Need quick help on a Clutch Master

[blakt out]

Hey guys:

I've got the Competition Clutch Stage 4 clutch kit and lightweight flywheel on my SR. I'm currently using the stock 1972 master cylinder, and with all the adjustment out of the rod (under the dash) it doesn't engage.... in other words, it's hard to get in and out of first and reverse.

I need to go to a larger master cylinder, right? So, the stock one is 5/8", right? And Wilwood makes one that is a 3/4". Or... can I just go down to AutoZone and get a 280ZX master? What size is it? 15/16? I read that with the ZX one, I'll have to drill on the firewall, which is just not a solution for me right now. Is this correct?

Thanks in advance, fellas.

Jared

[Rich 71 240Z]

Are you getting full travel at the slave? Before throwing parts at it, make sure you don't have a bleed issue, bad slave, or a mismatched throwout collar/pressure plate. I'd bet that the collar is wrong for the pressure plate since you have been swapping parts around. There are several different length collars to choose from and if they aren't matched, it won't work right.

[Gary in NJ]

Wow, Rich waited 3 years to make his first post. Moreover, your advice is spot-on.

[blakt out]

Hey guys:

Yeah, I'm getting good travel at the slave. It's just that it needs that little bit more to fully let go.

No bleed issue. Parts are good.

I've found out the following:

An S14 has a 3/4" master. That's what my transmission is and my clutch made for. The slave is from an S14 too. So the OEM 240Z Master (5/8") is a bit smaller. The whole system is getting less than it was designed for. However, I wondered if there was a way not to go with the Wilwood 3/4" master and instead go with a 280ZX (or some other larger OEM) master without having to drill into my firewall for new mounting points. I want to keep the mounting at 12 and 6.

Thanks again for the help!

[Bruce Palmer]

Murphy's Law: If there were more than one length of collar, you will have the wrong one. You do not need a larger master cylinder.... you'll only spit the piston out of the slave.

[blakt out]

Bruce:

Thanks a ton. I've used your company before on another build and very much appreciate it.

So we're clear though... from what I can find online, the Sylvia/240SX has a 3/4" master cylinder (but I'm not positive yet). That's what my trans came from, and I have that same slave on it. That's also what the clutch was made for. But I'm pushing it with an OEM 240Z Master, which is a 5/8". Seems that if I go to 3/4" on the master, I'll be back to good.

And I'll be straight up with you, I don't know what the collar is. Is that the part with the actual male piece on the slave that pushes on the clutch, or is that inside (in other words, does this mean that if it IS the collar, I have to take the trans out to get to it?)

[Zed Head]

This web page has some good information - http://zparts.com/zptech/articles/trans_swap%20parts/4tobear_specs1.html

If you're trying to match the bore of the master to the bore of the slave, have you considered a smaller bore slave? A lot easier if you can find one that fits, and the end result is the same. I don't know about specific interchangeability, but wouldn't be surprised if there was one out there.

[blakt out]

Zed Head:

Great. Thank you all for your help on this. Thing is, all of this is for Z hardware. My drivetrain is a Sylvia S15 with a Sylvia/240SX S14 trans.

That's a great point about getting a correctly matching slave...

Jared

[Zed Head]

I sent it mainly for the pictures of the collars, so you could see what one was.

Check out this link - http://www.oreillyauto.com/site/c/detail/WAG0/F131353.oap?year=1972&make=Nissan&model=240Z&vi=1209169&keyword=clutch+slave&forcedVehicle=true&pt=01352&ppt=C0015

What's interesting is they list the same slave cylinder for early 240Z's up to 280ZX's and including 240SX's. So I would guess it's not a big difference maker, or they are not different. Just another thing to consider.

Also, the slave cylinders tend to go bad without obvious signs. Pull the boot off and see if any fluid comes out. It might be leaking mid-stroke, giving only partial movement.

Which reminds me, the master cylinders do the same thing. But harder to tell.

If you didn't have the odd drivetrain, all signs would point to a bad slave or master cylinder.

[blakt out]

The slave is brand new and we've tested it, so I don't think it's that. We've done exactly as you say. Actually, EVERYTHING is brand new, they just haven't paired well together.

Thanks again!

[ajmcforester]

OK different diameter of master cylinders deals with the amount of force applied, the larger the diameter the less force it takes to push in. Fluids don't compress all that much, only under 1,000s of PSI.

Have you watched the slave when someone pushes in the clutch? Just to see if it is moving. Have you made adjustments at the slave cylinder, the little rod has an adjustment on it?

If this don't work I'd look at the collar. Try pushing the arm over till it won't go any farther, did it disengage the clutch? If "no" you need a longer collar, "yes" you need to bleed the clutch fluid or something is not right with the fluid system

[ajmcforester]

Sorry I also notice that their are two different size forks this could also be the problem if you have the wrong one