Front brakes lightly dragging

[horse123]

Doesn't seem to be anything I can really do about it except to wait for them to wear enough where there isn't constant light pressure on them.

Noticed because I purposely drove about 10 miles without touching the brakes, parked (without using front brakes), and they were still slightly hot, but not so much I couldn't touch the rotors. Tried taking them out, greasing the shims and everything up, did absolutely nothing to make a difference. The front pistons are extremely hard to push in for some reason, and I believe they're the cause of the light pressure, they just won't back off when I don't have my foot on the pedal.

Anyone got any ideas?

 

[Chris142]

There is a residual check valve that keeps a few psi of pressure so that they don't back off from the rotors

 

[Sawdusted]

classic case of caliper piston seized. it comes out a little to brake but won't push back.

Looks like you;re in for a caliper rebuild job. but if I were you, I would put in a new or quality rebuilt caliper.

Items sch as brakes, I don't want to mess around with. When you need them, you need them. don't wait till after an accident to replace.

 

[horse123]

Originally Posted By: Sawdusted
classic case of caliper piston seized. it comes out a little to brake but won't push back.

Looks like you;re in for a caliper rebuild job. but if I were you, I would put in a new or quality rebuilt caliper.

Items sch as brakes, I don't want to mess around with. When you need them, you need them. don't wait till after an accident to replace.


It's a less than 4 year old car with the problem on both front wheels. I highly doubt the piston is seized or will be seized any time in the next 10 years.

Originally Posted By: Chris142
There is a residual check valve that keeps a few psi of pressure so that they don't back off from the rotors


How does that make any sense? What's the purpose?

 

[bubbatime]

Originally Posted By: horse123
It's a less than 4 year old car with the problem on both front wheels. I highly doubt the piston is seized or will be seized any time in the next 10 years.


Calipers seize all the time. Doesn't matter that the car is 4 years old. Did you just replace the brake pads?

If the rotor doesn't get too hot to touch, then I dont see what the problem is. If it was dragging, the rotors would be too hot to touch.

Sounds like you need to get it checked out by a person that knows what they are doing.

 

[Olas]

It's either he pistons or the sliders - shouldn't take more than 30 minutes a side to pull, inspect & diagnose. Repairs will be cheap.

 

[HerrStig]

The valve keep slight pressure in the calipers, the pads lightly touch the rotors so water doesn't build up on the surface and lead to a braking delay. It also keeps the pads warm so they don't loose their bite in cold weather.

 

[4wheeldog]

Originally Posted By: HerrStig
The valve keep slight pressure in the calipers, the pads lightly touch the rotors so water doesn't build up on the surface and lead to a braking delay. It also keeps the pads warm so they don't loose their bite in cold weather.


It also keeps the pads from being "Knocked back". It doesn't take much pad movement away from the disc, for the pedal to go way too far, to bring them back into contact. A bit of residual pressure keeps the pads lightly touching, so the pedal stays high.

 

[BrocLuno]

And all that is why I still run drums on the pick-up and the Buivelle... Disc's always drag a little. Plus the dirty up wheels in about a day.

Unless you are on the track, I don't really see the advantage? We get all wiggy on BITOG about 20 grade oils and MPG and folks are running around with dragging brakes and the lights on all the time - yeah EPA...

 

[eljefino]

I had a bad master cylinder. When the pedal is at rest the piston inside is supposed to let fluid work its way up to the reservoir. This didn't happen. It was obvious after I bought both new front calipers and hoses and they still didn't push back with a c-clamp. New MC fixed things.

 

[horse123]

Originally Posted By: HerrStig
The valve keep slight pressure in the calipers, the pads lightly touch the rotors so water doesn't build up on the surface and lead to a braking delay. It also keeps the pads warm so they don't loose their bite in cold weather.


So they rotors and calipers being warm to the touch but not too hot after not using them isn't cause for concern? Won't cause unnecessary wear?

 

[HerrStig]

Originally Posted By: horse123
Originally Posted By: HerrStig
The valve keep slight pressure in the calipers, the pads lightly touch the rotors so water doesn't build up on the surface and lead to a braking delay. It also keeps the pads warm so they don't loose their bite in cold weather.


So they rotors and calipers being warm to the touch but not too hot after not using them isn't cause for concern? Won't cause unnecessary wear?
Would you rather have a 25 foot delay in braking in bad weather. Brake pads are cheap compared to what an accident costs.

 

[horse123]

I don't follow people 5 feet away in rain...

 

[asand1]

Due to the relative size of the caliper and master cylinder pistons,the seals and residual check valves keep the pads in contact to reduce pedal travel, among other things. Dont forget that heat will also be generated in the wheel bearings as well.

Wheels, hubs, and brakes will get warm wile driving, that's just science fact. You have nothing to worry about.