Pinions!!!!

[Busdriver 6209]

A very newbie question from an old crinkly!! I always get confused with high/low gearing etc in respect of getting higher top speeds or low speed control. I have an entry level crawler that does exactly what it says on the box. It crawls over rocks!!! However unlike the lucky members that have rock strewn river beds or the Ricky Mountains on their doorsteps,  the woods of a sleepy Hertfordshire village are rather lacking in rocky outcrops!!! There are though some really interesting trails and hill climbs in the woods just metres from my front door. This requires more of a trail truck first and a crawler second. It also needs higher road speed to get between hills and possibly throw a few shapes on the way. The vehicle I have claims to be able to do both with the right gearing. My question is to get more Road speed, it’s brushed but can do 3S do I increase the number of teeth on the pinion or decrease the number. Also do I need to change the spur. I’m not sure if the motor mount is variable? I’m keeping the identity secret for the moment as this is one of my usual non stock body swaps and more will follow. Suffice to say the original body is top heavy with a full roll cage and your dead lucky if it doesn’t roll on hill traverses!.

[bRIBEGuy 3044]

Pinion: More teeth = more faster.
Spur: Less teeth = less slow.

Usually changing one is sufficient.  Pinion is generally easier... if the motor mount is adjustable.

If the motor/ESC can handle the load and not get too hot, then leaving the gearing alone and just bumping up from 2S to 3S could give you the speed you want.  If you want to stay on 2S, then get a bigger pinion.  Or a faster motor...

[alvinlwh 5894]

Use a speed calculation app or website and play around with the numbers and you will get your answer, and with the right input regarding the IR and KV, you can even find out the top speed.

Example:

NOTE: do not go for a 60/50 like I did, it is a motor killer!

[Juggular 4964]

Most Tamiya gearboxes only allow you to change pinions.  If you want more speed, more teeth on the pinion would do the job.  

Usually, changing 1-2 teeth isn't going to change the speed drastically.  But going from crawling to trailing wouldn't require too much.  Just upgrading to 3S could be enough.  It might be better to keep the pinion, though.  Brushed motors don't like heavy loads (i.e. larger pinion).  Sometimes, higher voltage + larger pinion = Smoke (unless the chassis is light).  I would check the motor temperature.  If it feels hot, I'd even lower the gearing (smaller pinion) to reduce the load, and just rely on higher RPM to get the speed.  

If 3S creates too much heat on the motor?  You might consider a brushess.  It's got more torque (i.e. it could handle a larger pinion better).  

P.S. I still can't think of abstract numbers in my head. So I think of the pinion as the gear attached to a pair of bicycle pedals.  If the gear on the pedals is small, you pedal more to go up a hill (slower).  When you go downhill, you sift to a larger pinion on the pedals, so each stroke would carry you farther.  

P.P.S.  

Maybe Tamiya could build chassis with an automatic 2-speed gearshift (they had done it before). We could use it as a Crawler in the 1st gear. And it could turn into a Trail truck in the 2nd gear as it speeds up.  It can be finicky to adjust, so they could sell it as an optional setup? Just a thought...but it could be fun if a crawler can pick up speed.  

[Busdriver 6209]

3 hours ago, Juggular said:

Most Tamiya gearboxes only allow you to change pinions.  If you want more speed, more teeth on the pinion would do the job.  

Usually, changing 1-2 teeth isn't going to change the speed drastically.  But going from crawling to trailing wouldn't require too much.  Just upgrading to 3S could be enough.  It might be better to keep the pinion, though.  Brushed motors don't like heavy loads (i.e. larger pinion).  Sometimes, higher voltage + larger pinion = Smoke (unless the chassis is light).  I would check the motor temperature.  If it feels hot, I'd even lower the gearing (smaller pinion) to reduce the load, and just rely on higher RPM to get the speed.  

If 3S creates too much heat on the motor?  You might consider a brushess.  It's got more torque (i.e. it could handle a larger pinion better).  

P.S. I still can't think of abstract numbers in my head. So I think of the pinion as the gear attached to a pair of bicycle pedals.  If the gear on the pedals is small, you pedal more to go up a hill (slower).  When you go downhill, you sift to a larger pinion on the pedals, so each stroke would carry you farther.  

P.P.S.  

Maybe Tamiya could build chassis with an automatic 2-speed gearshift (they had done it before). We could use it as a Crawler in the 1st gear. And it could turn into a Trail truck in the 2nd gear as it speeds up.  It can be finicky to adjust, so they could sell it as an optional setup? Just a thought...but it could be fun if a crawler can pick up speed.  

Brushless is definitely an option but a little down the road to save the pennies!! I’ll try +2t and maybe +4t and 3s and see how I go. Currently it’s fitted with a 35t motor 

[SuperChamp82 743]

All of the above is true but old school is simpler ?

