unseenmagik

Hiya folks,

I would like to know what the difference in Increasing and Decreasing the Pinion gear will do.

I have a standard setup Buggy on 45/15

Questions:

What will happen if i Increase the pinion gears teeth ?
Will it run hotter or cooler, accelorate slower or faster, increase or decrease Run Times?

Im looking at loosing some acceloration as i have so much and its not needed, ill be running on an outside open track, and would like to increase run times.

Anyone ???

Thanks Ben

K.Copeland

iTrader: (96)

Swap them out and try it.

unseenmagik

Well it would be nice to have that feature but it would cost a fair bit to go out and buy all the different size's to find out that i only need one or two of them lol.

I was hoping that someone that has thins knowledge or previous testings would be able to help and offer some advice.

K.Copeland

iTrader: (96)

Bigger pinion will give you higher tire speed ( top end). Sometimes a larger pinion is used to make driving on a slick track easier too. Hard to explain, but all I can say is to go buy 2 pinions and see what happens. I'd say a 2 or 3 tooth difference from what you have now, one larger, one smaller. Start with a fresh battery and keep a close on eye not just on run time, but also the car out of corners.

SikKustomz

iTrader: (10)

It also depends on what motor your runing. Alot of brushless motors have the correct size one should run. I have a 2 wheel buggy and i race stock and im at a 72 28.

tntpoof

iTrader: (3)

we need to know your setup. what motor ? what esc? what battery lipo-nicad -nimh.. size mah so on what tires. what buggy? this is my sons setup with a b44 with a mess load of alluminium parts . with cut prolines tekin G11pro esc. 78 spur with a 12 tooth pinion.. 12 turn Revolution v2 Tops racing motor..45 weigh oil up front with 35 in rear..motor runs at 135 degrees F..3800 mah 7.4v orion spec battery (lipo) he can run for about 20 minutes but he does 7 minutes at a time tops.(so not to over heat anything)on a open flat street buggy with hit full speed in less than4.2 seconds top speed about 52 mph..

My MRC SBV2 I run a Hacker 10.5 brushless. with a SnT 110 brushless esc..62 tooth spur with a 10 tooth pinion my top speed is about 75 mph it takes me about 5.1 seconds with my slipper clutch setup 1 way diff up front with DD all around we race indoor offroad carpet.. bluebird MG631MG servos great servo for the proce why speed $140 for a single heck I buy 5 for $100 shipped to my door same specs as Jr Z9000s for 1/8 the price..

In general a larger pinion with make buggy go faster might not have acceleration you are looking for but Top speed will be there ..smaller will make buggy jump outa the hole. but slower top speed but that is not always great.. being able to jump outa a hairpin instead of roll outa it will make you faster.but if there is a long straightaway then top end is what you might want..also you dont need to go 2 teeth up or down a single tooth will make a great difference also you need to worry about over heating .. most drivers around me have a few extra pinions they might let you use but at $5 bucks each its not like your buying a new esc ..also track condition have alot to do with gearing so do tires..and so does your driving skills

nelson6500

iTrader: (49)

Here ya go

Pinion/Spur


Smaller Gear Ratio
(bigger number means smaller ratio) More punch and accelleration.
More runtime.
Lower top speed.
Bigger Gear Ratio
(smaller number means bigger ratio) Less punch, but more top speed.
Less runtime.
Smaller Pinion Gear Smaller gear ratio
Bigger pinion Gear Bigger gear ratio
Smaller Spur Gear Bigger gear ratio
Bigger Spur Gear Smaller gear ratio
Overall Ratio Overall Ratio = (Spur/Pinion)*Internal Gearbox Ratio


more info here http://users.telenet.be/elvo/

matt

ifuonlyknew

iTrader: (7)

NO. There is no way that your car does 75mph with that setup. A Hacker 10.5 is a 3080kv motor. Here is the info from R/C Calculations.

Transmission Ratio: 2.3
Spur Tooth Count: 62
Pinion Tooth Count: 10
Total Voltage: 7.4
Motor KV: 3080
Tire Diameter (inches): 3.5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 6.2 : 1
Total Ratio: 14.26 : 1
Tire Circumference (inches): 11 inches (279.29 mm)
Rollout: 0.77:1
Total Motor Speed: 22792 RPM
Vehicle Speed: 16.64 mph (26.73 km/h)
Effective KV Value: 3080
KT constant: 0.44 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

If you want to input the info into the calculator yourself, here is the link.

For the original poster, when a brushless motor is geared correctly it will run about 120-150 degrees and have good speed and acceleration. If it is over geared it won't get any faster but it will build more heat. If it is under geared it will be slower, have less torque and build more heat. If you feel that your car may be over/under geared then do like the other guy said, buy 2 pinion gears one that is 2 teeth bigger than the pinion you are running and one that is 2 teeth smaller than the pinion you are running, try them and see how your car runs.

