SixSpeedSS
I'm Awesome
I need a master cylinder for my K2500 ECSB. I looked it up on RockAuto and they show 2 different Raybestos part numbers. One is 1.25" bore and the other is a stepped bore at 40mm & 28.6mm. So I go on Raybestos site and they lst the same two master cylinders for my truck. I called the GM dealer figuring I could give him my VIN and he could tell what belongs on it. He gave me a GM# 18029968, which crosses over to the 1.25" bore master cylinder on Raybestos' site (MC390257).
My question is this...Could the step bore MC (Raybestos #MC390259) be designed to correct the known issues with these trucks and the poor braking performance? The truck has new pads/calipers (done before I got it, but looked brand new), and I did new shoes/wheel cylinders/hardware in the rear. I also bought a Stainless line kit from Inline Tube and plan to replace all 3 hoses with stainless braided hose. Before I do the lines/hoses I want the truck to stop properly.
It seems that there isn't much pressure to the fronts. The rears seem to be doing all the work. It takes nothing to lock up the rear wheels and the truck does not stop all that well. The other day it started making a bunch of noise when coming to a complete stop, so I decided to pull the rear drums. They were completely full of brake dust. All the rivet holes werre filled and my guess is there was so much dust it was between the shoes/drum and making the noise. When I pulled the front wheels, there was almost no brake dust on/around the front pads. The fronts don't seem to be doing much.
I decided to try and bleed the system again. I am getting fluid at every wheel, the ABS unit, and the master cylinder. When I bleed the master cylinder, I get a strong pressure of fluid from the front 'smaller' reservoir of the MC (rear brakes) and just a dribble from the rear 'large' reservoir (front brakes). This is why I think it needs a MC. But since I am going to replace it, I want the best I can get for it. If the step bore MC is a 'fix' for these trucks, then I want to try it. I'm pretty confident that a new MC will make the truck stop better, but I want to make it stop the best it can. With the big rotors and 13" rear drums, this truck should stop pretty well.
My 454SS stops pretty well and it is completely stock braking system with Hawk front pads. The rears are still original. I understand it is a lot lighter truck, but it still aint no featherweight.
My question is this...Could the step bore MC (Raybestos #MC390259) be designed to correct the known issues with these trucks and the poor braking performance? The truck has new pads/calipers (done before I got it, but looked brand new), and I did new shoes/wheel cylinders/hardware in the rear. I also bought a Stainless line kit from Inline Tube and plan to replace all 3 hoses with stainless braided hose. Before I do the lines/hoses I want the truck to stop properly.
It seems that there isn't much pressure to the fronts. The rears seem to be doing all the work. It takes nothing to lock up the rear wheels and the truck does not stop all that well. The other day it started making a bunch of noise when coming to a complete stop, so I decided to pull the rear drums. They were completely full of brake dust. All the rivet holes werre filled and my guess is there was so much dust it was between the shoes/drum and making the noise. When I pulled the front wheels, there was almost no brake dust on/around the front pads. The fronts don't seem to be doing much.
I decided to try and bleed the system again. I am getting fluid at every wheel, the ABS unit, and the master cylinder. When I bleed the master cylinder, I get a strong pressure of fluid from the front 'smaller' reservoir of the MC (rear brakes) and just a dribble from the rear 'large' reservoir (front brakes). This is why I think it needs a MC. But since I am going to replace it, I want the best I can get for it. If the step bore MC is a 'fix' for these trucks, then I want to try it. I'm pretty confident that a new MC will make the truck stop better, but I want to make it stop the best it can. With the big rotors and 13" rear drums, this truck should stop pretty well.
My 454SS stops pretty well and it is completely stock braking system with Hawk front pads. The rears are still original. I understand it is a lot lighter truck, but it still aint no featherweight.