Major Track Faults of the 370
 

So did my 3rd track event in about 6 weeks and here are my two major problems.

• Clutch gets stuck to the floor after about 20 minutes of being out there.
• Fuel starvation is KILLING me!! I hate it so much.

Does anybody have any idea how to fix either item? Can somebody give me a definitive answer about how to beef up the lines, fluid, whatever needed to make my clutch freaking work? As it heats up, the catch point gets closer and closer to the floor and eventually it just gets stuck. Am I shifting wrong or does this happen to others?

Did you ever flush your clutch fluid with a racing type brake fluid? That would be step one.

Keep the tank full every session, I carry a 5 gallon gas tank as part of my check list

The track I goto has a gas station up the road (2 minute drive FROM pit) so that's what I do now, I just would like to be able to run longer than 25 minutes out there at a time. I have not flushed my fluid, should I get a stainless cable too?

get the z1 cable and put some motul in there.

I had no issues at the track event I went to. Fluid alone might do it for you too, i believe Mike just changed his fluid and hasnt had issues.

Maybe a swirl pot for the fuel?

Changing the fluid would help, you probably boiled them over. You shouldn't be on track for 25 min. straight in a street car anyway, let it cool down a little. Hot tires+hot brakes+hot engine=slow lap times

agreed, take a break after a few decent hot laps.

Motul fluid for your brakes and clutch are the way to go for long track stints.

also, keep an eye on your oil temps, the newer VQs tend to get VERY hot on track days.

I'm highly suspicious of these reported clutch issues. Sure, some Zs have bad secondary cylinders that needed replacement, but that has largely been in Zs with aftermarket clutches installed. I can tell you that we just had 3 370Zs on track at Road America running 20-25min sessions and none of us had any clutch problems. Many of the turns require shifting down from 5th to 2nd and then winding it back out to 5th again in the subsequent straights. If we're not having clutch problems there, I can't imagine it's a fluid or mechanical issue (ie it's likely driver related).

You are assuming then that each and every CSC was built exactly the same to be in perfect working order. If we were so lucky on everything that nissan put into this car then no one woul dhave an issues period.

but then some people burn alot of oil
some people have sensor issues
some people have rattles
some have clutch issues
some have gear issues.

Its not a widespread 99% of people will have the problem.. I think Nissan's QC is good enough to prevent that from happening, but every company has issues with a small % of its things.

Think of anything that every went wrong on a car or product of yours. I guarantee you that you will be in the minority compared to people who didnt. Does that mean that you were the problem with it (whatever it was)?

Perhaps I didn't convey my opinion well in the first post. The clutch is a relatively fragile aspect of any manual transmission car that will readily be destroyed if improperly used. With the heresay available on this forum, the explanation of a defective CSC is just as likely as driver-induced destruction. Until people post videos of their clutching technique, it will remain a hazy area. I merely stated my suspicion that driver use/misuse may be a factor.

The OP is having a problem that many many other owners who track their Zs will never experience. I don't want people reading the OP's thread thinking that a clutch upgrade is a mandatory part of tracking the Z. It's not.

ahh yeah agree there.

Most of the time when someone posts something about "hey this happened to me, but i swear i wasnt doing anything wrong" or "I got a ticket but the cop was an *** I wasn't speeding etc" .. the OP is ussually bullshittin a bit. Not saying this OP is, but agreeing with your point spearfish..

Okay well how can I be shifting wrong? I have SRM on the whole time, so I doubt downshifting is the problem and I upshift perfectly with no jerking. What is the technique you guys are using that could be overheating my clutch?

I'm pretty sure it's a temperature problem that is causing it for a couple reasons. It progressively gets worse out on the track, and it goes back to normal after I let it sit for 30 mins or so. Is it was possible that there was air in my system or that the fluid is subpar?

It's not even that, if I go out for 20 mins, come out and wait 30 mins my clutch is still acting weird. After about 40-60 minutes of total track time it starts to get stuck to the floor. I'm pretty sure this is a problem with my particular car if people out on Road America/Atlanta (cant remember which but both are WAY more intensive on the car then my track) are doing fine.

Are you doing a lot of shifting? are you sure your in the right gear for that corner? Maybe your shifting more then you should be, idk how that is possible, but it an idea???????

Are you holding in the clutch to long?

Nope, there are only 9 shifts on each lap. I shift the same each lap, and run consecutive lap times within 0.5-1 second of each other. There is no way to go around this track without maybe cutting one more shift because I'm each gear I shift into for at least 3 seconds (which is 2nd gear, and I'm only in 2nd once on the whole track). I clutch in, gear up, drop clutch at right RPM. How could I do anything differently?

