Loose pinions

[Deslot]

New to 1/24 racing. We have been racing flex chassis on my routes wood track. The tire are silicone covered foams problem after a couple of nights on the track the pinions come loose and slide towards the motor. I’m wanting to know what the fix is for this problem. By the way these cars are a blast to rip around the track very fast and hooked ip👍🏁. Thanks in advance, Tim

[4424ever]

If the pinion is brass solder it
if it’s not brass get brass pinions

[Pappy]

There are two types of pinions, solder-on and press-on. The only reason I can see for the pinions to come loose is either they are press on and someone used them more than once or they are solder on and someone didn't do it right. Way back in the early sixties when I was a kid we sometimes used loctite to hold them on only because we didn't know any better.

[Deslot]

Thank you very much will be heating up the soldering iron👍

[Kevan]

Tin the motor shaft first with good flux

[Deslot]

Thank you Kevan with additional info. Like I said not real knowledgeable with 1/24. But they are Fun and fast

[chrisguyw]

And do yourself a favour, use steel (not brass) pinions.

Cheers
Chris Walker

[Deslot]

Got it👍

[Bill from NH]

Steel pinions wear better than brass, so they'll last longer Tim. Both steel & brass pinions can be soldered on. When i ran flexi cars 15-20 yrs ago, Sonic made stainless steel press-on pinions with a bore that was hexagonal shaped instead of cylindrical. These pinions could be pressed-on & removed numerous times before they had to be soldered on. I do not know if Sonic still makes these pinions or not. Soldering is my preferred method for attaching pinions to motors.

[Pappy]

Tin the motor shaft first with good flux

Yes, and don't use acid flux. If you are going to use a new solder on pinion tin the shaft and place the pinion on the end of the shaft. Place a clean/hot soldering iron on the other side of the pinion and press on it until the heat melts the solder on the shaft and the pinion slides on. If you have any solder on the iron the solder will end up between the teeth on the pinion and you'll have to cut it out with an Xacto knife.

[Bill from NH]

I've always used acid flux, even with brass solder-on pinions. It's the easiest way to tin the arm shaft.

[mattb]

I'm not good at it, but I do it like Butch said. No solder on the gear, just the shaft. Clean iron heat the end of the pinion till it slides on. It's about 50-50 whether I get it where it needs to be and no solder on the teeth.

[SpeedyNH]

i usually put a phenolic arm spacer next to the motor bearing (freshly oiled) to keep the carp out, put some acid flux on the shaft and in the pinion, slide it on, wick the solder in (quickly, with a 90W iron), spin it around to distribute the solder while it's still hot, hit it again and then flush it off and re-oil the bearing. i leave the phenolic spacer on the shaft to protect the bearing, and also in case i want to change the pinion.
about half the time i tin the shaft first (and sometimes the pinion as well), but i do get lazy or in a hurry.
but that's just me. comes from what i used to do with high-end commercial track cars.
it's harder to get the right spacing than it is to solder it on. but after a while you get used to it.

hiya Bill!
(sorry, i couldn't resist. but i bet that you haven't seen too many of My pinions come off! LOL.)
speed

[Bill from NH]

No Speedy, you're not a person I've seen loose pinions. I addition to your one phenolic spacer, I take a second, sometimes two additional spacers & slot them to the arm hole. I put all spacers on the arm & solder on the pinion.Then I remove the slotted one(s) with an X-acto knife, tweezers, or something else pointed. This spaces the pinion away from the bearing/bushing & provides enough clearance to slide in a gear puller for pinion removal.

[Pappy]

Acid flux is very corrosive but it does work better. I have used it on motor shafts but if I do I push the motor shaft through a paper towel and wrap the towel around the motor to protect it from the acid flux. Then I'll wash the whole motor down in water. Water doesn't hurt a motor, just dry it out real good.

Another trick to make sure the pinion is positioned right on the shaft is to put the motor in the chassis, place the pinion on the shaft, position it where you want it, mark any extra shaft sticking out beyond the pinion, take the motor out of the chassis and cut off the extra shaft. So when you slide the pinion on while soldering just push it in until it's even with the end of the shaft.

[Bill from NH]

Another tip is to put your motor in a parts small plastic bag or a sandwich bag & stick the arm shaft through the plastic for soldering.

[SpeedyNH]

the plastic bag will melt!

[RichD]

I always used acid flux when soldering on pinions. First I would rough up the armature shaft with 200 grit paper, then I would tin the shaft. I put a little flux on the inside of the pinion and used a clean iron to push the pinion on to the shaft. Using that method I never had a pinion come loose and I never got solder between the pinion's teeth. If you are concerned about the pinion ending up in the wrong place you can use a gear press to push the pinion on and then apply heat to the end of the shaft. Acid flux should be washed off when you are done or you will get some rust.

[Deslot]

Wow thanks for all the insight. It’s always nice to have questions and technical issues answered with all the knowledge that frequent this board. Thank you again. Tim