Gearing Formula's
 

Can someone run thru the process of working out the gearing for the different buggies, trucks and cars please?

Need the formula's. Cheers :yes:

Many of us use BrianG's Speed Calculator program found here:
http://scriptasylum.com/rc_speed/index.html
This won't tell you the exact setup to use but it can definitely get you going.

You could always look at the source code from that site and see what the formulas are. Not brain surgery:

mph=(((battery_voltage*kv)/tranny_ratio/diff_ratio)*(tire_diameter*TT))/1056

Sorry guys I didn't explain it well enough....
The gear formulas I need are center diff, front and rear diff and final drive.
16T pinion 44T spur, 43T rear diff 19T transfer.
how do you find each separate gear ratio and then the final drive?

I believe for your example it might look like this:

44/16 43/19

then just divide by the smallest number and you get your ratio I think the example would look like:

2.75:1:2.26:1 since having the X : 1 : X : 1 is redundant so you then have:

2.75 : 2.26 : 1 or for a simple clean ratio you take (A x B = FDR : 1) :

6.215 : 1



Edit: Hmmm that looks silly only haing it taht way so I guess I'll use a E-revos drivetrain ratios to better explain, just to avoid confusion or try to.

E-revo

Motor pinion/spur
58/24
Tranny
33/20 x 20/18
Differential(s)
37/13
so we have all the gear tooth ratios so total would look like
(only 3 gears in the tranny)
58/24 : 33/20/18 : 37/13

now for the X : 1 part we get

2.42 : 1.65 : 1.11 : 2.85 : 1 is your gearing and for FDR just multiply (x : y : z) and toss a :1 on the end and its you FDR so for the revo we have a fdr of.....


12.632 : 1

Brians gearing calculator does all that plus it tells you the FDR.

To find the gear ration themselves for each diff I'd say either look on the packaing of the diffs or on the manufactures website or count the teeth out if you don't already know what the count is, hopefully that answers your question.