Gearing Question

[Sh0rtBus]

Okay, so I searched a little and didn't really come up with a great answer, although I'm sure it's probably here somewhere. Just don't have hours to search.

So here it is:

Picked a Reedy Stump Puller and installed it in my MRC RTR last night. Damn that thing's fast! My MRC can do donuts now! Wheelspeed is probably almost double that of the stock Losi motor.

Problem is it gets hot fairly quickly. Currently running a 2s lipo, which worked fine with the stock motor and gave pretty decent power and awesome run time.

I'm looking for suggestions as to what gearing I should swap in to keep that motor running nice and cool. Not certain what's on it right now, as I didn't take the time to count the teeth, but I'm assuming stock ratio right now.

So....what suggestions do you more experienced MRC guys have for me? I have added a little weight to my rig in the form of Dark Soul OMF beadlocks with lead weight in the fronts. So I'll need good low-end torque with enough of a bump to get over tough obstacles.

[JeremyH]

How quickly? I've found that most of these smaller brushed motors (Anarchy, HH, Insane and others) that perform well in the MRC get hot quickly, no matter what. I run my comp MRC (with a performance brushed motor) for one pack at a time then let it cool.

Originally Posted by Sh0rtBus

So....what suggestions do you more experienced MRC guys have for me? I have added a little weight to my rig in the form of Dark Soul OMF beadlocks with lead weight in the fronts. So I'll need good low-end torque with enough of a bump to get over tough obstacles.

I've found that these trucks need weight in the front and rear. If the rear is too light, it will flip over easily on descents. I have 3/4oz on each of my rear lockouts (mounted using the Dlux holders).

[Sh0rtBus]

Well.....my 1 pack that I'm running yeilds better than 30 minutes of good, solid run time on a full charge. This motor gets hot within less than 5 minutes. And as it worked fine on the stock motor, I'm pretty certain there's no binding anywhere in the drive line.

[JeremyH]

Hummm.....yeah, 5 minutes is pretty quick. I can usually run mine for 10-15 mins straight (depending on ambient temps) before it gets too hot for my liking....

[winnerone23]

A quick count on ur gearing now is important for good help..

I ran a brood anarchy 17t on 14/66, 12/62, an 11/60. Too fast.
HH mini torque master 33t on 11/60.. too slow, great torque!

[Sh0rtBus]

After talking to the original owner of this motor & trans, I believe it was in fact stock gearing. The previous rig it was installed on was never run for more than about 5 mintues at a time, or about the length of a comp course, before being allowed to cool down.

So having said all that now, any recommendations on what gearing I should be running? IIRC, the Stump Puller is a 19T.

[JeremyH]

If it's simply too fast for you, then your easiest bet to cool off the motor is to install a smaller pinion on the motor...

[Sh0rtBus]

Originally Posted by JeremyH

If it's simply too fast for you, then your easiest bet to cool off the motor is to install a smaller pinion on the motor...

Which would have a better effect? Smaller pinion, or smaller spur? or am I stupid because it's Monday and a smaller spur equals more speed? I can't think today.....stayed up too late playing Far Cry 3.

Edit: NVM....I'm stupid and answered my own question. Anyone know what the stock pinion happens to be?

[JeremyH]

Either a smaller pinion or larger spur will slow the truck down (you are looking for making the spur:pinion ratio a larger number).

[Sh0rtBus]

Originally Posted by JeremyH

Either a smaller pinion or larger spur will slow the truck down (you are looking for making the spur:pinion ratio a larger number).

Yeah....like I said...stayed up too late on my PS3. And the stock pinion happens to be a 14T, making the ratio 86:1, according to the owner's manual. If I drop it to a 13T the ratio becomes 92:1. Wondering if I should drop down to a 12T.

I know some people like 32P for larger scaler rigs. Any benefit to going that route on the MRC?

[JeremyH]

I would get a handful of those pinions and try some different ones. IIRC, I run an 11t on my truck. I've never had an issue with the stock (48p) spur on my truck, so I just keep running those...

[Sh0rtBus]

So 11T pinion and stock spur? I'll give it a shot.