MikeGyver

iTrader: (5)

When I said I don't think that you are moving the piston enough, that means that with this size piston in your master cylinder, you should move the pin down to get a longer stroke with more effort.
When you get a M/C with a bigger piston, then you will need to move the pin up to its current location.

MikeGyver

iTrader: (5)

I disagree that you need a smaller piston, that will intensify the sensation of the pedal moving all of the way without doing much. A bigger piston will give a firmer pedal with too much effort.

wardlws

Urg! I thought it was larger, but you said smaller in your post. I was just reading through quickly. I see that you meant that powered brake systems typically have larger diameter Master Cylinders and manual brake systems have smaller (than powered) diameter MCs.

Larger diameter MC = less pedal travel to move the same amount of fluid as a smaller diameter MC, so more effort is needed, but less distanced pushed.
Smaller diameter MC = more pedal travel to move the caliper pistons to begin contacting the rotors, so less effort, but more distance before pads engage rotors.

I still agree with MikeGyver, just using my brain this time and not just my gut feeling.

BuckNasty92

Okay I think I am following what you’re both saying.

So if I were to put the booster pin back to stock I should see an improvement as the piston will move more and give me less of that “tons of pedal movement with hardly anything happening”? Am I understanding that correctly?

I reread the instructions that came with the conversion kit thinking I may have put the pin in the wrong place but everything is per the instructions.

Also, thanks for the link to the calculator Wardlws

BuckNasty92

I got some time to mess with this again tonight. I picked up an unmodified brake pedal from the junkyard and bolted it in.

I rebled the brakes and checked over the truck for leaks just to be sure. The pedal feels more like it should.

When I get it back on the ground I’ll drive it around and see how it goes.

BuckNasty92

With the push rod back in the stock location the pedal travel feels correct and firm like it should be. It just lacks the ability to stop the truck very well.

BuckNasty92

I think I may have found a problem.

The 1320Wheels 15 inch conversion brackets uses a 1991 C1500 NON HD CHASSIS caliper and has a single 2-1/2 inch piston.

I didn’t paint the calipers I bought for the conversion and the bleeder screws stripped out so I ordered a set of Power Stop S4299 painted calipers and there lies the problem.

Power Stop only rebuilds the 1991 C1500 F44 HD CHASSIS calipers which are a single 2-15/16 and does not offer the standard 2-1/2 inch piston caliper.

I think it takes almost the whole M/C stroke to fill the larger piston areas and then I don’t have enough pedal travel left to build the pressure needed before it bottoms out in the bore

I’ll confirm this by getting two proper sized calipers from the auto parts store and returning the brake pedal ratio to a 6:1.