DanMardik

iTrader: (7)

The other day I tried to do a high RPM drop on my G37S to see how the car would react, and instead of what I expected (total burnout) the car experienced complete clutch slippage and of course accompanied by the very familiar clutch smell.

Now I thought that was completely odd, so I waited a few more minutes and tried again but this time it worked. Although I had mild wheel hop where the burnout lines resembled something like ___ _ _ _ _ _ _____ I still had a burn out. The only difference between the two burnout tries was that the second more successful burnout was done at a lower RPM. Also as a side note, my clutch is now behaving normally with complete grip.

Now what would be causing this? I suspect that the clutch system on our G37's have a safety feature built in by the form of a clutch delay valve. Did some search on that but found nothing.

Looking for some input on this. Can anyone with some experience comment?

Also, about wheel hop? What can be done to keep this at a minimum?

Thanks!

DanMardik

iTrader: (7)

The other day I tried to do a high RPM drop on my G37S to see how the car would react, and instead of what I expected (total burnout) the car experienced complete clutch slippage and of course accompanied by the very familiar clutch smell.

Now I thought that was completely odd, so I waited a few more minutes and tried again but this time it worked. Although I had mild wheel hop where the burnout lines resembled something like ___ _ _ _ _ _ _____ I still had a burn out. The only difference between the two burnout tries was that the second more successful burnout was done at a lower RPM. Also as a side note, my clutch is now behaving normally with complete grip.

Now what would be causing this? I suspect that the clutch system on our G37's have a safety feature built in by the form of a clutch delay valve. Did some search on that but found nothing.

Looking for some input on this. Can anyone with some experience comment?

Also, about wheel hop? What can be done to keep this at a minimum?

Thanks!

mal_TX

I think the intense heat created by the high rev friction heats the hydraulic fluid to the point where it does not have the same properties anymore.

Similar to having air in the line? Just a theory.

DanMardik

iTrader: (7)

So based on your theory; because the first non successful burn out was done at a high RPM, you have concluded that due to the second burn out having success at a lower RPM, it must be that the higher RPM burnout caused the heating of Hydraulic fluid and also caused the temporary failure.

This could be something to look into, but I'm not convinced that this is the problem quite yet.

Anyone else?

mal_TX

Well, kind of. This is also my third 6mt G coupe, the first two being 1st gen models, so I have a little experience with these clutches.

My experience is basically that these cars cook the clutch fluid. If you drive the car aggressively, it cooks the fluid. The fluid gets worse and worse until one day your pedal will stay down just because it is really hot outside and you are in stuck in traffic (true story!).

So, I change the fluid to a better fluid (synthetic DOT4) anytime the clutch starts to feel weird. I use the reservoir/transfusion method rather than a drain/fill/bleed as it is less error-prone and not that much more expensive. Since I've started doing this my clutch has NEVER stuck.

So yes.. I think your fluid is iffy and you had it really hot the first time and it had a little time to cool down before the second attempt.

DanMardik

iTrader: (7)

Hmm, maybe you didn't understand. The first attempt was the failed attempt. The second attempt went as planned and was a success. So if we're talking about overheating fluid, I really doubt that is the case because the second attempt would have been a much HOTTER attempt then the first one, and would have been the one that failed.

Also, my car only has 2300 miles on it.

mal_TX

Well it is designed to cool off.. how much time elapsed between your two attempts? Also, did you release the pedal faster on your second attempt than your first? It could obviously be something else but my Infinitis have done this due to fluid.

DanMardik

iTrader: (7)

About 3-4 minutes between first FAILED attempt and 2nd Successful attempt.

mal_TX

Weird. I can't imagine the clutch would slip but hey, maybe it did!

Let's talk about the obvious -- what was the "high" rpm on the first launch?

DanMardik

iTrader: (7)

Yes, it was definitely slipping. At first I thought hey maybe I'm having so much wheel spin that the car isn't even moving forward, so I actually shifted to second gear and had more of the same. Nothing but clutch smell and no tire marks.

The first clutch drop was done at around 7,000RPM
The second clutch drop was done around 5,500RPM

IP37

you know.. i got onto it one day from a light, and i noticed that the car kind of lagged. not sure if it was the clutch slipping, or just the throttle lagging or what. i kind of figured it was the throttle lagging though

TomG37

Mabe the slave cylinder, these cars have a problem with them too.

mal_TX

7,000 rpm! Holy crap.

This isn't a torque-less Honda S2000! This car is launched from about 3500rpm or less with a fast clutch feather Any higher and its a side-step w/ the tires smoking.

At those rpms I think you will damage your drivetrain.

DanMardik

iTrader: (7)

I think most of the damage will be done to the tires.

sharif@forged

iTrader: (2)

There is no clutch delay valve, nor does such a beast exist. As long as the VDC is off, you are going to smoke your tires, OR slip the clutch. The OEM clutch is fairly crappy, and a high RPM drop, on a sticky piece of road, might slip the clutch, rather than hook and spin the tires. You probably just got lucky the second time around. But for best effect, you need to mat the gas pedal, and 100% POP the clutch. I have done this many times in our shop's parking lot....no delay...just smoke, and a couple dark lines on the ground.