Larger or smaller spur gear ?
 

Right Guys,
I run 27t stocks with a Yok BD, I have a few questions regards spur gear sizes and what effects they have on motors. At the moment I have an 83 tooth spur 48 pitch. If I ran an overall gearing of 7.5 with a monster motor and then changed to a 75 spur but kept the overall gearing at 7.5 would this change the performance of the motor ? and how.
I beleive alot of drivers just change the spur to move the weight of the motor back or forward. Lastly is it better to run a large/small spur gear with either a torque based motor like a co27 or an rpm based motor like a roar 27.
Thanks for any help guys :)

Stock 64 pitch. The bigger the spur the better. Its easier on the motor to turn the drive train. And a smoother power band from 0 to top speed. Off power you'll have a smoother off power roll very good for stock.
The smaller the pinion in reference to the spur is over all efficiency and less work on the motor. This will also give a wider gearing range. In rubber that will help.
64 vs 48 pitch?
I use 48, The larger teeth will almost last forever in any race condition.
Of coarse now day's spur's are effortless to change.
In stock I would run the 64 pitch.
Hope that helps? I'm not the wizard but maybe he'll show up and help us both. :tire:
Later.

I should mention that there are a lot of variable's to this question as is most.
My post was based on indoor carpet. Medium size track. :nod:

does this apply to all motors?

If you mean 48 pitch I suppose you could use this theory.
48 pitch is good with 19 turn or mod motors, or just any motor with a lot of torque.
64 pitch has finer teeth and your more likely to shred the teeth.
But stock I think its important to have a larger spur.
Its a much smoother feel and it would also be the same with a mod.
I'm surprised a wizard hasn't shown up on this thread, it would make for some good discussion. And get us away from the controversy threads. :nod:

Did you say controversy... :sneaky: 48 pitch spurs only...it's a conspiracy by ROAR to ban LiPo if you use anything else... :lol: Kidding of course. I just had to add that but I would like to see peoples answers to help give me some idea of where to start.

The only differences you will see by going to a smaller spur/pinion combo with the same ratio is a change in weight balance by how much it moves the motor and a decrease in efficiency due to smaller guys not having as good of a tooth alignment.