Brake problems on 94
Thread Starter
7th Gear
Joined: Feb 2026
Posts: 7
Likes: 3
Brake problems on 94
I am having trouble with the brakes on my 94. It had a hard pedal, but brakes were not stopping well, could not lock up brakes. I had ad the brake booster replaced, better at slower speeds, but no good on harder stop ( still has a hard pedal).
I noticed that the replacement booster is approximately 5/8 to 3/4” thinner than the original. Has anyone had similar issues? I was wondering if the thinner booster is a problem?
I noticed that the replacement booster is approximately 5/8 to 3/4” thinner than the original. Has anyone had similar issues? I was wondering if the thinner booster is a problem?
Melting Slicks
Joined: Oct 2003
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From: Chapel Hill NC
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I believe your car has antilock brakes therefore you will not lock them. How are your pads and rotors? How old are your flexible brake lines?
Instructor
Joined: Aug 2025
Posts: 181
Likes: 21
From: north central Iowa
I have quality new brakes and rotors on my 1994....just had a new brake booster and check-calve installed, and have very well flushed my fluid. Like you, my braking is poor, unable to activate the abs system no matter how hard I depress the brake pedal. I've no clue what else I can do.
Thread Starter
7th Gear
Joined: Feb 2026
Posts: 7
Likes: 3
I am completely baffled, one day everything worked great, since then not so much. I have not changed the master cylinder but it does not seem like that would cause this issue. Pads and rotors look great. Could this be a problem with the ABS?
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
There is a thing informally called "ice mode" with ABS systems - especially GM systems - where the pedal gets very hard and you don't get much braking. It normally only happens when you jump on the brake pedal really hard and fast over a bump or with at least one tire in sand or other low-grip spit. When it gets invoked, it's pants-shitting time, especially if you're on an autocross or track lap (which is normally when it can happen). The intent was for the system to default to this on ice and other very-low-grip surfaces, but on some cars it's too easily triggered. But it should go away within a couple seconds or so. If that's what's happening to the OP and it's in that mode all the time, then something is malfunctioning. The obvious possible cause would be a bad wheel speed sensor: I never had one go bad, but I can see how that might trigger constant ice mode. I would think you'd get a light on the dash, though. You can try pulling the fuse to the ABS to disable it. You should be able to easily lock the front tires without much brake pedal pressure (obviously find an empty and open space to try this). That would at least tell you it's something in that system rather than a mechanical issue.
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Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
You really won't be fine without it. Like it or not, the whole braking system is set up use it, and when you run without it's way overly proportioned to the front brakes. You end up with a car that locks the fronts way too easily, and it's hard to modulate out of the lock once it begins. I'm not suggesting pulling the fuse as a permanent solution - just for diagnostic purposes. If it helps you narrow down your current problem with the brakes, then you should fix the problem and restore ABS to proper functionality.
Instructor
Joined: Aug 2025
Posts: 181
Likes: 21
From: north central Iowa
You really won't be fine without it. Like it or not, the whole braking system is set up use it, and when you run without it's way overly proportioned to the front brakes. You end up with a car that locks the fronts way too easily, and it's hard to modulate out of the lock once it begins. I'm not suggesting pulling the fuse as a permanent solution - just for diagnostic purposes. If it helps you narrow down your current problem with the brakes, then you should fix the problem and restore ABS to proper functionality.
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
- If that condition still exists, then we're seeing a problem in the master cylinder, lines, or calipers. My bet would be the m/c if it hasn't been replaced already.
- If the problem goes away when you pull the ABS fuse (i.e. it becomes really easy to lock the front wheels), then the issue is somewhere in the ABS system. My best guess (and that's all this is) is that something is making the ABS module think we're in ice-mode conditions. I ***-ume there is some kind of "brain" for these old ABS systems in the form of a module, as there is in newer cars? I do wonder if that might have somehow gone bad. If that's easy to access and swap, it might be worth trying to swap it with a known-good module.
Instructor
Joined: Aug 2025
Posts: 181
Likes: 21
From: north central Iowa
I've done everything except brake lines and ABS. If my ABS diagnostic is clear, I'll be checking out brake lines, though I didn't think a non-leaking brake line could have such a dramatic effect.
Racer
Joined: Sep 2017
Posts: 369
Likes: 89
From: Alaska
I seem to recall from the manuals that once you've had the system open and bleed the air from it, to regain full braking authority you have to trigger the ABS "pump."
I think there is something you can jumper to do that, but I don't recall what that is.
I think there is something you can jumper to do that, but I don't recall what that is.
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
I've never had to "trigger the ABS pump" after bleeding brakes on any car, ever. There is a procedure to cycle the ABS system if you suspect air is trapped in it, but that would result in a soft/long pedal, not this problem (which is pretty much the opposite).
I think even if one line were entirely blocked, the other lines would work and three of four calipers would still lock up. At this point, I think we're most likely looking at either the brake booster or the vacuum supply to it. I forgot to include that in Post 13. To the OP, if the replacement booster is thinner than the original, that seems wrong, but I'm not sure.
I think even if one line were entirely blocked, the other lines would work and three of four calipers would still lock up. At this point, I think we're most likely looking at either the brake booster or the vacuum supply to it. I forgot to include that in Post 13. To the OP, if the replacement booster is thinner than the original, that seems wrong, but I'm not sure.
