Same mtr in both machines.

[Lukas666 39]

Is a buggy always gonna be faster with the same motor as say a lunchbox or midnight pumpkin with the same mtr? I assume it’s because of the tiny wheels and the difference in pinion? Little gear driving a bigger one for more torque in say a lunchbox and bigger gear driving another in the hornet. I have a 23T sport tuned in my hornet and a 20T in my Lunchbox and the Hornet is quiet a bit faster. Off the line and pretty sure top speed.

[87lc2 2659]

It doesn't have as much to do with the type of vehicle as it does with weight, gearing (pinion, spur, final drive), and tire diameter.  These are the main factors that determine punch & top end, along with voltage and motor health of course.  I dont know the final drive ratios for the Hornet/Lunchbox off hand, but there is most likely less weight in the Hornet to push around.  As far as tire diameter, a larger tire will result in more top end speed if the motor has the torque to get it there and the gearing is right.  

I'm sure someone can explain this much better than I, but short answer is every vehicle is different and speed will be determined by the factors mentioned above.  There are some good RC gear ratio calculators out there is you are trying to determine speed for a certain vehicle/gear ratio.

[Lukas666 39]

Well I’m a mechanic so a pinion with less teeth than another driving the same crown should result in a reduction creating more torque from one to the other. I’d guess that’s why these monster wheel trucks have a smaller pinion with less teeth to drive those bigger tires and in some cases heavier chassis. I’ve read some about people putting a 18tooth hornet/grasshopper pinion in a lunchbox but it doesn’t seem to be advisable. Could figure out the ratio easy enough. Pinion is ten teeth, whatever the crown is would determine the ratio if you knew how many teeth that had. I don’t tho off hand.

[87lc2 2659]

Yes, a smaller pinion equals more torque & less speed.  Conversely, a larger pinion equals more speed & less torque.  Final drive also plays a role between different models.  You can have the same pinion/spur setup on two vehicles and speed will be different depending on final drive from the transmission/gearbox.

If you're looking for more speed, go up in pinion size but keep an eye on motor temps. As long as the motor doesn't get hot a larger pinion is just fine.  550 size motors are much more forgiving with gearing and have more torque than their 540 counterparts.  With that said, if you go up in can size go down in turns, with equal turn counts the 550 will be slower.  

[Lukas666 39]

Both are new re releases built them starting at x mas. Both have brand new 6 cell NIMH batteries and ball bearings throughout. Hornet has a 3000mah, Lunchbox 5000, but that’s just the size of the gas tank. The lunchbox doesn’t seem to much heavier, I should weigh them tho. I think there’s something good to say about these Tamiya brushed motors. With the stock RS 540 I’d get like an hr of run time with that new 5000mah gens battery. Changed to a Dynamite 20T and it’s I’d say around 40 mins maybe... hard to tell cause I’ll burn around with it for 1/2 hr then put it away and the battery isn’t even slowing down yet. Next day I’ll turn it on and the esc kicks in and out?.... charge the battery up and were off to the races again? I don’t think it’s the 20T kicking out the stock esc cause it never does it the first 1/2 hr with a full battery? Sorry getting a little off topic but don’t feel like opening a new thread for every little thing. I ordered a sport tuned 23T for the lunchie now and going to try that. I doubt I’ll notice any speed loss from the 20T to the 23 sport tuned and probably get better battery life from the 23T... be a good comparison to the hornet with the same mtr too. I read once that’s the best mtr for the lunchbox.

[87lc2 2659]

Don't own a Lunchbox and my Hornet is still in the box (hope to build it soon, it's a re-release), but on the motors I agree than Tamiya brushed motors are great quality.  I really like the Sport & Torque Tuned motors and use silver cans in all of my crawlers, they seem to last a lot longer when exposed to water/mud than other cheap motors do.  They also have great run time as you said.

With the ESC, there are really only two things that will cause it to cut out > 1) Lipo cutoff  OR  2) Thermal Cutoff   Not sure if your ESC has Lipo mode but make sure it's not set to Lipo if not using them.  As for thermal cutoff, if it's a stock Tamiya TEU-104BK you might be hitting the thermal cutoff with the 20t motor.  Is the motor/ESC hot when it cuts out?  I had that issue on a Clod a looong time ago with the dual motor TEU-106BK, it would cut out all the time when I went to lower turn motors.  

[Lukas666 39]

25 minutes ago, 87lc2 said:

Yes, a smaller pinion equals more torque & less speed.  Conversely, a larger pinion equals more speed & less torque.  Final drive also plays a role between different models.  You can have the same pinion/spur setup on two vehicles and speed will be different depending on final drive from the transmission/gearbox.

