Spur And Pinions

[chinaman SS]

Am I right to say that if i were to change to a larger pinion, then the car will theoretically go faster but will then accelerate slower? All else being equal.

If that is the case then if I were to change to a more powerful motor, ie higher torque and rpm, keeping everything else the same, then i will need to go for a smaller pinion gear to maintain some sort of control over the car?

So a greater ratio between the spur and pinion increases the torque and actually slows down the rpm at the wheels?

[TA-Mark]

A larger pinion will increase the load on the motor. If the motor has enough torque the car will go faster. More load is also more heat and faster drain on the battery.

When you change to a low turn, high rpm motor you need to use a smaller pinion so that the power band of the motor is in the right range. A silvercan motor is about 16,000rpm, a 23 turn BZ/TZ/RZ is around 26,000rpm, a big different in rpm. The 23 turn will need to use a smaller pinion to let the motor rev to it's ideal running rpm. Standard gearing with the 23 turn would make it and the ESC run very hot due to the excessive load.

Keeping control of the car is up to you, no matter how fast the motor or the car goes. You are the one with your finger on the trigger. A MambaMax motor is safe to 70,000rpm, which it will do on a 3s Li-Po, obviously you don't pull straight to full throttle as you would with a silvercan motor.

[terry.sc]

If that is the case then if I were to change to a more powerful motor, ie higher torque and rpm,

A lower turn motor will have more power and speed, but less torque. The lower the number of turns the more the motor will rev, but the smaller the pinion/bigger spur will be needed to let the motor spin up into it's power band.

Putting a 10 turn motor in a car with the standard gearing will usually run slower than the kit motor because the big pinion puts too much load on the motor. The reduced torque of the low turn motor means the extra load prevents it from turning over fast enough to release it's power. The greater torque of the kit motor means that for the same gearing the kit motor will accelerate faster, and will reach it's top speed much faster. Even if there's plenty of space the lower torque of the low turn motor means it may never get fast enough to be able to use it's extra power.

[94eg!]

As Terry said, the lower-turn motor has less torque and must be combined with shorter gearing (smaller pinion and/or bigger spur). The shorter gearing then acts as a torque multiplyer. This is why the car seems to accelerate quicker even though the motor has less torque. If done right, this combo will be producing much more torque at the wheels than before...

Ideally you want to have many gear options for your car. This allows you to change gears for different circumstances. If your motor is getting too hot, you need shorter gearing. If your motor is not hot and lacks top-speed, you need longer gearing. Different tracks and bashing-grounds will tax your setup differently. Plus every motor is different and it's no fun having only one...

[evil2004]

Spare me guys, this is my first post. I have just built a TB-03 chassis Xanavi gtr skyline. I have replaced the stock motor with an Ansman 21 turn motor which has greatly improved the speed and acceleration, what i am asking now is do i need to run a high pinion gear (i.e33t or 35t) or lower (i.e 19t or21t) to match the new motor. This might sound a bit trivial to you guys because you lot are more into than i am at the moment. cheers.

[94eg!]

Spare me guys, this is my first post. I have just built a TB-03 chassis Xanavi gtr skyline. I have replaced the stock motor with an Ansman 21 turn motor which has greatly improved the speed and acceleration, what i am asking now is do i need to run a high pinion gear (i.e33t or 35t) or lower (i.e 19t or21t) to match the new motor. This might sound a bit trivial to you guys because you lot are more into than i am at the moment. cheers.

If the motors not getting too hot then your okay for gearing. If you want more top speed, you can go to a larger pinion, but be weary of motor temp. Be aware you will loose a little low-end punch though. If you cannot hold your thumb on the can for 3-5 seconds, it's too hot!

If the motor is getting too hot, then you need a smaller pinion...

[evil2004]

If the motors not getting too hot then your okay for gearing. If you want more top speed, you can go to a larger pinion, but be weary of motor temp. Be aware you will loose a little low-end punch though. If you cannot hold your thumb on the can for 3-5 seconds, it's too hot!

If the motor is getting too hot, then you need a smaller pinion...

My motror isnt getting hot so that seems ok, so if i put a 32t pinion will that give me faster acceleration with less top speed or the opposite? Thanks for the help.

[94eg!]

...If you want more top speed, you can go to a larger pinion, but be weary of motor temp. Be aware you will loose a little low-end punch though...

If the motor is getting too hot, then you need a smaller pinion...