You may very well have a bad CSC. Are you sure you don't accidentally rest your foot on the clutch as you approach a corner? It's easy to prepare for a downshift, rest your foot on the clutch (partially, even just slightly depressing it), brake for the corner, and then finally shift. If the clutch is partially engaged during this time, you could overheat it.

I was expecting to see brake pads and oil cooler as the two top things.

Like others have said, replacing the fluid with some good DOT 4 like Motul and bleeding the lines should do the trick. If not, they you probably have a bad CSC.

it happened to zcarman also at the znationals track day. but his came back up after he let it cool. I would def say that changing out the fluid is a MUST for everyone who plans on doin this.

No, I made absolutely sure that I was not riding the clutch this last time. I do know better than that. My real question is what could be causing the engagement point to move closer to the engine and eventually stick to the floor?

Brake pads and oil cooler have already been taken care of :tup:

I will try doing this first, if I have a bad CSC how do I tell the dealer to fix it without having to explain its weak point is at the track?

As Daisuke said, after letting it cool down the clutch was fine. When I got back from Z Nats I replaced the oil (Nissan Ester), brake/clutch (Motul RBF-600). Haven't been back on the track since Taladegha but clutch is performing fine.

It takes 30 minutes to bleed the clutch.

Since bleeding is mentioned, what's the best way to bleed brake lines and the clutch: 1. empty all old fluid first, then fill with new and bleed, or 2. fill reservoir periodically as the old fluid is bled out?

Is the clutch pressure occuring because you are downshifting too early and carrying too many engine rev's for the road speed as you downshift.

Most folks tracking their cars for the first time inevitably can carry one gear higher than they reckon - if you reckon your need 2nd, try using 3rd instead, same for 3rd/4th. IMHO, 2nd gear is only required for a 25mph ultra-tight hairpin - there are no tracks here in Ausrtralia with a 2nd gear corner, apart from some extended gymkhana tracks (Autotest is the nearest US equivalent I think, although Autotest seems to involve higher speeds than I'd expect with a gymkhana, so maybe I am wrong here).

The reason a clutch overheats is because it is slipped. This can only occur if the driver is modulating traction via the clutch and the friction plates overheat and lose effectvieness, OR road speed is too high for engine speed and the clutch is acting as a brake and slipping .... or the clutch pressure plate clamping force is exceeded - which can occur if downshifting at too high a road speed for the gear.

I regulary run 20-25 minute sessions in my Z34 and have never had a clutch problem.

As a rule, downshift is the last thing you do before turn-in .... braking is effectively done, execute the downshift whilst still on the brakes, and turn the car in and get onto the gas in one easy fluid motion as you hot the corner apex - engine speed needs to be such that you do not run out of rev's before most of the steering lock is off the car and you are pointing at the next straight - if you find yourself running out of revs close to the corner exit, then try entering the corner in the next higher gear. The VQ37 engine is torque-rich and can carry a gear at 3500/4000 rpm as well as at 5000 or 5500 rpm.

REmember, corner entry technique is brake, downshift into the gear you need to exit the corner right before turning-in and thengetting back onto the gas as you apex ..... on downshift, gigure that you need to be at or slightly above 50% engine speed 3800-4200rpm ideally, never more than 5000rpm especially if you are using 2nd gear !!

Of course, you may well have a warranty issue with your clutch, but not especially likely.

RB

The clutch is not slipping or being slipped, I only shift to 2nd once on the track and when the clutch is out I'm doing about 4500 RPM in 2nd. I am pretty sure since nobody else is experiencing this it is a problem with my car...thanks all. I will try flushing with a better fluid and lines and see how it goes.

Technically, go under the car and open the bleeder valve. Since I am lazy, I did what you said. Of course I have been doing it since the car had about 2500 miles.

I empty the old fluid out with a high-tech turkey baster. The clutch reservoir is pretty small. I haven't had any clutch stick issues in a couple of hard track days but I did swap the fluid out before going as CSC's are prone to overheating.

Fortunately, I haven't had any clutch issues at all with over 4000 track miles on the car now. But for those with problems, I would flush the system and replace fluid with Motul or some other high temp brake fluid.

Fuel starvation is another issue though. At Road America with Spearfish this weekend, it was fricking ridiculous! Engine stumbling exiting the carousel with only two dots down on fuel, once when I was only one dot down! I couldn't go more than 15 minutes into a session before it started happening.

damn..i hope somebody comes up with a tank baffle or some other solution for this..

too many smarta$$es here :rolleyes:

Lay off the OP, he's not an idiot. I too get the exact same problem with the clutch. It happened to me 3 times when on mosport ddt during lapping days. Near the end of a 15 or 20 min session, my clutch gets stuck to the bottom and i have to lift it up with my foot. I then pull over into the pits and within a few seconds the clutch is fine, albeit a bit soft feeling. And if you didn't know, mosport ddt is a short, tight twisty low speed track done almost totally in 2nd gear except for the one single straight where you upshift to 3rd for a few seconds before downshifting into 2nd again for the turn. So the clutch can't be working that hard. And yes I had the stock fluid.

