Brake Master Cylinder Brace

Here I will document the progress made on the brake master cylinder brace. Everything will be listed in reverse order so the newest news is always at the top.


     See, if you just wait a few months you'll eventually get an update... Okay, sometimes its longer. In any case I have finally got around to actually testing the brake master cylinder brace. I put it back on my Paseo and had my lovely assistant (the wife) stomp on the brakes again. The result was that the brake master cylinder brace reduces master cylinder movement by roughly 60%. The testing showed that the brake master cylinder still moved .030" (.76mm) with the brace installed.

     Here is the video of the testing. Again, each marker on the gauge is .010" since you can't read it.

     This is a fair increase, and I am happy with it. I think better could be done by simply preloading the brace a bit more. To do this all you would need to do is unscrew the bolt that goes up against the brake master cylinder a bit more. In my defense, my hands were quite cold as it was less than 20F outside today and the car wasn't in the garage while I was mounting the brace. In any case, here are some pictures of the setup.

     So, that pretty much wraps up this project. The results are at least a 60% reduction in brake master cylinder movement, and a much improved pedal feel upon braking.


     Well, while messaging Loki today he reminded me of this project. Let me tell you, when you get so many that you forget that your almost done with one you probably have too much to do (that just means I need a little more time off work to do this stuff, right? ). In any case, I do have a prototype made up. Its a bit rough, but here are some pics.

     There is one snag I have found with this design though. You need the tray that holds the stock air box (its the rusty piece under the brace). Now, my Paseo did not have one of these. So, with my Tercel stripped down right now I borrowed the one out of it. I had to pop a plug out of one of the mounting holes, but the holes are there. Three bolts and the tray is in.
     I should also note that this will not be able to be installed on a car with the stock airbox in place. There is just no room to get any bracing in there with the airbox in the way.
     So, how does it work? Well, that is what I did tonight. I put it in the Paseo. It was very easy to put in. I didn't even take out the intake plumbing. The wire harness does get in the way a bit. I'll have to see what I can do with that. Anyway, here are the pics.

     But, how did it perform? How did the testing go? Well, I'm sorry to say that I don't have the lovely wife around to slam on the brake pedal tonight. But, I did take it for a quick spin around the block... and it is NICE. It really firms up the pedal. Its very noticable and solid. I honestly didn't think it would work as well as it does, but I was wrong (yay). Hopefully I'll be able to get some dial indicator readings soon.


     Alright, that was a bit too easy. One day and more updates? Well... yeah! The testing was incredibly easy and I was done in less than 1/2 hour with the help of my wife. The dial indicator was setup as shown in the picture below and under very hard braking was found to move .070" (1.778mm). Now, this does not seem like much at all. But, you have to remember that once the master cylinder piston hits that liquid and puts it under pressure the piston doesn't really move hardly at all (liquid is not compressable thus the reason it is used in hydraulic systems). It is then that it becomes a larger number. Also, the brake pedal is a lever. The point of contact between the cylinder pushrod and the pedal compounds this increases this distance at the point your foot touches the pedal. So, all that is left now is to see how much the brake master cylinder brace can reduce that movement and the effect on pedal feel.

I also have a video of the testing here. Each marker on the gauge is .010" since you can't read it.


     Actually, the next step is to test and get baseline readings for this project. I almost forgot that didn't I? In any case this should be very easy. The setup for testing this is very simple. One dial indicator, one magnetic stand, one car. Setup the dial indicator to measure brake master cylinder movement. Get in the car and start it up. Mash the pedal down and measure how much the brake master cylinder moves. Piece of cake, right? If any of that was unclear I made a picture to ease your mind.


     Good news on the BMCS front. The initial rough (very rough) design has been drawn up in SolidWorks. As you can see, the plan is to use angle iron for the construction. This has the benefit of being quite strong as well as fairly cheap. The design has been stress tested with FEA (finite element analysis) software and found to be up to the task of holding our brake master cylinder in place. There are some concerns however. Specifically, the area to worry about seems to be the welds as they will weaken the steel around them. I'll be looking into stress relieving the braces because of this concern. Other than that everything seems to be ready to go.
     Obviously, the next step here is to actually make one. That is the plan. I'm sure the actual bracket will be slightly differnet in design, but it should resemble the pictures below fairly well.


     Yeah, another project. For a while now I have heard things about the Cucso brake master cylinder stopper. Unfortunatly, if you know anything about it, its only made for right hand drive cars. Recently I was reminded of this item and thought to myself, "hey, I can make one of those." So we'll begin by looking at what we have to work with.
     This is the Cusco brake master cylinder stopper. As you can clearly see it is on the wrong side of the vehicle. That is because it is made for a right hand drive car. I got these pictures off Riko on This is the product I'll be trying to duplicate for a left hand drive car.

     Its a fairly simple device but after looking at my car it won't be the easiest thing to reproduce. The main problem is clearance. On left hand drive cars the intake airbox is very close to the end of the brake master cylinder. This restriction as well as other things like lack of points to mount the device to will prove difficult. We'll see where it all leads.