BTW: You never mentioned what size pinion is in the car now... lol

[evil2004]

BTW: You never mentioned what size pinion is in the car now... lol

at the moment its running a 22 or 24 pinion i think, just had to count roughly. cheers

[94eg!]

at the moment its running a 22 or 24 pinion i think, just had to count roughly. cheers

Well then going from a 22T to a 32T will definitely give you more top-speed, but that seems to me way to big of a change. Chances are that big of a jump will kill the cars all around performance making it VERY hot and sluggish. Usually when you make gear changes, you want to move only a few teeth at a time. You might jump to a 25T at first, but that's it. BTW: If it's a Tamiya 0.6mod pinion, it should have the number of teeth stanped on one of the flat faces of the pinion. In fact I think all modern pinions have a stamp on them...

Larger pinion = more heat, more top speed & slower acceleration

Smaller pinion = less heat, less top speed & qucker acceleration

In addition:

Smaller spur = more heat, more top speed & slower acceleration

Larger spur = less heat, less top speed & qucker acceleration

[chinaman SS]

Cheers for all that all that time ago ... Never actually thanked you all for the clarification

On the same note of pinions and spurs ...

If you have a choice of using 2 different pitch sized (higher or lower), pinion and spur combination, which will you go for?

I have a F103 which comes standard with the 'AV sized' spur and pinion. This measures to be a slightly lower pitch than the industry standard of 48.

I know there is available a higher pitch size of M 0.4, which I believe is a 64 pitch, (correctly if I am wrong) (The teeth are closer together) spur that I can also use.

Do the pitch size affect the transfer of power from the motor to the axel?

[94eg!]

Cheers for all that all that time ago ... Never actually thanked you all for the clarification

On the same note of pinions and spurs ...

If you have a choice of using 2 different pitch sized (higher or lower), pinion and spur combination, which will you go for?

I have a F103 which comes standard with the 'AV sized' spur and pinion. This measures to be a slightly lower pitch than the industry standard of 48.

I know there is available a higher pitch size of M 0.4, which I believe is a 64 pitch, (correctly if I am wrong) (The teeth are closer together) spur that I can also use.

Do the pitch size affect the transfer of power from the motor to the axel?

The smaller the teeth, the more contact area you have so the more power you can transfer before damage occurs. In addition, smaller teeth cause less noise and therefore should be more efficient. Now keep in mind that these are just technicalities. Typically people have more trouble with 64pitch (and metric 0.4module) gears as they are more difficult to mesh and can be damaged by debris more easily. Having said that, I've never had trouble with my 0.4module gears in my 2 years of parking lot touring car racing. I also love the lack of noise from the fine pitch...

Also keep in mind the availability of pinions. If you run the metric gears, you can pretty much only purchase your pinions from Tamiya. Robinson racing makes what they call metric 48pitch that are 0.6module for Tamiya cars. If you run the finer metric 0.4module, you can only get pinions from Tamiya (which is what I do). If you already have tons of gears in standard 48pitch, then you may as well stick with them as they are durable and will save you money...

PS: None of the different pitches are truly compatible. 64pitch will not match 0.4mod perfectly. They will be difficult to mesh, slowly wear each other, and run noisy the whole time. In 0.6mod, Tamiya makes both AV and HP pinions. The AV are the larger ones and are aluminum, while HP are the smaller steel ones. Tamiya's RD pinions are the smaller 0.4mod steel pinions. All other Tamiya 0.4mod pinions are aluminum...

[chinaman SS]

PS: None of the different pitches are truly compatible. 64pitch will not match 0.4mod perfectly. They will be difficult to mesh, slowly wear each other, and run noisy the whole time. In 0.6mod, Tamiya makes both AV and HP pinions. The AV are the larger ones and are aluminum, while HP are the smaller steel ones. Tamiya's RD pinions are the smaller 0.4mod steel pinions. All other Tamiya 0.4mod pinions are aluminum...

Cheers for that ... have gone ahead and got a few more AV pinions and will stick with them, including 2 sets of the smaller HP steel ones.

I just need a wider spread of gearing ratios from about 3.5 to 5.0 max and as the AV and HP pinions have a smaller number of teeth to complement my standard 63T spur, with just a single increment of teeth on the pinion makes a slightly larger change in ratio.

[TA-Mark]

The Tamiya alloy AV pinions should be tossed in the bin (as I do with every new kit that contains them). Far too soft alloy to be used in a runner. Modelsport UK has RW Steel 0.6m pinions that will last 50 times longer in a runner. Alternatively there are Robinson Racing steel 0.6m pinions from the US.

Some of the coined phrases about Tamiya's alloy AV pinions:

"Tamiya's finest alloy butter."

"Friends don't let friends drive with Tamiya alloy AV pinions."

"Suitable to display only."

[OCD]

The Tamiya alloy AV pinions should be tossed in the bin (as I do with every new kit that contains them). Far too soft alloy to be used in a runner.

