I have a 54‘ Chevy 3100 that I’m doing a frame off resto that a few years ago I bought the Brothers, actually CPP branded, dual master cylinder upgrade kit. I installed most of the kit when I had the cab off a little bit over a year ago. Kept it under the cab as the original one was. As projects go they take longer than you think and instructions end up missing and remaining parts get scattered. It appears that there is a new version of this kit and no mention of the older the instructions and parts list. I think I figured it out now. But my question is about the pedal arm contacting the cab firewall when the brake is in the up position. I also purchased a new return spring for the arm. I’m looking at the service manual for the truck they do talk about how to adjust this with the suggested spacing. But the issue is that the cylinder push rod on the new kit doesn’t allow this adjustment like the original. The new spring wants to pull the arm so much that it forces the brake arm to contact the lower „toe pan“. In looking at the brake arm there is a slight notch where I think it was contacting the cab before with the original setup.
Has anyone done one of these kits and have this clearance issue with the brake arm and cab? Did you put in a bump stop or do something else? Just let it contact? Thanks for any thoughts.
The Factory Assembly Manual (FAM) doesn’t show any bump stop but does have instructions on adjusting the pedal outlined in red on the attachment.
Last edited by Phak1; 08/04/202412:44 PM.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
Thanks for the response. The assembly manual and service manual both describe the same procedure. The issue is that the push rod on the new kit is free floating in the master cylinder. Unlike the factory original. So there’s no way to use it as an adjustment piece like the original. There is adjustment on the new rod but it’s more about keeping pressure off the master cylinder valve so you’re not applying the brakes all the time. The spring pulls on the arm and forces the contact with the cab in the up position. That’s why I was trying to decide if I wanted to put in some type of a bump stop so there’s not metal on metal contact. Or maybe someone else did something to allow adjustment.
Just put a rubber spacer on the brake pedal rod on the engine side of the firewall. Pieces cut from the sidewall of a discarded tire with a gasket cutter punch will last three days past forever, and several of them can be stacked up if necessary to get the right pedal height. Jerry
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On my truck, there is no rubber brake bumper. Yes, the brake pedal stops when it hits the seam between the floor board and the toe board. The seam is cut back at this point to allow the brake and clutch pedals to return. So far, not having a bumper on the brake does not seem to be an issue at all. There is a bumper on the clutch pedal. When driving, I think you tend to let off the brakes easier than you do with the clutch.
I have the same set-up on my 54' and yes, it hits the toeboard/floor panel. I originally tried a rubber "bump stop" on the pedal arm itself but couldn't get it to stay in place. I ended up adding a piece of rubber to the body seam to cushion it. (In order to keep from the metal-on-metal contact)
Thanks for the thoughts guys. Interesting that so many seem to make contact. I may do like you did Tom and try to add some rubber to that area. Thanks again everyone.
