Harry's GPS Suite Forum

Hello,

I was able to retrieve some gear ratio data for my vehicule but I am not able to make them match to what Harry's laptimer expects:
Car: Lotus Exige Sport 350.

Data I got from Lotus:

Type - Manual - Sports Ratio
Designation 6 speed manual type EA60
Differential Open bevel gear.
Gear Ratio Final Drive mph(km/h)/1000 rpm

First 3.54:1 3.78:1 5.6 (9.1)
Second 1.91:1 3.78:1 10.4 (16.7)
Third 1.41:1 3.78:1 14.1 (22.8)
Fourth 1.09:1 3.78:1 18.2 (29.4)
Fifth 0.97:1 3.24:1 23.9 (38.5)
Sixth 0.86:1 3.24:1 27.0 (43.5)
Reverse 3.83:1 3.24:1

Can somebody help me?

Thanks in advance.

Tom

It looks like your car has multiple drive ratios. Please have a look into the FAQ on setting gear and drive ratios: viewtopic.php?f=39&t=3425

- Harry

Hi Harry,

If I understood correctly gear ratio for gear 1 should be 3.54*3.78 with a drive ratio set to 1.0. Is that correct?
Edit: Problem is 3.54*3.78=13.38 which is above the max value allowed by the app. In that case can I enter this:
Gear ratio 1 : (3.54*3.78)/2
Drive ratio: 1.0/2 or 1.0 * 2 ???

Thanks

Yes.

In case any of the values exceeds 9.99, you need to add another tweak: instead of entering 1.0 as drive ratio, enter e.g. 2.0 and divide all calculated gear ratios by 2.0 again. In our example for gear 3, this means 3.19 and common drive ratio 2.

- Harry

Hi Harry, I would like to bring alive this topic. I´m trying to calculate drive ratios for 6 (7) speed DSG which have 2 final drives.

Problem is this: if I calculare everything to 1:1, then 5th gear is higher than 4th and 6th and app can´t handle this. Yes, I´ve tried your HOW-TO as you mentioned above. But I can´t use it, because you calculate with gear sets 1-2-4-5-R and 3-6-7 for AMG trans. But VW DSG have sets 1-3-5-7 and 2-4-6 (R is not relevant for this case). Can I ask for some advice how to solve its?

I have these ratios:

Go through gears one by one. Multiply gear ratio with the final drive ratio that applies for this gear. Samples:
Gear 1: 2,933 x 3,444 = 10,101
Gear 2: 1,833 x 4,769 = 8,746

Enter the results as gear ratios, set drive ratio to 1.

Harry

Hi, I updated my recent post with sheet, where you can see the difference

Yes, but the 1:1 values do not match the 1/2 gear sample? Why not?

math is correct, all numbers in my table in 1:1 ratio are correct. As I mentioned I have to calculate FD1 = 1-3-5 gears, FD2 = 2-4-6 gears.

Yes, if I try to use your sample with 1-2-4-5-R and 3-6-7 for AMG trans then yes, it will be good but it does not agree with the actual sorting of gears in the transmission on their FDs. Or should I just ignore it and calculate it with your sample of gear sets?

Please recheck the final drive mapping of the gears. The multiplication from gear ratio and final drive represents the ratio between engine rpm and wheel rotations. So when applying this for all gears, the number needs to go down from high to low and for 1 to higher gears. This is independent from LapTimer, it is mechanics.