under or over geared? - RC-Monster Forums

jhautz · 09.11.2007, 01:53 PM

Quote:

Originally Posted by Hakan_J

I really wonder if "cold esc + hot motor + cold battery = under geared" is correct, it doesnt seem to be true for me atleast. I have no sticky driveline or anything like that but when I overgear my motor gets really hot but everything else stays cool

Whats your setup? If you have a very capable ESC and Battery setup, but a marginal motor, it is possible to see that.

Hakan_J · 02:35 PM

Quote:

Originally Posted by jhautz

Whats your setup? If you have a very capable ESC and Battery setup, but a marginal motor, it is possible to see that.

MM, 4s 8000mah TrueRc lipo and lehner 1940/8 geared 16/48 or 13/48 in a matrix rtr and the same setup in a matrix pro.

EDIT:
The RTR get a little hotter, I think the the RTR has higher gear ration in the diffs.

jhautz · 09.11.2007, 03:22 PM

Im rather surprised to see that. I would think the MM and TrueRC lipos would get stressed sooner than the Lehner 1940.

I also have a converted Matrix buggy. You are right about the diffs. They do run a screwy setup in there. The RTR and the FTE both come with 9/26 mod 1.5 gearing (2.889 ratio). Thats a really tall ratio compared to most standard diff buggys (13/43 3.308 ratio), which forces you to run what seems to be a very low pinion/spur ratio when you listen to what others are running. I found that the 13/46 was about as high as I wanted to go with the stock diffs before I started seeing heat issues.

But I am still surprised that you are seeing heat in only the motor and not the ESC.

Also, is that just a typo or are you really running a 48T spur??? Most are running 46T.

Hakan_J · 09.11.2007, 03:33 PM

Quote:

Originally Posted by jhautz

Also, is that just a typo or are you really running a 48T spur??? Most are running 46T.

No your right its 46!

If I'm running 16/46 in my Pro I get about 170-180 F on the motor but my brother gets up to 200F in his RTR. Esc and lipos are not getting hot at all.

We will experiment with 13 pinions this weekend to see how much of a difference that makes, but still "over geared -> cool motor" doesn't fit very well for us. I really don't think that his rtr with 16/46 is under geared? Do you?

lutach · 09.11.2007, 03:49 PM

Quote:

Originally Posted by Hakan_J

No your right its 46!

If I'm running 16/46 in my Pro I get about 170-180 F on the motor but my brother gets up to 200F in his RTR. Esc and lipos are not getting hot at all.

We will experiment with 13 pinions this weekend to see how much of a difference that makes, but still "over geared -> cool motor" doesn't fit very well for us. I really don't think that his rtr with 16/46 is under geared? Do you?

I ran a 13T/51T and the motor got pretty hot and that is a 3.9:1 ratio. Now with the 17T/51 it will be a 3:1 ratio. This to me will make everything run hotter right? Let me know how the 13T/46T (3.5:1 ratio) turns out.