jthan.ami

Greetings!

I have a 2006 350z Roadster I purchased last month with 50k miles. I've been doing a bunch of work on it, mostly servicings, and recently did the clutch pedal adjustment. While it very much appears and drives like a new car I'm under no illusions that the clutch isn't probably 70% +/- worn after 16 years. One of the services I did was to (twice) pump out and refill the brake fluid in the clutch master cylinder.

I looked up the threads on this forum and did the adjustment but I have a question about my particular situation.

After adjustment I've gotten the engagement point to a very good place, far lower but there is the typical slack in the pedal. Right now it's almost even with the brake pedal. I'm referring to the dead space where it goes 'click-clack' but does not really do anything. So I noticed when I turned the adjusting rod 2 full turns counter-clockwise after popping the lock nut, it mostly eliminates the slack and has perfect engagement and disengagement. But it doesn't pop ALL the way back up with that dead space included for the most part. It will if you pull it back with your toe.

I then reduced the adjuster to about 1-1/2 turns from the starting point, and it still has good engagement but the useless dead slack where it goes 'click-clack' and pops all the way out returns.

By removing most of the dead space, am I adjusting it too far or am I not going far enough by leaving that space in there? Even when it does not spring all the way back there is plenty of clutch engagement, and disengagement. I tested it with the car off facing downhill in the driveway to make sure it was freely disengaging. I also am not feeling any sort of slippage in any gear or shifting at higher RPMs. I'm wondering if anyone has been through this before.

Without the dead space it feels much more like a clutch that I remember on other cars and felt on other Z's that I test drove that did not have this. I guess I'm asking for advice if this is safe for the clutch or if this will burn it up with the lower point set at 2 turns to remove the majority of the slack.

timeltel

Regards jthan.ami:

https://en.wikipedia.org/wiki/Master...er_diagram.svg

Take a look at the above diagram. The components you're adjusting are the push rod and consequently the plunger. Take note of the fluid intake/return ports. If you're trying to move the clutch disengage point nearer the floor, the seals are pushed beyond the intake ports, the master cylinder reservoir can no longer refresh brake fluid that has "leaked" (a minuscule amount with each stroke of the pedal) past the seals. The outcome is as you describe. At some point the lines lose fluid and the system fails.

The Z has an engagement point designed to engage/disengage the clutch at near the point where the pedal is at rest, adjusting the stroke so it "feels like other cars" is in effect reducing the stroke of the plunger and defeats the intended function of the master cylinder.

Hope this helps,

Peace


(edit): Lots of happy users- https://rjmperformance.com/350z-g35/

jthan.ami

Hi! I've replaced many and rebuilt a few MC's before on other cars such as old Toyotas, Hondas and my 68' Mustang. I don't doubt the need to keep the circulating ports open. But this generic diagram did make me think and possibly answer my own next question by looking into it further.

So looking at an actual 350z clutch MC the adjustment force screw on the pushrod is adjusting the pedal, not pushing in the plunger. I can see it on both the part itself

https://www.z1motorsports.com/clutch...xoCgWoQAvD_BwE

and on an exploded diagram:

https://www.nissanpartstristate.com/..._2.html#30650J

So the fork and pedal are being moved down. Not the plunger and pushrod. Plunger is releasing completely still. Yes perhaps if you cranked down on it excessively but the main problem I've read about here is that the clutch is riding on the pressure plate and disengagement isn't happening if you do that. I'd find it hard to believe Nissan would ever include an adjustable pedal if changing it in any (like two turns) and it needed to stay exactly in the stock original position.

Also, the cruise cancel switch is adjustable too so you can shim that into the clutch pedal once it's moved down. Looks like it will be a bugger to get it to turn.

icer5160

iTrader: (4)

Pro-tip. Look into the RJM performance clutch pedal. One of the best quality of life improvements your money can buy for a MT 350Z.
-Icer

jthan.ami

I did. Thankyou. I will definitely install one of these when I replace the clutch. Hopefully that will not be a for a year or two but nevertheless I stand ready and can take it to a shop that will let me use their lifts and do all the work myself.

But for now the carefully adjusted pedal is working ok and no signs of slippage or lack any lack of hydraulic pressure.

travlee

iTrader: (8)

you can replace the clutch with the car on jackstands..... done it many of times

jthan.ami

Oh yeah? That's good to know! But I like to work out my back and legs in less destructive ways if I'm not in a pinch. I did all the brakes a few weeks ago in one shot on stands, and wowzer. Felt after working that low like my quads had been pumping dead squats all day. And I have only begun my decay at 44 yrs young