HPI R40 Conversion

[Z06jim]

Well, I finally managed to get this thing converted to Brushless with a lot of kludging.

Installed:
7XL
4s Lipo
9920
UBEC

66/20 32p gears (3.3)
65mm dia tires
diff ratio 46/19 (2.42)
Final Gear Ratio 7.99
Estimated Weight ~ 5lbs
Estimated Speed by spreadsheet ~30 mph
Stock Speed Nitro ~ 45mph


Issues are:
Gearing
Motor ~ 160F :013:
Controller ~ 110F :027:
Batteries ~ 110F :027:

Everything I've read says this is geared too low???? :032:
Gear center spacing is at a premium ~1 3/8" center to center minimum
Know where I can get a 22T 5mm 32p pinion?

Any Thoughts?

[squeeforever]

E-mail Mike. He can possibly get you one.

[coolhandcountry]

the biggest I have seen is a 24 tooth 32pitch gear. I can't recall where i got it. Mike should be able to help you out. Do you have a heat sink on the motor?

[highhat]

Try Kershaw Designs

http://home.comcast.net/~milemarkers...ns/Pinions.htm

[Z06jim]

7XL has heat sink case
May have found part of the problem though, the 7XL was missing the set screw in the end cap and it was spinning loose. Hopefully didn't damage the motor.

Still trying to figure out how to get 65mm tires to run 45 mph.
Looks like total gear ratio of 6:1 may get me there with 4s Lipo
7.5:1 with 5s lipo

By the way Prop shaft adapters will give a good straight hub for use on a smooth shaft.
Come in 6mm and 5mm to 5/16" threaded shaft.
Radio Shack project enclosure #270-1805 ($3.79) is a perfect fit for Mike's Lipo's

No broken parts yet and drives like a go-cart:027: