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Old 09-17-2003, 10:54 PM   #1
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Default shifting armatures

Quick question,
are armatures setup exactly for the cans they come in?

Basically, I have an old TO Rush can with a busted TO Rush armature...
I'm wondering if something like the TO Element armature would work in the TO Rush can...
without doubt, this isn't the best way to get the most out of
your motor...but i'm wondering if this is a viable economical solution

thanks in advance...
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Old 09-17-2003, 11:19 PM   #2
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ya just for messing around it should work. Try it and see if the are fits it will work.
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Old 09-17-2003, 11:50 PM   #3
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should work, just make sure that your motor is shimmed properly then your all set. goodluck
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Old 09-18-2003, 08:14 AM   #4
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Although I'm not familiar with your particular motor, moving armatures from one can to another can have suprising results. So don't be afraid to experiment! The main thing is to ensure your armature is sitting in the strongest part of the field at all times - it's simple to achieve but takes a few moments to do. Put your chosen armature in to the can with no shims, and put the end bell on. Spin the armature (you'll probably need to slip a pinion on to do this!). Where it comes to rest is where you want the armature to spin whilst in use, so pull on the armature and note how much 'end-float' there is. You need to eliminate the float in this direction, so add a shim and repeat the process again. Spin & then pull on the shaft - how much float is there now? Keep doing this until there is only the smallest 'tick' of float when you pull on the shaft. Now you need to check the float in the other direction - towards the endbell - by pushing the shaft. Does it have loads of float? Probably, so in the same way add a shim or 2 at a time until there is just a 'tick' of free movement. You don't want the armature to be tight in the can!! Assuming your comms are clean and round, the brushes healthy etc you should find this improves the performance of all your motors - not just the 'custom built' ones
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Old 09-18-2003, 10:14 AM   #5
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If the motor is going to center itself in the can's natural magnetic field by itself, especially when there is current attached to the leads, why do you need to shim? It is going to sping right where it wants to anyway.
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Old 09-18-2003, 10:54 AM   #6
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Good question holycow! The thing is, the armature doesn't stay in the nice big, fat, part of the magnetic field once the motor is in use - it settles in the correct part of the magnetic field only when it stops spinning, if left un-shimmed! As soon as current is 'applied to the leads' ie when you open the throttle, the armature shifts out towards the pinion end of the motor and when you brake, it shifts towards the endbell side of the motor - in either case, the armature is shifting out of the optimum part of the magnetic field. So, by finding the where the armature settles inside the can by spinning it by hand, then adding shims until the motor doesn't have any float towards the pinion side, then shimming up the comm end of the armature to allow just a 'tick' of float, you can be sure that your motor is always running freely - right in the 'sweet spot' of the magnetic field. So don't throw those shims away just yet, OK! Manufacturers are supposed to set this 'just right' in the factory, but as soon as we take our motors apart and loose the shims, the advantage is lost. Also, once you know how to do this, you could probably set it even better than when it was new - assuming you always have a few shims in your pit-box. Try it!
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Old 09-18-2003, 11:07 AM   #7
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Thanks for the info,
I'll give it a try and see how the results go
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Old 09-18-2003, 11:20 AM   #8
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GR8!! U wont b dissappointed with the results!
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Old 09-18-2003, 12:19 PM   #9
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Ok I see... I thought that when current is attached to the leads, that the spinning arm would go to center (in the field) This being the case, there would be no need for a shim. But what you are saying, is that the cyntrifical force of the spin is stronger then the mag field, forcing the arm towards the endbell?

This is new news to me.... I would of guessed that the magnetic field was stonger...
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Old 09-18-2003, 01:31 PM   #10
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Try using an un-shimmed motor in a car, with the cars tyres off the ground and watch the pinion move out away from the motor. The movement is quite considerable isn't it? Now brake and observe the pinion shoot back in towards the motor. The overall movement can be millimeters between the two extremes of movement. In some cars, this can actually be so severe that a stripped spur gear is the end result, without the owner actually realising why! Magnetism is no match for Centrifugal force! Putting too many shims in a motor and not allowing any float isn't good either, so shimming has to be done methodically for it to work. If it didn't matter, all the big motor manufacturers wouldn't bother shimming their motors at all - it would save them the cost of the shims If you race stock motors, it matters - every bit of performance counts, there is no surplus of power!
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Old 09-18-2003, 03:00 PM   #11
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Part of the problem I have, is that one of my monsters has almost no play at all, with no shims. My other monster has just a tiny bit of play, but I can't tell for the life of me where the mag center is... impossible.
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Old 09-18-2003, 04:37 PM   #12
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Oh, right - I see what you mean. If the armature has virtually no play, I suppose you don't have to worry about it being off the magnetic centre So long as it doesn't bind whilst in use, don't worry.
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