I was looking for a starting point on gearing in a edm with 17.5 lipo on a 80ft flat indoor carpet track.
My tire circumference is 7.3. this will be a 2.4 tranny. Any help will be great.
Also this is a complete novak system if that matters.
Thanks

wow i cant believe all the help im not hearing.

Well going by what goes on in pan car, you're going to need a tiny spur and huge pinion with the 2.4 reduction thrown in there. I'd start out with at least an 88 spur and 44 pinion. You'll probably be going much higher than this though, even on a small track like that. Generally, everyone is shooting for about 140 degrees motor temp after 4 mins. At the 100ft runline track I race at on Wednesdays, that has us at crazy rollouts of 3.50+.

Hopefully that gets you started. 17.5 is gonna be tough in a gearbox car since they need so much gear. Gearing could get real interesting at a place like JT's...

Matt

We've been running this class for a while now and have some experience. Most recently I was running a 94 spur with pinions ranging from 55 to 64. I would start around a 94/58 and watch your motor temps. If you get high in the pinion range you can risk a motor meltdown. I have seen temps approaching 200 degrees so be careful.

thanks guys i will try it this friday and see what i come up with. im new to bl and would like to get a jump on next years tour
ill let you know what i find out

Watson can you turn on you pm's i have a question for you id like to ask

Mark,
Sorry, was off-line for a few days. I think my PM is active now.

jeffrey racing concepts is now making a direct drive conversion for the 2.40 terminator type cars. Check out dirt oval . com under his jrc threads.

You didn't list what kind of lap times you are shooting for, but I crunched some numbers figuring around a 3.4 second lap. +/-

80 ft track (Carpet)
Tire Size 2.32" Diam (7.3" Cir) = .608333333 Ft
80/.608333 = 131.5 Tire Rotations Per Lap
131.5/3.4 = 38.676 Tire Rotations Per Second ( 38.676 x 60 = 2320.588 Tire Rotations Per Minute)

2320.588 x 2.4 (gear box ratio) 5569.4112 (Motor RPM Needed)

17.5 motor w/ 7.2 v LIPO = approx 2200 x 7.2 = 15840 "unloaded rpm" x approx 60% (loaded rpm) 9504 usable RPM

9504 / 5569.4112 = 1.706

1.70 motor/gear ratio 88/52

How does this compare to what was run on the track?

SWTOUR,
Good math, almost exactly what I told him would work. It's nice when the numbers confirm the track results. Still though we have found these brushless can run a wide range of ratios with the same results.