Tamiya semi truck 3 speed

[Legato]

Would it be worth to try and use in a crawler? I figure it would have crazy low gears.

[slugzracing]

It could help with gear reduction but they are big and will require a transfer case (another tranny, or custom gearbox) to be added since they only have one output shaft. An E-max tranny with a gear reduction from a cordless drill would probably be a better tranny for a devoted crawler.

[mrwonderful]

If you talk to fullmodtxt he figured out a way to bypass the extra tranny. I think he lengthend the output shaft and got drive cups on both ends.

[fullmodtxt]

Legato, I would not reccomend the trannies for real crawlers. They are a bit "clumsy", as in odd shaped, big and heavy. The gearing is not as low as you'd think it is! They are intended to use the extremely short tires on the semi-trucks; so when you add even 5-inch 2.2 tires, you cancel out the original overall gear ratio. With a 7-inch full size crawler tire, you'd never get the gearing right without getting crazy with additional reduction units.

I have one in my 2.2 truck. It's a bunch of fun, but it took a bunch of work to get it to function properly. I still had to adda single GD-600 to get the gearing right. A lathe motor might work w/o the GD, but I haven't tried it yet to find out for sure. The trannies are a bit fragile too. I've already killed one of them, and I don't push the truck very hard. You can see a few pics of it here:

http://www.nercc.net/photoalbum/thumbnails.php?album=14

[rbgerrish]

I'll second that. I've ran a 3 speed in my F150 crawler, and it didnt have the range of gears I was looking for. With a lathe motor 1st gear was good, but 2nd and 3rd were a little too fast. With a GD600, all the gears were super low and nice for crawling, but not enough difference between the 3. Perhaps a bigger pinion in the GD would be better? All in all, it makes for a fun and unique truck, but it's a pretty complicated and expensive way to do it.