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Old 12-05-2012, 12:19 PM   #17941
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Been reading the motor posts with some interest cause the results that you are posting have been contrary to what I've seen. Admittedly, I have not been doing any motor work for a couple of years, so these motors have come from a newer production run.

However, the motors I've seen have all run slightly faster in normal rotation than than reverse. The variation has been c. 400 rpm or less measured at 5v. If as some have posted, the motors are advanced anywhere from 3 to 10 degrees, you would see rpm variations in excess of 1,000 rpm and up to several thousand rpms. This just doesn't happen.

I'm going to suggest that in taking the motors apart, that the brush orientation may have been disturbed. Measurements taken in this situation cannot be relied upon.
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Old 12-06-2012, 10:09 AM   #17942
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Here's a few pics of what I mean.

The first pic is a close up showing the alignment of the brushes. The black line drawn is the middle point between the two magnets. You can see that the brushes are not symetrical to the black line.

The second pic shows how far I believe the timing is reduced. The small black line is where I believe 0 is on the endbell. The distance between the two lines is 4mm, which translates to 13 degrees.
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Last edited by jha07; 12-06-2012 at 11:06 AM.
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Old 12-06-2012, 10:55 AM   #17943
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I was talking about the timing advance on the armature. The armatures timing is retarded that causes heat and a loss of rpms. I was going to reverse zap the magnets and i will get a big perfomance gain.
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Old 12-06-2012, 01:44 PM   #17944
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Quote:
Originally Posted by vivo quevas View Post
I was talking about the timing advance on the armature. The armatures timing is retarded that causes heat and a loss of rpms. I was going to reverse zap the magnets and i will get a big perfomance gain.
No you won't.
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Old 12-06-2012, 01:52 PM   #17945
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Quote:
Originally Posted by jha07 View Post
Here's a few pics of what I mean.

The first pic is a close up showing the alignment of the brushes. The black line drawn is the middle point between the two magnets. You can see that the brushes are not symetrical to the black line.

The second pic shows how far I believe the timing is reduced. The small black line is where I believe 0 is on the endbell. The distance between the two lines is 4mm, which translates to 13 degrees.
If what you believe is true, your motor will turn over a thousand rpm faster in the reverse direction. Probably should turn several thousand rpms faster. If it doesn't, you've made an error in measurement.
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Old 12-06-2012, 02:07 PM   #17946
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Quote:
Originally Posted by Granpa View Post
If what you believe is true, your motor will turn over a thousand rpm faster in the reverse direction. Probably should turn several thousand rpms faster. If it doesn't, you've made an error in measurement.
I don't have a dyno, so I can't tell you what the rpm difference is, but reverse is noticeably faster from the sound.

But forget my measurement, doesn't the brushes look like they are not at zero from the pic? It's very noticeable to me.

I did a search for mabuchi motor pics online and found some motors like mine where the power tabs are turned to the side a bit, but others where the power tabs are centered over the vent hole.
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Old 12-06-2012, 03:05 PM   #17947
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The thing you have to remember about silver cans is that they've been in production for better than 50 years and used in every low voltage appliance known to exist. I've got silver cans from blow dryers, drills, vacuum cleaners, etc that were all marked as being the same model of Mabuchi rs540sh, that had very different performance characteristics. (Don't even get me started on the various sub-models within that product line.) Tamiya has, on occasion, put different variations of the motors into their packaging. EG: The CS motors of the last few years.

This brings us to the next and perhaps more important point - These motors are slapped out at an insane rate by dozens of factories across China, each one varies just a little bit from the last. Sure, the ones Tamiya buys are built to a spec, but there can be discrepancies within those runs. A thousand RPM up or down would not be surprising between a few motors and it would be silly for Tamiya to not sell them, considering how cheap these things are when you buy 100,000 at a time.

Jim

PS: About the variations within the 540SH product line. I've had some spin over 30,000 rpm out of the box and others creep along at 5,500rpm. It all depends on the variant.)
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Old 12-06-2012, 08:20 PM   #17948
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Hi, just bought a Tamiya M05 Mini as a Christmas present I bought the kit and some ball bearings. I just want to know any tips or anything else i should get before I start building it???

Thank you!
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Old 12-06-2012, 11:52 PM   #17949
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^ check rc-mini.net for building hints and tips.
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Old 12-07-2012, 12:46 AM   #17950
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Quote:
Originally Posted by jha07 View Post
I don't have a dyno, so I can't tell you what the rpm difference is, but reverse is noticeably faster from the sound.

But forget my measurement, doesn't the brushes look like they are not at zero from the pic? It's very noticeable to me.

I did a search for mabuchi motor pics online and found some motors like mine where the power tabs are turned to the side a bit, but others where the power tabs are centered over the vent hole.
Hard to evaluate cause I don't know what noticeably faster means. A variation of a couple of hundred rpms may be discernible to some and not to others. Unless you have a way of measuring actual rpms this discussion is difficult at best.

I also use the midpoint between the magnets as a Zero point, but whether it truly is, is open to question. It probably isn't, but I use it cause it's a convenient and repeatable reference point. At true zero, the motor should spin at the same speed in both directions. The point is that in the #53689 Johnson 540J motors, which is the Silvercan motor, they ALL run faster in the forward direction without exception.

Hopefully, this will clear up some of the confusion surrounding the term Silvercan. A Silvercan motor is the Tamiya #53689 540J motor period. Any other motor, Mabuchi type or not, is merely a motor with a can that is silver in color. The motor that comes in many of the kits, I believe is a 540SH type motor. Now that is a 540 sized, sealed end bell motor with a silver motor can, but is not a Silvercan. It is not legal in the TCS races. To refer to anything other than the #53689 540J as a Silvercan, is an error.
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Old 12-07-2012, 10:46 AM   #17951
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Thanks for the info. I'm almost positive mine isn't a 53689 540J, but will confirm when I get home.
I did a search for 53689 540J motors and all the pics I found have their power tabs centered over the vent hole, unlike mine. I guess I need to get a new motor.
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Old 12-07-2012, 11:04 AM   #17952
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Quote:
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Thanks for the info. I'm almost positive mine isn't a 53689 540J, but will confirm when I get home.
I did a search for 53689 540J motors and all the pics I found have their power tabs centered over the vent hole, unlike mine. I guess I need to get a new motor.
The TCS Canada rules are a little different than the USA rules. In the USA, the #53689 motor is the only one allowed.
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Old 12-07-2012, 12:26 PM   #17953
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Quote:
Originally Posted by Granpa View Post
The TCS Canada rules are a little different than the USA rules. In the USA, the #53689 motor is the only one allowed.
I'm not really concerned about TCS rules, since I'm only planning to do club races. But I am concerned that it's slower forward than reverse. Getting killed on the straightaway is not my idea of fun.
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Old 12-07-2012, 04:27 PM   #17954
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jha07, if you're running in the WCICS series get the ORCA bl system.
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Old 12-07-2012, 05:03 PM   #17955
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jha07, if you're running in the WCICS series get the ORCA bl system.
How much are they?
I know people run them at our track, and while I like brushless, I don't like the idea of spending a ton of money only to have it go the same speed as a silvercan.
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