08 trailblazer brakes sticking

[metallica21156]

my parents have a 08 trailblazer and the brakes stick. basically sometimes you stop and wait at a light or a stop sign, let off the brake and you can feel them stick for about a second and then release. they took it to the dealer, they said they felt it also but dont know what it is. we know its related to the brakes cause they take it there and they say they cleaned up the brakes and then it wont do it for a week or two then it will start doing it again. its still under warr. any ideas on what it might be?

[maxwedge]

All the brakes, ft rear? Not much info to really help out here.

[metallica21156]

dont know if its the front or back. just as only after a stop. it doest it like 1 time out of 50 stops so you never know when its gonna do it. i was talking to another mech and he said it might be computer related or something with the abs. how would i be able to find out if its the front or back?

[maxwedge]

Are you sure it is the brakes doing this? Could be a delay in throttle response or even a hesitation in the trans. I would have the brake system checked, could be a sticking caliper or the problematic rear parking brake shoes inside the rotors, they could do this also.

[metallica21156]

well she never uses the parking brake so it cant be that. as for the throttle or trans, it does it before you hit the throttle. you come to a light and sit there it turns green and u let off the brake and it acts like they are still on for a sec and then it releases and then all is fine.

[maxwedge]

Ok, check the brake fluid make sure it doesn't look contaminated like some put some p/s fluid in it by mistake. It will not mix with the brake fluid and has an oily feel on your fingers, brake fluid is almost more water like. If so this causes the by pass port in the m/c to be partially blocked by swelled piston seals, of course without a thorough onsite brake system check this is all 2cnd hand guess work.

[metallica21156]

its been doing it so i dont know about the fluid being able to be contaminated. but is there any way to test the master cylinder to see if maybe its just a bad factory one?

[maxwedge]

Never seen a m/c go bad in this manner without the seals swelling from wrong fluid. There is really no definitive test other than getting the brakes not to release then cracking the lines and releasing pressure to confirm the m/c is the culprit.

[j cAT]

Originally Posted by metallica21156

well she never uses the parking brake so it cant be that. as for the throttle or trans, it does it before you hit the throttle. you come to a light and sit there it turns green and u let off the brake and it acts like they are still on for a sec and then it releases and then all is fine.

I would bring to another dealership and have them check it out ! keep all paper work ..

If you have the ability to jack up vehicle , do so and with vehicle running apply brakes and release then see if the brakes work correctly.

since this is a 2008 I would say a defective brake caliper / piston.. I had this on my 2000 silverado..piston would hang up when brake pads worn at 50 %.

removed these pistons found them to be bell shaped..

a defective caliper will show itself with greater pad wear/more dust on wheels than the other wheels !

if the other dealership is just as bad , best get this repaired at a competent auto repair shop where the work is guarranted.

keep all paper work ..then with the defective parts and your failed GM repair papers have them cover these costs.

report back how this all worked out ! could be a recall because of these issues here !

[j cAT]

found this from a 2008 trailblazer owner !

4/28/2009 - RENTON, WA
I WAS STOPPED FOR A RED LIGHT ON A SLIGHT HILL. WHEN IT TURNED GREEN I TRIED TO MOVE AHEAD AND ALL 4 BRAKES HAD LOCKED UP AND I HAD NO FORWARD MOTION. I PUSHED HAD ON GAS PEDAL AND WAS ABLE TO CREEP AT ABOUT 1 MPH TO A DRIVEWAY. WHEN I ENTERED DRIVEWAY I HEARD A "CLINK" AND BRAKES RELEASED.THIS VEH HAS 5200 MILES AND IS A 2008 TRAILBLAZER SS AWD. THIS IS THE 1ST INSTANCE OF THIS TYPE.I TOOK IT TO MY SERVICING CHEVY DEALER AND THEY CHECKED IT OUT AND SAID THAT "MECHANICALLY " IT WAS FINE. THEY CONTACTED CHEVROLET TAC AND WERE TOLD THIS HAS NEVER EVER HAPPENED IN THE WHOLE DATA BASE FOR GM AND NO REPAIRS AUTHORIZED TILL IT CAN BE REPLICATED FOR THEM TO SEE. THERE WERE NO CODES STORED . THIS HAPPENED 0N 4-25-09. I WENT BACK TO DEALERSHIP ON 4-28-09 AND THE AGAIN CALLED TAC TO SEE IF THERE WAS ANYONE WHO HAD INFO ON THIS TYPE OF FAILURE OF THE BRAKES....BUT AGAIN NO LUCK. I FEEL STRONGLY THAT THIS IS A SAFETY ISSUE AND CHEVROLET SHOULD BE DOING MORE THAN LIP SERVICE....

[j cAT]

some found the master cylinder is incorrect for your vehicle. this causes intermittent brake lock up , all wheels..

they used a shim to change the master cylinder length , this solved the problem..

[maxwedge]

So the rod from the booster to the m/c was in effect too long, not allowing the by pass port to open, from day one of manufacture?

[j cAT]

Originally Posted by maxwedge

So the rod from the booster to the m/c was in effect too long, not allowing the by pass port to open, from day one of manufacture?

the fleet mechanics that have these vehicles in there owners business stated that this shimming is the fix...I believe too, that the rod must be too long.. thin washer was used to fix the problem ..

GM so far has no clue on what is the fix... to intermittent ..

pedal does not fully return, brakes stay applied to full or some lesser amount.

you see this before ?

[metallica21156]

so i can add a washer to it and it should take care of it? i know the dealer told them that since it hasnt cause a safety issue that gm isnt going to recall it or do anything about it.

[maxwedge]

Originally Posted by j cAT

the fleet mechanics that have these vehicles in there owners business stated that this shimming is the fix...I believe too, that the rod must be too long.. thin washer was used to fix the problem ..

GM so far has no clue on what is the fix... to intermittent ..

pedal does not fully return, brakes stay applied to full or some lesser amount.

you see this before ?

Yes but on classic car disc brake conversions I do in my shop, I have not heard of the issue on a modern car, seems this would have been corrected from day one if the truck was built that way, there are no TSB's related to this.