Ever since I purchased my s2000 I have known that it was not a drag car and avoided any sort of aggressive starts as in most cases they are not required. I know the differential can be damaged and the clutch worn however I wanted others opinions if I am being "overly" cautious.

I just completed an advanced driver training / autocross course on the weekend and it was kind of embarrassing when I was expected to leave the gate with some sort of aggression and the car would just almost bog from my weak launches. The instructors kept telling me to get the revs up and just get some mild wheel spin. However from all the posts I have read about people wrecking their cars, I refrained from doing anything too crazy. I am aware the "least" damaging launch is rev the car to 8k and let the clutch out very quickly so the tires take the shock and not the differential....this however is to get the FASTEST launch possible, something I am not interested in doing. What do others do when they don't want to set a new world record drag time, but just get the car moving briskly from the get go? I find it especially hard with the RE-01Rs to overcome this situation and get a decent start. Or am I just being too paranoid?

 

If I'm trying to get off the line fast I rev it up to about 7500 or so, depending upon the conditions of the road/track, and then drop the clutch. you want the tires to sidestep a bit, otherwise your diff is taking on all that strain. if you launch it at lower rpms, you're not going to get the tires spinning at all, and the car will hook, but it will put ALL of that stress on the diff.

And I'd not recommend launching the car alot, unless you want to be looking for a new diff soon.

 

rev to 6 grand. let off the clutch till you feel it starts to grab, get back on a tiny bit. Smoothly transfer from clutch to gas and feather the gas until you hook then romp on it. To quote the best ever description I've heard, "Let off the clutch like you just stepped in dog shit." It works wonders on the STi and on my old S/C'd RSX.

 

I too noticed that when you launch a S2000, you have to go all-out.

 

if you get the tires to hook with no sidestep it's only a matter of time til you blow up your differential, stock they're pretty weak.

 

as a tangent on this conversation- what is sort of the next step up in terms of differentials, how much is it

 

Hardtop guy

This is what I'd do.

 

Don't do this.

 

Also, complete your profile information and let us know what year S2000 you have. This matters due to the CDV.

High rpms and drop the clutch.

If going to sticky tires autocrossing, you increase the chance of breaking your diff.

The pinion gear teeth tend to chip, though. Some of the National-grade S2000 drivers consider them a "wear item" and stock extra diffs for WHEN they break. They figure about 100-200 drag launches and have to replace the diff every year or two.

One of the S2000 guys broke his diff at Nationals last year.

BTW, aftermarket diff bumps you out of stock class.

I've been through two diffs and both were sheared / chipped pinion gear teeth. The first one was the Hardtopguy installed cryo'd 4.57 gears in a Comptech reinforced housing, FWIW. I think they're better constructed now with Ben (PuddyDad) making them.

If you're just learning autocross, there's no point in launching. There are plenty of other places you're hemorrhaging time so get better in the other areas and then work on the launches when you're competing for trophies.

 

If your goal is to spin tires, more than anything, you have to drop the clutch very quickly. You can spin tires from just 4k-5k RPMs (at least with my MY06 and D1 SS tires I can) if you're quick with the clutch. And if you drop from 8k/9k RPMs but are quite slow with the clutch, you can burn clutch instead of tires.

But even though something spins/burns, you're still reacting shock loads right up until the slip unloads your differential and everything else up the powertrain. However it's done--from low or high RPM, how fast, etc--the differential and powertrain have to carry/react the full shock load until the tires can break loose and spin freely.

If you bog, they carry the full load first, and then they counter it when you feel the car jerk back/bog. Think about what's happening to the shafts, gears, and so on.

The best advice I hear is not to abuse anything you can't afford to replace. This falls into that category. Most all the long time members on the board attest that if you get into the habit of dropping the clutch regularly with this car, you WILL upgrade your differential, like it or not. If CKit has been through 2 already, he's probably a good guy to listen to.