Possible solutions to aftermarket clutch master cylinder
 

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. :shakes head:

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.

http://i248.photobucket.com/albums/g...psb0ee3138.jpg

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

http://i248.photobucket.com/albums/g...psb1868800.jpg

http://i248.photobucket.com/albums/g...ps2479b7b1.jpg

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:

http://i248.photobucket.com/albums/g...ps35ff3430.jpg

http://i248.photobucket.com/albums/g...ps6f7c29ef.jpg

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? :tup: 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.

Hmmmm......the second one has me thinkin'.

Great thinking.

I think the second one is the way to go. I'm gonna take some time today and see realistically how much I can remove from the ABS mounting bracket, and look into that. The space is small to work with, but I think I can make it work with a Dremel flex attachment, and a cutoff wheel, or an air cut-off tool. Worst case, the ABS hard lines need to be disconnected, the ABS module would have to be removed, and the bracket grinded down on a bench. I also don't think an ABS module can be bled at home - I think it requires dealership/shop assistance.

The OEM CMC has embossed on the side "11/16", which I assume is the bore diameter. Wilwood does not sell a 11/16 (or .6875) in bore diameter, but in the second option, they offer it with a .70 in bore. This slightly larger bore will decrease pedal travel slightly, if I am correct. Should feel like OEM in terms of travel, though.

My second thoughts are concerning mounting the OEM hard line, to another piece of hard line. I've never really had to do that, but I'm sure there's a solution, possibly a coupler of some sort?

Can a aftermarket CMC from a 350 work with some trimming too?

I am dealing with the exact same issue and was thinking about picking up on of the Willwood units to see if it could be modified to fit since a new OEM one is the only option at this time.

No matter how many times I bleed my clutch fluid, take out the air etc I am still having problems once the car is fully warmed up and I start boosting. (Clutch pressure dropping drastically, sticking to floor} Cant even enjoy the car it seems! I took out my shorter clutch helper spring and replaced it with the OEM and it still keeps happening.

The CMC is the only possible thing that could warrant these problems - Already have upgraded CSC -Southbend clutch/SSFW - SS lines.

Mine did that once after it sat in the sun all day at work. When I left the clutch worked fine but the pressure through out was soft. After it sat over night it went back to normal and never happened again.

Talk to Joe@ZSpeed. He already has one for the HR. He said he was working on something for the VHR.

That was awhile back. I need to call him and order a bunch of fluids.

I couldn't seem to find the unit they use for the 350z HR master cylinder upgrade on Wilwood's website. From what I can see from this picture:

http://i248.photobucket.com/albums/g...psd74f7567.jpg

The unit is definitely longer than OEM, but I'm exactly unsure as to how long. Also, the black piece that connects to where the firewall goes is most certainly an adapter plate that allows usage of the OEM holes. This adds more length to the body though, and I think drilling the firewall is no big deal with an angle drill.

Although, looking at this picture, this gives me hope for something though - a banjo bolt setup for the second CMC I linked in the OP will only increase the body length by maybe a bit over a 1/3 of an inch, so it's actually not that much removal necessary from the ABS unit. I'm gonna look into a way to couple the stock hard line, and this SS line together.

I'm thinking it might be happening to my car, after hard drives. I had a recent night where I did the equivalent of 8 drag strip passes, back to back. That must have taken a toll on the fluid at least, and that might explain why there was air in my line, as well as the fluid looking wonky. I may have boiled it over.

Yeah, like Spohn said, I think it's a project on hold. Maybe not though! Although realistically, I don't see any way to make an aftermarket unit fit without any drilling or trimming. Unless a completely new, custom unit is made bespoke by Wilwood.

It has been 4 years. I really hope there's a product out by now. Like the steering wheel lock, the clutch hydraulics are also a ticking time bomb.

Unfortunately, you are right. I want to definitely spearhead the research into getting us an aftermarket CMC setup. I don't think there is any new information on the HD CMC from ZSpeed, though. :ugh2:

I also sent Wilwood an email earlier today, talking about upgraded CMC for our car, as well as asking them a few questions about sizing the right CMC for the car, if I do decide to go the custom route. I'm just probably gonna order the CMC and work from there - I'll only be in the hole about $60 bucks.

Also, after looking at the ABS mounting bracket, I'm fairly certain I can just unbolt the ABS system and remove it for now, and grind the bracket on the bench. I think that will be the cleanest way to go. I'll have to look into how to get the system restored, though. Most likely end up going to the dealership though.

All in all, I don't see this setup costing more than $70 bucks in hardware. :tup:

I also forgot to mention: My clutch pedal feel, since bleeding it and letting the car sit overnight, has returned to normal. The pedal is rock solid. Still, I don't trust the OEM unit anymore.

I just did a power bleed and still to no avail the clutch is squishy and getting stuck. Only thing left is a new MS I believe at this point. In contact with my shop though trying to figure out a solution as this is really an annoyance.

Any word from willwood?

Sent from my SAMSUNG-SGH-I317 using Tapatalk 4 Beta

Have an update for you all:

So after several attempts at reverse bleeding, (Using a MityVac, applying vacuum to the top of CMS and pumping clutch) I still was losing pressure after driving for short periods of time.

I was about to pull the trigger on a new CMC, and before I did so I wanted to double check there were no leaks or out of the ordinary issues that I was not seeing.

Everytime I would pump the clutch, I could hear a little swoosh as the pedal returned to the top. I noticed the CMC piston was coming out a lot, and when being depressed, would pull a tiny bit of air back in the lines.

This is when I decided to remove almost all play by adjusting the top bump stop point further forward. This left around 1/4 of an inch of play up top, and there was no more noise when engaging.

So far it has been 3 days, lots of spirited driving, and no issues!

I think that since the new clutch install, the engagement point is a lot lower than the oem causing the CMC to pull air back into the system every time it over extended.

Hey guys, sorry for such a long time of silence! After I replaced my master cylinder, I became lazy and had no reason to look into a replacement. :tup:

So, bad news. I was too bored waiting for my GTM turbo kit to arrive, so I reassembled my Z, and all was fantastic. God it's nice having a fun car to drive again. But...after 3 days, I am unhappy to report my clutch master cylinder failed. Again. I actually just limped my car home not 15 minutes ago.

However, I have some promising news!

First off, I would like to say Wilwood never gave me any insight on what to do - they just gave me a generic "We do not make a master cylinder for the 370z" statement. Duh. :shakes head:

But then, I looked into Tilton Racing, and I came across what must be the PERFECT aftermarket master cylinder: The 76-Series:

http://i248.photobucket.com/albums/g...ps5847a9bc.png

http://i248.photobucket.com/albums/g...ps5b40151a.png

It's SHORTER than the length of the Wilwood unit, AND!, it has the flexibility to put the outlet to the slave cylinder on the back, or the top! It's perfect! This would save another half inch off the Wilwood unit, which would make super easy to just trim off a tiny bit of the ABS module, and install this puppy!

I plan on ordering it tonight, and having it in my hands ASAP so I can get this install underway. Like the Wilwood unit, they make a .70 piston diameter version which is a tiny bit larger than stock, but it should work great! Also, the stock resevoir can be used with the right adapters.

I truly believe I can get this to fit without any crazy modification. I could even reuse the stock line to the slave cylinder, with a bit of bending! :happydance::happydance::happydance:

Just curious: How has it been holding up? I want to test for this when I install my next master cylinder.