Let me preface this by saying I have searched and spoken to many s2000 owners and no one can quite figure out what is going on.

Vehicle: 2003 Honda S2000
Bolt ons and EMS
stock rear end

I completed my first track weekend at Sebring (have been to a few other tracks) but encountered a problem that caused me to retire the car early. On the straights I would be taking the vehicle up to 115 or so (thats where the rev limiter is for 4th) before i shift into 5th gear. I noticed as the laps would go on, i would be at 9200 rpm, bouncing off the rev limiter but my speed would be 105mph. Third gear would only go to 79-80 instead of where it normally bounces off at 89mph. Track conditions were perfectly sunny with a high of 82 degrees.

Also, the gear box has become incredibly hard to shift and gets worse on track when everything is blazing hot. I do have a leaky clutch master with contaminated fluid (i have ordered a new one). I thought it may be important to mention the notchy/dry feeling shifting issue along with the rev limit.

MY first thought, slipping clutch. On the way home, put the vehicle in 6th at 35mph and put my foot to the floor. rpms rise exactly as the mphs do. Rule out slipping clutch.
I then took 3rd gear to its rev limit (89mph) where before it was only getting to 80mph and it had no issues.
"
Gears are very hard to shift about 65% of the time even when cruising home on the highway or around town. First noticed the "notchier" transmission up at the Dragon 3 weeks ago but never thought anything of it. Fluid was changed out 2 months ago with oem Honda transmission fluid.

Summary:
Has anyone heard of or know why the rpms still go to redline but the mph would be significantly less (10mph or so)?

 

The only thing I can think of is a slipping clutch. I know when mine went out, I never could get Honda to warranty it, because it would only slip when it was really hot - several minutes of spirited driving. They, somewhat thankfully, never pushed it hard enough to reveal the issue. So you may not see it slip on the freeway when its cool, but on the track when its blazing hot you start to get some slip. However, if it was very consistent to stop at 80 each time, I'm less inclined to think this is the culprit. I can't think of any other component in the drivetrain that would allow for some variation in "engine RPM : MPH" though.

EMS = AEM Series 1?

 

I was fairly certain it would be a slipping clutch but its only the last 7-10mph of each gear while on the track as the laps went on. i would think it would show in a few other circumstances as well.

btw ems is Haltech, car has 75k miles on it and its the oem clutch. car was babied for the first 50k, and since ive had it, no launching or anything besides 6 track days and 2 dragon trips on it.

 

Well if you're confident the clutch is ok - and I agree I think you would see issues in other circumstances as well, if it weren't - then I'm left with the Haltech as the only other likely source. Not reading a sensor right, or some sort of protection kicking in, or something like that. I know nothing about the Haltech though, so I'm useless on that.

 

Have you checked the clutch fluid level? I saw you said the CMC was leaking but have you been refilling the fluid and has it gotten low enough to get air in it? Could be an issue with that...replace the CMC as soon as you can and bleed the system.

 

It has to be the clutch. Gears don't slip. When your up in the power band with a hot clutch, that is where the clutch is going to slip. Only other thing it could be is that your S has so much TQ that its just spinning your tires. J/K

ROD

 

Great points both of you. Yes I have been staying on top of the clutch fluid and it hasn't gone dry. The fluid is blacker than my Berlina and has turned to a black sludge at the bottom.

I got out all that I could with the tools I had. I was thinking it had to be a slipping clutch for the mph issue. The grinding gears I'm thinking is a cmc/fluid issue.

Replacing cmc first and will do a track day to test this new theory. If I get the same issue then it's time for a new clutch. *sigh* must be all that raw torque of an ap1.