Thread: Ever think about building one of these---????

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I know I did. I didn't want to mount a master cylinder on my firewall, and I didn't really want to mount it under the floor. The under dash 90 degree mounted cylinder seemed like the perfect answer, untill I started thinking about the issues involved with filling the master cylinder, and the amount of machining necessary to build it correctly. The fact that I have no lathe or mill played a big part in why I didn't build one for myself. A friend of mine recently purchased a "manufactured" one from an aftermarket supplier, and it is very impressively built. Follow along with me, and have a look. Don't ask me to send any solid models or design specs, because I won't---this is someone elses property. and I will not do that. This is simply a post to show whats involved in a well thought out and engineered product.

The main frame of this unit is a peice of 1 1/2" square tubing. The two light blue peices are welded to it, and they are solid steel round stock, drilled and tapped for 3/8" diameter bolts, which act as mounts for the master cylinder mounting plate. The green part is a solid steel shaft, with one end turned down to fit into the brake pedal arm hub, and has a snap ring groove machined into the end of it to retain the brake pedal arm in place. The gold/orange part is a peice of steel tubing, with the inside "step-bored" from both ends to accept a pair of oilite bronze bushings, and it too is welded to the main square tube. The peice of dark plue flat bar is welded into place, and acts as a mounting point for the stop-light switch.

The bell crank is machined (or plasma cut) from a peice of 1/4" plate, and it has a solid steel shaft welded to it, as well as a 1/4" split pin pressed into it, to operate the stop-light switch. Again, you can see that the round shaft has a snap ring groove machined into it to keep everything together after it is assembled.

Great pictures....I'll build one for my Rolls project. I did not have room for a booster under the floor or on the frewall. This will let a hydro boost to fit under the dash.( Oops-looks like I replied to your post before you were done posting)
Thanks Don

The pushrod is machined from a 3/8" diameter steel rod, with right hand threads on one end and left hand threads on the other. It is equipped with a conventional "spherical rod end" on one end, and a "spherical rod end with double shank" on the other end, and a pair of 3/8" hex. jam-nuts.

The pedal arm is plasma cut from 3/8" plate, and has a round steel hub welded into it, that is machined to accept an oilite bronze bushing.

The master cylinder mounting plate is plasma cut from 3/8" steel plate, and the master cylinder mounting holes are slotted to accept a number of different master cylinders.

These assemblies are set up to take the master cylinder directly, or they can also be used with a small vacuum booster mounted in between the master cylinder and the master cylinder mounting plate. I have found out that they can also be used with a "remote fill" unit that mounts in a more exposed location, so that you don't have to perform a Houdini act to add fluid to the master cylinder (which will be hidden up under the dash). This is a very well thought out design, and if I had known more about them at the time I built my roadster pickup, I might have either purchased the one shown or attempted to build my own. However, I will point out that building one of these units is not for the faint of heart----There is a lot of machining and precision fitting necessary to make one of these units work correctly, and a failure of any part of it could have some very horrific consequences for the builder/user.

Ever think about building one of these

I doubt it.......

i'd either find an early 80's dodge van or just buy one made. but then i don't have the machines to do all that fine work anyway. but that is some nice work Brian......joe

Thanks Brian. I've seen these advertised, but could never quite figure out the exact geometry and layout to build one at home. I'm gonna store this thread for future reference. As usual, your graphics make it crystal clear.

Don

Nice work Brian, I have these in my truck and new roadster. I used a remote fill in the roadster threw the cowl vent. Another advantage to this is bleeding the brakes, by the master cylinder being above the calipers and you don't need residual valves.

The remote fillers I have seen advertised are a flat peice of aluminum plate about 3/8" thick with an o-ring groove milled around the perimeter so that the o-ring sets directly above the perimeter of the master cylinder reservoir. There is a clamp which holds the plate securely in place and compresses the o-ring, so that nothing can leak. there are 2-small diameter pipes (tubes) coming out of the top of the plate, one over each side of the reservoir (if it is a divided reservoir master cylinder). There are flexible lines that lead from these tubes to the remote filler, which is simply a small billet reservoir with screw on caps and a flange for bolting to the firewall (or where ever.)---These remote filler 'kits' will work for under-floor master cylinders also.

Dont know ,its just me Im sure but I like the K.I.S.S. rule especially when it comes to brakes.

Originally Posted by brianrupnow

The master cylinder mounting plate is plasma cut from 3/8" steel plate, and the master cylinder mounting holes are slotted to accept a number of different master cylinders.

Being that you are pushing on center of the master cylinder and you are mounted below the center, you will need another brace to the top side of the bracket to balance the push, or something will bend, especially if you need to hit them hard.

Pat

They work nice, especially on some of the skinny dash cars. Works good on fat fendered cars for mounting the master cylinder below the floor, too!!!! Puts all that wasted space in the rear portion of the front fender to good use!!!!