Gernby

Do any of you know what the "Secondary Reduction Gear" is? The Helm's manual shows that this gear has a 1.16:1 ratio. I'm wondering if this is similar to the final drive gear (which is a 4.1:1 ratio).

I'm trying to calculate the correct gear ratios to enter into the "Car Accelleration Simulation" program. Do these ratios look correct?

1st gear: 3.133 x 1.16 = 3.634
2nd gear: 2.045 x 1.16 = 2.372
3rd gear: 1.481 x 1.16 = 1.718
4th gear: 1.161 x 1.16 = 1.347
5th gear: .970 x 1.16 = 1.125
6th gear: .810 x 1.16 = .940

infinitebass

Actually, I think so. I'm too lazy to check, but I think in the Library it lists the actual ratios.

Blake

The Reverend

Click on the link in my signature for my gear calculator. That will list all the ratios for the s2000 and plot a graph of what speed you can go at a given rpm for each gear.

The transmission has a 1.16 reduction gear after the reduction from 1-6 gears and before the reduction from the rear end. So in first gear, you have a reduction of 3.133 for first gear, a 1.16 secondary reduction, and a 4.10 reduction at the final drive gear on the diff. Total: 3.133 x 1.16 x 4.10 = 14.900548 : 1

If you are using a simulation program that doesn't allow for a secondary reduction gear, just list your final drive as 4.10 x 1.16 = 4.756

hth.

Gernby

Thanks. Multiplying the 4.10 and 1.16 would have been an easier way to achieve the same result. The simulator is listing the same MPH for each gear that your calculator has.

The simulator is pretty nice, but it doesn't seem to be very accurate on the acceleration times. The best 1/4 mile time I have gotten for a stock S2000 with the proper parameters is 14.7 seconds.

Gernby

While I was at lunch, I drove the car in 1st, 2nd, and 3rd gears at 4500 RPMs and recorded the speeds. I was at 19 mph in 1st, 31 mph in 2nd, and 44 mph in 3rd. So it looks to me that the speeds at 9000 RPM would be twice that (38 mph, 62 mph, and 88 mph). Don't our speedometers also read a little fast?

The Unabageler

I can't believe I'm actually copy/pasting this crap again.

max speed in 1st is 43.
max speed in 2nd is 66.
max speed in 3rd is 91.
max speed in 4th is 117.
max speed in 5th is 140.
max speed in 6th is 167.
max speed in reverse is 48.

Gernby

I'm not sure why you feel like you had to post this crap. I saw this in another thread, but I think it mentioned that it came from a magazine, with no supporting mathematical data. Based on what I've found, this data is not correct. In my S2000, my max speeds in 1st, 2nd, and 3rd are 4 mph less than these.

twohoos

Don't take either the speedo or tach readings as dead-on accurate. There will always be calibration and round-off errors, plus "lag" errors under acceleration and braking. Also, the effective tire circumference is always changing due to pressure and wear. Finally, since the two readings are derived from independent sources, inferring a specific rpm/speed relationship in any gear (using only the dash readings) just compunds the errors.

The spreadsheet method is the way to go to get the best "unbiased" estimate. As they say, YMMV.

John

speed_bump

[QUOTE]Originally posted by gernby
[B]

I'm not sure why you feel like you had to post this crap.

infinitebass

[QUOTE]Originally posted by gernby
[B]

I'm not sure why you feel like you had to post this crap.