Corolla brakes

On a 93 Corolla how can I tell if brakes dragging are caused by caliper,master cylinder or proportioning valve? I suspect left front disc but have heard it could be any of them. No evident leaks or break wear and slight pull at times to right.
Thanks for any input
MIKE

 

a dragging brake will be hotter, maybe even smell if it's hot enough. if you jack up the wheels and spin by hand, more drag will also be evident.

most all dragging/locking disc brakes are caused by a bad caliper or brake hose. trapped fluid under pressure is hard to get to return to the master cyl so if you crack open the bleeder (careful here, don't break it off) and push the caliper piston back into the caliper easily, it's a bad hose (collapsed inside). if the piston won't move at all...it's a bad caliper.

 

On the road again. This site is so awesome, thanks so much for the help. It was the caliper but nice to know for future on how to tell which is bad.

 

K, I'm glad to find this post... 94 corolla I have a nightmare of a dragging front left brake just like this. I have changed the caliper already(bought at salvage). and now it is better but not solved. I have done some testing... I know I can push no problem on the caliper pucks and push the fluid back in the master cylinder, and it comes back just like it should after pumping at the brake pedal. I have bled the brakes.. still dragging a bit. I kind of wish my problem would be just the hose. Does the fact I can back bleed it and it works well pushing the fluid back to the caliper proves my problem is deeper than a bad hose? Or a bad caliper again? What should I do next? I'm loosing it with this brake problem... Thanks!!!

 

Just raise that wheel and spin it. If you have brake drag, crack the bleeder. If that ends the drag you have a problem in the brake hose or ABS (if so equipped) that's holding pressure in the caliper = brake drag. If it does nothing to reduce the drag the problem is in the caliper - either in the mounting bracket that won't allow the caliper to slide or there is corrosion in the caliper that the piston hangs up on and can't return to a no brake position.

The latter is what I've found most often on older/high mileage cars. For that pull off the caliper, leaving the brake line attached and pump the brake until you force the piston out. Clean the piston off and replace the caliper piston O ring. If the inside of the caliper or the piston itself is badly corroded, you need to replace the caliper assembly.

 

Thanks a lot, that's very helpful. I can understand and everything is clear. I shure am gonna go after this caliper and tear it appart. Thanks a million!!