Brake Problem
Thread Starter
Intermediate
Joined: Jun 2007
Posts: 39
Likes: 0
From: Spotsylvania Va.
Brake Problem
I just puchased a C4 1987. The brakes have good stopping but they are at the floor. If you hit them for panic stop, so no panic stop. they are all the way down. They are not spongy, no brake light is on. I don't even know if the brake warning light even works. The master cylinder is full. I just got the car so I havn't had time to go thru anything. Any help would be great.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Find out if any brake work has been done.
Possible bad master cylinder.
Possible a large miss-adjustment on the booster actuator rod.
Wrong brake booster installed (inside rod wrong to pedal - been there - new part made wrong)
Might try bleeding brakes just to see if there is an improvement.
Possible bad master cylinder.
Possible a large miss-adjustment on the booster actuator rod.
Wrong brake booster installed (inside rod wrong to pedal - been there - new part made wrong)
Might try bleeding brakes just to see if there is an improvement.
Thread Starter
Intermediate
Joined: Jun 2007
Posts: 39
Likes: 0
From: Spotsylvania Va.
How would I check to see if it has the wrong actuator rod ? What length is supposed to be?
Yes, the pedal does hold, And if I pump the brakes, is stays at the same spot. Since I have the lug nut problem solved I was going remove the wheels to check calipers and brake pads tomorrow. With the engine off and key out the brake pedal sets higher. It is about where it should be.
Stopping is a good thing......
And yes, the ever important thing, where would i find a manual? I do have original owners manual.
Yes, the pedal does hold, And if I pump the brakes, is stays at the same spot. Since I have the lug nut problem solved I was going remove the wheels to check calipers and brake pads tomorrow. With the engine off and key out the brake pedal sets higher. It is about where it should be.
Stopping is a good thing......
And yes, the ever important thing, where would i find a manual? I do have original owners manual.
Last edited by OlrustysGhost; Mar 25, 2016 at 04:18 PM.
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
Here's an easy test to see if the pushrod between the booster and the m/c is too short:
1. Remove your m/c reservoir cap.
2. Engine off. Slowly depress your brake pedal.
3. Watch for a spurt or a disturbance on the surface of the brake fluid.
4. This disturbance should be seen as soon as you start to depress the pedal. If this isn't noticed right away, you pushrod is too short.
This pushrod is adjustable. You don't need to remove the brake lines from the m/c.
1. Remove the bolts between the m/c and the booster and move the m/c aside.
2. Gently pull the pushrod out of the booster just enough to grab the shaft with pliers.
3. Adjust the hex nut on the end of the shaft.
The alternative is a pushrod that's too long (not your problem). If there is NO disturbance, that means the m/c piston isn't allowing the vent port in the bottom of the reservoir to open when the brake pedal is in its relaxed position. This will cause pressure to build in the system as the fluid expands with increasing temperature, which will cause your brakes to drag.
1. Remove your m/c reservoir cap.
2. Engine off. Slowly depress your brake pedal.
3. Watch for a spurt or a disturbance on the surface of the brake fluid.
4. This disturbance should be seen as soon as you start to depress the pedal. If this isn't noticed right away, you pushrod is too short.
This pushrod is adjustable. You don't need to remove the brake lines from the m/c.
1. Remove the bolts between the m/c and the booster and move the m/c aside.
2. Gently pull the pushrod out of the booster just enough to grab the shaft with pliers.
3. Adjust the hex nut on the end of the shaft.
The alternative is a pushrod that's too long (not your problem). If there is NO disturbance, that means the m/c piston isn't allowing the vent port in the bottom of the reservoir to open when the brake pedal is in its relaxed position. This will cause pressure to build in the system as the fluid expands with increasing temperature, which will cause your brakes to drag.
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Hot Rod has a good procedure to check the rod.
I am only suspicious because you just got the car and was wondering if a problem was installed.
Is the pedal initially in the right spot high enough off the floor where it should be to begin with.
I ask this because I had a new booster where it was built incorrectly where the rod from the booster to the pedal was too short and the pedal height was too close to the floor.
I realize this might be a bit out of the box but just something to be considered if things look strange. I actually had this situation once. If all looks normal, check out the actuator rod. There should be about1/8" clearance between the master and the rod.
If the rod is too long, it will lock up the brakes, front wheels mainly. Jack up a wheel and you can tell. If that happens, back off the nut on the rod (screw in) about 1/2 turn or so. Might be a trial and error procedure.
I am only suspicious because you just got the car and was wondering if a problem was installed.
Is the pedal initially in the right spot high enough off the floor where it should be to begin with.
I ask this because I had a new booster where it was built incorrectly where the rod from the booster to the pedal was too short and the pedal height was too close to the floor.
I realize this might be a bit out of the box but just something to be considered if things look strange. I actually had this situation once. If all looks normal, check out the actuator rod. There should be about1/8" clearance between the master and the rod.
If the rod is too long, it will lock up the brakes, front wheels mainly. Jack up a wheel and you can tell. If that happens, back off the nut on the rod (screw in) about 1/2 turn or so. Might be a trial and error procedure.
Last edited by pcolt94; Mar 25, 2016 at 10:29 PM.
Thread Starter
Intermediate
Joined: Jun 2007
Posts: 39
Likes: 0
From: Spotsylvania Va.
Solved !! It was the rod . I adjusted it out about 5/16 " and I have a great brake pedal now.
I made sure that when I rebolted the master cylinder that I still a little play betwen it and the rod.
I then found out that the emergency Brake needs adjusted to. I did find the how to for that.
thanks. Now, on to something else...!
I made sure that when I rebolted the master cylinder that I still a little play betwen it and the rod.
I then found out that the emergency Brake needs adjusted to. I did find the how to for that.
thanks. Now, on to something else...!
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Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
Good work and it resolved.
There has to be clearance as you indicated due to hear expansion of the rod and metal parts and in the summer the brakes could start dragging but I think you probably have it adjusted OK.
There has to be clearance as you indicated due to hear expansion of the rod and metal parts and in the summer the brakes could start dragging but I think you probably have it adjusted OK.