project: dogbox transmission for st205 Options

[tufy]

Ater i had several transmisson proplems. i realized that i need a stronger one. i decided to build a custom gearbox. so i can decide for ratios. what would you chose if you build one?
here is some ratios

......................Standart...................fensport.............custom
1 st gear......3.38 - 57 Km/h.............3.58....................?
2 nd gear.....1.91 - 100 Km/h...........2.045..................?
3 rd gear.....1.26 - 150 Km/h............1.33...................?
4 th gear.....0.92 - 210 Km/h............0.97...................?
5 th gear.....0.73 - 239 Km/h............0.73...................?

Final drive 4.285............................3.933...................?

can any one tell me what is relationship between final drive and gear ratios.
if gear ratio x final drive ratio is equal, speed is same.

those are thinks that i am planning to have.
*seq. Shifter

*new input and output shafts,
staright cut gears,
dog clutches,
hubs,
forks

*final drive (pinion and crown), front & rear


*front lsd
(not sure about front lsd, fensport is using stock one)

This post has been edited by tufy: Mar 8, 2007 - 6:34 AM

[playr158]

Theoretically, the final drive changes the overall ratio to taller or shorter gearing, so by the looks of it the fensport has a bit higher top end, but i see the individual gears themselves are a bit shorter so it MIGHT cancel itself out, regardless the fensport might give you another 10-15 mph on 5 gear.

5th gear has the same ratio as stock so it shouldn't perform any different ?

[Bitter]

Theoretically, the final drive changes the overall ratio to taller or shorter gearing, so by the looks of it the fensport has a bit higher top end, but i see the individual gears themselves are a bit shorter so it MIGHT cancel itself out, regardless the fensport might give you another 10-15 mph on 5 gear.

5th gear has the same ratio as stock so it shouldn't perform any different ?

but the final drive is different, calculate that into the math.

[jgreening]

Here is some basic information:

Understanding Gear Ratios

I suspect that the answer to your question depends on your desired application. If the answer is drag application, I strongly suspect that you will want to pick ratios that allow you to cross the finish line without shifting to fourth gear. This would require calculating what gear-set is necessary for your trap speed given the OD of your tires. Unfortunately, my knowledge of how to do that is lacking. Perhaps someone else can help in that regard.