Larz

I was having a brake dragging problem. I adjusted the rod leading to the master cylinder, and it got better. I could no longer hear it dragging while driving. I put the car in the air and spun a wheel. Still drags a little. On all four wheels. I tried adjusting the rod all the way one way and all the way the other while my brother spun wheels. Couldn't get it to go away. Ideas?

David Beale

Disk brakes rely on the "spring" in the rubber piston seals to pull the pistons back from the disk. If they're old they will have lost some of this spring. Also, disk brakes tend to drag a tiny bit anyway.

You can also get dragging brakes if you have a little air in the lines. Just changed fluid?

Larz

I've got fresh fluid.

Mahjik

iTrader: (1)

Larz,

When you make adjustments to the brake piston, you actually need to drive the car around for a few minutes for the changes to "settle in". Make some adjustments, then drive the car around the block to see how it feels. Keep doing that until you have it just right.

Larz

Yeah, I've been doing that. You have to at least turn the car on for the pedal to travel as far down as it should. I've got it better. I'll come back to the garage, jack a wheel, and spin it. Still the slight sound of it dragging. So what does screwing the rod in or out do in relation to the calipers? Which direction loosens pressure allowing them to retract more?
Obviously I don't want them too loose, or I'll get pad slapping, right? I know if I retract the rod in one direction too much, the brake lights will always be on due to the pedal not contacting the switch.

Larz

Is there a measurement I can use or something? I looked at the FSM and didn't garner anything uselfull from it as far as adjustments go. This all happened because the nut that holds the rod in it's position loosened. I've got 54K on mine. So all of you take a 14mm wrench out there and make sure that thing is tight so you don't have to go through this crap.

Mahjik

iTrader: (1)

The piston is what pushes on the master cylinder. The farther the piston is INTO the firewall, the more the master cylinder is pre-engaged. In your case, you want to rotate to make the rod go back towards the driver's seat.

EDIT: Also, there are TWO adjustment points on the brake pedal. The one closest to the firewall is for the piston engagement.

Larz

I screwed in the rod as far as I could towards the rear of the car. I had to adjust the light switch on the other side of the brake pedal. Still dragging. The pistons seem partially extended while the car sits. Bad master cylinder? I bled the brakes from all four calipers already. Where are the other places I can bleed it from?

Mahjik

iTrader: (1)

How many miles on the calipers? You may just need to rebuild them. If dirt gets into the boots on the brake pistons, it will gum up the pistons and not allow them to move/retract freely.

Larz

54K. But this is on all four of them. What are the odds?

Larz

Could there be something in the lines that is gummed up?

Larz

Perhaps the pistons need to all be pushed in. I'll try that tommorrow. Got to go to work.

KevinK2

With foot off brake, the MC pistons should be positioned to allow line pressure to vent through the reservoir. This allows "pressure bleeding' procedures.

a pedal adjusted low, and a a plunger set too deep, could prevent fluid venting. it could also bottom out the mc before full line pressure is developed. as long as this is avoided, there is no "looser" adjustment ... it's either properly vented or it isn't.

Larz

Still getting a little drag on all four brakes. The MC rod is screwed in as far as I can get it toward the driver's seat. All the dust boots on the calipers look great. I took a wheel off And the pistons retract without any problem when pushed in as if I was changing brake pads. I took the shims off to see if that would allow the pistons to retract more upon release of the brake pedal. This did not remedy the problem. I screwed in the MC rod with my pliers gripped around the slotted circumfrence. I can no longer screw it in. I had to adjust the brake light so that the light wasn't on constantly. I am thoroughly convinced that rebuilding all four calipers may be a good idea, but will not help me with my current dilema. If anyone has any ideas, I'm all ears. Don't know what to do now.

Larz

Could the rotors warping due to the heat when they were dragging badly have caused this? I've got some new rotors. But don't want to put them on just to have the same thing happen to them.

Larz

Bump 1.