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mtbkym01

This old chestnut! Sport Tuned Motors - advanced timing or not.

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The point of the thread isn’t about performance, it’s about timing. A Clodbuster uses 2 motors, one of which runs in reverse to drive the truck forward, anything other than zero timing will create an imbalance, hence why I asked for evidence of the suggestion that a black sport tuned motor does intact have some timing built into it.

Having said that, there is some very interesting stuff coming out in addition to the timing findings

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Does having an imbalance actually matter? You might get slightly more wear out of one compared to the other, but I'd wager you'd get less wear in either of them compared to if a single motor were used on its own, since when you use two together, it is sharing the load with another motor, so each does less work. 

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5 minutes ago, rich_f said:

Does having an imbalance actually matter? You might get slightly more wear out of one compared to the other, but I'd wager you'd get less wear in either of them compared to if a single motor were used on its own, since when you use two together, it is sharing the load with another motor, so each does less work. 

But if one is doing 22000 rpm, and the other is doing 18000 rpm, then each end of the truck will have significantly different speeds, which has to be an issue doesnt it? Or am I missing something?

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6 minutes ago, mtbkym01 said:

The point of the thread isn’t about performance, it’s about timing. A Clodbuster uses 2 motors, one of which runs in reverse to drive the truck forward, anything other than zero timing will create an imbalance, hence why I asked for evidence of the suggestion that a black sport tuned motor does intact have some timing built into it.

Having said that, there is some very interesting stuff coming out in addition to the timing findings

From a manufacturing perspective the standard motor cans and endbells will be mass produced.  The rotors inside will be different.  Try explaining to a worker the difference between 5-10 degree timing and assemble the correct parts to correct rotors.  All pictures I’ve seen show the cable tabs inline with the magnet gaps and therefore the brushes at 90degrees to those.   
The older standard motors have 3 notches in the cans so they could in theory have positive or negative timing introduced  but the tabs holding the back on would need to be modified to suit if twisting either way to run in with those settings.  It would give access to positive timing if running one motor in reverse to match a forward running motor with positive timing.
 

BAB6336D-75D5-4E62-B5D2-DFB37B200DD8.jpeg

BCF30C01-6B9D-4307-8268-C10673F57F8E.jpeg

F5F47D8E-45C5-4CB3-BC8D-392CB8CF1BEC.jpeg

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24 minutes ago, Toolmaker72 said:

From a manufacturing perspective the standard motor cans and endbells will be mass produced.  The rotors inside will be different.  Try explaining to a worker the difference between 5-10 degree timing and assemble the correct parts to correct rotors.  All pictures I’ve seen show the cable tabs inline with the magnet gaps and therefore the brushes at 90degrees to those.   
The older standard motors have 3 notches in the cans so they could in theory have positive or negative timing introduced  but the tabs holding the back on would need to be modified to suit if twisting either way to run in with those settings.  It would give access to positive timing if running one motor in reverse to match a forward running motor with positive timing.
 

BAB6336D-75D5-4E62-B5D2-DFB37B200DD8.jpeg

BCF30C01-6B9D-4307-8268-C10673F57F8E.jpeg

F5F47D8E-45C5-4CB3-BC8D-392CB8CF1BEC.jpeg

So now I’m confused, doesn’t this below illustrate a difference in brush position? Suggesting there is some timing?

On 4/27/2020 at 6:33 AM, Juggular said:

Thank you for suggesting that. That was a good idea. 

The brushes are mounted at different angles.  Magnet spacers and the windows are at the same point, but the brushes are mounted at an angle.  In the photo, it's only showing the mounting pin for the brush.  But the point is that they are at a different angle.  Which means the timing is different.  

This could explain 11% faster speed one way for Sport Tuned (brand new, unused before testing).  But the (used) 540 only had 2% discrepancy (which is a normal behavior, as you explained).  

xmqJ5xY.jpg

 

 

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I was trying to show that timing is possible with the old plastic ended motors provided you alter the can tabs to secure the end.  Otherwise it’s neutral

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1 hour ago, mtbkym01 said:

But if one is doing 22000 rpm, and the other is doing 18000 rpm, then each end of the truck will have significantly different speeds, which has to be an issue doesnt it? Or am I missing something?

You could have the worlds first counter steer Clod? :lol:

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2 hours ago, mtbkym01 said:

But if one is doing 22000 rpm, and the other is doing 18000 rpm, then each end of the truck will have significantly different speeds, which has to be an issue doesnt it? Or am I missing something?

Yes you are missing something - even if the gearboxes are not connected (I don't own any dual motor chassis so don't know if they are or not), the car will only be going at one speed. With the same ratios in each gearbox, that means the motors will also be going at the same speed. 

