Gear size question

[hksk25]

I want to convert my Thunderslot Lola to a 18k H&R motor for a class in our club. My question is, what size diameter spur gear to use and sidewinder or anglewinder. The original gears are, Spur Diameter – 17.20 MM – Pinion Diameter – 6.75 MM . The motor is mounted as a slight anglewinder, for those not familiar car.

Thanks, Harry

[War Eagle River]

Use the same spur, and put the same size pinion gear on the new motor.

[hksk25]

I want to experiment with different ratios.

Harry

[Brumos RSR]

The NSR sidewinder gears are your best choice as they manufacture both the pinion and the spur. OEM is 12/32 12/31 may still allow you to max an 18k without killing you out of the corners. Search the Can Am 2019 proxy, DRW21 left some great tips for building a killer TS

[Kevan]

H&R 18 is a great motor capable of gearing down around 2.8:1

[Pappy]

I would add the 17.2mm and the 6.75mm diameters of the two gears and find two new gears that add up to 23.95mm.

The problem I've found is gears are usually not exactly the size the factory says they are. The manufacturers might all say their spur gear is 17.5mm in diameter but if you measure them you'll find out the brands are all a little different. Check the mess that your current gears are and you might want to find a gear that is a little larger or smaller in diameter for a better mesh.

The NSR 6913 lightweight pinion gear use to be listed as a 6.75mm diameter pinion but now it's listed as a 6.5mm. Same pinion.