Quote:

not always true, i had this exact problem on my car, took it to the pros and the back calipers fell apart cause they didnt d the bolts up, the pro's can be just as bloody dangerous as the nuff nuff DIYer's


anyway..... beside that


have you replaced the master cylinder recently?

i has all sorts of grief with a new master and the fix eventually was to remove the valves out of the master, they were holding enough pressure in front and back lines to create enough drag on the brakes until they heated and jammed up

the valves are a black plastic piece and a spring, they are just inside the boss section where you screw the brake lines in to the master

proportioning valves in pic below

I'm having the same problem. Cleaned every bit of it and realigned it to the stock setting. It works for a month or two at most and jams again. The biggest problem is the atmosphere and material selection. The pins, the housing of pads; they all make a good enough electro-chemical cell that works faster in humid conditions (like the hemisphere I'm in). Now I'm thinking of making the pins of a different material that will be passive to corrosion.

yes, got your point.

The problem is some of the corrosion is still there, the tolerance is too tight now.

1. The parts need to be carefully cleaned to restore the proper gap between the caliper frame/holder and the piston body
2. Proper lubricant applied to prevent further corrosion, and to allow smooth operation

I would say its always a smart move to ask the experts here in this forum before paying a visit to the "money minded" mechanic. it could be a small leak in the brake hose and u'll might end up changing the master pump or the calipers without knowing the actual symptoms. Got my point ??

if you dont know enough to work this out yourself then you dont know enough to fix it
go to a proffesional brake shop
im all for "have a go yourself" but brakes need to be 100% right the first time
its your ass
dazza

edit : assume that most of the time people on forums dont know S#it. most of the time you will be right

Thanks for the flexible hose advice, i will try changing that first.

1.) DD, Piston was initially corroded a little, but when i serviced it, i sanded the piston and also the bore. Its clean now. The caliper "sliding" area was also scraped and well lubricated.

2.) WhiteSedan, no twists were found at the brake lines.

3.) Woody, im worried it is the pin, as u said. Well, actually, this problem has occured several times. I have tried solving this problem by a can of WD-40 and knocking & pushin the caliper back n forth. Initially, it will be difficult, gotta use a hammer though. But after a minute later, it becomes easy, can grip it with fingers to move it back n forth. By doin this, it would last for probably 3 days, before the same thing happens again.

What i would like to know is how should i make sure the pins are aligned well and it is not stucked. Please help

When you had the brakes off maybe one of the flexible lines was twisted which would cause this to happen.

i agree with dd, the caliper slides (the pins which the caliper moves in and out on) are sticking causing the brakes to drag. in the past week i have had two of these cases happen to cars at work. pull the caliper off and i will bet you you wont be able to pull the caliper slide pins out of the caliper. the easyest fix....get a new one if you cant get it out.

One problem is a corroded piston, yes it sticks then gets hot and wears the pads out on that side. You can sometimes get the piston to move, but replacing the seals won't fix the problem. So make sure there is the right amount of clearance between pistons and bore (these are double-piston units) and no corrosion in the caliper or on the pistons.

But also common -- especially with Sunny brakes, is the caliper sliding surfaces are sticking. Remove all rust, carefully scrape the sliding surfaces, get it to move firmly but smoothly, and properly lubricate it.

I'm assuming the callipers are working correctly and the piston can return into the bore when the pressure is released.
One possibility is a separation inside the flexible brake hose.
This can occur on old hoses.
The layers separate and crate a crude "one way valve" inside the hose.
This allows the fluid to pass into the calliper to apply pressure but closes it off when you release the pedal, thus retaining pressure in the calliper.
Try fitting a new flexible hose to the offending calliper and see if that helps