Possible solutions to aftermarket clutch master cylinder

Alstann

EDIT: For first time readers - I have figured out a solution and will be posting a DIY later as I do the install this friday. I went with a Tilton Racing MC which is perfect for our application.

So, I have some bad news to report. I believe my second CMC has begun to fail.

I fear the extremely hard driving I do on the car must have either pushed the design of the OEM CMC to the limit, or there is something else wrong. I just finished lifting the car and bleeding the fluid out to make sure it wasn't air, but no dice as of now. I am actually gonna call Joe@ZSpeed tomorrow to discuss some possible weak points other than the CMC, as my knowledge serves, it's the same issues I have when my first CMC started to fail - pedal has lots of dead play, and it's not as stiff.

In looking into a replacement for the OEM CMC, I researched extensively on Wilwood's website, and I think I might have been able to figure something out.


The main issue with aftermarket CMC's, like the one sold for 350z HR's, is the body of the CMC extends too far out, and contacts the mounting bracket of the ABS module. After looking around it, I believe that if one could grind off the corner that would contact first to the CMC, you could expose about 2 more inches of space for an aftermarket unit. I believe that the other bolt holding the ABS unit, combined with the rubber standoff washers, and the hard lines themselves, will be enough to hold the unit. If not, a bracket can be made elsewhere to hold the ABS in place.

I then looked into the shortest, most compact unit Wilwood manufactures, and I came across these:

Wilwood High-Performance Disc Brakes - Master Cylinders: Integral Reservoir Compact Master Cylinder

Wilwood High-Performance Disc Brakes - Master Cylinders: Compact Remote Combination Master Cylinder

The types are Integral Reservoir CMC, and Compact CMC, respectively.

The OEM CMC has a "body length" into the engine bay, as measured by my caliper, of 2.05 inches. Body length being what you can see in the engine bay, and not inside the car.



The first link is the Integral Reservoir, and as the name suggests, it has the fluid reservoir built right into the housing:





With a body length of 3.91 inches, it's nearly 2 more inches longer than the OEM one, and due to the slight tilt of the OEM CMC, the reservoir will be tilted as well. Not ideal, but it's not terrible.

The second CMC is the compact remote reservoir CMC:





And with a body length of 3.36 inches, it's very doable! Only caveat is that the output for the fluid that heads to the slave cylinder is at the end of the body, which may be hard to get a hard line there. But it may be possible. This design also has the benefit of being able to use the OEM clutch fluid reservoir.

Both of these CMC's, however, have a different mounting bolt pattern than the OEM one. The OEM CMC has a bolt spacing of 2.75 inches, where the Wilwood units have a bolt spacing as seen as 2.25 inches. One of the bolts will line up perfect with the OEM hole, and center the CMC perfectly, but the other bolt will require you to drill the firewall. No big deal. Just add nuts and bolts afterwards.

As for the rod that attaches to the clutch pedal, there is waaaaay more than enough for the rod to reach the clutch pedal. It's probably necessary to trim it, but it should be okay.

These aftermarket solutions will all require custom clutch hard lines. NAPA/Brake repair stores sell line, and they can have them bent for you. I'm not that worried about the line, to be honest. It's all gonna be custom bent, flared, and then with a standardized nut. Nothing too crazy a shop or store couldn't handle. Hardest part would be to attach the OEM hard line to the custom section of hard line. Possibly might even look into stainless steel flexible line, for ease.

Any thoughts, guys? I really wanna figure out an aftermarket CMC for our cars. I drive the car too aggressively to warrant replacing the OEM CMC over and over again.

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