gear ration question

[spookyseven]

ok, i figured out a plan to build a transfer case and tranny. the way i want to build my transfercase wont change my gear ratio, so the only way to change my gear ratio is to change my spur gear and pinion gear. so if im going to use a 55 turn lathe mortor and 2.2 wheels, and maxx diffs, how many teeth would i need on my spur and pinion gear to get a descent crawling ratio?

[spookyseven]

wow, i cant spell, i meant gear RATIO question...

[TwistedCreations]

yeah a ration is food

[spookyseven]

Originally Posted by TwistedCreations

yeah a ration is food

does your village ration thier food....


no really, does anyone have an answer for my question?

[toyofast]

You want to know what pinion and spur to run to get a good crawl ratio but you don't mention what your final tranny/t-case ratio is or will be..... ? Or will the tranny and t-case both be completely 1:1 ratio?

[spookyseven]

my tranny will only consist of the spur and pinion gear, and it will drive the transfer case with a shaft. the transfer case has a 1:1 ratio. so the only way to change my gear ratio is changing the spur and pinion gear. so my question is how many teeth should i run on each gear to to get a descent crawl ratio?

[Jeckler]

I doubt you'll be able to do it with only two gears. Maxx diffs are 2.84:1 ratio. Let's say you want a final of 70:1. That means your tranny will need to be at 25:1 (roughly). With a 9t pinion, you'd need a 225t spur gear. Yea, that'll happen.

[spookyseven]

Originally Posted by Jeckler

I doubt you'll be able to do it with only two gears. Maxx diffs are 2.84:1 ratio. Let's say you want a final of 70:1. That means your tranny will need to be at 25:1 (roughly). With a 9t pinion, you'd need a 225t spur gear. Yea, that'll happen.

well, thanx for the help, i think that if the spur gear would have to be that big i think ill just go find a pede tranny, does anyone have one they want to sell?

[Grizzly4x4]

Axshully with 2.2 wheels (I'm assuming no bigger than 5" tire) and a lathe motor you really only need a crawl ration ( ) of about 25 to 1. A stock clod has 30 to 1 and with a lathe motor will crawl well with the stock tires.

So if you use a Maxx diff: 25/2.84 = 8.8

8.8 x 9 (pinion) = 79

I dont know if they make a 79 tooth spur but a 75 tooth spur would net you.

75/9 x 2.84 = 23.7 to 1 crawl ratio. I bet that would werk.

[spookyseven]

Originally Posted by Grizzly4x4

Axshully with 2.2 wheels (I'm assuming no bigger than 5" tire) and a lathe motor you really only need a crawl ration ( ) of about 25 to 1. A stock clod has 30 to 1 and with a lathe motor will crawl well with the stock tires.

So if you use a Maxx diff: 25/2.84 = 8.8

8.8 x 9 (pinion) = 79

I dont know if they make a 79 tooth spur but a 75 tooth spur would net you.

75/9 x 2.84 = 23.7 to 1 crawl ratio. I bet that would werk.

ok, so 75 tooth it is, off to towerhobbies i go.....hehe

[spookyseven]

hey griz, what would the ratio be with a 81 tooth spur? but its 48 pitch, so i would have to find a different pinion

[Ace]

If you still want 8.33:1 you'll need a 81/x=8.33 or 9.72 tooth or 10 tooth.

Don't think they make'm!

I see 12 tooth in tower... 93 spur also

93/12=7.75:1

7.75*2.84=22:1

22:1 with 5" tires and say 10,000 rpm lathe motor gives a top speed of about:

6.73 mph so if I didn't screw up it should work well!

[Grizzly4x4]

Great answer Ace. I just did some checking.

My Traxxas 4Tec crawler has a 96T/14T and the belt drive is 2.13 reduction. For a final reduction of: 6.86 x 2.13 = 14.6
With 4" tall Dirt Daws and a lathe motor it werks great so the numbers Ace gave you should be fine.

[JasonInAugusta]

Originally Posted by spookyseven

ok, i figured out a plan to build a transfer case and tranny. the way i want to build my transfercase wont change my gear ratio, so the only way to change my gear ratio is to change my spur gear and pinion gear. so if im going to use a 55 turn lathe mortor and 2.2 wheels, and maxx diffs, how many teeth would i need on my spur and pinion gear to get a descent crawling ratio?

RC Alloys makes a 1:1 transfer case that was designed for the plastic Tamiya 3-speed trannies.

He was making them for Hua, but Hua can't get the trannies anymore. If you get with Bill I'm sure he'll sell you one.

[spookyseven]

Originally Posted by Grizzly4x4

Great answer Ace. I just did some checking.

My Traxxas 4Tec crawler has a 96T/14T and the belt drive is 2.13 reduction. For a final reduction of: 6.86 x 2.13 = 14.6
With 4" tall Dirt Daws and a lathe motor it werks great so the numbers Ace gave you should be fine.

4 tec crawler? how do u get that to work? is it just longer a arms? how did u get the 2.2 wheels to fit? are they the same hexes?

[Grizzly4x4]

The chassis is stock except for some very minor mods and different shocks. It doesn't have much suspension travel but the low CG helps make up for it.

Touring cars use a 12mm hex just like so the 2.2 wheels fit right on. The outer stub axle is a little short so the wheel nut just barely fits on but I have not had any problems.

It's not badass or anything but it sure is fun at the construction site or in the backyard. Here's a link to some pics:
http://www.rccrawler.com/forum/showthread.php?t=4981

[spookyseven]

hey griz, will a maxx slider hook up to the u joint on the axle tub of a 4 tec?

[Grizzly4x4]

Originally Posted by spookyseven

hey griz, will a maxx slider hook up to the u joint on the axle tub of a 4 tec?

No, but a Stampede slider will.
I have all the part to widen my 4Tec, the nitro 4Tec is wider than the electric so with a few simple mods you can put those components on and the conversion also uses Stampede sliders. That's how I discovered that.