How to calculate diff ratio's for a Gen & Gen 2 MPS 3

[240MPS]

Ok got this for you, if i'm on the Dyno and I'm in 5th gear how do i calculate the fact that my final drive is 3.526 and my 5th gear ratio is 0.948 ??????? so whats the true ratio when you put the two together ????need to work it out for 4th gear as well when final drive is 4.187 and the 4th gear ratio is 1.025 know where i'm coming from. This is for a Gen 2.

Now for a Gen 1 I'm in 5th gear now how do i calculate the fact that my final drive is 3.350 and my 5th gear ratio is 1.085 ??????? so whats the true ratio when you put the two together ????need to work it out for 4th gear as well when final drive is 3.941 and the 4th gear ratio is 1.171....

[240MPS]

Must have people stomped on this one.... ???????

[shakespeare]

Rino, I am pretty sure you take the gear ratio and multiply it by the diff ratio which gives you the ratio of engine to wheels

eg: Fourth 1.00:1 x Diff 3:00:1 = engine to wheels 3.00:1

So

MPS Gen 1 Fourth = 4.291675 Fifth = 3.342648

MPS Gen II Fourth = 4.614911 Fifth = 3.63475

The Wikipedia explaination

Gear ratio - Wikipedia, the free encyclopedia

[shakespeare]

Found this too, it's for 4wd so just the put the transfer case ratio at 1:1 and I've put together a spreadsheet to calculate this if you have the other gears I can calculate these and post them if you want.

Gear Design Equations Formulas Calculator Crawl Gear Ratio Rear Axle Differential Transfer Case Transmission

[240MPS]

Thanks Chris, still getting some wierd figures of just under 600NM, might try and get a whole of Brackaus who worked it out on the day when talking with the boys...

[2XS]

Allstar explained it to me this way:

Mine is:

1440nm + 1/3 (? Dunno why? Drivetrain loss?) 1920nm divide by diff ratio 3.5 = 548nm

But I think you need to allow 5th gear ratio into it.

1440nm + 1/3 = 1920 / 3.5 = 548nm X 0.948 = 520nm

[240MPS]

Allstar explained it to me this way:

Mine is:

1440nm + 1/3 (? Dunno why? Drivetrain loss?) 1920nm divide by diff ratio 3.5 = 548nm

But I think you need to allow 5th gear ratio into it.

1440nm + 1/3 = 1920 / 3.5 = 548nm X 0.948 = 520nm

Mine was 1640nm in Feb on 18psi +1/3 = 2186.66 divide diff 3.5 = 624.76nm???????

on Dyno day i had 1442nm + 1/3 = 1922.66 divide diff = 549.33nn on 14.5psi

[240MPS]

Found this too, it's for 4wd so just the put the transfer case ratio at 1:1 and I've put together a spreadsheet to calculate this if you have the other gears I can calculate these and post them if you want.

Gear Design Equations Formulas Calculator Crawl Gear Ratio Rear Axle Differential Transfer Case Transmission

I may have work this out the boys have always told me that my final drive in 5th was 4.5 and looking at the excel sheet for a BK 5th gear ratio is .948 + 3.526 for diff = 4.474 (4.5). BL 5th gear ratio is 1.085 and diff 3.350= 4.435 pretty close I will calculate the BK at 4.47 and BL at 4.44... and give the sheet to Dug to load up the dyno figures...

[SarcasticOne]

im pretty sure they're multiplied, not added... at least that's what i've seen/understand

[240MPS]