Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (
-   Suspension - Brakes - Steering (
-   -   need help on brake pedal assembly (

Studedean 11-05-2011 05:19 PM

need help on brake pedal assembly
I have my piston from the booster coming through the firewall and wondered since brake pedals are pushed to stop, anyone have photos or ideas on how to push the pedal and compress the piston? thinking I need an assembly to push the pedal and not pull out the piston but push it in, but im not sure what it would look like.

evolvo 11-05-2011 05:40 PM

I'm confused by your description. Can you post pics?

eloc431962 11-05-2011 06:01 PM

What are you working on ?


cobalt327 11-05-2011 06:05 PM


Originally Posted by Studedean
I have my piston from the booster coming through the firewall and wondered since brake pedals are pushed to stop, anyone have photos or ideas on how to push the pedal and compress the piston? thinking I need an assembly to push the pedal and not pull out the piston but push it in, but im not sure what it would look like.

You want to PUSH the piston, not pull it.


Cape Cod Bob 11-05-2011 07:50 PM

the site cobalt sent u to has a lot of pictures and you may be confused as most of the pics are for under the floor; The assembly you need is for hanging on the firewall. Commonly called a swing pedal and there are plenty at that site but you may not recognize them.
So try to look for one that says swing or firewall mount.
Go to another car and take a look at how the pedal works.
It is a basic lever and fulcrum setup
You must have the proper parts to work together. Don't want those brakes to fail from a poor or wrong instalation. Luck :welcome:

Studedean 11-07-2011 10:59 AM

I realize the piston needs to be pushed. cape cod bob I think realized what I am trying to accomplish. I bought roughly the 28-31 for assembly from the website link to place under neath the truck. well the trans cross member is in the way. So I mounted support metal on the front and inside drivers side of the firewall to support the booster and m cyl. the issue is now the install will be backwards. I have the booster mounted to the firewall w/ the master cyl in front of it. The piston comes through the firewall high and towards the drivers door. so I imagine theres a fulcrum type assemble to mount for a pedal to push the piston. My issue will be the piston comes through around 4" and its no where near where a conventional brake pedal would be. I've got approx. a foot between the piston and the gas pedal at the hump. I didnt think photos would help as I just need to see when pushing down the brake pedal what contraption to the left of the pedal pushes the piston?
im doing a 50 stude truck body, on a s10 frame front, 2x4 steel tube rear frame. 350 w/ auto trans. trans cross member is exactly where the unit I bought should have been installed.

evolvo 11-07-2011 11:30 AM

I'm still a bit confused by your description, photos' would really help.
But, if I understand the original problem of the underfloor mount having the trans cross member in the way of the master cylinder......would it be possible to mount the master further back, behind the cross member and simply install a longer rod between the pedal mount and the master. This long rod could run through a hole in the cross member. As I said, pics would really help!!!

This photo shows a link rod. It could be as long as needed, as long as its' diameter is big enough to keep it from flexing under load.

Hope this makes sense and helps a bit.

cobalt327 11-07-2011 11:35 AM

If I'm understanding you, the M/C and booster assembly is backwards- i.e. the booster is facing away from the pedal.

If the correct set-up isn't available for whatever reason, and there are no other mods that could be made to the existing set-up to make it work w/the M/C correctly positioned, it could be done mechanically if you used linkages and bell cranks, but it'll take a few tries to get it sorted out. Your best bet might be to adapt it to hydraulic opreation between the pedal and the brake booster, if I understand the layout.

