The Stovebolt Site Forums The Shop Area The HiPo Shop 52 GMC modified for modern brakes

My original master cylinder went out on me. My original brakes were never very powerful anyway, and it would have cost $180 just for the original-style master cylinder. So not wanting to replace mediocre with mediocre, I looked to Speedway Motors for power brake solutions.

Initially I bought P/N 91031977, '47-'54 Chevy pickup power brake pedal assembly (under floor frame-mount) for $70 bucks, P/N 91031411 7" dual brake booster & master cylinder combo, 1" bore for $180 bucks, and a round stainless steel pedal pad, P/N 7024852 for $20 bucks. It is designed to use EXISTING holes, so no modifications need be made to your truck. But upon attempting to install it, I saw that it was not going to fit if a stock manual transmission clutch fork and pedal are being used. Once I checked with the part manufacturer, I learned it is for automatic transmission upgrades only, and does not appear like the pedal rod itself would likely clear the exhaust of a V8 engine. So it looked to me like it was intended for automatic conversions with a stock stovebolt engine.

That was frustrating, because how many people convert their trucks to automatics and still keep their stock stovebolt motors. I needed something made for the stock manual transmission. So Speedway gave me the manufacturer's number and they DO sell a kit for the application I needed; just not to Speedway. My apologies, I did not keep the info, but a call to Speedway looking for the manufacturer of these parts will get you to this manufacturer.

I sent back my Speedway parts for a refund and ordered direct from the manufacturer, and just got it installed. The darn thing works! Very well! Plus, the stock brake pedal and pedal rod are reused, although the end of it needs a little ground off to clear a V8's exhaust. Thing is though, this would be perfectly compatible with a stock stovebolt with stock transmission with ZERO permanent modifications.

The only thing is, now that my brakes are so powerful, I need to adjust the drums on the left and right sides because the right tends to grab more, pulling me to that side.

This is a mod that might be of interest here.

Wow, lots of interest...

I'm curious who made the parts. But you didn't ask any questions, so there isn't much to respond to...

Thanks Hot Rod Dad,

I just finished a similar upgrade from CCP on my 50' 3/4 Ton. It works pretty well, but I get about 3-4 inches on the pedal before they really start to grab. Talking to my dad, he tells me that's part of having drums on all four wheels. I've seen some 10lb residual valves advertised that are supposed to help with this problem, but it seems like that would lead to premature brake shoe wear and loss of power. Should I just learn to live with it?

I dunno. I'm learning to live with mine. Like with you, mine works pretty well. But it's a [censored] to check my brake fluid level and refill it. I pretty much have to do it by touch.

OldSub, I thought this would be of interest to others concerned with their 60-year old brakes going out on them. I didn't have any questions. The inventor of the brake conversion kit lives in New Mexico, and I got his information from Speedway, who sells some of his stuff. But instead, I noted a 5-page long thread on people wondering how to modernize the brakes, and here I mentioned the parts are readily available. So whatever.

Thats some good interesting info. If everything is right you should have a real high pedal. 10 lb. residual pressure will not hurt with drum brakes. They have strong return springs that overcome the pressure.

Thanks Wrenchbender,

I just got the residual valves in the mail and hope to have them installed early next week. Like you, I suspect the return springs will overpower the residual valve making for a wasted afternoon and some more wasted money. I'll post an update when I know.