You might be thinking 'The wheels on the gearbox with the faster motor will be spinning faster!' but this will just produce more forward force on the car, which in turn pushes the wheels on the other gearbox, which in turn makes the slower motor spin faster, until eventually they spin at the same speed. This process happens very quickly and if you try it (especially on a moderately grippy surface like tarmac) you probably won't get any wheels spinning as the difference is very small between to two ends of the chassis. 

 

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19 hours ago, mtbkym01 said:

But if one is doing 22000 rpm, and the other is doing 18000 rpm, then each end of the truck will have significantly different speeds, which has to be an issue doesnt it? Or am I missing something?

Only when jumping at full throttle will the motors spin free. No motor is going to hit its free spin revs anyway with the weight of a Clod on it. The motor revs are determined by the vehicle speed and gearing so the faster motor will still spin at the same speed as the slower one. 
 

We really need to be measuring torque. Just because a motor can spin at high revs does not mean it actually will given the load placed on it. 

 

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Ok, so to finally confirm my very initial fear. The black Sport tuned motors I have wired up and fitted into my Clod will not cause me any issues what so ever?

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15 minutes ago, mtbkym01 said:

Ok, so to finally confirm my very initial fear. The black Sport tuned motors I have wired up and fitted into my Clod will not cause me any issues what so ever?

It will just not be as fast as it possibly could be. Give it a good run and compare motor temps. I bet the rear will be hotter than the front because it is doing more of the “work”

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The main thing I got from this thread is that magic is real and a silvercan can be made fast - can @Toolmaker72 replicate that fast silvercan that his dad made for him? Be keen to try that on one of my silvercans lying around

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The gearboxes ARE connected - by the road 

there is no on car connection but the road connects the wheels and thus connects the motors together

The same electricity goes into each motor and each wants to turn at different speeds for the same input but the road doesn’t allow it 

don’t know if the car travels at the speed of the fastest motor (dragging the other motor with it) or at the speed of the slowest motor (loading the faster motor) or they both go at the speed they are going and the strain of that is applied to the gearbox through the wheels 

JJ 

 

 

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The road connecting two gearboxes is an interesting thought.  I haven't thought of it that way.  

However, I think I'll take that idea in, only about half way... 

Wild Dagger has the most toy-like driving characteristics out of all the chassis I have.  Something is off at strange moments.  I'd characterize it as "disorganized."  No harmony.  Welding two ends of FWD cars just won't make the best 4WD car.  

Putting two motors in one gear would work. The gear itself would force the motors to synchronize.  It was used in Juggernaut 1, Juggernaut 2, TXT-1 and more recently TXT-2.  This is not as bad as two gearboxes.  Even though the gears could wear out a bit more, the wheels are all turning at the same rate, like any other 4WD.  

lNKfJMg.jpg

 

The other reason why I bought a tachometer is to measure RPMs for Wild Dagger motors.  No two motors can be the same.  The magnet strengths, how tightly the wire is wound, how the brushes make contact, and the timing cannot be so exact as to produce the same exact RPM.  Even tiny bit of oil on the bushings would increase 100 RPM (at 3.7v).  If one motor turns faster, I wanted to use it at the front.  Front 2 wheels should rotate more when turning.  On a straight run, the front will pull, the rear will slightly drag; that's better than front dragging and the rear pushing.  

You see cars and motorcycles doing donuts, they turn rear wheels while holding the front brake.  One axle of Wild Dagger or Clod won't turn that fast, but the speed difference can make you lose traction.  We have differentials so the small difference between right and left won't result in lost traction.  SRB doesn't have a diff, so it flips much easier on tarmac.  Because the speeds of the motors are always different, it has a similar effect if you have 2 motors running 2 different gearboxes.  

Especially, if you are used to 4WD vehicles with limited-slip-differentials that gives you excellent traction, Wild Dagger feels like all 4 wheels are going at 4 different directions.  I never had Clod, but one other dual axle chassis I had was Kyosho Double Dare back in the 1992.  I was totally unimpressed. I never regretted selling this dual-gearbox chassis (though it did look good).  FY7E7wh.jpg

I think Tamiya recognized the problem of separate gearboxes and just went with 1 motor with GF01 and even G6-01 Konghead.  One motor might be more burdened than having 2, but Tamiya went with all 6 wheels turning at the same speed. 

