Stumped On Brake Problem - I need technical-specific help!

[94grandam]

1994 Pontiac Grand AM SE 4 Cyl. 138 2.3L MFI SOHC QUAD

[u]History: [/U]
June '03 - RF Wheel Outer Brake Pad Broke = Damaged Rotor
Replaced both L&R Front Rotors and Pads
Alignment & Balanced - Tech mentioned RF Caliper too tight *RF Caliper is a "Fixed Caliper" If it is to be torqued to specs, how can it be too tight? (Note: LF Caliper tightened the same but no prob.)
Occassionally noticed RF Brakes not releasing from Rotor/Dragging

Sept '03 - ABS Light Occasionally Illuminated
RF Wheel Outer Brake Pad Broke = Damaged Rotor
Prognosis - Due to dragging Brake Pads, obviously Brake Pad is failing due to high temperatures.
ABS Diagnosed at Automotive Shop - Code 51 "Rear ABS Motor Free Spins" Suspected Stripped Gear; Estimated $600 Repair or $400 for Gear Kit. Tech said that the Rear ABS Motor would not cause the Dragging Brakes, it is a mechanical problem. He said I could get by without a repair, the ABS Light would just be Illuminated but would not cause any problems. It was suggested that there was a damaged Brake Line, thus preventing fluid from returning back to Master Cyl./Reservoir
Inspected RF Brake Line/Brake Hose = No visible damage found
Proceeded with Pad/Rotor Replacement = Found Dust Boot on Caliper Piston torn and seperated from Piston.
Removed Piston from Bore = Found slight scratches and scoring. Assumed Piston was getting jammed in Bore.
Replaced RF Caliper/Rotor/Brake Pads - Greased
LF Rotor Turned and Replaced Brake Pads - Greased
Bled ABS System per proper proceedures (Note: Fluid flowed smoothly and cleanly out of Bleeder Valve on RF Caliper during Bleeding Process)

Oct '03 (2 wks. later) - ABS Light Illuminating less frequently than before
RF Wheel Outer Pad is slightly rubbing Rotor. No significant "felt" dragging noticed. When finished driving, Brake Pad/Caliper Area radiates excessive heat and smokes from behind tire. No significant wear on Rotor but have stopped driving vehicle.
Removed RF Brake Pads/Rotor
Prognosis - All mechanical parts on RF Brake Assy. are brand new; therefore, I am assuming problem lies somewhere from the Caliper back to the Mstr. Cyl. Again questioning the "overtightening" theory. At this point the LF Caliper has been removed and replaced just as many times and in the same manner as the RF has, but does not pose any mechanical problem whatsoever.

*At this point I suspect the problem is the ABS Module, specifically the Rear Motor.
(Note: The RF Brake Line connects to the ABS Module at the REAR of the module.)

AM I OVER-LOOKING SOMETHING?
WHAT COULD BE THE PROBLEM?
WHY IS IT ONLY THE RF OUTER PAD THAT IS AFFECTED?
COULD THE ABS BE SENDING/SENSING THE WRONG PRESSURE DATA TO THE WHEEL?

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*The Mst. Cyl./ABS Mod./Electronic Mod. are one assy. and must be removed/replaced together. This process requires a Gear Tension Relief Sequence performed by a Tech I or T-100 Scan Tool. This has to be done initially or personal injury may develop. (Note* There is no Sequence to be performed after the Mstr. Cyl. is replaced.)


*Question - Theoretically, if I replace the Mstr. Cyl. or replace the Gear using a Kit, I would have to get the Gear Tension Relief done at an Automotive Shop. If I do this, then would I be able to operate the vehicle under Conventional Braking in order to get it back home so I could replace the assy. myself?
Would that action cause the gears to again build tension before I am able to perform any work on it?

I NEED TO UNDERSTAND MORE ABOUT THIS TYPE OF MODULE SO THAT I CAN DETERMINE WHAT MY OPTIONS FOR REPAIR ARE.
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Please understand that I had to write a long, detailed explanation in order to gain specific information. Unless you understand what I've described, please do not reply. I can not have any useless information. Thank You for your time, I will greatly appreciate it if you can help.

Brad

[GMMerlin]

SO many problems,so little time.
The gear tension relief procedure must be done to remove the motor pack from the master cylinder assembly. If you turn the key on after the procedure is done the gears retension.

Most likely the slides are binding or there is a small flap of rubber on the inside of the front brake hose that has come loose allowing fluid to move one way in the hose and not the other. Thus causing pressure to be applied to the caliper when the brakes are released.
You have 2 seperate problems
The rear ABS motor controls the rear brakes.
If you need more specific information PM me and I'll see what I can do.

[94grandam]

That answers my question about the Gear Tension issue.
I'll go ahead and replace the Brake Hose and see if it helps.

Thanks!

[GMMerlin]

For safety sake...replace both front hoses

[94grandam]

I replaced the brake hoses last weekend and it's running great. After bleeding the brakes yet again, I noticed I'm not getting the ABS light; I'm just gonna go with it and hope that helped eliminate the freespin prob. Thanks again GMMerlin!

[RABarrett]

Any problem restricting the free flow of brake fluid to and from the caliper will adversely affect the wheel in question. The purpose of ABS is to apply and release the brake fluid pressure to keep that wheel on the verge of lock-up. If the fluid cannot release, the result will be dragging and overheating brakes. ANY other reason that the fluid cannot freely through the system, erratic performance should be expected. Carefully check hoses, calipers and the master cylinder for retrictions. If all is well there, it will require ABS servicing. The computer operates solenoids which control brake fluid flow TO AND FROM the caliper. It reapplies fluid pressure from the accumulator to reapply the brakes once they are released. That is the only way the wheels continue to brake during an ABS event. It then re-releases the pressure, allowing the wheel to turn again. It requires complete solenoid control to allow the correct fluid control to do this effectively. Restrictions anywhere on the system, including the solenoids themselves will cause problems. Ray

[Kimjio]

Originally Posted by GMMerlin

SO many problems,so little time.
The gear tension relief procedure must be done to remove the motor pack from the master cylinder assembly. If you turn the key on after the procedure is done the gears retension.

Most likely the slides are binding or there is a small flap of rubber on the inside of the front brake hose that has come loose allowing fluid to move one way in the hose and not the other. Thus causing pressure to be applied to the caliper when the brakes are released.
You have 2 seperate problems
The rear ABS motor controls the rear brakes.
If you need more specific information PM me and I'll see what I can do.

hi, brother, i had a similiar problem, after turbo charging my small car, i upgraded to a 2POT mitsubishi (unknown model) brake kit for my front.

I exprerience some squeezing sound on my right front brake. sometime, no sound and it roll well, but sometime, it will lock the wheels( i suspect front right) .

My car is automatic transmission, so when i engage to 'D' , the car wont move and until i step on some gas, this is what i mean by my brake get STUCK or something. sometime it cause very bad steering wheel shake. and yesterday. i went to a workshop and seek a mechanic help, i am shocked to lsee that my RIGHT FRONT brake is smoking like hell, and that mechanic dismantle the my brake caliper assembly. He told me the rubber part inside the caliper might be gone, if after replacing, still cant work, might need to replace the whole caliper.

please help.