Hey Rich, you are right to a point. I think alot depends on the track you are running on. If you run on a track with a lot of longer straights, then you would want a larger spur cuz you can pull longer going down the straight before your motor tops out and the performance curve flattens. If you run on a medium track with medium straights or a smaller track, the smaller spur will be better because you can get to top speed quicker. I have always been told you want your car to be pulling(accelerating) at least 3/4 of the length of the longest straight on your track. Just my $0.02

Torq

If the pinion is the same while changing the spur gear the overall gear ratio changes. The same (and easier method) is to change the pinion and keep the same spur gear. And, yep, this changes acceleration and top-end characteristics.

If the ratio is kept the same when changing the spur gear by also adjusting the pinion, then there is no difference in acceleration and top-end characteristics.

lem2 was keeping his ratio the same.

-Rich

Yeah that's pretty much what i was trying to say...

I replied to his post above. :)

Spur Gear
 

Thanks guys!!!

I was just a bit confused if I will use it since I have 69, 72 and 75.

Thanks for clearing up the cloud in my head!!!!!


So if the ratio is the same, regardless of spur size, it will accelerate the same with a smaller spur as long as it has the same ratio.

Cause all along, I thought, with a bigger spur the stock motor will have a harder time turning the shaft. even with the same ratio.
Thanks again. . . .

will be back soon with my ignoramous questions, hehehehe.

Hey Rich, even if the gear ratio stays the same, the time it takes to reach top end changes. I forgot to say that he has to change the pinion also when he changes the spur gear. It will take a 100/25 (4.0 ratio) longer to top out than it would take a 80/20 (also a 4.0) to reach top speed. IT is easier to spin a smaller spur gear faster than a larger one. It doesnt really affect the bottom end much. It just feels like it is faster out of the corner. Ill try to explain it this way.(perfect world situation-Identical cars with exactly the same esc, motor, everyting is the same) A guy with a 75 tooth gear will beat a guy with a 100 tooth out of the corner but at the end of a long straight away, the two cars will be side by side, it just took the 100 tooth car a little longer to get to top speed.

Torquer - I sent an email to a guy I know who works with the Honda racing development folks and asked him to poke his head on here and post.

He and I had this same discussion a while ago and I was taking your point of view. But, they were able to explain to me why what I thought (and what you think :) ) is not the case.

He won't see my email until tomorrow, however.

Anyways, I'm off to go race! First race of the outdoor season is today. The TC3 is on the shelf since it is nitro all summer for me.

-Rich

Torquer--- are you sure which would you rather drive a big rig equiped with a standard 24" diameter steering wheel, or one decked out with a 6" diameter topfuel dragster steering wheel...... seems to me the 24: wheel would spin alot easier!??

Impact, it's not really how easy it spins, we are talking about the speed in which it turns. the small 6 in steering wheel with turn at a faster rate. Put spinner knob on each steering wheel and time how long it takes for each one to do 5 revolutions. The 6" wheel well be faster. Same thing applies to any round object. The larger diameter will take longer to do one full revolution and use more power to make it spin at the same rpm as one with a smaller diameter.

Torquer

HOWEVER, if you keep the same gear ratio then the pinion turning your tiny fingernob of a steering wheel will be so small that it will offset the size difference.

I agree that it is harder - FOR US - to turn a smaller steering wheel, that is mostly because we have a "built in gear ratio" that we tend to build steering wheels to match.

John Stranahan explained the gear issue in the TC3 thread on here.

Basically, he said what I wanted to say. :)

http://www.rctech.net/forum/showthre...2&goto=newpost

-Rich

Torquer-- no a bigger spur doesn't turn slower, if the r=gear ratioa are the same.... 4:1 is 4:1 period, the motor pinion will still spin 4 times per revolution to every 1 of the spur.... and if the spur takes less power (torque) to turn over the spur the big spur car will actually accelerate faster, and could potentially have higher top end if the motor doesn't have the torque to push the spur past an RPM level that below the maximium RPM of the motor.......

That being said I also agree that the tc3 and most tourers for that matter don't have enough adjustability in the spur/pinion sizes to make enough difference..... now if it was possible to mount a 69 and 98 tooth spur on the car then we could do an actual test that would prove something....... but from 69-75 all you get is enough to "fine tune" you ratio, which isn't a bad thing either!

Hey all.....hows everybody doing?????Been about 5 months since i've turned a wheel.......My first race should be interesting.....does TPHalen still come here?????Later

If you have to identical cars with the exact same gear ratio (4:1 or whatever) the only variable that comes into play is the moment of the gear. When comparing a small and large disk (gear in this case) the smaller disk will accelerate faster than the larger, and the larger will maintain its final speed longer.

BUT, because the gears we are using are so light and they are so small, it is nearly impossible to tell any difference.

In conclusion, the only reason to get a bigger vs a smaller gear is so acheive a specific gear ratio that is unattainable with smaller gears.

The information and opinion about overall gear ratios and "moment of gear" is correct.......but....all of you forgot one crucial item.

Torque multiplication.

Any time that a larger spur is used, less torque output from the motor is needed to start (dead stop or otherwise) to accelerate the weight you are trying to move (in this case...and R/C).