On the other end of the extreme, Konghead is stretching the "all wheels turning at the same speed" thing a bit too far.  While Wild Dagger suffers from a spit personality, Konghead is too uniform.  At least the front axle should have a center diff. (I don't mean the diff in the axle. I mean a diff between axles) 

rZr8Pax.png

The reason why 1:1 Subaru AWD is one of the best is because of their center differential is best adjusted in the industry.  The longer the wheel base, the more likely you'd need a center diff.  That means having 4-5 differentials for Konghead. That's too complex for an RC truck that costs $100 cheaper than TRX4.  Which is why Konghead has that "floaty" feel to it.  The front and the rear axles always want to lose traction a bit, making Konghead pivot around the center axle. But I think Konghead's "link-everything" is better than 3 separate gearboxes. 

If I could, I would find out which motor turns faster going backward and forward, and install the faster one on the front of Clod or Wild Dagger.  I'd choose 2 of the same motors without advanced timing.  If one motor is like 500RPM faster, I'd choose another closely matched set of 2 motors. 

Or I'd get a pair of these 21t or 19t motors. Start at the timing of 0 and then adjust little by little until I'd get few RPMs faster at the front wheels.  

NuVTems.jpg

Just as @Toolmaker72 said, lower turns doesn't always make motors go faster.  Even though above GoolRC motor says 21turn, I just found out that it's actually slower than 23t Sport Tuned.  

10,600 RPM forward (at 3.7v) as opposed to 11,100 of Sport Tuned. 4.7% slower than Sport Tuned. (but still 20% faster than 8800 of silver can)

8,800 RPM backward (at 3.7v) as opposed to 9,900 of Sport Tuned. 12.5% slower than Sport Tuned: it's got more timing than Sport Tuned. 

GoolRC's wires might be thinner, which means that even if it's similar to Sport Tuned in RPM, the torque would be lower.  The only saving grace for this motor is that it's adjustable and has bearings.  

Just out of curiosity, I also tested a brand new silver can.  It got 8800 RPM going forward at 3.7v. (8700 backward) The other silver can was like 20 years older. That should have gotten a few % slower.  Who knows, the older motor won the magnet lottery and ended up with stronger magnets. (that, or magnets don't grow weak--but I've always heard that it weakens over time)  

FehIqLA.jpg

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@Juggular do you have a 23T Tamiya Super Stock motor to test against the others? Mu suspicion is that it will be far better than a cheap 17T or even 15T motor, but I have nothing to base that on.

If you don't then you should tell your wife that you need one for science so it comes out of the science budget, not the RC budget.

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Bumping to add 2S RPMs for posterity (instead of 1S I tested earlier). 

C9dQfOL.jpg

(GoolRC has bearings. I installed bearings on Reedy MVP.)

 

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So this old thread was mostly about testing the various ST motors, and a great read overall. My wonder ; 

What about the current Torque tuned? 
Tamiya website ( and other sources ) claim it’s a 25T.  Anyone dissected or tested to see if these are truly 25T and zero timing ? I’m also interested in running them In a Clod like the OP was with the Sport Tuned . 

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1 hour ago, Dakratfink said:

So this old thread was mostly about testing the various ST motors, and a great read overall. My wonder ; 

What about the current Torque tuned? 
Tamiya website ( and other sources ) claim it’s a 25T.  Anyone dissected or tested to see if these are truly 25T and zero timing ? I’m also interested in running them In a Clod like the OP was with the Sport Tuned . 

I believe all three motors (540sh, Torque Tuned and Sport Tuned) have some timing advance. You can tell by looking at where the magnets are and how the endbell is clocked. They would be needlessly inefficient if they had 0 timing. They also have 3 slightly different timing, in increasing amount from 540sh to ST.

Regarding the number of turns: I have a Torque Tuned motor that came in a TT-02 '99 Impreza kit. It has done it's time and I am thinking of opening it, snipping the very end of a wire on one of the three poles and counting the turns. I'll only do that if anyone is interested. Thoughts?

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9 minutes ago, Pylon80 said:

I'll only do that if anyone is interested. Thoughts?

Count me as interested!

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38 minutes ago, Pylon80 said:

I am thinking of opening it, snipping the very end of a wire on one of the three poles and counting the turns. I'll only do that if anyone is interested. Thoughts?

If it is truly done it’s time and dead , and you don’t mind your time and effort in the interest of knowledge,

please do! 

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Don’t forget to measure the diameter of the wire used.  Just counting turns isn’t the only measurable 😉

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1 minute ago, Toolmaker72 said:

Don’t forget to measure the diameter of the wire used.  Just counting turns isn’t the only measurable 😉

Absolutely. Looking through the oblong hole of a ST I can already tell that the wire is bigger. It's going to be interesting to open up that TT.

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Out of interest,  have the £10 - 15t Firebolts (Corerc 15t) ever been tested for RPM in each direction? 

They're not arrowed, so just presume they're not.

860/880 esc, 2x 15t firebolts , 2s lipo👍

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