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Old 04-03-2009, 05:21 AM   #1
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Default Gear Ratio help

i need some help im running a grass meet soon with my b4 and i need some advice on gearing.Im running a 5.5 or 6.5 X11 lrp with a 87 spur.I dont want to cook it any suggestions on both motors.Also is the diff ratio on a b4 2.6?

Last edited by nhodd; 04-03-2009 at 05:39 AM.
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Old 04-03-2009, 07:34 AM   #2
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i need some help im running a grass meet soon with my b4 and i need some advice on gearing.Im running a 5.5 or 6.5 X11 lrp with a 87 spur.I dont want to cook it any suggestions on both motors.Also is the diff ratio on a b4 2.6?
2:6 1 is the exact gear ratio for your RC10B4. The Losi uses 2:5 1.
That sounds like a hot motor around 6000KV, try 15T Pinion, Mines a 5700KV and it has crazy power. Teiken was the golden standard back in the day, and now they make motors again. They can be more expensive but they are top notch. Castle Creations makes some pretty nice budget motors. Novak is good as well. All brushless motors are 3-phase motors which are pretty reliable in industry. Teiken, Novak, Castle Creations, Xceleron. That is my opinion on the order of quality. It is critical to get the gearing right, I'd suggest E-mailing the support staff and ask for gearing suggestions.
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Old 04-03-2009, 07:36 AM   #3
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I'd go with the 6.5 at around 23/87 and the 5.5 at aroun 21/87. You might want to look at a smaller spur gear... Check out this website:

http://www.comeseethis.com/gearing/gearing.htm

It's designed for Novak motors, but will work well with most brushless motors. Your B4 tranny ratio is 2.6:1.

I hope this helps; your car should be ballistically fast with a 6.5 or 5.5. I run an 8.5 in my B4 and 6.5 in my B44.
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Old 04-03-2009, 07:55 AM   #4
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There really is no answer anyone can suggest here since gearing choice comes down to the track you are running, every track isn't the same and requires different gearing, as well as being dependant on your batteries. Try checking at the track and see what people are running.
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Old 04-03-2009, 08:17 AM   #5
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true, +1, but it's also a good idea to E-mail the support staff to the manufacturer of your motor and ESC
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Old 04-03-2009, 08:25 AM   #6
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There really is no answer anyone can suggest here since gearing choice comes down to the track you are running, every track isn't the same and requires different gearing, as well as being dependant on your batteries. Try checking at the track and see what people are running.

This isn't exactly true... Motors do have a sweetspot and manufacturers recommend certain ratios because it's a good balance betwee heat and speed. Our motors produce a great deal of torque and a bigger pinion almost always makes you faster as the limiting factor in most off road situations is traction. Furthermore, it used to be very important to adjust gearing to make run time and changed from track to track. With our equipment these days, you probably don't ever need to adjust 1 tooth in either direction after you get your gearing in the sweet spot.

He doesn't need to call the manufacturer, just try the my recommendations above and take a look at the link I provided.
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Old 04-03-2009, 08:35 AM   #7
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This isn't exactly true... Motors do have a sweetspot and manufacturers recommend certain ratios because it's a good balance betwee heat and speed. Our motors produce a great deal of torque and a bigger pinion almost always makes you faster as the limiting factor in most off road situations is traction. Furthermore, it used to be very important to adjust gearing to make run time and changed from track to track. With our equipment these days, you probably don't ever need to adjust 1 tooth in either direction after you get your gearing in the sweet spot.

He doesn't need to call the manufacturer, just try the my recommendations above and take a look at the link I provided.

What motor manufacturer are you with?

I'm not saying that motors don't have "sweet spots," but are you suggesting that there is only one size motor that is a fits-all for all tracks and all situations? If that's so then a whole lot of companies need to cut back on their offerings.
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Old 04-03-2009, 09:01 AM   #8
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What motor manufacturer are you with?

