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[art-n-motion]

http://www.gearchart.com/index.cfm?fuseaction=chart.create
(use this link to find out what your FDR is)

EXAMPLE: (here's mine)

chassis: associated tc5

motor: ss5800 novak w/ rotor upgrade

pitch: 48

spur: 87

pinion: 35

FDR: 4.97

[BapeSta]

chassis: Hot Bodies Cyclone WCE

motor: novak 6.5r

pitch: 64

spur: 108

pinion: 29

FDR: 9.08

[AE86DrifterSprin...]

chassis: yokomo bd
motor: novak 8.5

pitch: 64

spur: 81

pinion: 47

FDR: 3.46?

[drifterrolly]

wtf? you guys in the low numbers, are you guys just doing the wrong equation? because thats really high for the motors you have.

generally speaking here's how it is, the lower the number=more top end and less torque, the higher the number=more torque and less top end.

with 8.5's you generally want to be in the 8's 9's for perfect torque. if you are running 3-4's theres virtually no bottom end at all.

you dont need that calculator to figure out the Final drive dudes just use this equation.

Spur/Pinion X Internal Ratio(the teeth of your belts or internal bevel gears on shaft drives)=Final

im personally running an 8.5 myself so heres mine: 76/23 x 2.43=8.02

[awdracer]

i dont really care for final drive ratios for some reason..even in games wen i need to fix the gear ratio..wats the big deal about them? someone pls elaborate on how ppl use this in racing/drifting

[irollgen4s]

actually bean of groovydrift said you want your ratio for the 8.5 to be from 6.5-7. also i beleive the lower the FDR is the more torque you get but less top end. the higher the FRD the moretop end but less torque. Cause on the stock tt-01 motor i went from a 19 tooth pinion to a 21 tooth pinion and it had less torque but more top end.

[spoondori]

^^Big fat negative right there junior. With a final drive ratio of 8:1, this means that for every ONE complete revolution of the wheel, the motor would have to revolve EIGHT times. This would mean a SLOWER top end speed, then say, a 4:1 final drive ratio.

My specs - 122/40 x 2.13 = 6.50


EDIT: Oops, kinda revived this topic didn't I?

This post has been edited by spoondori: May 14 2008, 03:55 AM

[Grip]

im glad you revived this.. im a little confused.. maybe you guys can help..

chassis: HPI Sprint 2

motor: Novak XBR Sport/EX 10.5 Brushless System

pitch: ???

spur: 120

pinion: 35

FDR: 8.36

i believe my chassis runs PERFECT.. but what is my pitch?..

[ccondrup]

Gear Pitch explained: http://www.rcdriftclub.com/home/archives/9

In short, 48p is the standard. You can use higher pitch like 64p ("smaller teeth" = more fragile, more silent), for running on very fine/debris-free tarmac, or if you have a sealed drivetrain like the Losi xxx-s.

[spoondori]

motor: Novak XBR Sport/EX 10.5 Brushless System

pitch: ???


i believe my chassis runs PERFECT.. but what is my pitch?..

Your motor has absoletly positively nothing at all in the whole world to do with your FDR, FYI.

Anyhow, I'd assume that with that high a number of teeth on your spur, I'd say you're using 64pitch spur/pinion gears. I may be wrong though, but I'd like to see how large a 48p 120+ tooth spur gear looks like!

[Grip]

ok thanks ccondrup for the link.. so pitch the teeth size.. it think.. how do i know what pitch im running?.. by looking at the spur?..

[JT]

Just to clear up a couple of posts above..... Your motor has EVERYTHING to do with the FDR you should be running!!! And you SHOULD care about the FDR!

The importance of using a FDR is that is can be employed across any chassis, regardless of make, model and internal ratio. If two cars are running similar motors on the same track, if the gear ratios employed are correct, the FDRs of both should be about the same because both are hauling about the same weight. Its then just a matter of factoring out the internal ratio to find the correct spur/pinion ratio to use. Very helpful, especially in racing but also in drifting.

FDRs will vary from track to track, the bigger, faster tracks needing a lower FDR. The lower the ratio, the slower the acceleration but the higher the speed, and visa versa. High revving brushless cans will typically need a higher FDR than a slower revving brushed can. As a guide, a good quality 19turn brushed motor will run well with a FDR or around 6.0 to 6.5 on a medium sized RC track. Brushless need higher, eg 8.0-9.0 or so, depending on the motor. So as i said, your motor has EVERYTHING to do with the FDR you should use. And you should care about FDRs or you'll not be getting best performance and could cook your motor/esc.

For my 18t Orion Drift Machine I use an FDR of 6.5 in my XRay, lowering it to 6.2 for the biggest of tracks. You guys running 3.x on brushless could enter the Bonneville Speed Trials, not sure about drifting though

[spoondori]

Just to clear up a couple of posts above..... Your motor has EVERYTHING to do with the FDR you should be running!!!

To clarify what I meant by "motor doesn't matter"...

When calculating the FDR, MOTOR DOES NOT MATTER! It doesn't matter whether I am running a 6T single or a 27T stocker, the FDR will stay EXACTLY THE SAME. You don't even have to have a motor in your car and you can STILL calculate your Final Drive. That's a moot point now. That said, I completely agree with you in that having the correct FDR/motor combination is EVERYTHING when it comes to racing these little cars. Now where's my beer...

This post has been edited by spoondori: May 22 2008, 04:37 AM

[JT]

Now where's my beer...

Cheers!!! Yep, agreed.

[sir slide alot]

It does somewhat have a point to gear BL motor's in the low numbers, as they have most torque at 0 RPM (stall) and it only goes down from that point.

Altough it is crazy to use a 8.5 at 4.5 FDR because you dont need that. And then we didn't mention the risk's of blowing wires in the motor from overcurrent and heat yet.

A Brushless should in a drift car NEVER exceed 50°C or ~120°F

Drift tires dont have much traction at all, so what's up with the "owww my motor has that much torque"? you dont need much, just enough to be comfortable.

more torque/speed means less control.


I have a 8.5 at 7.50/1 now, wich is were it should be at the minimum point.