Clod Buster internal ratio... - RC-Monster Forums

lincpimp · **Clod Buster internal ratio... -** 01.07.2009, 12:17 PM

Wondering what it is? I know they come stock with a 13-14t pinion (not sure which...)

I am looking for the ratio of the tranny and the "spur" gear size... It has a 3 gear tranny, and the "spur" is directly attached to the first gear in the tranny. Maybe it would be considered a 4 gear tranny, as it has a double reduction internally... Anyways i want an easy way to plug numbers into the speed calc so that I can determine what motors to use.

Any help is greatly appreciated!

lincpimp · 01.07.2009, 12:53 PM

May have answered my own question, but have a look and see if I am anywhere near correct...

Pinion 13t
Spur 50t

Diff gear 40t
Counter gear 44t

And the spur and counter gear have 15t gears attached to them.

So here is the speed calc with a 55t motor on 3s lipo with Moab xl tires.

Differential Ratio: 2.66
Transmission Ratio: 2.9333
Other Ratio: 1
Spur Tooth Count: 50
Pinion Tooth Count: 13
Total Voltage: 11.1
Motor KV: 1150
Tire Diameter (inches): 7.25
Tire Ballooning (inches): 0
Spur/Pinion Ratio: 3.85 : 1
Total Ratio: 30.00992 : 1
Tire Circumference (inches): 22.78 inches (578.52 mm)
Total Motor Speed: 12765 RPM
Vehicle Speed: 9.17 mph (14.74 km/h)
Effective KV Value: 1150

So Chip Cross seems to think a pair of 45t motors will be a bit better than the 55t motors, but with 7t pinions instead of the stock 13t pinions... That would drop the speed to about 5 mph, which is a bit slow for my uses.

Maybe a 10t pinion, that would be around 7mph.

skellyo · 01.07.2009, 12:59 PM

You can extrapolate the final gear ratio from here too:
http://www.clodtalk.com/viewtopic.php?f=11&t=237

lincpimp · 01.07.2009, 01:09 PM

Quote:

Originally Posted by skellyo

You can extrapolate the final gear ratio from here too:
http://www.clodtalk.com/viewtopic.php?f=11&t=237

Thanks Sean, looks like I got it right. I think I will pick up another 45t motor and give that setup a try...

kulangflow · 01.07.2009, 01:32 PM

In my Clod crawler, I ran 55t motors on 2s. I had a 10t up front and a 9t in back to help even out the infamous "Clod-stall". It had enough wheel-speed for everything I did with it.

Never should have sold that one. It was a great rig.

What's_nitro? · 01.07.2009, 01:40 PM

Could you please explain this "clod stall" phenomenon? Is it related to the dual motor arrangement? I have the Berg 2.2, so I'm a bit concerned.

Arct1k · 01.07.2009, 01:40 PM

Running 3s 55t on 9T / 8T with xls

lincpimp · 01.07.2009, 01:57 PM

Quote:

Originally Posted by Arct1k

Running 3s 55t on 9T / 8T with xls

Thanks, and BTW, nice avatar...

Quote:

Originally Posted by What's_nitro?

Could you please explain this "clod stall" phenomenon? Is it related to the dual motor arrangement? I have the Berg 2.2, so I'm a bit concerned.

Cold stall is when you are running at a certain throttle amount, both motors get the same voltage. Well if you are climbing the rear motor takes more load, and that voltage may not be enough to keep the motor turning so it stops. Only real way to help this is to run a lower pinion in the rear for more reduction, or run 2 seperate speed controls off of a stick radio independently. So you control both motors with a seperate sticks, and when you climb you give the rear a bit more than the front... That is how I understand it...

What's_nitro? · 01.07.2009, 02:04 PM

I get it, thanks Linc!

lincpimp · 01.07.2009, 02:12 PM

Quote:

Originally Posted by What's_nitro?

I get it, thanks Linc!

No prob, now I have to find a 45t integy... Anyone got a spare?

kulangflow · 01.07.2009, 02:24 PM

Quote:

Originally Posted by lincpimp

That is how I understand it...

That is how I understand it as well.

It's actually an advantage on some uphill climbs because the back wheels won't flip you over backward. It allows the front wheels to pull you up. You do want to have some control over it though which is what Linc was talking about.

Watch 2:08-2:22 of this video of my Clod. I was able to get up a near vertical climb that would be impossible for most shafty's I've ever seen/used. It was even more impressive in person than on the video. MOA crawlers are nuts, which is why Bergs are becoming so popular.

lincpimp · 01.07.2009, 02:30 PM

Cool vid. I may have to mismatch my gearing. I have a few pinions here, and an not sure the truck has adj motor mounts as it is still in the mail...

I will post pics when I get it!

What's_nitro? · 01.07.2009, 02:44 PM

Nice video, I love that song too. That was a pretty steep climb.

kulangflow · 01.07.2009, 03:20 PM

Thanks! Did you notice the rear diff was unlocked? :-)

You can see the clod-stall working on a couple of climbs right at the beginning too at 0:07 and 0:13.

Linc,

If you need them, I have two brand new 8t long pinions from RC4WD that are made for Clodbusters. I bought them from JRH, but never installed them.

They're this only 8t.

Anyway, they're yours if you think you can use them.

lincpimp · 01.07.2009, 03:32 PM

Quote:

Originally Posted by kulangflow

Thanks! Did you notice the rear diff was unlocked? :-)

You can see the clod-stall working on a couple of climbs right at the beginning too at 0:07 and 0:13.

Linc,

If you need them, I have two brand new 8t long pinions from RC4WD that are made for Clodbusters. I bought them from JRH, but never installed them.

They're this only 8t.

Anyway, they're yours if you think you can use them.

Sent you a pm about them!