Need some help with brakes
Thread Starter
4th Gear
Joined: Dec 2006
Posts: 4
Likes: 0
Need some help with brakes
I need some help! Here is the history for background: 1981 Corvette. A few years back i installed stainless steel sleeved brake calipers from Lone Star. Brakes worked great after that for a few years. Last year, under braking the car initially dove to the right before straightening out. Despite this, it had good stopping power and you could easily lock the brakes up. I figured the diving was due to a weak rubber line (they were all original and were visibly cracking when i inspected them), so i replaced all of the rubber lines with new braided steel lines. Now the car doesn't dive to one side under braking, but it has no stopping power. I've bled the brakes at least a half dozen times. I don't think air in the lines is the problem--pedal is pretty firm, and the total pedal travel seems to match the spec. That is, you can't put the pedal all the way to the floor, and pumping seems to make no difference. But it behaves like a manual-brake car in that you need to really stomp on it to get the car to stop and you can't lock the brakes up no matter how hard you push on the pedal.
Any ideas on what could be wrong or what i can do to figure this out and fix it?
Any ideas on what could be wrong or what i can do to figure this out and fix it?
Race Director
Joined: May 2006
Posts: 18,729
Likes: 2,581
Turn on the engine and step on the brake a few times. Turn off the engine and step on the brake a few times.
If after a couple of brake applications with the engine off you do Not feel the pedal get harder you have a brake booster issue.
If after a couple of brake applications with the engine off you do Not feel the pedal get harder you have a brake booster issue.
Le Mans Master
Joined: Jan 2001
Posts: 6,741
Likes: 1,383
How did you bleed them? If you did NOT pressure bleed them, then go do that. The regular push-&-bleed does nothing for bleeding the brakes on mine.
I need some help! Here is the history for background: 1981 Corvette. A few years back i installed stainless steel sleeved brake calipers from Lone Star. Brakes worked great after that for a few years. Last year, under braking the car initially dove to the right before straightening out. Despite this, it had good stopping power and you could easily lock the brakes up. I figured the diving was due to a weak rubber line (they were all original and were visibly cracking when i inspected them), so i replaced all of the rubber lines with new braided steel lines. Now the car doesn't dive to one side under braking, but it has no stopping power. I've bled the brakes at least a half dozen times. I don't think air in the lines is the problem--pedal is pretty firm, and the total pedal travel seems to match the spec. That is, you can't put the pedal all the way to the floor, and pumping seems to make no difference. But it behaves like a manual-brake car in that you need to really stomp on it to get the car to stop and you can't lock the brakes up no matter how hard you push on the pedal.
Any ideas on what could be wrong or what i can do to figure this out and fix it?
Any ideas on what could be wrong or what i can do to figure this out and fix it?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Has it been 10 days since somebody had a brake problem already? Time flies.
With any "new" brake issue, always backtrack your last repair.
You had a pull to the right. The left caliper was doing nothing. Just along for the ride.
You fixed that.
You replaced all the hoses and now have a new issue.
It's been said that the fronts do 80% of the braking. Did the new front hose lines come with copper crush washers? If not, I believe they should have.
Is that the problem? Not likely. But check for a leak on the front calipers.
You opened up a lot of the brake system when swapping out the hoses. Each new part introduced more & more air.
And what method was used to bleed the system?
With any "new" brake issue, always backtrack your last repair.
You had a pull to the right. The left caliper was doing nothing. Just along for the ride.
You fixed that.
You replaced all the hoses and now have a new issue.
It's been said that the fronts do 80% of the braking. Did the new front hose lines come with copper crush washers? If not, I believe they should have.
Is that the problem? Not likely. But check for a leak on the front calipers.
You opened up a lot of the brake system when swapping out the hoses. Each new part introduced more & more air.
And what method was used to bleed the system?
Last edited by HeadsU.P.; Mar 4, 2025 at 03:38 PM.
Advanced
Joined: Oct 2024
Posts: 79
Likes: 21
From: Michigan
It seems like the entire brake system has a restriction. Good pedal position. no pulls, no pedal softness...what was changed? Brake hoses. If the inside diameter of the hoses are less than 3/16", you have a restriction from each hose. Maybe not enough fluid volume to produce the hydraulic pressure needed at the pistons. Sounds fantastical. Never heard of anything like that. I can't believe that could be true. MelWff opined the possibility of a coincidental issue with the brake booster. That sounds more logical than bad brake hoses. What about a master cylinder issue? HeadsU.P. said "front brakes do 80% of the braking". If rear brakes are doing more work than the fronts, would you be able to lock up rear brakes during a hard stop? Could the issue be only the front brakes? Am I missing anything else?
Where does the OP start to diagnose and resolve this issue?
Where does the OP start to diagnose and resolve this issue?
