391 replies to this topic

[NSwanberg]

Hi Nelson,
Thanks for stopping by the raceway Saturday night.

So you are saying you get in some sort of special wreck where both braid are still in the slot, but the rear tires are up on the air, free reving at 12-14V?

Sort of like traversing the slot in a reverse wheelie?

That seems highly unlikely.

Wouldn't you hear a high pitched revving sound?

I've stood in the Deadman a good portion of the last 12 years of my life, race directing/marshaling, and I've never witnessed any sort of phenomena like that.

 

 

Both times it happened on the lead-on where I could see the car looked like it was going to climb over the other car and out of the slot but the rear wheels came back down and then the car was dead. One motor was in a retro CanAm and the other one was in what Downriver calls a flexi coupe. I would say the wheels were off of the track for less than a 1/4 of a second.

 

I am not sure a PSFK is capable of making a high pitched revving sound.

[swodem]

Can't see it being a cause. Can run them flat out on a power supply unloaded without even being in a car and they don't blow up.
I admire your vision though


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[gotboostedvr6]

Overlap and strong magnetic field causes the initial push start. If ignored, it adds a good bit of heat to the phenolic material in the comm. Centrifugal force combined with a weakened bond lifts the segment. Once the segment lifts the push start will continue and worsen.

[MSwiss]

It's not just strong magnetic field, it's the heavy cog.

 

A lot of racers associate heavy cog with a strong magnetic field.

 

For instance, you can have multimag G7 motor with a massive magnetic field, and it will have very little cog.

 

IOW, if those motors had a strong field, but with a smooth cog, they would start up fine, or at least much, much easier.

 

Regardless, if the arm has one comm segment that if trued, trues up, without touching the other two segments, it's junk and unusable for competition.

 

And talking with my old boss, Stu Koford, the less than perfect true job, on these arms is probably a product of it being done in one quick pass, but still with a diamond cutting tool.

 

In retrospect, my association with abrasion, was how the inexpensive arms, outside OD, is (sort of) trued/excess hysol is removed.

[gotboostedvr6]

Agreed on all points

[swodem]

Is there 'heavy cog' when the arm becomes activated? Why can I start a motor and run it slowly and smoothly at 2v if there is such heavy cog?
The arm will have some seriously heaving cog of its own generated by the poles magnetic field - you're only feeling the magnetic cog when the arm poles are not working...
just like compression in a petrol motor...the ignition of fuel in once cylinder far overcomes the difficultly of cranking another piston to the top of its stroke with the valves closed


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[MSwiss]

Is the above a serious post?

 

It's been explained numerous times, the ceramic mag, low cog 4002, NEVER has the problem.

 

At low voltage you can feel the motor cogging, while running.

 

You are starting a motor at 2V,

A-that is running fine. Take a motor with a push start problem, take out the back axle assembly, and in the same trouble spot in the rotation, try to start it at 2V.

B-doesn't have a load on it (IE-turning over a gear, attached to two sticky tires, that are contacting a sticky track surface)

C-a Retro Hawk will start up at .5V(1/2V) on a power supply.

 

On our low current flat track, you can sometimes see a pushstart car move a minuscule amount, trying to, but not getting past the cog.

[swodem]

Yes it's a serious post
I am wondering about yours, you seem not able to think this through. It's an intermittent problem. That's because there are 3 segments so it's happening maybe 1/3 of the time - depending on the place the armature stops rotating at
I understand the cog
It's only a problem when the motor is NOT powering the next segment properly. Otherwise it would happen 100% of the time. That's also why a PUSH gets it going - it moves the brush until contact
The only thing that is stopping it must be lack of contact from brush to next segment until it gets pushed
Do YOU not understand that?


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[MSwiss]

One last time.

 

It's not lack of contact, it's over lap, which will vary depending on brush alignment and slot spacing,  and heavy cog

 

If it was lack of contact, the 4002, coming out of the same factory, would do it too.

[swodem]

So explain to me, Einstein, if it was solely overlap, why it does not happen every time.

If it was overlap, the 4002 would do it too


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[MSwiss]

Imperfect/variable comm slot spacing.

 

Put an armature on an optical comparator and see if the motor has perfect 120 degree spacing and each comm is exactly the same as the next.

[swodem]

Gerroff!!!

What are the variances you have measured?


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[MSwiss]

I added some text to my last post.

[swodem]

It's plausible, I don't have one but I will find a way to do this

If you do, please do so and post



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[MSwiss]

I just got reinvolved in this thread because, you and Bazzie were posting, referring to untrued comms.

 

Along with not being true, it was unfair to Proslot. Unless you start adding something new, to this thread, it will get locked.

 

The 4002FK is just another great value motor, that has made slot racing more enjoyable, and affordable.

 

Like I said previously,

One way to prove it to yourself.

 

Get a chronic "needs a pushstar"t motor, while it is still running well, true the comm, and see if it cures it.(without realigning the hoods, replacing the, brushes, etc.)

 

Cure 2 or 3 motors with chronic pushstarts, with a comm true, and then your theory will hold water.

[swodem]

Mike, no-one is denying the 4002FK is a good value motor that delivers exception racetime hours for the money

But like all thing inexpensive it has shortcomings

To extract max performance from the motor, the slotcar racer ends up doing the work/labour that the factory can't spend the time to do to meet a cost

We all accept that and I don't think it's a slight on ProSlot - it's a fact of life

It's also an engaging, fun and challenging part of the hobby!

I'll carry on and find my answers....but I don't think you can say that it's untrue to say the comms are not true, if you can put it on a lathe and they are not (true).

Perhaps the new owner of ProSlot who has undoubtedly been to the factory can share exactly the process of making the comm. that'll clear it up. It'll be the same process I imagine for all the FK motors.


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[MSwiss]

In the meantime, I can't let you continually perpetuate something negative, about a slot company, that has clearly been debunked, by the rest of the slot car world.

 

When you get some NEW info, please PM me, and I'll reopen this thread.

 

Thank you.