light years ahead of anything else on the road at the time outside of Ferrari etc. If the car doesn't slow down rapidly when you hit the brake pedal, it is because the pads are not pressing against the rotor with enough force. This could be due to a number of reasons, but one component that I would check is the flexible line between frame and caliper. If original, this (rubber) line is thirty years old and probably swollen inside. This will restrict or even totally block the flow of fluid to the caliper. It could also explain why the rotor was "locked" as the fluid would not be able to flow back to the master cylinder.
Take the hose off and have it checked and preferably replaced. Do both sides. Then the fluid will flow to the calipers. If the car's braking is still slow, then check the rubber seals in the MC, then the seals in the calipers. It has to be something that's easy to spot, it's not rocket science. Good luck!
Regards from Down Under
aussiejohn
You have to be kidding, don't you? The C2 and C3 disc brakes were light years ahead of anything else on the road at the time outside of Ferrari etc. If the car doesn't slow down rapidly when you hit the brake pedal, it is because the pads are not pressing against the rotor with enough force. This could be due to a number of reasons, but one component that I would check is the flexible line between frame and caliper. If original, this (rubber) line is thirty years old and probably swollen inside. This will restrict or even totally block the flow of fluid to the caliper. It could also explain why the rotor was "locked" as the fluid would not be able to flow back to the master cylinder.
Take the hose off and have it checked and preferably replaced. Do both sides. Then the fluid will flow to the calipers. If the car's braking is still slow, then check the rubber seals in the MC, then the seals in the calipers. It has to be something that's easy to spot, it's not rocket science. Good luck!
Regards from Down Under
aussiejohn
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
defsegx,
You have to be kidding, don't you? The C2 and C3 disc brakes were light years ahead of anything else on the road at the time outside of Ferrari etc. If the car doesn't slow down rapidly when you hit the brake pedal, it is because the pads are not pressing against the rotor with enough force.
Regards from Down Under
aussiejohn
You have to be kidding, don't you? The C2 and C3 disc brakes were light years ahead of anything else on the road at the time outside of Ferrari etc. If the car doesn't slow down rapidly when you hit the brake pedal, it is because the pads are not pressing against the rotor with enough force.
Regards from Down Under
aussiejohn
Cheers,
Pete
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Pro
Joined: Nov 2001
Posts: 684
Likes: 0
From: Winnipeg Manitoba
Hi, I had the same problem last month. I checked around for leaks and there where none at all. I know that over time the rear brakes may get air into them via the seals. I purchased a set of Russell speed bleeders from Summit and installed them on all four calipers. The rear calipers need 3 bleeders each. I had a problem last year bleeding the brakes on my 1970 buick, I needed to take care of the bleeding of the 1980 vette and wasent looking forward to it. Everyone suggested the speed bleeders and I swear by them, once installed I had all 4 calipers bleed in under 15 min and that solved the soft pedal that I had. Start with the speed bleeders and bleed the whole system, that should resolve the problem.
Thread Starter
Pro
Joined: Oct 2007
Posts: 587
Likes: 0
From: Overland Park Kansas
Ok, well sorry I didn't mean to insult the cars, I just see a lot of people complain about the brakes being soft 
I really did bleed the whole car 3 times, in the right order, and they're still not right. I suppose I can get speed bleeders, does anyone know the thread size/etc we need for these calipers? I got some at AutoZone last night but they were too large. Also, how do you use them? Is it a one man job or what?
I'll also change the front two lines tonight if I can.
Thanks for all the help.
-Josh
I really did bleed the whole car 3 times, in the right order, and they're still not right. I suppose I can get speed bleeders, does anyone know the thread size/etc we need for these calipers? I got some at AutoZone last night but they were too large. Also, how do you use them? Is it a one man job or what?
I'll also change the front two lines tonight if I can.
Thanks for all the help.
-Josh
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
I have a similar issue, but it is a 1979 and it is the driver rear that is problematic.. The guy I bought it from swears up and down they had the brakes re-done 6 months ago.. Whoever did it was either an idiot, or did not do a very good job.
From what I can tell the rotors were turned and do seem to be in great shape..
Looking forward to replies on this topic.
From what I can tell the rotors were turned and do seem to be in great shape..
Looking forward to replies on this topic.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Since you don't know the history on this car and you have serious brake problems there are some steps you need to go thru to make sure everything is working correctly.
Roger pointed out Rotor Runout, that absolutely needs to be checked and corrected. Turning the rotors to fix it may not be the best solution since the rotor itself is only part of it. The hub contributes to the total runout also. Indexing the rotor to the hub and then shimming it for <.001 is the way to go.
Change all 4 rubber lines, cheap insurance for a weak point in all brake systems
Now bleed them clear and all should be well. If you still have to Stand on the pedal as you indicated check out the booster. It is a power assist booster, that means when it dies you have to put more force on the brake pedal to stop.
The MC is also a suspect, but what I usually see is the pedal goes to the floor or goes slowly to the floor.
Roger pointed out Rotor Runout, that absolutely needs to be checked and corrected. Turning the rotors to fix it may not be the best solution since the rotor itself is only part of it. The hub contributes to the total runout also. Indexing the rotor to the hub and then shimming it for <.001 is the way to go.
Change all 4 rubber lines, cheap insurance for a weak point in all brake systems
Now bleed them clear and all should be well. If you still have to Stand on the pedal as you indicated check out the booster. It is a power assist booster, that means when it dies you have to put more force on the brake pedal to stop.
The MC is also a suspect, but what I usually see is the pedal goes to the floor or goes slowly to the floor.
Thread Starter
Pro
Joined: Oct 2007
Posts: 587
Likes: 0
From: Overland Park Kansas
Well, I replaced the brakes lines and re-bled the system tonight. I still have to stand on it to get it to stop. I might just take it to a shop tomorrow and let them try to fix it, I'm really tired of bleeding the brakes every night and throwing money at it with no fix yet.
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Before you do, do this,, run the engine for a few minutes,, then turn it off, let it sit for about 5 mins, then remove the check valve from the brake booster, you should hear a "snap-hissing" sound as the vacume that's held in the booster by the check valve releases. If you don't hear this sound then check the vacume with engine running at the line, check the valve by blowing into it both directions. If both these pass it's probably a bad booster. The brake rod should also just make contact with the back of the hole in the M/C piston, it souldn't be pressing it in at all when no brakes are applied.
Thread Starter
Pro
Joined: Oct 2007
Posts: 587
Likes: 0
From: Overland Park Kansas
I checked the vacuum going to the booster, it is fine. Lots of suction while the engine is running.
According to the last owner he replaced the MC so I guess maybe the booster could be bad? I'm just going to bring it to Midas I think. I'm not confident enough in my bleeding ability to say 100% that air is not the problem.
According to the last owner he replaced the MC so I guess maybe the booster could be bad? I'm just going to bring it to Midas I think. I'm not confident enough in my bleeding ability to say 100% that air is not the problem.
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
Sounds like the booster, Midas will at least pressure bleed it through,, did you check the ability of the brake booster to hold vacume, with the check valve removal methode? Mine will hold vacume for literally weeks. tha's the last check I would do.
Burning Brakes
Joined: Oct 2007
Posts: 946
Likes: 0
From: Lake Geneva WI
Guys, thanks! Great information! On my 79, I do have a new master cylinder. The right drivers side rear that was causing problems did have a collapsed brake line, so I think I will change all 4 lines and then bleed again.. Will let you know. I am re-doing the front end this weekend, so I will try to tackle the brakes at the same time.