As I continue to work on creating the Sportsman Oval class for the kids, can anyone give me an approximate gearing for 27T brushed motors? I run all brushless in my cars, so I don't even know where to start on a brushed motor.

It's wide open throttle for 4 minutes on 4-cell. 300+ runline (I think) banked tri-oval (the grove for those familiar)

They will be running cap tires, so figure approx 2.35-2.45 dia on the tires.

Thanks!

what roll out are you running in b/l 13.5

Right around a 3.5, but that's for 7 seconds. I would say around a 2.6 or so for 8 seconds based on rough guess at the ratio for a 13.5 at that speed.

depends which stock motor it is ?

monster based like a 2.85 - 2.94


Blue colbolt motor like 2.70 - 2.56


those are gear ratios not rollout numbers

Dave,

Thank you. That's what I was looking for was a good starting point.

Most of what I have are Epic I believe. Picked them up as a used lot for these loaner cars.

Monsters have more RPM than Cobalts so they would need to be rolled out lower than a Cobalt.

Cobalts always seemed to be about 1.5 to 4 teeth higher than a Monster depending on the track size

I put 100/35 on all 4 cars and I'll adjust each from there based on temp and times. I'm not going for top speed, just reliable times and as close to the same times across all 4, so if I'm a bit under geared, it's not a deal breaker.

Now to open up that question, what's a good temp to shoot for after a 4 minute run?

Thanks!

I think my Co27's normally finish 4 min. around 150-160 F... They can be geared "hotter" than that, but they just slowed down, so that was sort of my optimum. (4-cells, carpet oval with about 160' racing line -- track laid out as rounded rectangle, with "sort of" 4 corners)