Questions about gearing

[kevden45]

Hello this is really two questions in one, firstly I have a Yokomo b max 2 that i've just got set up it has a 6.5turn speed passion competition v3 motor and I'll be running saddle lipo's at 5000mah, I understand how FDR works for gearing and that but looking at the instructions the lowest pinion size you can use is 20t now I have set this up at 23/80 will this be okay as the track I'll be running on is pretty tight so I'm looking more for accelaration it gives me an FDR of 9.4. My second question is concerning at Associated B44.2 again it's about gearing but this time with a 13.5T would it be okay setting this up at 23/81 that gives me a FDR of 8.80, I hope someone can help as I'm having trouble figuring out whats needed cheers. 

[Si Coe]

OK - First things first take the 6.5t out of the Bmax and put it in the B44!

6.5t is really a bit much for a 2wd buggy on a big open outdoor astro track in summer - indoors its mental. I've started using a 13.5 indoors myself and found it quicker than running my normal 8.5t because control matters much more on a tight track.

 

As for gearing - I don't know the internal ratios for the Bmax or B44 of the top of my head, but in my Durango 210 I was running 23/87 for 6.5t, 26/78 for 10.5t and 28/78 for 13.5t

 

13.5t's especially can pull some remarkably high gearings while still managing decent acceleration. You'll need a high gearing and some timing boost to avoid being left behind on the straights.

Edited January 10, 2015 by Si Coe

[kevden45]

Cheers si coe, yeah I thought 6.5t was a bit mental for indoors I got it with the buggy but I am going to replace it with a 13.5t soon, The transmission ratio for the B44 is 2.5.1 I'm not sure what it is for the b-max, I've popped a 24/81 in the B44 I'll see how it feels with that in, when you say left behind on the straights if you don't have a high gearing, is that due to the car just having more acceleration and not much top speed with low gearing? and is it just trying to find a blance between good acceleration and good overall top speed? sorry for the noob questions I'm pretty new to this cheers. 

[Si Coe]

Yeah, 13.5t's have loads of torque so can pull a high gear, but don't have much top speed. Run one at the same gearing as the 6.5t and it will be really slow. I'd be running some with 25+ teeth for sure in any car.

[kevden45]

Okay cheers si coe, I'll see what the b44 feels like with the 24t pinion in if it's slow i'll up the gearing because I have pinions between 23-33 so I should find something to suit thanks for the advice.