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#1
30-11-2014
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Different Pinions?
I noticed all these different pinions, which I assume are just different amounts of teeth on them but how do different pinions effect the car? is it best to use certain pinions for certain track surfaces?
I just use the one that came in my bmax2 but curious to know about different ones and weather and if there is any difference on the car etc cheers 
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#3
30-11-2014
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Pinions alter the gear ratio. The gear ratio needs altering so that the available torque from the motor is used effectively. It would be unusual to change ratio for track surfaces, but it would be usual to try different ratios for different track layouts.
Ratio changes usually go with motor changes. The less winds the motor has (6.5 turn is less than 10.5 turn, for example) the smaller the pinion must be fitted. Also, ratio changes go with the amount of fixed timing you have on the motor; more timing usually needs a smaller pinion. If you are not changing your motor you are usually not changing you gear ratio and therefore not changing your pinion. If you don't have a range of motors to use don't bother buying a load of pinions. When you do change your motor ask around for what ratio people are running, that allows you to choose the right pinion and saves buying lots of them. HTH
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#5
30-11-2014
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Is the bmax fitted with the kit standard pinion & what motor did you have in the car before last night?
As a rule of thumb see the reply above from slowone.. Broadly, and I am sure I might get hammered here, there is a difference in gearing for brushed and brushless motors, however for the same "turn" motor using a smaller than standard pinion the car will accelerate faster but will have less top speed.. fitting a larger than standard pinion the car will accelerate slower but will have a higher top speed...
__________________
Don't believe the hype... Think for yourself.. 
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#6
30-11-2014
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prior to the Orion going in last night I had a 17.5t speed passion motor fitted
Quote:
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#7
01-12-2014
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You'll change gearing dependent on motor turns, equipment temperatures (ESC and motor) and track size.
The car manufacturer will (usually) state a recommended pinion size or overall gear ratio for each motor turn (given that you still have the stock spur gear). That's usually your best starting point. You might go up a tooth for a big, open course with no/few tight turns, you might go down a tooth for a small, tight course with lots of acceleration from almost stationary (indoors for instance). Then you might also choose a smaller or larger pinion depending on how hot your electrics get, which is dependent on how you've set up your ESC, boost/turbo etc, How much grip you have, and how you drive. Best off actually speaking to someone at the club to get some advice which is better related to the track you are driving at. (How big is it, what tyres are common, what surface is it and so on) But also worth having a small selection of pinions (4 or 5 maybe?), and possibly a couple of spur gears to play with, this will give you a nice range of gear ratios to play with, and it's not like they are expensive. An IR temp probe might be worth investing in too.
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#8
01-12-2014
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You will definitely need a pinion with less teeth to go from a 17.5 to an 11.5. Don't run the car with the kit pinion as you will very likely damage the motor, speedo or transmission - or all three!
As recommended above, ask at your local club about pinion selection for your new motor. If one of the faster drivers recommends a ratio, take one tooth off the pinion to start with to be on the safe side. Run the car for about two minutes, then stop and put your thumb on the motor. If you can hold it there for two seconds then you are about right for temperature. If you can't fit a smaller pinion, if it's easy (the motor feels no more than hand-warm) then go up by one tooth. The reason there is not definitive ratios for brushless motors is that it depends how you drive. If you have high corner speed and the motor does not lose a lot of revs at the apex, you can gear higher (more pinion teeth) because it is doing less work to accelerate the car. If you have low corner speeds or use the brakes a lot, you will need to gear lower (less pinion teeth) because the motor will be doing more work. The problem with the motor doing more work is that it gets hotter and that will eventually cause the motor to fail. In doing so, it can take your speedo with it. Too high gearing will put lots of strain on the transmission and could break something there. HTH
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#10
02-12-2014
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TBH, i'd not rely on the thumb test.
Far too much variability, i can happily plonk my thumb on a motor that's hot enough to make others yelp and suck their thumbs. And i'm sure there are people (kitchen workers for instance) who could go another 10-15 degrees hotter than that without breaking sweat..........
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#11
02-12-2014
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The thumb has to be calibrated! I've calibrated mine over the years and do have asbestos fingers. If someone has a temp gauge, read it then do the thumb test. It doesn't take long to work out if you've overdone it by using a thumb.
Gear ratios should only be checked against the clock, never a temp gauge. The right ratio is the one that goes fastest round the track, not the one giving a certain temp reading. The thumb test helps make sure that you don't wreck a motor, the clock tells you if that ratio is right. HTH
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