Tuesday, September 17, 2013

Manual Brakes and NiCopp lines

After seeing some of the brake booster delete kits I stated weighing the option.  I was really interested in the Chase Bays kit, because its one of the more widely used kits in the 240sx world.  However after some research I decided that running a single circuit master cylinder for brakes wasn't something that I would do.  So I decided I would make my own, along with a pedal with an increased leverage ratio to hopefully make my manual brake conversion more liveable.  The end goal is a firm pedal with good modulation, hopefully without having to go too aggressive on the brake pad compound.

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Made two of the master cylinder adapter plates in the CNC with some assistance, it was pretty exciting to push that green button after the program was made.

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Facing my new brake pedal pivot to length in the lathe.

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Brake pedal with a new pivot added 1" below the factory pivot

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We added another hole in the brake bracket as well to keep the same pedal height, keeping the brake push rod going out the same hole in the firewall.

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Finished modified pedal on the bottom, the finished product should have about a 5.5:1 pedal ratio in place of the stock 4:1 for boosted brakes.  That places my modified pedal right about in the middle of standard car manual brake pedals (5-6:1 ratio).

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My super fancy brake push rod.  I might make something a little prettier without the length adjustment after some testing.

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I added some stainless steel M8 thread inserts into the master cylinder adapter to make it easier to remove the master cylinder so I can make brake rod adjustments without too much drama while setting things up.
For the brake lines I ran all new.  I chose NiCopp for the corrosion resistance and formability.  NiCopp lines are supposed to combine the corrosion resistance of stainless with easier forming than mild steel.  Its a Nickel, Copper alloy, and somehow you gain resistance to fatigue and work hardening from the Nickel in the alloy over plain Copper (which is a no no in automotive braking systems).  The lines in a 240 are 3/16" OD with M10 x 1.0 inverted flare fittings.  The NiCopp bent surprisingly easy, I used a basic bend tool and some bend pliers for some of the tighter stuff and occasionally a 3/8 socket.

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The factory master cylinder doesn't have a boot since it typically goes on the front of a brake booster.  Since its going to be poking through the firewall right above my feet now it probably should have one.

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To mount the brake lines to the firewall I'm using some Earl's aluminum line clamps.  I drilled the threads out of a couple so that I could run the bolt through to some closed end rivnuts I installed into the firewall.

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I equally spaced two #10-32 rivnuts into the firewall just below the pinch seam for a nice low profile clean place to run the brake lines.

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Nice, new, shiny NiCopp brake lines all bent up.

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