# Timing advance on Tomy cars



## Mike(^RacerX^) (Mar 15, 2003)

I remember hearing something,somewhere,that you could advance or retard the timing on certain model of Tomy car.

Can't remember which model it was,and since I read so much HO slot related stuff on the net,I don;t remember where I read it.

Anyone out there help me out on this??? I have all flavors of Tomy slots,and would like to give it a whirl if possible.

Mike


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## mking (Apr 25, 2000)

Hello

it is the Tomy super g plus model that has the adjustable timing. The end bell is a plastic housing that sits between the armature and the front axle, and I believe it contains the brushes. The end bell pivots on its center, that is you can push the extreme left side or extreme right side up or down. When you push one side of the end bell up or down you will feel like click as it moves from one position to another. Moving the end bell from one position to another advances or retards the timing. I don't remember which direction is which, play around with it and see if you notice a difference. I never really noticed a difference one way or are another.


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## Mike(^RacerX^) (Mar 15, 2003)

Ok,I gave it a shot like you said,and I don't feel any difference either.

Maybe someone can let us know what it is that this actually does.

Thanks for the response!!!!!!   

Mike


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## EBasil (Jan 11, 2000)

It's a subtle difference, but it's there.


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## AfxToo (Aug 29, 2003)

Yes, the Tomy Super G+ has adjustable timing. If you rotate the endbell in the opposite direction as the arm turns you are advancing the timing. Rotate it toward the direction of rotation and you are retarding it. That would be down on the drivers side of the car for advanced timing. 

You can also advance the timing by moving the commutator plates relative to the arm windings. That's how the Super II arm, Patriot Storm, and other modified (off zero) timing arms are done. 

I can explain the theory of how this all works but I feel like I'm Bogarting the board as it is.


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## Mike(^RacerX^) (Mar 15, 2003)

I can explain the theory of how this all works but I feel like I'm Bogarting the board as it is.[/QUOTE]

Actually,you always give good answers if I do say so myself.

I'd be interested in hearing the theory,as I am sure others would too.

Mike


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## AfxToo (Aug 29, 2003)

To put it briefly, here's basically what happens with DC motor timing... 


There is a brush position on all motor comms where you get maximum voltage potential across the brushes and minimum commutation arcing. This is called the brush neutral postion and on typical 3-pole slot car permanent magnet motors is generally around the center of the comm segment (but not necessarily there). This is a static setting for the motor. All this is fine and good, but when you apply current to the armature windings with their magnetic mass, they become electromagnets with their own magnetic fields. The armature's magnetic field is out of phase with the magnetic field created by the permanent magnets. These two fields interact in a process called "reaction." The "reaction" causes the total magnetic field to rotate to the point that the effective comm timing is no longer at the neutral postion. This causes arcing and sparking of the brushes, limiting the overall performance of the motor. If the timing is way out of whack brush life will decrease drastically, 100x-1000x worse.

Having adjustable timing allows you to move the brushes back to the neutral position when the motor is running and under the effects of armature reaction. On large brushed motors (and generators) there are quite elaborate ways to compensate for reaction, but for small brushed DC motors the usual fix is to have adjustable brush rigging. The Tomy endbell is a form of adjustable brush rigging. Moving the comm plates instead of the brushes is another way to compensate, and that's how the Super II and Patriot Storm arms do it.

Here's the rub and the reason I don't lose too much sleep over the constant "high timed arm" arguments that seem to plague other slot boards: Armature reaction is directly proportional to the armature current. If you run a motor over a very narrow range of currents the timing can be set for optimal performance - end of story. But slot cars tend to be run over a wide range of currents, so putting in an arm with fixed off neutral timing is a compromise solution, at best. 

The timing adjustement must be well chosen for the particular armature winding, motor magnets, and motor load, and even the power supply capability. Overly advancing the timing is as bad or worse as not advancing it at all. The Tomy adjustable timing strategy is nice because it allows some degree of tuning for the total racing situation. Trial and error and testing. On the other hand, putting in a fixed off neutral timed arm is kind of a crap shoot. Hopefully the guys who sell cars with off neutral timed arms have done their homework and have picked a timing value for their cars that deliver a net improvement over a wide range of operational scenarios. No matter what you do to set the timing, it's unlikely that you'll pick a perfect setting for the entire racing situation unless you're running flat out on a banked oval or something like that. But even if the timing adjustment only improves the performance for certain parts of the race scenario, it can still deliver a net if somewhat subtle improvement. Whether this makes the difference between winning and losing is the point of many an argument.