If the motor is too hot to hold your finger on for 2sec, the pinion is too big and it's overloaded the motor.

If the battery is the only thing getting hot when you finish a run the pinion is too small.

Trial and error in pinion size to get the balance of temp between esc/ battery/ motor to get the system sweet 👍

[Mad Ax 9310]

If you have a 3S battery already and the electrics can handle that, I'd try that to start with.  I run most of my crawlers on 3S because I still have smaller pinion for better torque and finer control on the technical sections, but the extra RPM for getting between sections before the sun goes down.  Some of my friends have trucks with 2 speed transmissions, and 3S is the only way I'll ever keep up with them (although to be fair they run 3S batteries too).  I use 55T crawler motors (usually cheaper fixed timing ones but I have a couple of rebuildables too) and they never get hot either crawling or blasting between crawls.  That said, they aren't really that quick, and if I did more trails than technicals I'd want to run bigger pinions and possibly lower-turn motors.

If a 3S still doesn't give you enough speed then you can try a bigger pinion, or even throw in a spare silvercan or torque tuned - it'll probably have more RPMs than the 35T, although the higher turn motors will probably take the additional heat from a bigger pinion and more voltage better than the lower turn ones will.  It's always a compromise but you don't need to try every possible combination, start with what you already have and see what works

A timely thread actually, as only yesterday I placed an order for some parts to turn my spare Element Enduro chassis into a more race-oriented vehicle, and I'll be playing with higher speeds once I get it all together.

[Busdriver 6209]

15 minutes ago, Mad Ax said:

If you have a 3S battery already and the electrics can handle that, I'd try that to start with.  I run most of my crawlers on 3S because I still have smaller pinion for better torque and finer control on the technical sections, but the extra RPM for getting between sections before the sun goes down.  Some of my friends have trucks with 2 speed transmissions, and 3S is the only way I'll ever keep up with them (although to be fair they run 3S batteries too).  I use 55T crawler motors (usually cheaper fixed timing ones but I have a couple of rebuildables too) and they never get hot either crawling or blasting between crawls.  That said, they aren't really that quick, and if I did more trails than technicals I'd want to run bigger pinions and possibly lower-turn motors.

If a 3S still doesn't give you enough speed then you can try a bigger pinion, or even throw in a spare silvercan or torque tuned - it'll probably have more RPMs than the 35T, although the higher turn motors will probably take the additional heat from a bigger pinion and more voltage better than the lower turn ones will.  It's always a compromise but you don't need to try every possible combination, start with what you already have and see what works

A timely thread actually, as only yesterday I placed an order for some parts to turn my spare Element Enduro chassis into a more race-oriented vehicle, and I'll be playing with higher speeds once I get it all together.

I’ll follow with interest. Good idea to try a silvercan. I have a drawer full of them doing nothing so even if I cook it I have another 10 to fall back on. ( just realised out of 30 odd Tamiya’s I only have one actually fitted with a silvercan and that’s my Dynamog 6x6) Once I get my project together I’ll post more info about it and se how I progress

[Busdriver 6209]

So this is what I’ve been working on that relates to this thread 

It’s an Axial Deadbolt chassis(RTR) so 300mm wb, Tra!!as Canyon 1.9 wheels and tyres and a ? Body from L&L. It seems to be cross between a Jeep and a Suzuki???  I never really got on with the deadbolt body, in fact I have a 1:24 scale one as well that I’m going to change soon, it’s too top heavy and seems to waddle when seen from behind on the trail. Strangely enough although it’s top heavy to me the roll cage isn’t high enough aesthetically but hey what do I know. So going to charge up a 3s pack and see what it will do. Also might do some window frames as none come with the body.

 

ps could also do with a driver???

[Busdriver 6209]

So just took it for a spin round the garden. Had forgotten how to disable the drag brag so had quite a few nose overs!!! So on 3s with the 35t motor it accelerated really well but just runs out of puff a I guess around 7-9 mph. After about 15 minutes of doing Roly Poleys I gave up came inside and found the instructions… I now know how to reduce/disable the drag brake. I also found a pinion/spur chart. The stock pinion 13t with stock spur 56t gives an fdr of 42. It says you can go up to 18t pinion giving you an fdr of 30.33. That’s with the stock motor. I think I will purchase 15 and an 18 and experiment. These are Axial recommendations so should be interesting to see the outcome. Just need to measure the motor shaft to ensure I get the right pinion. Have say grass is not it’s happiest stomping ground, too much grip.

 

Ps I think it is FDR . 30 is in buggy territory is it not?

[Busdriver 6209]

Ordered 15t and 18t in 32 dp from Neil at RW Racing. . Let the games begin!!!