If you're looking for more speed, go up in pinion size but keep an eye on motor temps. As long as the motor doesn't get hot a larger pinion is just fine.  550 size motors are much more forgiving with gearing and have more torque than their 540 counterparts.  With that said, if you go up in can size go down in turns, with equal turn counts the 550 will be slower.  

What “final drive” are you referring to? In my trade a final drive would be a pinion driving a crown driving two axles out to yet another set of gears out at the wheels for yet another reduction multiplying torque yet again like in a wheel loader or bulldozer.... the gear set out at the wheels is the final drive. I haven’t seen that in any RC car... I see a crown and pinion with spider gears/ differential. Pretty simple like in an everyday car.one reduction really.

[Lukas666 39]

17 minutes ago, 87lc2 said:

Don't own a Lunchbox and my Hornet is still in the box (hope to build it soon, it's a re-release), but on the motors I agree than Tamiya brushed motors are great quality.  I really like the Sport & Torque Tuned motors and use silver cans in all of my crawlers, they seem to last a lot longer when exposed to water/mud than other cheap motors do.  They also have great run time as you said.

With the ESC, there are really only two things that will cause it to cut out > 1) Lipo cutoff  OR  2) Thermal Cutoff   Not sure if your ESC has Lipo mode but make sure it's not set to Lipo if not using them.  As for thermal cutoff, if it's a stock Tamiya TEU-104BK you might be hitting the thermal cutoff with the 20t motor.  Is the motor/ESC hot when it cuts out?  I had that issue on a Clod a looong time ago with the dual motor TEU-106BK, it would cut out all the time when I went to lower turn motors.  

It’s a TBLE 02s the re releases seem to come with now. They must of changed that cause I dont think that’s what they used to come with. Can’t run lipo on it there’s warnings against that. There is however brush or brushless options for this esc. One of my questions no one answered awhile back was do you need to set it up out of the box? ie: brush, brushless, high point set up etc. what are the default settings on it out of the box cause I never did anything to it I just put it in connected it and we were off lol. I’m assuming if it were on brushless I’d notice a problem? The orange wire isn’t even connected from the esc so if it were in brushless I dont think it would work with a brushed mtr. I read there’s like 3 reasons it’ll cut out and low voltage is one of them. The mtr isn’t hot when it cuts out. Warm yes, hot no.

[87lc2 2659]

3 minutes ago, Lukas666 said:

What “final drive” are you referring to? In my trade a final drive would be a pinion driving a crown driving two axles out to yet another set of gears out at the wheels for yet another reduction multiplying torque yet again like in a wheel loader or bulldozer.... the gear set out at the wheels is the final drive. I haven’t seen that in any RC car... I see a crown and pinion with spider gears/ differential. Pretty simple like in an everyday car.one reduction really.

There is more going on in the gearbox than just the pinion driving the spur and the spur turning the wheels.  The pinion turns the spur (or counter gear) and the spur gear drives the differential spur gear which turns the output shafts.  Diff gears are irrelevant when it comes to final ratios, but there is further reduction between the spur (counter) gear and diff spur which contributes to the final drive.  It really doesnt matter much in the case of the simple transmissions, these things matter more in more complex models where more changes can be made.  In this case you can really only change the pinion anyway, so bigger = faster, smaller = slower.

As for that ESC, I haven't personally used one but have seen a few people have issues with them on the forum recently.  Maybe check out the electronics section or post in there.  I do know that ESC is Lipo capable, but not sure if it has a programmable cutoff that would be interfering...

 

[Big Jon 684]

The Dynamite 20T isn't nearly as fast as the Tamiya 23t, so there's a start. The two vehicles both use fairly efficient transmissions of similar design, so should be about equal assuming equal rollout, with the 'Box being slightly slower due to weight. Rollout is how far the vehicle moves per motor revolution, and is a great way to compare final drive ratios between dissimilar vehicles or when changing tire size.

One of my rigs uses a 3800kV motor on 3S high voltage lipo, and is easily outrun by a buggy with a 17.5 on 2S. I don't know the rollout on either, but the truck has about a 45:1 FDR, and the buggy has about 8:1.

Finally, when dealing with low power levels, every little bit matters. BITD, we put a tremendous amount of effort into reducing friction and rolling resistance, motor tuning and maintenance, minimizing voltage drop, etc. Look at some old pics of race cars, and you'll see three wire speedos directly soldered to motors and batteries, no connectors. Small improvements in efficiency have big results in low power applications.

[Lukas666 39]

Why wouldn’t the 20T be as fast? Should be close or a touch faster at 3 turns less no? I mean I don’t disagree yet but doesn’t make sense, but something is fishy as the 20T should be wayyyyy faster than the stock 540. I have a sport tuned 23T coming for the Van so I’m gonna try it as soon as it’s in my hands.

