1st Z - 23,000 Miles - Stiff Factory Clutch TT

[Peabody]

This is my 1st Z so please excuse me if my question seems silly.

I know that the clutch on my TT has a Vacuum assist feature. I want to know if this makes the clutch very easy to depress or just makes it not so stiff? I had the slave fail on me last week and had the master and slave replaced. To me the clutch seems a little stiff when I depress it. When the car is running it does get softer (hence the vacuum) but it does not feel like a factory clutch. It seems like as I go through the gears it gets a tiny bit stiffer with each shift. I have had back surgery and have pain in my left leg most of the time and after dealing with this clutch my back/leg really hurt after some driving time.

I owned a S13 for 22 years and its factory clutch was very soft as it is with most 4 cylinder cars. I also ran a ACT Extreme HD that was very hard and a Exedy Stage 1 that was a tiny bit stiff but did not kill my back.

The factory clutch on my Z seems a little harder then the Exedy Stage 1 that was on my 240. My question is if the vacuum and clutch system are working properly should the clutch be easy to depress? Or is the factory clutch on the Z not going to be as soft as a economy car like the 140HP S13. I think the more HP you have the greater clamping force is needed creating a stiffer clutch.

Once or twice when I first started the car the clutch seemed very very easy and then it stiffened up back to the way it usually is. I thought I would replace the check valve but not sure it that is something that would help meaning it ether works or not. Or can it half way work causing the clutch to get softer with the vacuum but not 100%. If the factory clutch on the Z is a performance/racing clutch then that answers my question but should the vacuum assist make it feel like a factory (not a performance) clutch?

THANKS SO MUCH

[twinturbozxtacy]

you might have a vac leak or bad booster for the clutch. i have two zx, one with a stage what ever for 600hp and a stock one. the aftermarket one is brutal, and takes time to get use to, and im no slouch. the stock one is nice and i cant really see it giving any one a big problem, compared to my moms 09 camry and my girls 99 beetle the clutch is not all that much stiffer, really not much at all. And those clutches are soft... maybe they gave you an stiffer clutch? otherwise the clutch booster or vac leak.

[DCaff300ZX]

Funny, when I got mine it was opposite yours in that it would be VERY stiff the first time depressed, then fine from there...and that has gone away as it operates correctly now for about the last 6 months.
I assumed that from reading the below site info that my problem was the clutch actuator fork, for the reasons they describe on their site:
http://www.zspeedperformance.com/Nissan ... SP1005.htm
You may want to look into this as perhaps your clutch fork has bent, I believe that mine must have been a tight/bad fit from when the clutch had been serviced before I purchased the car.

[Peabody]

So from the 1st reply it seems like the clutch should be pretty soft if everything is working properly. How can I check the clutch booster? Please don't say replace it and if it gets softer then it was bad.

THANKS

[DCaff300ZX]

So from the 1st reply it seems like the clutch should be pretty soft if everything is working properly. How can I check the clutch booster? Please don't say replace it and if it gets softer then it was bad.

THANKS

Yes, the Z32 clutch action IMO is VERY soft.

I've never heard of a clutch booster and as far as I know there is no such thing for the Z32, although I can only say this from knowledge of my own TT and 5-speed swapped NA which both have a "normal" clutch system: pedal, master cylinder supplying/pushing fluid to the lines through two bleed points to a slave cylinder, which pushes the clutch fork actuator described in the link I sent, which moves the clutch.
Where would a "clutch booster" be involved in this system?
Do you have pics, or a page in the FSM detailing this?

[typhusfever]

When I bought my Z32 I was told by the previous owner that the clutch was stiff due to it being an BD organic clutch. I drove it around with my left leg becoming HUGE... then (showing my complete lack of knowledge on this car) was told that the clutch was stiff because the automatic-manual conversion hadn't been done properly. They hadn't fitted/connected the clutch assist...they hadn't even fitted the manual balance tube to do the job.

Just to prove his point (he runs a Z32 garage) he sat me in another Z32, I tested the clutch and it was fantastic... that had the exact same clutch as mine.

I would just check potential leaks on the connections from the balance tube. But I don't know the best way to check the clutch "booster" ... apparently they do tend to fail.

[DCaff300ZX]

Yes, the Z32 clutch action IMO is VERY soft.

I've never heard of a clutch booster and as far as I know there is no such thing for the Z32, although I can only say this from knowledge of my own TT and 5-speed swapped NA which both have a "normal" clutch system: pedal, master cylinder supplying/pushing fluid to the lines through two bleed points to a slave cylinder, which pushes the clutch fork actuator described in the link I sent, which moves the clutch.
Where would a "clutch booster" be involved in this system?
Do you have pics, or a page in the FSM detailing this?

I stand corrected on this one after this time taking the time to actually CHECK before blabbing something...on page 5 of the OSM under clutch the diagram clearly shows a clutch booster apparently on the inside of the driving compartment firewall, between the pedal and reservoir mounted on the outside firewall near the brake booster.

I would definitely get this checked to see if this is your problem, but other than swapping a known good unit I can't imagine a test.
My apologies for an incorrect, off the cuff reply earlier...

[z32loverboy]

I hadn't heard of this either but I can't think up a test for it either.. there may be something in the troubleshooting section of the FSM MAYBE but other than that I'd call a shop that works on Z's or call ConceptZ or SpecialtyZ and see what they have to say on it.

[300ZXttZMAN]

Long time no see Peabody! If you take the drivers side fender off you will see a little black box looking thing under the AIV tanks.. The lower most tank has something to do with the clutch booster/check valve, from what I understand the box will hold vacuum for a short while during shifts - but don't quote me on that, I'm simply telling you what I have heard. You might want to look into that little box, maybe it has something to do with your problem?

Another possible solution would be to contact SZ and ask for a milder clutch after telling him your situation. I know that the SZ High 5 has a very stock feel to it even though it is a very high performance clutch.

But unfortunately the other problem could just be your sensitivity from surgery, maybe you should look into going to a chiropractor? I wonder if a good chiropractor could help you regain some strength in those areas?

[Peabody]

Thanks for the help. I live in New Orleans and cannot find any shops that have any knowledge of these cars. I hate to bring it to Nissan cause they might be the same. The shop that changed my slave/master has been in business for 30 years but usually work on average cars. Maybe I can let them read this post.

300ZXttZMAN You said to contact SZ for a milder clutch. Are you saying that the factory clutch is not mild? And that is why the Nissan has the booster system to soften the clutch?

I found a replacement booster online but I cannot find a replacement for that black box thing.

Could it be the CHECK VALVE? Does a check valve either work or not? Meaning if it is bad then it does not work causing the clutch to be firm at all times. Or can it be weak causing the problems I have? I am not even sure what the valve does. I think it lets the vacuum go past it.

Sorry for the stupidity.

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