I have a 91 240sx HICAS with abs brakes. Lately after the cars been warmed up it feels like the brakes are dragging. The car starts slowing down and I kinda have to give it more gas. Also when coming to a light I don't have to apply the brakes very much in order to stop...at about 10 mph the car will stop by itself.
The only aftermarket addition I added to the brakes are cross drilled slotted rotors. For the first few months the brakes didn't feel like they were grabbing on their own. Now after I've been driving a while they do feel like they're grabbing. When I'm on the interstate is the worst because it's creating so much heat. When I get off I can smell the brakes almost burning. I've noticed that I lost a significant amount of pad in the rear brakes compared to the front. And even after I've parked from driving I look at the left rear caliper and it is actually smoking because it's so hot.
Today I replaced both rear calipers because my guess was they were sticking. So after I did I got on the interstate to see if they would grab. Felt like nothing was dragging. Then after I got off the interstate about 10-15 minutes of driving they started to drag again!

I've replaced the master cylinder, rotors, pads and now rear calipers. This is really aggravating not to mention is killing my gas mileage. Does anyone have any idea what else it could be?

 

try disconnecting your e-brake for a test run. for shits n gigs.

 

release some pressure of your lines. just a littleeeeeeee bit lol

 

since you mentioned replacing the master, im willing to bet the pedal length adjustment is off.

 

also worth mentioning, ive had a car come in before with a blown head gasket due to the brakes dragging and overworking the motor!

 

True. Also if a brake booster takes a shit or just that check valve that connects the vaccum line that comes off the booster it could cause them to lock. Is it all 4 brakes or just the rears? And have you replaced the little button on your brake pedal that cuts the brake lights on and off? If you did that and it is too big it could be pressing the pedal down a little bit the whole time and that would explain why it takes some to lock up.

 

Don't have a blown headgasket. My e-brake mechanism is good. It's just the rear brakes....someone mentioned to me maybe the proportioning valve is bad? what do you guys think? also I guess this is an intermittent thing...meaning it doesn't happen all the time. I drove my car to work today and on the interstate they started to grab again. I was gonna let someone look at my car so then I got back in it and noticed they weren't grabbing anymore. So I took it back on the interstate and they never grabbed while I was on it. I did 2 passes and both times nothing. It's weird.

 

yeah, that makes no sense... best I could tell ya is to flush the fluid all the way out and make sure there is good fluid in there... if it is old then it has moisture/water in it and that will cause problems...

 

Thanks for the suggestion but there's new fluid in there too lol

 

Alright so I took the car for another run....this time they dragged the most they've ever done before. I was cruising in 5th and almost had my foot to the floor and the car was actually slowing down! got back to the shop, put it in the air and tried turning the wheels by hand...turns out all 4 were locked up. Pulled off the master cylinder to check things out and....it was leaking. And the more I think about it, the more I don't remember replacing the master cylinder. I thought I did but guess not. Awaiting for a new master cylinder as I speak.