If you're on this post, its probably because you're annoyed by the G35/G37 clutch action, specifically the high engagement point and rocky shifting especially from 1-3 gears. I've tried both of the popular methods for dealing with this and wanted to share my results.
Background: I bought an '08 G37 S 6MT, coming off a Boxster with a new clutch which obviously is already going to leave me with some grumblings over the shifting. I test drove the G37 and loved the power and handling, and assumed that the jerky shifting was just me being unfamiliar with it.
After a few days, I wasn't much better at the shifting, and started digging thru the forums looking for info.
There are basically two mods which people have performed: lowering (effectively) the engagement point by adjusting a rod which lowers the pedal, or adding a block below the clutch which raises the 'floor' of the clutch action, thereby decreasing the engagement length. I've tried both the approaches with pros and cons.
First I lowered the engagement point on the clutch using the directions here:
This mod is built into the design of the pedal - its an adjustable rod, meant to be adjusted, and doesn't cause any issues with clutch wear unless you are able to turn it down so low that the clutch doesn't completely disengage. I don't believe its possible with the newer G37s to get it down that far - the rod wouldn't thread lower than about 3 rotations, which left it still above the engagement point. I found that 2 complete rotations of the rod was about right for me, but its such a quick adjustment (<5 minutes once you've done it a couple times), that its worth trying a few different spots to see what you like. Don't forget to mark the rod with a marker before you start so that you can keep track of the revolutions.
This adjustment improved the shifting greatly, and had the advantage of lowering the pedal to a similar height as the brake pedal (though still slightly higher), which felt more intuitive. At two rotations, I did not need to adjust the cruise control, it still worked fine.
I was also interested in trying out the nickel penny trick, or the DIY version of the D-wolf kit, as described here:
Basically what this mod does is a) puts a stopper below the pedal so that it doesn't go down as far, and b) adds a similar shorter stopper which presses the clutch interlock switch (which is what allows your car to start).
After reversing the changes to the adjustment rod back to factory setting, I tried this first using the materials shown in the post, but then switched to nickels because it allowed me to vary the length of the stopper. I found that about 4 nickels felt pretty good - anything longer than that was just too short a travel for my tastes.
I drove it like this for about a week, and it does make driving the car very easy, however I ended up going back to the first mod for a couple of reasons:
a) the clutch action was too binary - it was either on or off, and I felt like I was missing some of the fun of driving a stick - I wanted more play in the action
b) the tactical response of the stopper never felt quite right - possibly due to the tape - it just felt a bit 'off' to me, even after a week
c) I was worried that at some point, the stack that was engaging the interlock switch would fall off, meaning the car wouldn't be able to start. That would be ok if it happened to me, but I didn't want to have that phone call with the wife if she was driving it ("uh yeah, look for a stack of nickels taped to a plate behind the clutch pedal…)
d) associated jankiness in general of taped solution just bothered me
So I went back to two turns of the adjustment rod, and felt pretty good about it. The only part of the clutch action that I didn't quite like was how far you have to go down when you're in first gear - the base seems very far away. moving between other gears doesn't matter as much - you can shift when the pedal is only halfway down, which is why the second mod works (its just moving the base up closer to the engagement point, which you can mimic by shifting with the pedal not depressed all the way).
So I took an Australian dollar coin (which is slightly thicker than a nickel and about as wide as a quarter), and taped it in place on the clutch stop. The distance of the coin plus the tape is just enough to increase the base to where it feels comfortable to me, and the advantage of this approach with my car anyway was that I didn't have to adjust anything with the interlock switch - the change wasn't enough to require a separate stack to engage the switch. That means if the coin every does fall off the clutch stop, there's no particular repercussions.
I've been driving it this way for a couple weeks now (essentially a hybrid of the two mods), and love the clutch now. It feels perfect to me.
Some other related thoughts:
a) the hardest shift seems to be between 1st and 2nd. I've found (after reading somewhere in the forums) that it doesn't seem to really like shifting between 2000 and 3000 rpms. So I generally will perform a quick shift at around 2k rpms, and that misses the jerky lurch. If I'm in more of a hurry, I'll wait to over 3000 rpms. Anything in between makes it a challenge to feather the accelerator & clutch to avoid a lurch - possible, but you really have to concentrate.
b) as mentioned earlier, no need to depress the clutch all the way to the bottom for shifting between gears - halfway is fine, you'll figure it out after driving it for a while
c) rev-matching is crucial on this car, it wasn't something I had to think a lot about in the boxster but down-shifting in this car requires a ton of rev matching practice, at least in my experience.
Sorry for the novel, but hopefully this information is helpful for other new G37 owners trying to decide how to deal with the cranky clutch...