I'm not saying that motors don't have "sweet spots," but are you suggesting that there is only one size motor that is a fits-all for all tracks and all situations? If that's so then a whole lot of companies need to cut back on their offerings.
I offered him solutions for a 6.5 and 5.5...
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Old 04-03-2009, 09:35 AM   #9
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I offered him solutions for a 6.5 and 5.5...
Yes, but you also said "Our motors produce a great deal of torque" so I am curious if you are just generalizing or giving out info based on your company's products?? It's generally accepted that ALL 6.5's or 5.5's are not the same, nor do all manufacturer's claim them to be.
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Old 04-03-2009, 10:28 AM   #10
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Yes, but you also said "Our motors produce a great deal of torque" so I am curious if you are just generalizing or giving out info based on your company's products?? It's generally accepted that ALL 6.5's or 5.5's are not the same, nor do all manufacturer's claim them to be.
When I said "our motors" I was referring to all of the brushless motors available. I have no affiliation with any manufacturer and pay retail for my equipment. I would agree that motors do vary from manufacturer to manufacturer for particular winds. That being said, the reference link above is for a Novak motors but will get you extremely close for any make of motor as they do vary but are close when you use the motors from the more popular manufacturers.

My biggest disagreement with your post above was your comment about track layouts and size. Because brushless motors do have a sweet spot, you shouldn't have to change gearing much once you find a ratio that is in the sweet spot (for this motor) without the motor overheating. On a bigger track, you made need to "motor up" and change to a faster wind; this of course will require adjusting your gear ratio to extract the best performance from the motor.

My comment about a bigger pinion will almost always make your car faster is true. It will however come at the expense of heat. This is why manufacturers offer motors of different winds; you can change motor and gearing to achieve the straight away speed needed on large tracks and use a different wind motor for the smaller and tighter tracks. With brushless, it's much better than it was with brushed motors and one motor seems to work in more situations than it did with brushed motors.
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Old 04-03-2009, 10:36 AM   #11
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My biggest disagreement with your post above was your comment about track layouts and size. Because brushless motors do have a sweet spot, you shouldn't have to change gearing much once you find a ratio that is in the sweet spot (for this motor) without the motor overheating. On a bigger track, you made need to "motor up" and change to a faster wind; this of course will require adjusting your gear ratio to extract the best performance from the motor.
But that is exactly why I first posted that there is no "pat/standing answer," because tracks and layouts vary so much that a guy can have too much motor and when he has it geared to the motor's sweetspot he's never able to get it up to speed because the motor is too big a particular the track. Then the motor runs hot because it's getting bogged down constantly.
Using your own "sweet spot" theory there appears an even greater need for more motor options in any racer's pitbox to properly match the track and layout they are running.
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Old 04-03-2009, 04:09 PM   #12
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2:6 1 is the exact gear ratio for your RC10B4. The Losi uses 2:5 1.
Depends on the Losi model, but the current XXX CRs, both buggy and truck, are a 2.43:1 transmission ratio.

I'm not aware of any Losi that has a 2.5:1 ratio. 2.56 perhaps??? (BK2/MF2)

Last edited by Dave H; 04-03-2009 at 04:20 PM.
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Old 04-03-2009, 04:14 PM   #13
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Depends on the Losi model, but the current XXX CRs, both buggy and truck, are a 2.43:1 transmission ratio.

I'm not aware of any Losi that has a 2.5:1 ratio. 2.56 perhaps???
It's Actually 2:43:1 I put some wrong info out there which I should know as I race the buggy

Novak appears to suggest the following:

http://www.hrcdistribution.com/pdf/m...k_velociti.pdf

Note this is for 6S NiMH

RC10B4-

5.5Turn
81T spur
16-17T pinion

6.5 Turn
81T spur
17-18T Pinion
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Old 04-03-2009, 04:59 PM   #14
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It's Actually 2:43:1 I put some wrong info out there which I should know as I race the buggy
Umm, a little trivial here, my bad, but hey might as well get it right, the gear ratio is correctly written as “2.43:1”. Spoken as 2 point 43 to 1. Commonly referred to as just 2.43, the 1 is frequently assumed in ratios. The : separates the two factors, it does not replace the decimal point.

The expanded Novak chart, and it’s important to note this is just a safe starting point, not necessarily recommended race gearing. In my experience it is quite common to be geared a little higher (lower ratio/FDR, i.e. bigger pinion) than this, especially with high turn motors like a 17.5. Bottom line is track performance and temps of course. And other brands might be a little different, but should be somewhat close.

http://teamnovak.com/tech_info/brush...r_gearing.html
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