'87 c4 FR brake issues maybe abs?
Thread Starter
1st Gear
Joined: Oct 2024
Posts: 1
Likes: 0
'87 c4 FR brake issues maybe abs?
Hello, looking for ideas on solving an issue im having.
My front right brake is sticking bad, when i try to bleed it i dont get much and when i open that bleeder the brake pedal doesnt go soft like all the others. when i drive the caliper is stuck- pulls left when braking, right when driving and makes the entire wheel very hot if i drive more than a few miles.
I first assumed caliper issue so i rebuilt it, works fine. then i replaced the rubber lines on all 4 with stainless and no change.
when i got the car the fluid was very dark and i saw little particles in it likely degraded soft line i assume, ive been flushing the fluid and it looks far better.
I can get the abs to trigger on a dirt road idk if that helps.
from what ive read online so far im assuming its one of a few issues-
blockage in hardline after abs
blockage in abs module
issue with Brake Pressure Modulator Valve
issue with brake portioning valve
someone said abs pump in one?
im assuming its a blockage and about to just try blasting air into it somehow with my air compressor but figured id get some advice as i feel thats risky, any advice on how to best diagnose and solve this issue is greatly appreciated thanks.
My front right brake is sticking bad, when i try to bleed it i dont get much and when i open that bleeder the brake pedal doesnt go soft like all the others. when i drive the caliper is stuck- pulls left when braking, right when driving and makes the entire wheel very hot if i drive more than a few miles.
I first assumed caliper issue so i rebuilt it, works fine. then i replaced the rubber lines on all 4 with stainless and no change.
when i got the car the fluid was very dark and i saw little particles in it likely degraded soft line i assume, ive been flushing the fluid and it looks far better.
I can get the abs to trigger on a dirt road idk if that helps.
from what ive read online so far im assuming its one of a few issues-
blockage in hardline after abs
blockage in abs module
issue with Brake Pressure Modulator Valve
issue with brake portioning valve
someone said abs pump in one?
im assuming its a blockage and about to just try blasting air into it somehow with my air compressor but figured id get some advice as i feel thats risky, any advice on how to best diagnose and solve this issue is greatly appreciated thanks.
Last edited by Borg95; Oct 18, 2024 at 07:21 PM.
Melting Slicks
Joined: Apr 2001
Posts: 2,120
Likes: 222
From: Ca.
If a solenoid in the abs is sticking in closed position it should trigger abs fault light. Is it on? You could pull the line at the abs and blow compressed air thru it with bleeder open at the wheel-not going to hurt, just have to bleed it again.
Melting Slicks
Joined: Jan 2014
Posts: 2,192
Likes: 381
From: Lunenburg MA
Heel & Toe
Joined: Jul 2014
Posts: 19
Likes: 1
From: The Woodlands Texas
Contact Dino.
https://www.corvettesalvage.com/prod...ice-1986-1991/
They rebuild the Brake Pressure Modulator Valve. Most likely your issue. I was unable to bleed the brake caliper on right front.
https://www.corvettesalvage.com/prod...ice-1986-1991/
They rebuild the Brake Pressure Modulator Valve. Most likely your issue. I was unable to bleed the brake caliper on right front.
Burning Brakes
Joined: Aug 2006
Posts: 1,061
Likes: 99
From: Seattle WA
Yep, sounds just like my 87. One way to know for sure if it's the abs unit is to remove the line at the abs and caliper and blow air trough it. I'm guessing the line is fine and the abs unit has the block. There isn't any way to fix it just by blowing air or fluid through it. There's a spring in the stuck solenoid that's likely rusted out, and the solenoid internals collapse and block the fluid flow. A used unit (with a short warranty) is a good option, or, more expensive would be the rebuilt unit.
