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I just signed up to say I did this mod but I did have to swap the master cylinder. My truck is 08 wt model and it did not have traction control. I changed to the master cylinder that does have have that option and it solved my pedal travel. I had already power bled the original master and all the wheels multiple times. The larger bore 1.25" vs my old 1.125" made the difference. Overall I dont feel a huge difference in stopping power. The back tires lock up for sure if you slam the brake now. I did it because the drums have been giving me ongoing problems ever since I bought it in 2013. I had to buy a 3/16 brake line kit from amazon and I used the newer style double flaring tool. It took me awhile to figure out you have to smooth the flare when your done or it can tear up the mating seat in the brake hose and have leaks. That fitting should screw all the way in by hand and then use a wrench to tighten up the last bit, if you have to use wrenches to get it going something is wrong. Also gm used a plastic coating so the tube nuts wont go on unless you drill them out larger. In my case I just went ahead and formed new steel lines. The hose fitting size is standard 3/8 24. I used some rubber and a small c clamp to hold the junction above the rear axle closed while I bent and flared the lines. I also had to buy a acdelco emergency brake kit so I could get the rubber seals and the parking brake levers. The part number was 179-2236, the pic shows the s hook type but the levers that it came with I think fit the d type cables. One last thing, the sheet metal backing plates I got would rub the rotor in spots. I turned the rotor and push or pulled in different spots to find where it was rubbing, super annoying! Hope this helps someone save a lot of time and frustration.
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I just signed up to say I did this mod but I did have to swap the master cylinder. My truck is 08 wt model and it did not have traction control. I changed to the master cylinder that does have have that option and it solved my pedal travel. I had already power bled the original master and all the wheels multiple times. The larger bore 1.25" vs my old 1.125" made the difference. Overall I dont feel a huge difference in stopping power. The back tires lock up for sure if you slam the brake now. I did it because the drums have been giving me ongoing problems ever since I bought it in 2013. I had to buy a 3/16 brake line kit from amazon and I used the newer style double flaring tool. It took me awhile to figure out you have to smooth the flare when your done or it can tear up the mating seat in the brake hose and have leaks. That fitting should screw all the way in by hand and then use a wrench to tighten up the last bit, if you have to use wrenches to get it going something is wrong. Also gm used a plastic coating so the tube nuts wont go on unless you drill them out larger. In my case I just went ahead and formed new steel lines. The hose fitting size is standard 3/8 24. I used some rubber and a small c clamp to hold the junction above the rear axle closed while I bent and flared the lines. I also had to buy a acdelco emergency brake kit so I could get the rubber seals and the parking brake levers. The part number was 179-2236, the pic shows the s hook type but the levers that it came with I think fit the d type cables. One last thing, the sheet metal backing plates I got would rub the rotor in spots. I turned the rotor and push or pulled in different spots to find where it was rubbing, super annoying! Hope this helps someone save a lot of time and frustration.
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Nice job but I would have gone with braided stainless steel hoses. They firm up the pedal even more.
 

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I used Goodridge initially. But I have since installed Wilwood’s 16” 6-piston fronts and 14.25” rears which came with their own hoses so the only Goodridge one is the rear center that goes from the hard line on the truck side to the t-fitting at the center of the differential.
 

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So I've been doing more research. I wish I had gone with the single piston rear calipers. My brakes are good but pedal travel will never be what it was unless I find and even larger bore mc. The 2008 2500 series has dual piston front and back woth a 1.456 bore mc on hydroboost. I had 1.125 and now 1.25. The master cylinder size on the 2001 tahoe was 1.38 but the threads are a different size. My dads 2015 tahoe has a 1.31 bore with single rear pistons and his pedal barely moves, mine moves like 1.5 inches before you feel it really start to bite. Its not air in the system. At highway speeds it feels better but stop sign to stop sign your moving your foot 2 inches. I feel more confident with this vs drum but its not touchy because of the bore size. I have 4 new calipers, pads, front ss hoses, new rear rubber hoses and a master cylinder. I dont know what rocketman did with 6 and 4 piston calipers. Heres a link with some info on how to calibrate pedal feel to system size, but doesnt go to truck sizes.

 
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