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Gears in the open in many designs 7 months 1 week ago #58280

I've been watching several chassi designs of these crawlers and scale pickups/trucks, and many of them just leave their spur and pinion gears in the open. The gearbox is always encased and sealed but why leave the spur and pinion gears uncovered?

Last year I bought one of Axial's SCX II kits, this chassi is very well sealed, and there are even inner fenders to buy for it to prevent sand and dirt from getting in. All gears are well sealed.



But looking at the RC4WD Trail Finder 2 chassi, one which I'd love to get because of its scale looks and leaf springs, it has its spur and pionion gears completely unprotected so sand and small stones could enter and do damage. Why don't they cover these gears? It's so simple to do!

erh, .. I meant to post this thread in the Technical section, ... oops.

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Last edit: by uncletom.

Gears in the open in many designs 7 months 1 week ago #58281

I moved it to the "Vintage Tamiya" - "Technical" section for you ... not sure that's mych better ;)

I wouldn't say it's "so simple" to enclose the spur gear, designing & making the injection moulding tooling required is expensive, but I would agree that it is not just sensible to enclose it, it's necessary - but it's surprising how often you see an exposed gear.

IIRC a lot of some IC engined cars have a slot in the chassis the spur gear poked through (even better bit of design there :blink:) to aid starting - but it's a (silly) design choice to have it on electric cars.

:)

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Gears in the open in many designs 7 months 1 week ago #58283

Thanks for you input, Jonny, and for moving the thread to the correct section.

Yes well I can imagine stones and grit getting into the machinery, and pretty soon I'll be buying new gears. That's not much fun is it. I remember buying the SCXII, with the Jeep Cherokee body, because it was such a complete design, and because of the extra fenders / mud guards.

Just look how it sits fine between the chassi and the body. And with sealed gears. I think there's a leaf spring kit for this one ...

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Last edit: by uncletom.

Gears in the open in many designs 7 months 1 week ago #58285

The original SCX hat an open gearbox, also quite noisy.
They introduced a cover a little while after.

Tamiya's CR01 has a nice and quiet sealed gearbox same with the new CC02

Got a TA05 with open mod .4 spurgear ,great and silent streetrunner till a particle gets in the gear. The open f&r outdrive gears are less of a problem.
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Last edit: by waterbok.

Gears in the open in many designs 7 months 1 week ago #58287

For what it's worth, I've got a couple of RC4WD Trail Finder 2 trucks and haven't had any trouble with contaminants getting in the gears. I suppose one advantage of being open is that things can also get out, especially water and mud which are more likely to be ingested than rocks. These may well filter through even a "closed" spur gear and then be unable to get out.

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Gears in the open in many designs 7 months 1 week ago #58289

Good point there Blakbird. I was considering that as well. But driving through mud and water, letting smaller particles into the gear case, isn't as bad as getting a larger pebble between gears either jamming the transmission, or at worst deforming a gear. Besides, after the run I'd still remove the gear cover to check for any water or mud inside.

To me, omitting such an obvious protection in such an expensive kit, is arrogant. Assuming that I will be doing nothing but crawling and trailing with the Trail Finder 2 is just plain dumb - It's a Toyota, let it live up to its standards. One other great disappointment is that there's no aftermarket cover either.

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Gears in the open in many designs 7 months 4 days ago #58339

I've been running those type of vehicles for around 15 years now, and I never had problems running without spur covers , even when vehicles has been fully submerged in water or run in the fall with all the leafes etc.

The first ones was built using Stampede transmissions (way before there was a "scale " rig to buy, AX10 came in 08' and the org SCX10 followed soon after)

Same can be said for most 2wd buggies, most of them have exposed spur and pinion, and usually there is never a problem, and there is a lot more dirt thrown from tires in that area than with a org style SCX10. The SCX10 never had a spur cover before the KIT version of the SCX II entered the market in 2016.
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Last edit: by caprinut.

Gears in the open in many designs 7 months 3 days ago #58361

Thank you for your input, Capri. Very interesting.
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Gears in the open in many designs 7 months 3 days ago #58369

when you go on a sand-winning terrain or beach, a small stone will sometimes come between the gears
just don't drive there! except if you want to drive formula offroad but then you must have a closed transmission






I have driven a lot on sand-winning terrain and with or without a gear cover there certainly came a stone between the gears, but especially when the gearmesh was not right it happened! 48 pitch spur vs 0.5 pitch pinion (mistake!)



Fist rule, provide spare parts such as a spur gear!
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Last edit: by poebe.

Gears in the open in many designs 7 months 3 days ago #58376

Thanks Poe. Well, I always see to it using the correct pitch on the gears. Anything else is a disaster.
Ok, so you mean I should leave a small space between the pinion and spur gears, so that stones will not get stuck?

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