Good Luck,
ifuonlyknew

tntpoof

iTrader: (3)

you can feed us all the calculation you want .. your OFF.. already your motor RPM is off 3100+ rpm.. gear ratio is also off so is tire size and ballon rate..

anyway this is not some far fetched rc calculator This is a Police Officers radar unit actaully its THE IRSC 3... 72.78 mph.. but again a know it all knows more than a Radar unit LOL

so what your calculator is saying any high school track member could out run my BUGGY.. I will give any HS track star 1/2 a lap head start on a 1/4 mile track and beat him by no less than 60 yards.. thats 220 yards he will have to run..say $10,000 cash as long as he/she dont step on my buggy as a Pull a wheelie by them..

ifuonlyknew

iTrader: (7)

Strait off of Hacker website found here 3080kv for their 10.5 turn. I re-ran the calculator with the radius of the tires increasing 3 inches (meaning that the tire balloned 3 inches so the tire is 6 inches taller) although I really doubt they would balloon that much, or that you would be able to control the car if they did. Here is the info from the calculator with the tire ballooning info added.

Differential Ratio: 1
Transmission Ratio: 2.3
Other Ratio: 1
Spur Tooth Count: 62
Pinion Tooth Count: 10
Total Voltage: 7.4
Motor KV: 3080
Tire Diameter (inches): 3.5
Tire Ballooning (inches): 3
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 6.2 : 1
Total Ratio: 14.26 : 1
Tire Circumference (inches): 29.85 inches (758.07 mm)
Rollout: 2.09:1
Total Motor Speed: 22792 RPM
Vehicle Speed: 45.17 (72.56 km/h)
Effective KV Value: 3080
KT constant: 0.44 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...


I did get the ratio right, on the front of the manual it says 2.3:1! I know for a fact that there is no way a 3080kv motor is going to push a 4wd buggy close to 75 mph, radar guns designed to work on full size cars will not return an acurate enough radar signature off of a small object to be considered a reliable source. Why do you think they use a time trap for the worlds fastest r/c challenge? If you are so confident that your car will go about 75mph, make a video of you following your car in a full size car doing 75mph. Start or end the video with a close up shot of the motor so we can see that it is a 10.5

Good Luck

tntpoof

iTrader: (3)

.. max tire ballon is total of 4.125" not 6",, also battery voltage is wrong .. a 7.4 lipo charges to 8.4 volts not 7.4 all you stats are wrong A infrared speed unit will track a mouse as long as you get it in the crosshairs..check your facts.. all these guys on motorcycles that have gotten speeding tickets are void. get real.. another JAFA..

ifuonlyknew

iTrader: (7)

True, a lipos resting full charge voltage is 8.4 volts but as soon as you put a load across it you get a voltage drop. 7.4 is the nominal voltage so that is what I used. How about this you go to the speed calculator and input your values and post the results you get. The calculator is acurate. It is simple math.

3080 rpm per volt x battery voltage = max RPM (25872 RPM)
max RPM/pinion spur ratio (6.2:1) = RPM of Center driveshaft. (4172.9 RPM)
RPM of center driveshaft = RPM of pinion gears that drive diffs.
RPM of center driveshaft/ring pinion ratio (4172.9/2.3 = 1814 RPM = wheel rpm
wheel RPM (1814) x tire rollout 15.71 inches = distance traveled in inches in 1 min = 28502 inches per minute
28502in per min x 60 = inches per hour 1710120 in per hr
1710120 in per hr/12 = 142510 feet per hr
142510 feet per hr/5280 = 26.99 MPH

So unless you are using a 5s battery it is mathmatically impossible for your car to go that fast with the pinion/spur and motor combo. This is without aerodynamic drag or the parasitic loss due to the mechanical imperfections and drag in the drivetrain. I'm done arguing with you. You obviously have no grasp of mechanics or an in depth knowledge of how things work.

Good Day

Neu_Racer

iTrader: (211)

While not many people would call that "simple" math you, me, and every other sane person knows you are correct.

To think a 3000kv motor on a 10T pinion goes anywhere near 70 makes the person saying it look like an ass.

The Rustler VXL has a 3500kv motor and requires 31/72 gearing to hit 70mph on a 11.1V lipo. So cut the voltage by 1/3, the pinion by 2/3 and drop 500kv off the motor and we expect it to hit 75mph???

Very nice arguement with your calculator. I wouldn't have wasted my time going that route but it is definitely proof the guy is full of crap.

Neu_Racer

iTrader: (211)

I love it when people offer to bet a ridiculous amount of money on something they will never prove even to themselves.

burnineyes

iTrader: (17)

Police suck
75 on 2s 10.5 is funny I gotta get one of those!