I swapped my diff with drums to a an LSD with discs and have noticed that the back pads are riding on the rotors all of the time. I recently learned that the rear drum system always provided some residual pressure to keep the boots sealed. When I did the swap, I didn't change the proportioning valve or master. Is there a way to modify my existing proportioning valve and/or master so that my rear discs are fully released?

 

Disc brakes always ride on the rotor. That's how they clean themselves and also why the don't squeal(most of the time). Its totally normal. But now its not supposed to drag to bad but always have slight pressure on the rotor. Hope this helps.

 

I've got a '85 GS, and when I swapped in the LSD/disc rear end I did not change anything other than the rear end. I have no issues at all.

Maybe check and make sure the slide pins are well lubricated on the calipers?


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In addition, there's no way for the system to create "residual pressure" unless your foot is on the pedal - - there's no source of pressure for the valve to proportion unless you squeeze the master piston with your foot.

 

Here's some more information.

"The single-piston floating-caliper disc brake is self-centering and self-adjusting. The caliper is able to slide from side to side so it will move to the center each time the brakes are applied. Also, since there is no spring to pull the pads away from the disc, the pads always stay in light contact with the rotor (the rubber piston seal and any wobble in the rotor may actually pull the pads a small distance away from the rotor). This is important because the pistons in the brakes are much larger in diameter than the ones in the master cylinder. If the brake pistons retracted into their cylinders, it might take several applications of the brake pedal to pump enough fluid into the brake cylinder to engage the brake pads."
http://auto.howstuffworks.com/auto-p...isc-brake2.htm

Here's some more information.