What I'm talking about uses a small hydraulic cylinder to actuate a ram that can be mounted where ever it's needed. The basic components are shown below, these are from CNC Brakes, and are originally intended for use w/a clutch:

Problem w/all that is you'd need to adapt it to your pedal, etc. Possibly a different rod as mentioned above could work, does your deal look like:

Studedean 11-07-2011 01:25 PM

cobalt, the photo of the master / booster at the bottom of your post is exactly what I have, pedal and all. my booster (the gold part) has the piston coming out of it in pretty much the same direction the photo shows on your post. my booster is bolted flush to the firewall and the piston comes through into the cab.
id say the piston sticks into the cab about 4" and is approx. one foot towards the drivers door and one foot high for where the pedal would have come through the floor on a standard frame install. so I need a pedal assembly, that I can push the pedal and ...... (some mysterious voodoo occurs)..... and the piston gets depressed over where its at. crazy question. can master go against the frame and make booster and piston point forward? would be quite a distance away though...

evolvo, I considered creating the "set way back" master/booster on the frame deal and running a rod through the cross member to the piston, but decided against it because the rod in my case would have been well over a foot long, and I was afraid of it bending when slammed on in an emergency, and frame mounted that far back left no way to fill the master w/ fluid, as the Master would be directly under the gas tank. . I can take photos tonight if necessary, but everyone seems on the same page now.

im not commited any way on assemble. I did create plates in and out to hold the brake parts, but no harm done to go a different way. i do have an issue up in the firewall config. im hitting the steering shaft, so i have ot re-drill the firewall holds slightly over towards the dr door. i only need an 1/8"

cobalt327 11-07-2011 03:07 PM

I'll stick w/hydraulic actuation of one sort or another. That's the 'best' thing IMHO to get from "A" to "B". Rigging up a mechanical linkage would be a chore compared to running a hydraulic line.

That said, if there were a way to bleed/refill the M/C w/it under the tank, I wouldn't let the 12" push rod bother me- one could be made that would have basically no deflection. Would there be room for a remote reservoir lid on the existing M/C if it were mounted under the tank?

Studedean 11-08-2011 12:00 PM

theres no room to open the lid up under mounted to the frame. trust me id love for it to work out under there, but I dont think it will. remember ive got a 50 stude cab on a s10 frame and the guy before me purposely lowered the frame mounted cab pieces to get the truck lower.
the one foot push bar would be more like 2 feet, and thats what scared me. ive got approx a foot in front of the trans crossmemeber and the member itself is approx. 6 inches wide at the frame. so minimum would be 18-20 inches away. seemed to me to be alot of bar that could bend.
since I cant go farther w/ my project until this is resolved, ill post some photos to see if anyone has a solution. thanks for the help so far.

evolvo 11-08-2011 01:13 PM

A piece of 1" OD X .065 wall tubing two feet long would be overkill as far as resistance to flex. I think .75" OD would be plenty strong, too! Remember you're going to be pushing in a nearly straight line from the pedal to the master and that size tubing in compression is incredibly strong. Using a remote reservoir or building an access door in the floor so you can fill the master sounds easier to me than trying to adapt a swing pedal to your car. JMO!

Studedean 11-09-2011 09:37 AM

im beginning to lean towards taking the whole thing back under the truck. I wonder thopugh, I cant be the first guy to use an s10 frame for a old truck project. how has everyone else contended with this issue? would an s10 master and booster and s10 pedal assembyl be in order? instead of cobbling together alot of welded pieces?

Studedean 11-09-2011 10:18 AM

1 Attachment(s)
this is my brake assembly. the booster piston comes into the firewall 4"

Cape Cod Bob 11-09-2011 08:47 PM

Your gonna have to make up some el brackets with hole in them to slide a round bar through them. Have the holes so they are four inches from the bend that bolts to the firewall. Make the bar long enough to go from the piston to where you want the pedal located. Mount the brackets to the firewall high enough so that you have room for the proper ratio (you can find that at MPBrakes website)between pedal lenght and to fulcrum.
Weld the pedal arm to the bar. Tack the lever arm to the bar in the approximat location and see hpow that works and adjust as necessary. Use a hiem link on the lever end to piston.
I have seen some very inventive linkages here and on the HAMB.
Trial and error. You may have to do this a couple times.
Luck :welcome:

All times are GMT -6. The time now is 10:51 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999 - 2012. All Rights Reserved.