And a few days ago I was lapping at shannonville. The clutch didn't get stuck but after the same 20 min session the clutch would get progressively softer, and i got the occasional gear grinding when shifting. My guess is that it seems the clutch fluid boils a bit due to excess heat after about 15 or 20 min of hard lapping. I'll upgrade the clutch fluid over the winter and next year see if the problem replicates itself.

I experienced fuel starvation on shannonville that same day near the end of my 3rd 20 min session. I was running low on gas, about 4 dots (25% of the tank). Then on turn 3 which is a sharp right, the car just died down and i lost all drive to the wheels. the engine was idling at barely 1000 rpm. I was flooring the throttle and the engine wasnt responding. I shuffled through the gears 1 to 4 trying to get the car moving and it didn't. I was able to get it to creep very very slowly in 1st gear. It was pretty scary since i was stationary in the middle of the racing line, and a couple of cars whizzed by my side at 70 km/h or so. Finally I crept enough to get it to the grass and left it idling in neutral for a few seconds. by that time the fuel level was down to 2 dots. After a few seconds i tried to rev it and it responded, so i took off again to finish my lap. On the same lap at turn 10 which is a right hand hairpin before a long straight, right after the turn and getting ready to floor it for the very long back straight, the car died again for a few seconds before responding again. By that time fuel was down to 1 dot. I was able to finish my lap with no problems but pulled into the pits at the end. After leaving the car idling for a few minutes the fuel level crept back up to 4 dots again :facepalm: I left the track soon after and went back home.

In addition I did experience ice mode regularly after hard braking from long straights, especially since both mosport ddt and shannonville are very bumpy tracks. But that's no problem. As soon as i feel the abs pulsate the brake pedal i lift and then reapply the brakes and that seems to defeat ice mode.

I feel like I could have typed those first two paragraphs :tup:

That is exactly what happened to me! I will also be upgrading the fluid over the winter and see how she does this spring!

Let's ask this question. Who still has an intermittent clutch pedal after a high performance clutch fluid swap?

(I am highly aware of how bad the stock slaves are, but you usually won't get your pedal back if that is truly the case)

Maybe...
 

There is a California company named "Sector 111" that carries a great many track mods for Lotus cars. One such is a gas tank that is baffled somehow to eliminate fuel starvation and resultant lean-running engine damage. To fabricate a one-off would probably be prohibitively costly, but it's a place to start. Good luck. :driving:

i havnt read the entire thread, but i used to have the exact same problem in my 240sx. it turned out to be a bad hard line. there was a tiny pinhole leak in it. i replaced the hardlines and problem completely gone.

but first make sure there is no air in your system. after a good bleeding and it still does it, chances are you have a microscopic leak in the system somewhere - in which case, replacing your lines will fix the problem. in my car, the leak was so small there is no way to exactly locate it. but it was there b/c after the lines were replaced the problem went away.

good luck.

I've never had the pedal stick on track, but i have had it stick in the pits. How about you all? The engine and transmission produces an enormous amount of heat, and when you bring the car into the pits, that heat can cook the system.

The heat is the killer, and Nissan hydraulic systems have always been prone to issues with this. I would suggest a stainless line, heat wrap with the best warp money can buy, Motul RBF600 fluid and give that a shot.

This is not a very widespread issue, but it can happen.

Fuel starvation...now that IS very much a widespread issue.

Just did a Driver's Edge event this weekend in TWS and the fuel starvation issue killed me. Long right hander and into the straights, the car would practically die every time. I felt like an idiot for an entire day until a fellow Z driver let me know about the fuel issue. Never would have occurred to me.

I had to get towed off of Road Atlanta, I too felt like an idiot.

At Road America, I was getting it with only one dot from full coming out of the carousel!!!!!

So has anyone come up with a solution for fuel starve issue? Where are you safe with fuel level before this starts to become an issue? 1/2 tank safe? Not thrilled with needed to hual around extra fuel poundage!

See Mike's post above. The less aggressive you are, the more LEDs you can have OFF and still be OK. But yes, you can get fuel starvation with nearly a full tank.

I have done 2 track days in the Z and so far no clutch issues at all for me. Fuel starvation is a huge issue for me. 2 dots from full and I get fuel starvation coming out of long right hand corners.

my clutch used to stick all the time at the track, i think its just nissans fluids...they suck....after i put motul in there I cant even force it to happen anymore! its beautiful. As far as fuel starvation, this used to happen in my 350...but not in the 370Z at all.