Note that there are other timing related factors involved besides reaction, but it's probably the biggest factor for the simple 3-pole motors in most HO slot cars.


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## Mike(^RacerX^) (Mar 15, 2003)

Thank you for the explanation.You pretty much told me everything that I wanted to know on the subject.

After experimenting a bit,I did notice a difference.Subtle,but there just the same.

Thanks again.....

Mike


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## Pomfish (Oct 25, 2003)

I'll jump in here as I have played with lots of timing variables and used to Consult with the Great, Late Kipp of Kipp's HO in Lebanon (RIP)
He would build pretty much anything you wanted, so we would try different winds.
Some worked great, others not.

Anyway, on Tjet Afx Pancake type arms the Super II used 5 degrees advance.
I have had arms with up to 18 degrees advance. The advance timing will generally make the car come off the corner quicker but low end torque will suffer.

Retarded timing will give lots of Torque, but lose Top End Rpm, as the Drag arms from the Afx dragsters do.

Magnets, Power Supply and Brushes all come into play as well. Most of my experience was with lower ohm stuff, the high ohm arms probably will not yield as much of a difference.

In reference to Inline arms like the Tycos and Super G+ they didn't seem to like as much advance as the Pancakes.
Had good success with Tyco 4.7 ohms with 5 Degrees advance though. Life-Likes were very tempremental, never found one that stood out. The old Life-Like High5 M5 stock arms probably work the best for the M Chassis.

Glad I bought extras from Kipp as not many people do rewinds these days.

Thanks,
Keith


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## AfxToo (Aug 29, 2003)

What Keith is saying makes a lot of sense. Pancake armatures tend to run in a saturated state much more than inline motors. Saturation means that the armature has reached a point where applying more voltage no longer causes a proportional increase in the magnetism in the armature poles. Instead it causes a small increase in magnetism but a very large increase in current. This causes heat build up and it causes armature reation to become a major factor. Pancake motors really don't have a lot of magnetic mass compared to an inline motors so they saturate more easily. Even a quadralam pancake motor pales in comparison to an inline when it comes to magnetic mass. Since a pancake motor is more likely to run in high current situations, and since armature reaction is a function of the current in the armatuer windings, pancake motors will show more variation due to timing changes.

The other major timing related influence in these motors is called armature "reactance." It's unrelated to the similar sounding armature reaction. Basically, it is the effect caused by the inductance of the motor windings and the fact that the commutation process causes the current to change rapidly at the point where the brushes are shorting two adjacent comm segments. This effect tends to limit the maximum RPM that the motor can achieve. Advancing the timing sets up a situation where adjacent poles can actually aid in the reversal of current process for a small portion of the commutation cycle. (It's somewhat similar the effect that a hot camshaft with a small amount of exhaust cycle overlap can aid in drawing in the fuel-air mixture for the next cycle.) This is why slot car motors with advanced timing tend to achieve higher RPMs, at least in low load situations. Once you place any motor under load and the armature current increases you then have to deal with armature reaction. So you can see that there's at least a few very non-trivial things happening when you start playing around with your motor timing. And this is just the tip of the iceberg.


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## Mike(^RacerX^) (Mar 15, 2003)

Thanks for the great responses guys.Very educational stuff.

So I did about 1500 laps with a couple of G+ cars the other night.With the timing all three ways,and I definetly got a feel for what the different settings do.
Over the last month or so,I have done a pretty good sampling of all of the different types of cars that are out there.I'll always love T Jets,as they are the ones that brought me to the dance some 35+ years ago.They're my roots so to speak.
But out of all of the post t jet cars I have driven,I will have to say that I like the G+ the best.I think they are a good combo of screaming speed,with just enough magnet to keep them to the track,but still require a bit of driving skill to keep them to the track.
I have more questions,but I'll start other threads for those.

Thanks again guys.Much appreciated.

Mike


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