[Big Jon 684]

For some reason, the 20t is a dog. Maybe it's a lack of timing, maybe it's the brush compound or spring tension, but it's not much faster than a silvercan. The Sport Tuned seems more powerful, kinda like how the old ROAR stock 27T motors were faster than say, the old 21T budget modified motors. There's a lot more to brushed motor power than the turn count.

[Lukas666 39]

10 minutes ago, Big Jon said:

For some reason, the 20t is a dog. Maybe it's a lack of timing, maybe it's the brush compound or spring tension, but it's not much faster than a silvercan. The Sport Tuned seems more powerful, kinda like how the old ROAR stock 27T motors were faster than say, the old 21T budget modified motors. There's a lot more to brushed motor power than the turn count.

So it doesn’t matter that it’s a Dynamite 20T? It’s just the count that’s a dog? An axial 20T would be the same? Regardless it’s getting a sport tuned now but that’s interesting.... kinda like certain engines are just a dog by nature I guess.

[Big Jon 684]

Believe it or not, the Axial, RC4WD, Traxxas, ECX, whatever, 20T motors are probably exactly the same, because they're just off the shelf commodity motors. The vast majority of sealed can motors are used in a wide variety of consumer and industrial applications, where they're understressed and provide long reliable lifespans. Even the Technipower was used in industrial applications first, which explains the leaf spring brushes. There's also a huge production variance, so performance varies widely, which is why racers and tuners buy sealed motors by the case and test them.

The open endbell motors started as serviceable industrial motors, and hobbyists quickly realized the performance potential in serviceable brushes, springs, timing, and all of the little tweaks. There were a lot of slot car guys in the industry at the time. Last year, I found a letter from Mike Reedy last year submitting Yokomo open endbell motors for ROAR competition, for example, and Trinity was a slot car company first. So was Associated, Parma, and many others.

[Lukas666 39]

28 minutes ago, Big Jon said:

Believe it or not, the Axial, RC4WD, Traxxas, ECX, whatever, 20T motors are probably exactly the same, because they're just off the shelf commodity motors. The vast majority of sealed can motors are used in a wide variety of consumer and industrial applications, where they're understressed and provide long reliable lifespans. Even the Technipower was used in industrial applications first, which explains the leaf spring brushes. There's also a huge production variance, so performance varies widely, which is why racers and tuners buy sealed motors by the case and test them.

The open endbell motors started as serviceable industrial motors, and hobbyists quickly realized the performance potential in serviceable brushes, springs, timing, and all of the little tweaks. There were a lot of slot car guys in the industry at the time. Last year, I found a letter from Mike Reedy last year submitting Yokomo open endbell motors for ROAR competition, for example, and Trinity was a slot car company first. So was Associated, Parma, and many others.

Well either way I am super impressed with the Tamiya 23T sport tuned mtr. I mean it’s no 8T brushless but what it does to a 30 year old Tamiya RC is pretty impressive and I think that’s what I’m gonna stick with on these Tamiya legends.

[markbt73 5311]

When it comes to mass-produced motors, there is a huge difference between batches of motors, or even motors in the same batch, due to manufacturing tolerances. Back in the day, when I raced stock class, you'd buy a handful of them, test them all, and use the fastest one (after doing all sorts of mystical dark-arts tuning to them, like water-break-in and comm drops and whatnot). You can buy two motors from the same shop on the same day, and they might be identical in performance, or very close, or wildly different.

There is probably no meaningful difference between the two motors you describe, especially in a Hornet and a Lunchbox. Both are lightweight, both have the same very efficient gearbox, and the overall gearing is fairly close between them with stock-size tires. Any 540-size closed-endbell motor between 20 and 30 turns is going to feel very similar in them. The Hornet will probably always have the edge due to lower weight (especially rotating weight; Lunchbox tires are heavy, it's like having to spin up four big flywheels to get it moving). Try switching the motors between the two and leaving everything else the same, and I'd bet you'll see the same result.

[Lukas666 39]

37 minutes ago, markbt73 said:

When it comes to mass-produced motors, there is a huge difference between batches of motors, or even motors in the same batch, due to manufacturing tolerances. Back in the day, when I raced stock class, you'd buy a handful of them, test them all, and use the fastest one (after doing all sorts of mystical dark-arts tuning to them, like water-break-in and comm drops and whatnot). You can buy two motors from the same shop on the same day, and they might be identical in performance, or very close, or wildly different.

