2003 Tahoe 5.3L vacuum assist brakes (with supplemental brake assist (the little electronic vacuum pump attached to the outside of the booster)). Recently replaced my brake booster and master cylinder and am having issues with the front brakes dragging as well as the pedal traveling almost to the floor and mediocre braking power (not improved from old MC and booster). I have new calipers at all four corners as well as new OE rubber brake lines at all 4 corners and rear center.
Truck starts out with very long pedal travel, and when I back out my steep driveway the pedal goes to the floor before the truck stops seconds later (all my other GM trucks/SUVs stop immediately and have much higher travel). As I drive the pedal firms up and I get braking action right at the top of the pedal. If I continue to drive, especially at highway speeds, I can tell the brakes are on (harder than normal to accelerate) but just slightly. One time I pulled into my driveway and the front brakes were smoking. Haven't driven since then other than to test is my various fixes have worked (they havent).
I suspect the brake booster pushrod was not adjusted properly (measured the same as the one I took off, but I did not measure the new MC) and is not allowing the master cylinder to fully release therefore causing brake drag. I am going to take it apart today but I do not know how much clearance should be between the booster pushrod and the MC...I cannot find any spec for the tahoe or even any GM truck/suv. I have found a few articles related to classic cars and they call for 0.020 clearance but I have also come across youtube videos where mechanics say it can be zero clearance. Maybe it doesn't matter that much so long as there is drag and excessive clearance
Can anyone point me in the right direction or has experience with this?
Truck starts out with very long pedal travel, and when I back out my steep driveway the pedal goes to the floor before the truck stops seconds later (all my other GM trucks/SUVs stop immediately and have much higher travel). As I drive the pedal firms up and I get braking action right at the top of the pedal. If I continue to drive, especially at highway speeds, I can tell the brakes are on (harder than normal to accelerate) but just slightly. One time I pulled into my driveway and the front brakes were smoking. Haven't driven since then other than to test is my various fixes have worked (they havent).
I suspect the brake booster pushrod was not adjusted properly (measured the same as the one I took off, but I did not measure the new MC) and is not allowing the master cylinder to fully release therefore causing brake drag. I am going to take it apart today but I do not know how much clearance should be between the booster pushrod and the MC...I cannot find any spec for the tahoe or even any GM truck/suv. I have found a few articles related to classic cars and they call for 0.020 clearance but I have also come across youtube videos where mechanics say it can be zero clearance. Maybe it doesn't matter that much so long as there is drag and excessive clearance
Can anyone point me in the right direction or has experience with this?
