anyone else have problems with front calipers seizing?

[flubyux2]

ok, i was hoping this was only a problem i encounted with higher-mileage cars, but now my 74k mile car is doing it and i cannot figure out what the problem is caused by.

my ex's car did it and my old 91 did it. when her car started doing it, it was so bad you could see the front rotors glowing at night, the car was boosting at a steady speed and it began to overheat. i dont know if the caliper piston is sticking in the bore, the brake fluid pressure cant bleed back or the caliper slider pins are worn/seizing. but, when the car sits for an hour or more, the caliper releases its grip on the rotor and the car will roll freely again. right now, my car is only doing it "mildly". the car feels sluggish just cruising and when i come to a light, the car will rock back as it rolls to a stop or hold itself on a slight grade whereas normally the car will just slowly roll to a stop and if its on a grade, itll roll back/forward.

on my ex's car, i;
Swapped porportioning valves
-disassembled and cleaned them after swapping didnt cure it
swapped master cylinders w/ known-to-be-good units
-disassembled and cleaned them after swapping didnt cure it
Swapped ABS solenoid valve blocks
-unit from my 91 had a clogged Front-right channel and still didnt cure it
Swapped brake pads
-new pads installed when swapped pads didnt cure it
Swapped front calipers
-used units from my current 89, new units scavenged from my old 91 when the 89 units didnt cure it
Swapped caliper brackets with sliders
-lubed existing slider pins, swapped entire unit when lube didnt cure it

finally, i ended up completely removing the ABS unit and making brake lines to bypass it. but i heard thru the grapevine that a few years after i did the removal, her car began locking up the front calipers AGAIN even after she did a full non-ABS brake line conversion.

as you can tell, throwing parts at her car did not fix the problem completely. idk what to do about it. i know toyota has a special machine that can bleed the ABS system and cycle all the solenoids/valves at extremely high pressures... i wonder if thatd remove any/all contaminants that could possibly jam up my moving brake hydraulics?

please tell me someone has encountered this and actually figured it out :1zhelp:

 

[HommerSimpson]

Yes my left front is in need of replacing..Autozone said 56 bucks i think for rebuilt...

 

[flubyux2]

well, hurry up and get one to put on and see if it fixes it... it didnt last time i had this problem.

 

[jtran8]

Are you talking about 7mgte supra ? if so I used to have this problem about 3 years ago when i first bought my 89 7mgte supra , it was on the front left .I took my supra to several different shops and been told different stories ; so i did what they said tore off and clean every thing from caliper to ABS and ofcourse i bleeded but not thing changed . Brake locked but not totally locked , did not know what to do so i drove like that for two weeks and it finally toasted brake pads and messed up tie rod end . So i replaced tie rod end + new brake pads and went to junk yard bought a used ABS for $70. and replaced it . OMG! problem is solved . It was bad ABS unit ! (some thing clogged up in side ) so if you are going to replace ABS unit , make sure to bleed it well then drive it for coulple days then bleed it again to make sure there no more air in brake system .Well my true story end !:icon_bigg

 

[MK3.0dudeman]

change the caliper(s) it should be good and even if it dosent fix it it's always nice to have new parts on a older car.

I just changed my rear caliper and it did the job for me.also flush the old fluid out

 

[Poodles]

The slides stick...

Water gets in, they rust. If they don't sieze outright, the rust starts eating away and loosens the slides causing oddball wearing of the pads and they can stick/unstick randomly...

No normal rebuild fixes it, it has to have the bracket with the slides replaced (you can get the slides form the dealer, but the actual hole in the caliper cna be the issue too).

I've found that it's from having the brakes serviced by people that don't double check to make SURE the dustboots are where they are supposed to be once everything is together. At least on my car they wheren't...

 

[CyFi6]

I always take the sliders apart and clean and relube them every time i do a brake job. That stuff is 20 years old and the seals are not that great, some moisture is bound to get in there over time.

 

[suprabad]

Also, when the pins, bushings and sliders get worn out you're likely to hear a rattle sound over small bumps at low speed and a "crunching" sound when you apply the brakes. If you don't know what your listening for it can sound like bad steering or suspension componenets.

 

[flubyux2]

well, ive swapped all those components before and had no luck with it. so would a faulty brake booster have no bearing on the dragging of the calipers???

 

[IJ.]

I had one slider unscrew itself allowing the calliper to hit the inside of the wheel

 

[Kckazdude]

The booster itself woudnt cause the brakes to lock. However I have seen the actuator rods cause stcking LF calipers. Have also seen the rubber lines be a cause for sticking calipers.

 

[bluepearl]

Besides everything else that has been mentioned, I also have seen that the rubber brake lines have collapsed inside. They would work like a one way valve at times.

 

[SupraMario]

I had one slider unscrew itself allowing the calliper to hit the inside of the wheel

Same here, I dunno how it happened, but I was backing out of a parking spot and the driver front just locks up and bounces. My who caliper swung around and was dragging on the inside.

and flub, this is the first time I hear about something like this, it could be so many different things, brake booster, ABS going apeshit, boiling break fluid....GL man, and tell us what fixes it.