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plumbing race brake system


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Wow that's quite a spreadsheet. Mine is pretty elaborate but stops a little short of that. The problem is my computer was stolen and I only have an earlier version. So I guess I'm sort of recreating it now even thought my brake system is already installed and track tested satisfactory. I will play with yours and see if it predicts the same braking G's I measured with data acq.

 

Jon you are correct again. My MC rod is located at near the stock location which roughly measures 3.25" from the pivot point. That gives a 4.2 pedal ratio, same as stock. I don't know where the other number came from, maybe the Wilwood pedals I almost installed.

 

I am running 3/4 front and 7/8 rear MC's. According to my calcs, and with the corrected pedal ratio input, results in roughly 30% more pedal pressure to get the same results. So instead of 80lb of foot pressure, it now takes 105. That's probably about right. It takes a little more muscle but nothing like a Skip Barber car. All of my calcs are going from 15/16" stock MC to duals wth AZC front and rear Wilwood setup.

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That's good news! I had the early booster and 15/16" master and didn't have trouble, so I may get close to equal with the new setup, and if not a change down to 5/8" should get me there or better, by the sound of it. Lots of Wilwood and Tilton assemblies are available in 6.25:1, and there are others that are 5:1 and 7:1. 6.25:1 seems to be the most common.

 

What size pistons and calipers are you running? I have a weird situation where I bought Dynalite calipers for the front and then realized I wanted Superlites because they are bigger, so I have front and rear calipers with 1.75" pistons. I suppose I might have to go bigger with the rear master if I can't get the bias dialed in with the prop valve and balance bar. Hoping I don't have to do that.

 

Back to the plumbing, I was having a hard time figuring out the front brake line routing under the frame rail because of the mods I did there when I changed the TC rod mounts. I came up with a solution though. I am going to run a 90 degree bulkhead connector so the brake lines will run down the frame rails and to the bulkhead. I'll drill a hole through the fenderwell in the best spot and then connect the brake line on the other side. I think this will work pretty well for the front. Still considering what to do on the back...

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I have 1.75 superlites in front and 1.75 dynalites in rear. I ran at Daytona in November with this setup for the first time and needed a lot of rear bias. Was thinking about changing a MC. But then I ran Sebring in March and had to adjust back close to the middle. In between I made some camber changes and revalved the shocks. I also ran less fuel and the track was much colder at Sebring.

 

I still have the stock front lines running under the frame rails. I suppose a bulkhead connector would give a nice finished look.

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Brake plumbing is done. I made several boneheaded mistakes: I first drilled all the holes for the plumbing and installed nutserts down the driver's side of the tunnel. Then I decided to run the brake prop valve inside the car. This caused a bit of an issue. I'm going to see if the nutserts are in the way and drill them out and just leave open holes or put them back in from the topside if that is the case. I'll probably use the second set of nutserts for the gas line plumbing. Also had the brake lines running higher than the master, and then was thinking: "wait a minute, isn't that going to make it a ***** to bleed?" so I had to re-bend the line for the rear brakes, and wasted another couple nutserts. The last problem was the length of the braided lines. I should have probably gotten 10" lines for the front and 8" lines for the rear, but instead I had ordered up 12" lines all the way around. In the front they were interfering with the wheels, in the rear it was hard to find a spot where they wouldn't be running close to the CV shafts or wheels. I found spots that work front and rear, but I think if I need new lines in the future I'll buy the right size, even though that would require a redo of the hard lines in the back.

 

On the plus side I think the front brake line routing with the bulkhead fitting is pretty sweet, and none of my flares cracked even with my Summit Racing AN flare tool, which I suppose is not the best one out there. It will be interesting to eventually get the thing on the ground and put some fluid in it and see if it leaks at all.

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Looks good. Are you done with the engine compartment/underbody paint?

Yeah, it was a nice uniform flat black coat of Zero Rust, but then it got a lot of white overspray on it which is why the bottom looks grey. I'm not going to fix it, it's a race car.

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