My first post. I have a 2005 GMC Jimmy that I have owned since 2007. It’s been a great vehicle overall.

One problem I have had since I bought it, are the disc brakes. The front discs pads seem to drag more than they should. I measure the drag using a torque wrench with a 36 mm socket on the spindle nut to measure the drag. It takes 10 foot pounds to turn the front discs – it has always been the same. I replaced the calipers and discs last year, the torque to turn the discs is still the same.

The caliper pins are clean and lubricated.

I also tried opening and closing the bleeder valve on the calipers to relieve any pressure that might have built up from a bad master cylinder or bad rubber brake hoses – no difference – 10 ft pounds to turn the front discs.



I haven’t read anywhere what the actual measured acceptable drag should be. Any info about how much (measured) drag is acceptable would be appreciated!

 

Wow, I just wanted to say I think you measuring the drag with a torque wrench is a great idea. I don't know what is considered an acceptable amount of friction and am interested in finding out what you learn.

 

My approach to testing this is different. I get on a flat road, get up to 10 or so mph, put the truck in neutral and coast to a full stop with no braking. The key is that final moment as the truck completely stops. If your brakes are dragging then there is a slight grab right at the end vs a soft drop to zero mph. As to using a torque wrench I have never tried this but the interwebs suggest a value of 1-2 ft pounds. I am doing an oil change on a GMC 1500 tomorrow, I will check the value on that truck. Its not my Blazer but its a reference point.

Does the wheel pull, are the hubs noisy or do the brakes heat up? Why are you concerned about this?

George

 

I use an infrared thermometer to measure the heat from the discs. The front discs will get up to 140 degrees on a typical 60 degree day, and about 100 degrees on the rear discs. The drag on the discs and the heat seem to be higher than what they should be. The hubs are fine.

I checked the pad drag on the rear discs - about 6-7 pounds