Hi,

I bought a 2nd hand 450xl recently - 430LF motor
Had a 13 tooth pinion in it but looked quite worn, I received the 11 tooth with the heli as spare and have put that on, seems ok?

Was wondering - should I be using a 13 tooth instead and will an 11 make the motor run hotter or cooler ?
What differences can I expect to look for with an 11 tooth vs 13 tooth pinion.

any help appreciated...

The 11T is the 'longevity' setup. 13T is the 'performance' setup for that motor.

Beginners who are only hovering can use the 11T to get longer flight times. Once you're ready to go outside and fly around, switching to 13T will give you better performance, but will reduce flight time a bit.

I've heard of some folks running a 12T to sorta 'split the difference', and they report it works well. 12T is less common and harder to find though...

The 11T is good for flying and light 3D like loops flips and rolls. When you get into harder 3D stuff your going to want the 13T to gain headspeed... I like the longer flying times, and I'm no 3D pilot, so I use the 11T on all of my trex's.......

Thanks slider46...

I asked the question originally because most of what I have read before getting the Rex was to use the 11 tooth one as you suggested.
However, when I got the heli - I noticed that the guy was using a 13 tooth one - seeing this is my first computer radio and a step-up from the walkera's - I decided not to change anything as it was hovering as I bought it...

after playing a bit - I realised that the guy probably didn't know as much as I thought he did - so I copied the model in my optic 6 and began changing settings - such as pitch and throttle curves... seemd to go better!

When I crashed days later and had to change the main drive gear, I decided to change the pinion as I could now see how worn it really was. I only had an 11 spare so put it on!

Since then - I've noticed the motor RUNS HOTTER - which contradicts everything here and thus why I started asking, I thought it would run cooler due to the better ratio.

Now sitting at work reading and digesting, I think what's happened is now the lower gear ratio means lower head speed and so I do recall that I needed more throttle now with the 11 tooth than I did before with the 13.

This makes sense as more throttle will mean more pitch and thus more load! thus hotter motor..

I think what I might try/need is to increase the throttle curve now to compensate headspeed and thus require less pitch - I think this will bring the motor temperature back down!
Anyway - will try tomorrow after work I think

Pinion choice is governed by the target head speed you want to run.

Check this calulator: [link=http://www.readyheli.com/Online_Headspeed_Calculator_s/81.htm]Head Speed Calculator[/link]

You need to choose a target head speed, then gear it appropriately. Brushless motors run most efficiently and provide the most power the closer they're tun to 100%. This also benifits the ESC as well.

For the 430 motor which is a 3550kv motor:

2400 head speed = 11T pinion
2800 head speed = 12T pinion
3000 head speed = 13T pinion

Running a 13T pinion with a 2400 head speed put too much strain on the motor, thus the increased heat.

I Stuffed up...

It's actually a 420LF 3200kv - I guess that's why he had the 13 tooth pinion as I think that's the correct one for that motor...