[FMile Pontiacs]

I'm having a problem with the front brakes dragging or sticking. First I changed
the front calipers, rotors and pads but both calipers are still dragging. I can open the line from the master cyl to bleed of and it frees the brakes and allow it to be driven again untill I apply the brakes a couple times and then the dragging is present again. By this time im thinking it must be the master cyl so I changed it and the brake booster. The brakes are still dragging so I changed the front rubber lines. I have also tried disconnecting the abs electrical connections but that hasn't helped. What is the problem? I have spent a lot of time and money but no positive result as of today. Joe

[fyrffytr1]

Have you checked the proportioning valve?

[FMile Pontiacs]

I couldn't find a proportioning valve. They may not have one on the ABS equipped trucks?

[67drake]

I may be wrong, but do the pads set inside the frame that is bolted to the steering knuckle, then the Caliper slide over the pads? I forgot as my wife sold her ‘03 a few years ago. But I remember I had to actually clean the corrosion up with a file as a wire brush wouldn’t even budge the rust. The pads kept hanging up in that frame. Just a thought

[Scott Thelander]

might be time for hoses ..... just went thru this with my motorhome

1988 454 33 000 miles

was it doing it b4 you did the work ?

[Sirrotica]

This isn't an uncommon problem after searching the net a bit. I copied and pasted another 05 owner that sounds like the same situation as yours.

05 Silverado.. I had the same problem with the fronts locking up after driving a few miles and not even applying them on long stretches after having replaced pads,shoes, wheel cylinders, front calipers,hoses and master cylinder. Flushed lines completely twice. Checked booster by removing vacuum line and using long nylon pull tie as a dipstick to verify there was no fluid present as others have noted. After reading many blogs and the mention of possible ABS problems without the light on I removed the ABS fuse, drove about 5 miles and the brakes were locking up and cool. Replaced the fuse and drove another 5 miles, braking alot and letting the truck come to a natural stop in neutral to see if it was still partially locking up and there was no indication of it locking up. Felt the fronts and there were not hot as they were earlier in the day when I drove it just a short distance. Would let it come to a normal stop coasting in neutral with no indication of a problem. Even stopped on slight inclines and it would then roll backwards after coming to a stop. Have not had the problem since and feel more could get the same results should they try this. Wish I had of thought of it or read it somewhere long ago to save myself alot of frustration. Hopefully others will benefit.

There was also a mention of a defective MC that leaked into the power brake booster causing the issue, but because the problem was isolated to just a small run of trucks there was no recall on it:

I have 2006 of same truck and had same issue. If you have been adding brake fluid over the past year, pop the hose off the booster. Check in there and see if you see fluid in the bottom. I had this on mine, so replaced booster, master (leaking in booster), new pads and calipers as they roasted on mine. Flushed all the lines and been working great.

One more that replaced the booster and solved the problem:

SOLVED!!!!! Well it is finally fixed and I drove it to work today to make sure. I drove it Saturday and it locked up so I loosened the MC and it released immediately. So, ordered a now booster for the same truck and they gave me one that was different. UUUGGGG This one had an adjustable rod on it. So installed drove and worked after a little adjusting. Drove it all day Sunday and to work today (43 miles one way) and not hot at all! Thank you all for your help.

Hopefully one of these things will solve your problem..........

[FMile Pontiacs]

Do you have a part number and brand name for the booster with the adjustable rod?

[Sirrotica]

Originally Posted by FMile Pontiacs

Do you have a part number and brand name for the booster with the adjustable rod?

I just copied and pasted the replies I found verbatim, I have no idea of what brand or part numbers the guy used. I just know from a quick search that it is a fairly common problem, and seems to center around the brake booster that doesn't let the MC return all the way and residual pressure can't release causing the brakes to lock the more it is driven. The hotter the ambient air temperature was said to play a role too in some of the replies I ran across.

My personal take might be to try a shim/shims on the firewall to get some extra travel for the brake pedal. Or perhaps between the booster and MC. It would accomplish the same thing as an adjustable push rod.

Evidently the system is quite close to not having enough clearance as it was designed. As the truck gets miles on it the balance changes the wrong way causing this residual pressure due to too little/reduced travel of the components.

I personally have never worked on this problem, just getting some feedback from owners that have run into the problem, tried all the obvious fixes as you have and found out the problem is in the area of the booster.

Rock Auto has a bunch of them with notations, here's the link:

https://www.rockauto.com/en/catalog/...e+booster,1884

[FMile Pontiacs]

thanks I will try to fix the problem sometime this week and post the results here. Joe

[FMile Pontiacs]

Thanks everyone for the replies. I have replaced the booster and master cyl also because of the brake fluid in the booster. I may try a another booster with the adjustable rod

[FMile Pontiacs]

I just took a late night drive and the brakes started to drag bad I backed the master cyl nuts of about 3 full turns and the truck about ran off to leave me alone! I will shim it this week and hopefully be done with it if I can't find a booster with the adjustable rod.

[SRR]

Originally Posted by FMile Pontiacs

I just took a late night drive and the brakes started to drag bad I backed the master cyl nuts of about 3 full turns and the truck about ran off to leave me alone! I will shim it this week and hopefully be done with it if I can't find a booster with the adjustable rod.

You have found the problem. Not enough brake pedal free play. Sounds like the booster isn't going back to it's fully retract position.

[pontiacs-r-us]

Sorry I’m really late to replying to this post,& hopefully you have corrected the problem.... if not, it could possibly be the ABS brake control module? Could be it’s not fully releasing pump solenoid on one (or more) circuits? The pump & control are usually Mounted back under bed on left frame rail. Just saw this on an Impala where was holding 1 rear brake.(not locked,but dragging)

[fyrffytr1]

Can you tell us more about the truck? Is it a crew cab or heavy duty, 4 wheel disc brakes or front disc rear drum etc?

[RAIV55]

My '02 Silverado had a similar issue on the rear calipers. The brackets have a coating that swells when rust develops under it. Pealing the coating off and blasting the rust off the area where the anti-rattle clips sit, and lubing with caliper grease cured mine (for now).

[FMile Pontiacs]

The truck is a 2005 single cab 4 wheel drive 5 speed with the 4.8 front disc and rear drum

[Bill Eveland]

The hoses are breaking down internally and acting like a check valve. The hoses should be replaced first before anything else.

[FMile Pontiacs]

Shimmed the master cyl. 1/4 " from booster problem solved.

[SRR]

Originally Posted by FMile Pontiacs

Shimmed the master cyl. 1/4 " from booster problem solved.

It's fixed.

[Stuckinda60s]

Just curious. Could improper bleeding w/ABS cause air in the lines resulting in this??