Some of the coined phrases about Tamiya's alloy AV pinions:

"Tamiya's finest alloy butter."

"Friends don't let friends drive with Tamiya alloy AV pinions."

"Suitable to display only."

LOL Mark -- I think this should be stickied somewhere in this forum under a heading 'getting started'!

-Steve

[94eg!]

LOL Mark -- I think this should be stickied somewhere in this forum under a heading 'getting started'!

-Steve

I've got a 20 year old Vanquish that still runs it's original AV pinion. No problem here... \

I did switch to a steel 18T DF02 pinion last year to run with my SuperStock TZ though...

[OCD]

I've got a 20 year old Vanquish that still runs it's original AV pinion. No problem here... \

Yeah, and my neighbor has a 'pristine' 1973 Spitfire that he never drives

I'm sure these pinions can be nursed along for a reasonable lifetime, but why?

-S

[chinaman SS]

... Modelsport UK has RW Steel 0.6m pinions that will last 50 times longer in a runner.

...

"Tamiya's finest alloy butter." ...

Cheers for that Mark. Found the pinions from Modelsport. Will keep the link handy once the butter pinions wear out.

I have used my 18T AV pinion for about 40 x 5min runs and you can see the wear on one side, but nowadays I take a note of what is on the spur gear and I think my AV pinion will still last awhile. Maybe Tamiya did this so that the spur will not wear that quickly. One of them is bound to if dirt /grime get in between the spur and pinion.

[TA-Mark]

Maybe Tamiya did this so that the spur will not wear that quickly.

The opposite is actually correct. Once the pinion has worn some it will drag on the previous tooth and cut the plastic spur gear wearing it out faster. The alloy AV pinion is worn out when it starts touching the previous tooth of the spur. The steel pinions take much longer to get to this point (about 50 times longer).

The silver paste that builds up in the gearbox was once the pinion gear now powderised and mixed with ceramic grease. Makes a nice grinding paste to spread throughout the gearbox.

All good reasons to throw AV alloy pinions in the bin and never run with even once.

Some Tamiya gearboxes have alloy gears elsewhere in the driveline, some can be replaced by a plastic option, others there are no alternatives (DF03 mainshaft, 2nd gear on a high-lift). I'm currently on my 6th mainshaft in my main DF03 and the steel pinion and plastic spur (which does get fine dirt at it) shows no signs of wear. All 3 of my DF03s and every other DF03 I've gotten my hands on wears the alloy mainshaft gear quickly. I avoid 2nd gear like the plague on the F-350 high-lift.

[mix237]

A larger pinion will increase the load on the motor. If the motor has enough torque the car will go faster. More load is also more heat and faster drain on the battery.

When you change to a low turn, high rpm motor you need to use a smaller pinion so that the power band of the motor is in the right range. A silvercan motor is about 16,000rpm, a 23 turn BZ/TZ/RZ is around 26,000rpm, a big different in rpm. The 23 turn will need to use a smaller pinion to let the motor rev to it's ideal running rpm. Standard gearing with the 23 turn would make it and the ESC run very hot due to the excessive load.

Keeping control of the car is up to you, no matter how fast the motor or the car goes. You are the one with your finger on the trigger. A MambaMax motor is safe to 70,000rpm, which it will do on a 3s Li-Po, obviously you don't pull straight to full throttle as you would with a silvercan motor.

In your experience, what pinion and spur combination would be best for top speed for my DF02 Plasma Edge? Im running a SuperStock BZ.

Thanks.

[TA-Mark]

In your experience, what pinion and spur combination would be best for top speed for my DF02 Plasma Edge? Im running a SuperStock BZ.

Thanks.

I would say the 19T or 18T pinion with the kit 70T spur (9.58:1 or 10.11:1 FDR). But this would depend on your running surface and wheel diameter. Kit wheels (Star Dish and Spire/Square spikes) on hard pack dirt. Lean toward a smaller pinion if the running surface has more resistance like grass or soft dirt.

Going up to the next ratio 19T/67T (9.17:1 FDR) might be that touch too tall for the 23turn BZ motor offroad. Maybe would ok onroad with a street type tyre.

[mix237]

I would say the 19T or 18T pinion with the kit 70T spur (9.58:1 or 10.11:1 FDR). But this would depend on your running surface and wheel diameter. Kit wheels (Star Dish and Spire/Square spikes) on hard pack dirt. Lean toward a smaller pinion if the running surface has more resistance like grass or soft dirt.

Going up to the next ratio 19T/67T (9.17:1 FDR) might be that touch too tall for the 23turn BZ motor offroad. Maybe would ok onroad with a street type tyre.

Great advice! Thanks TA Mark.