REVOLUTION motor gearing for JRX2

[Bormac]

Hi Guys,
Ive got a Revolution motor (one of Losi's early mod's) and its a 16 triple. Can anyone provide me with a guide to what spur pinion combo would be good for this motor?

[DerbyDan]

I'm afraid I have no past experience of gearing a Jrx2 - but I guess if you had run a similar (wind) motor in another car with success, you could work out the o/a roll-out ratio & work backwards to get something suitable with the Losi?

As a thought - even a new/unused vintage motor is likely to have gone 'soft' over time & probably wouldn't give the performance it once would have. Will you 'Zap' the magnets to bring them up to strength (& re-align the N/S) before running it?

[Eau Rouge]

Back in the day, with the RC10, we'd start with the standard spur on the car, and then use the pinion number to match the motor turns, i.e. 16t pinion for a 16-turn motor with the stock 54t spur (32-pitch). That was the rule of thumb, and while not a specific gear ratio suggestion, you can at least figure out a good place to start for your car.

[Brandon G]

This is out of a JRX Pro manual. Hope it helps.

[Jirka]

Your 16*3 is called Brutus and it's not listed in Brandon G's list. There was however a Jr's Choice, that I know is a 17*1. But (almost?)all motors on the list were also so called "Wet"-magnet motors and Brutus was older "Dry"-magnet can based. Wet magnets did offer more magnetic field or something like that and therefor more torque but less RPM. So I think that You can start with Jr's Choice recommendation 20/86 and see how it goes with 2" wheels and tires. If motor gets too hot after a minute or two, use smaller pinion. If you use 2.2" wheels and larger diameter tires than there were in early 90, like Jrx2 stock tires, You should use smaller pinion gear. Gearing recommendation is also probably based for ROAR/US rules for 4-minute runtime and US style tracks.

If somebody knows all those winds in Brandon G's list, I would like to know them all.
Now I know that:
Motown Missle: 12*1
Jr's Choice: 17*1
MTM: 19*1 but with truck tires
stock, well...: 27*1.

Jirka

[Bormac]

Great info guys. Atleast I now have a better idea of where to start. I wonder what kind of ratio I need for this motor? ie: 6:1 or something.

[Bongo Fury]

I thought Jr's Choice was a 17 double?? Am I all wet again?

[Jirka]

I found Team Losi's old price list that was Effectice: 10/15/90 and on page 4 is a list of some Revolution motor winds.

So Bongo Fury ,You were right about Jr's Choice.

But I also found a MTM pic from Tamiyaclub, and on that pic MTM is 18*4.

Jirka

[Jirka]

And today I found an another "Team Losi Price List" Effective 3/15/93. There were couple of differences: Jr's Choice was now 17*3 and Motown Missile 12*4.

Jirka

[Bongo Fury]

And today I found an another "Team Losi Price List" Effective 3/15/93. There were couple of differences: Jr's Choice was now 17*3 and Motown Missile 12*4.

Jirka

Interesting. So maybe I'm half wet!