MR4 BX Help with motor & pinion etc

[gregnottage]

Hi Guys,

I've just purchased an MR4 BX from eBay and I'm after some advice on suitable spur gear & pinion setups.

I'm looking to buy an LRP 4.5 brushless motor with the Sphere Comp ESC. However, I'm unsure what I need to purchase in terms of spur gear & pinion to work with the LRP motor & ESC?

Please can you help me with what I need?

Also, do I need to worry about a fan & heatsync to keep the motor cool?

Thanks in advance for any help or advice you can share with me.

Kind Regards,

Greg.

[spenner]

Hi Greg,

Hope you enjoy the Yoke i did
The standard spur on the car is fine and with regard pinion you should be looking around 15-18.
I ran the Novak brushless in the car with the 5.5 i can honestly say i would have never put the 4.5 in.
By the way the car will be with you tomorrow.

[gregnottage]

Nice one!!!

I didn't realise you lived on here too ;-)

Looking forward to getting it and I'll have a play around with the different pinions as you suggest.

So I take it I don't need to alter the existing spur?

Thanks,

G.

[spenner]

You got to have something to look at on the tintin net.
The spur thats on the car is fine, but it could do with changing now as a stone got caught in there and marked it. There is one in there.

[geebee]

Hi,

I use 84/15 with my Vector X11 6.5. I think you will have gear mesh problems using a smaller pinion with this 84 spur gear. Change it to a 87 spur gear and start with a 14 tooth pinion with the 4.5. Then check the temperature. I think a 15 tooth pinion will be too big but you may have a try.

A 4.5 motor will be too powerful for an offroad car I think. You may also have ESC temperature issues with this motor if you don't use a fan. The body of the Yok is tight and needs to be cut if you decide to use a fan.
If I were you I would rather buy a 5.5 or even a 6.5.

I hope this helps.

Gil

[level-4]

i have a novak 4.5 in mine, ran it last weekend for the first time. had it geared 15/84 no heat issues. car was a bit loose so i have flipped the rear ball studs.