There is probably no meaningful difference between the two motors you describe, especially in a Hornet and a Lunchbox. Both are lightweight, both have the same very efficient gearbox, and the overall gearing is fairly close between them with stock-size tires. Any 540-size closed-endbell motor between 20 and 30 turns is going to feel very similar in them. The Hornet will probably always have the edge due to lower weight (especially rotating weight; Lunchbox tires are heavy, it's like having to spin up four big flywheels to get it moving). Try switching the motors between the two and leaving everything else the same, and I'd bet you'll see the same result.

Yes I’m aware of that... I’ve played guitar for 25 years and Vacuum tube amps are the same way. Same model built same day with same tubes and can sound quiet different. Automotive same too, one that rolls off the line 1/2hr after the first could be a lemon....This must be a good one I got tho the sport tuned cause holy crap that little hornet moves with it. I think I should have a spare set of rear tires on hand cause I don’t think they’re gonna last long. But that’s the problem lately there’s not much in stock anywhere.

[Toolmaker72 507]

Just adding about the motors, people forget about the actual diameter of the wire on the armature.  To compare turn counts you need to work out the cross sectional area of the copper wire first then the amount of turns.  The old vintage Parma cyclone motors used to quote the wire diameter together with the turns.  Then once you have worked that out you have variations in the magnet strength and the clearance between the rotating armature and magnet, then the timing, then soft carbon or hard carbon brushes and the difference of tension on the springs pushing against the brush on the armature commutator.  As mentioned above, 27 turn vintage roar motors are deceptively quick.  I have a couple with the little printouts showing 28000rpm at 7volts.  Getting the pinion size correct for the final drive ratio is key though.  The hornet and lunchbox use exactly the same size gearbox internals. The lunchbox 10 tooth pinion is the same as that used on a 380 grasshopper motor and same ratio except the lunchbox has a bigger diameter tyre to compensate.  Pi x d will calculate the circumference of a circle.  Use that to determine how many wheel revolutions per metre or yard depending your preference. Then work out that ratio compared to the final drive of each gearbox using either the 18 tooth or 10 tooth pinion.  That will show which gearbox and wheel diameter is lower or higher geared to then compare speed according to a specific motor. Hope that makes sense 😕

[LeftyAl 164]

As Toolmaker mentions there are lots of variables in brushed  motors.

Bushings vs bearing

Hard vs soft brushes

Hard vs soft springs. OG style rebuildable motors could cater for tuned springs for the -ve and +ve sides (different tensions)

Timing setup

Magnet strength

Brush contact with the Comm.

Balance of the armature.

Can design and how heat is managed.

Include  tolerances in manufacturing/assembly, just like the amp tubes example, and the motors have a range of performance. I have found 23T Tamiya motors tend to punch above their weight compared to similar "specced" motors. Not sure if it in the manufacturing/assembly side of things, or slick marketing from the competition....maybe both.

Another thing to consider in the lunch box versus hornet example is rotating mass. The weight of the wheels has a massive impact on performance. I swapped from rubber slicks to foam tyres on my TA03/04 cars and the acceleration difference is very noticeable.

Try the 20T in your Hornet and see how it goes. Maybe with using a GPS or phone to confirm the speed.

[Lukas666 39]

On 2/21/2021 at 8:29 AM, Big Jon said:

The Dynamite 20T isn't nearly as fast as the Tamiya 23t, so there's a start. The two vehicles both use fairly efficient transmissions of similar design, so should be about equal assuming equal rollout, with the 'Box being slightly slower due to weight. Rollout is how far the vehicle moves per motor revolution, and is a great way to compare final drive ratios between dissimilar vehicles or when changing tire size.

One of my rigs uses a 3800kV motor on 3S high voltage lipo, and is easily outrun by a buggy with a 17.5 on 2S. I don't know the rollout on either, but the truck has about a 45:1 FDR, and the buggy has about 8:1.

Finally, when dealing with low power levels, every little bit matters. BITD, we put a tremendous amount of effort into reducing friction and rolling resistance, motor tuning and maintenance, minimizing voltage drop, etc. Look at some old pics of race cars, and you'll see three wire speedos directly soldered to motors and batteries, no connectors. Small improvements in efficiency have big results in low power applications.

So I got my Sport tuned 23T silver can today. Charged up the Gens 5000 NIMH and changed out the Dynamite 20T for the 23T. Interestingly enough I’d say they’re pretty darn identical. If someone swapped these out behind my back I wouldn’t have noticed a lick of difference I don’t think. If the Sport tuned is any faster than the Dynamite it’s so marginal it’s not even worth mentioning. I looked at the specs a week or so ago and if I remember correctly they’re within like a couple hundred RPM. The Dynamite is about $15 cheaper as well. Ohhhh well good test I guess, now I know. So if anyone out there is contemplating a mtr change in a lunchbox you could go with either I’d say and get the same result and speed increase from the stock RS540.

[Lukas666 39]

These are the bit of specs I could find.