Brake Help

[ksurfer2]

I have wildwood disc brakes on all four corners of my 64 NSS car. The master cylinder is from a 90's Dakota. This set up worked fine since installed. However, now the fronts are dragging REALLY bad...I can hardly turn the hub by hand with the wheel off. Both sides are equally bad. If I crack a bleeder valve, it squirts out fluid and then both sides will turn freely. Stepping back on the brake pedal will result in the brakes locking up again. I replaced the flex lines on both sides with no change. Fluid flows through both sides freely. There is no proportioning valve. One brake line goes to the rears, the other goes to the line lock and then splits from the line lock to each wheel. It seems to me the problem may be with the line lock since that is all that effects both sides the same. It does function properly, but is there a reason it may not be properly releasing pressure.

 

[Cranky]

I have wildwood disc brakes on all four corners of my 64 NSS car. The master cylinder is from a 90's Dakota. This set up worked fine since installed. However, now the fronts are dragging REALLY bad...I can hardly turn the hub by hand with the wheel off. Both sides are equally bad. If I crack a bleeder valve, it squirts out fluid and then both sides will turn freely. Stepping back on the brake pedal will result in the brakes locking up again. I replaced the flex lines on both sides with no change. Fluid flows through both sides freely. There is no proportioning valve. One brake line goes to the rears, the other goes to the line lock and then splits from the line lock to each wheel. It seems to me the problem may be with the line lock since that is all that effects both sides the same. It does function properly, but is there a reason it may not be properly releasing pressure.

A gauge would tell you if the line lock is bad but other than that, don't know.....

 

[Aron Gleason]

Hmmm. I'm only running the wilwood disc brakes up front and no distribution block. And I too have a line lock. I did have to back off the rear drums a little. But on a 4 wheel disc brake setup...is the brake pedal all the way up at rest? Could be master cylinder going bad. If the line lock was bad, it just wouldn't work period.

 

[dvw]

Which master cylinder port goes to the front brakes? It should be the rear port. Dragging Willwood brakes has been an on going issue for years. But in mst cases opening the bleeder will not correct the problem. In your case it appears that you have residual fluid pressure at the front calipers. It's possible that the master has a check valve in the rear brake port as Dakota's had drum brakes in the rear. Though I doubt it. It's more ;ikely that the pedal pushrod is too long. Pump the brake up. Then loosen the master cyliner from the firewall about a 1/4". Leave evrything else connected. If that relieves the pressure you have found your issue. If the calipers stick regardless of opening the bleeder I can help with that issue as well.
Doug

 

[RemCharger]

Crack the front line at the master. If they don't loosen up then it's the linelock. If they do, then it's the master.

 

[pnora]

I have wildwood disc brakes on all four corners of my 64 NSS car. The master cylinder is from a 90's Dakota. This set up worked fine since installed. However, now the fronts are dragging REALLY bad...I can hardly turn the hub by hand with the wheel off. Both sides are equally bad. If I crack a bleeder valve, it squirts out fluid and then both sides will turn freely. Stepping back on the brake pedal will result in the brakes locking up again. I replaced the flex lines on both sides with no change. Fluid flows through both sides freely. There is no proportioning valve. One brake line goes to the rears, the other goes to the line lock and then splits from the line lock to each wheel. It seems to me the problem may be with the line lock since that is all that effects both sides the same. It does function properly, but is there a reason it may not be properly releasing pressure.

If it worked OK before and you have replaced the lines with no change I would try what has been mentioned. 1- loosen the line at the master. If no change 2- Loosen the master from the firewall. If no change its internal in the master.

 

[ksurfer2]

Which master cylinder port goes to the front brakes? It should be the rear port. Dragging Willwood brakes has been an on going issue for years. But in mst cases opening the bleeder will not correct the problem. In your case it appears that you have residual fluid pressure at the front calipers. It's possible that the master has a check valve in the rear brake port as Dakota's had drum brakes in the rear. Though I doubt it. It's more ;ikely that the pedal pushrod is too long. Pump the brake up. Then loosen the master cyliner from the firewall about a 1/4". Leave evrything else connected. If that relieves the pressure you have found your issue. If the calipers stick regardless of opening the bleeder I can help with that issue as well.
Doug

the front brakes are coming from the rear line on the master, so that is correct. The push rod has a bit of a gap (maybe a 1/4") when the brakes are not applied, so I don't think the pushrod is the issue. Also it is the same pushrod that has been in the car since before this was an issue. However I will try as you suggested in the morning.

I was under the dash doing some wiring last weekend. It is possible I may have disturbed something, but the line lock does appear to activating properly, it just doesn't seem to be releasing the pressure properly.

 

[dvw]

Make sure the brake lamp switch bracket didn't get bent holding the pedal partially down. I have had master cylinders stick internally. But maybe only 2 in all my years of auto repair.
Doug

 

[ksurfer2]

Make sure the brake lamp switch bracket didn't get bent holding the pedal partially down. I have had master cylinders stick internally. But maybe only 2 in all my years of auto repair.
Doug

After changing the master cylinder twice, bench bleeding twice, bleeding the brakes about 4 times, I still had the same issue. What I finally found was the brake pedal wasn't returning to fully up and keeping just enough pressure to hold the front brakes. After a bunch of fiddling with the pedal, I found using a spring the pull the brake pedal fully back solved the problem. Nearly 8 hours of work and it was a 5 minute fix to finally solve the issue. At least I know the brakes are fully bled and fresh fluid is in all the lines.

 

[dvw]

Although the spring fix worked, there has to be an underlying issue. These cars never had a pedal return spring. The weight of the pedal itself won't apply the master. My bet is the pushrod is too long. Unless the switch is holding the pedal down.
Doug

 

[Cranky]

Although the spring fix worked, there has to be an underlying issue. These cars never had a pedal return spring. The weight of the pedal itself won't apply the master. My bet is the pushrod is too long. Unless the switch is holding the pedal down.
Doug

Haven't worked on that many brake systems over the years but never ran across a switch that did that....unless it was adjusted wrong then the brake lights would be on all the time.

 

[dvw]

Haven't worked on that many brake systems over the years but never ran across a switch that did that....unless it was adjusted wrong then the brake lights would be on all the time.

If it's to tight it'll hold the pedal down the lights will still work normally. If it's too loose the lights will stay on.
Doug

 

[ksurfer2]

Although the spring fix worked, there has to be an underlying issue. These cars never had a pedal return spring. The weight of the pedal itself won't apply the master. My bet is the pushrod is too long. Unless the switch is holding the pedal down.
Doug

I do have a shorter pushrod in my toolbox. I may switch it out to see if that helps. However, the pushrod that is in the car now is the same one that has been in it since I have owned the car. There does seem to be a little "hitch" in the return of the brake pedal. The spring is helping with that.

 

[stage3]

I found using a spring the pull the brake pedal fully back solved the problem.

i too used a spring to solve the same problem. 7/8" new master cylinder with stock rod. been on the car now for several years. chalked it up to adding new style parts to an old car.