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I am prepping a Losi JRX Pro with the XX Retrofit trans for a vintage class at my local track. We are allowed to run period correct tires with a tamiya 540 silver can. So with my 2.19:1 trans & stock Losi tires on the yellow dish wheels, what can I expect to gear this thing at for a track that has a half tight technical portion & a sweeper with a decently long straight leading back to turn 1. Track diagram attached. Oh yeah, 6 cell NIMH batteries only, I got a Pro-Tek 4200 pack enroute.

Thanks in advance.

Wow that's going to be slow! Nevertheless if everyone is running the same motor it should be pretty fun. Start with an 86 tooth spur and 25 tooth pinion. Adjust as necessary. You may need to go down to a 23 or so but you should be in the ballpark.

There are actually 2 types of silver can 540 motors out there. Everyone knows the Mabuchis. These are identifiable because they have 2 vent holes. The others look very very similar and these are the Johnson 540 motors. They have 4 vent holes. Most people wouldn't know the difference but now that you know what to look for you should be able to tell them apart. The Johnsons are slightly faster than the Mabuchis and are still perfectly legal to use. Tamiya actually had both but mostly used the Mabuchi. A local electronics store here sells the Johnsons brand new for $5.

If you have a brand new never been run motor there is a break in method which sounds crazy yet absolutely works. Use 2 AA batteries in series to give you about 3 volts. Hook these directly up the motor leads so it spins slowly. Here's the catch. You want the motor (not the batteries) completely submerged in a glass of water! Yes it works without shorting out. After 3 or 4 minutes you'll notice the water getting a bit dark in color from the brushes breaking in. Change the water and repeat the process until the water stays fairly clean. Your brushes are now broken in and your commutator perfectly shaped with the brushes matching them. They didn't heat up much so they stayed very true. You're done. It's a perfectly legal way to break in your motor for max performance. Do this to a Johnson 540 and you should have an advantage, especially over the people who didn't learn this trick in the mid 80's like some of us did! Don't listen to the people who tell you to spray anything inside the motor during break in. Also don't make the mistake of not breaking the motor in. Don't forget to put a drop of oil on the bushings when you are done.

Thanks Fred,

I have a stash of a few 4 hole 540's that I have been using in a spec mini copper class when we race indoors, and I was certainly planning on using one. I break all my stock brushed motors in water (tamiya, slash, etc) so I know that trick too. As far as I knew those 4 hole motors were hard to come by, and I have been scouring them up whenever I find them, wish I had some around here for $5 a shot.

Check electronics parts outlet stores if you have them. We have 2 here in Houston and they both have bins of Johnson 540's. I don't think they'll ever run out so if you ever need any let me know. One of those stores is just a few minutes drive from where I work.

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The water dipping trick yields vary various results... do it carefully, and get a few spares to experiment with

Paul