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Old 09-16-2008, 05:20 AM   #1051
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I was running it at 82-85 degrees c for 5 races and only got faster but that what i have to gear it to be 2 or 3 secs a lap off top guys although it was a day for hot motors (thats not all my driving that is that slow its a [email protected] car so 416 on the way) can anyone explain why it was getting faster? and its done about 4 or 5 meets (5 races a meet) and was run in at no load

btw sorry i ask lots of qs
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Old 09-16-2008, 12:00 PM   #1052
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Originally Posted by monkeyracing View Post
If you read through some of this thread, even the posts just up from yours, you will find that all this information is covered.

Jim
I did read some of the posts, they were mostly about temps and how to break in the bushings.
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Old 09-16-2008, 01:39 PM   #1053
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Originally Posted by Drifting101 View Post
I was running it at 82-85 degrees c for 5 races and only got faster but that what i have to gear it to be 2 or 3 secs a lap off top guys although it was a day for hot motors (thats not all my driving that is that slow its a [email protected] car so 416 on the way) can anyone explain why it was getting faster? and its done about 4 or 5 meets (5 races a meet) and was run in at no load

btw sorry i ask lots of qs
maybe it's hotter then. from what I understood it was some kind of thermoplastic glue inside (stupid idea, I know.)
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Old 09-16-2008, 01:42 PM   #1054
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Maybe the magnets were weakened by the heat?? Weaker magnets give you more RPM and less torque.
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Originally Posted by Drifting101 View Post
I was running it at 82-85 degrees c for 5 races and only got faster but that what i have to gear it to be 2 or 3 secs a lap off top guys although it was a day for hot motors (thats not all my driving that is that slow its a [email protected] car so 416 on the way) can anyone explain why it was getting faster? and its done about 4 or 5 meets (5 races a meet) and was run in at no load

btw sorry i ask lots of qs
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Old 09-16-2008, 01:50 PM   #1055
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I have been running a silver can at sometimes up to 240F in my TT01. The thing is still crazy fast.
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Old 09-16-2008, 09:39 PM   #1056
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Maybe the magnets were weakened by the heat?? Weaker magnets give you more RPM and less torque.
I believe the Curie point on the ceramic magnets in a silvercan is in the neighborhood of 800 degrees F. What happens when you overheat a silvercan is you burn up the brushes or the armature, It's very difficult to overheat a motor enough in a car to significantly alter the magnetism. Magnets often weaken slightly with time, but I believe it's due more to vibration, shock etc rather than heat.
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Old 09-17-2008, 02:28 AM   #1057
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Maybe the magnets were weakened by the heat?? Weaker magnets give you more RPM and less torque.
I had the same amount of torque and feeling by hand the mags were just as good as new
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Old 09-17-2008, 05:12 AM   #1058
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Then it probably was just continuing to break in and the brushes seat better.

As far as the magnets go...I have for sure 100% watched a car slow because an overheated motor and then have a weak magnetic resistence after cooling compared to before the race....and not just once or twice so...And then checking on a dyno showed less overall power and more RPM.
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I had the same amount of torque and feeling by hand the mags were just as good as new
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Old 09-17-2008, 06:02 PM   #1059
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If you test a Johnson 3-5 times in a row (no rest)... you can see the effect of heat reducing torque and increasing RPM. (which is what happens on the track)

If you don't break in the brushes, you can ruin the motor, especially if you gear into it.

Temp, usually hot is the norm for me, anything under 200f usually is pretty safe, unless you don't breakin the brushes.
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Old 09-18-2008, 12:08 AM   #1060
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Then it probably was just continuing to break in and the brushes seat better.

As far as the magnets go...I have for sure 100% watched a car slow because an overheated motor and then have a weak magnetic resistence after cooling compared to before the race....and not just once or twice so...And then checking on a dyno showed less overall power and more RPM.

What you've experienced with overheated motors doesn't mean that the problem lies in the magnets getting weaker. It was probably burned brushes or a fried armature. If you'll remember from your TC days, turning the comm and puting in new brushes restored the power in a motor. Some of the guys would rarely buy a new motor, but would keep replacing armatures until the bushings wore out.

Magnets can weaken over time, but will never degenerate to the degree you state in a few runs. I do agree with your observations about overheated motors going slower. I just don't agree that it was due to weakened magnets
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Old 09-18-2008, 06:23 AM   #1061
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Gauss meter says differently.

And then once rezapped the motor is back and stronger than before. So I'm not sure I can agree about the magnets

As far as burning brushes and the arm...yes, I've seen that ruin motors too. But they tend to run slower and are very hard to bring back to life. A weakend motor that has weak magnets from being run too hot repeatedly will be returned to it's glory days via zapping most of the time..as long as everything else is taken care of. I've got some 4 slotters that were crap...once zapped and run a few times have shown HUGE improvements over previous performance. And they were checked on a gauss meter before and after zapping. And it's very noticeable on track. So yes, the magnetic strength does weaken. Science doesn't fib.
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What you've experienced with overheated motors doesn't mean that the problem lies in the magnets getting weaker. It was probably burned brushes or a fried armature. If you'll remember from your TC days, turning the comm and puting in new brushes restored the power in a motor. Some of the guys would rarely buy a new motor, but would keep replacing armatures until the bushings wore out.

Magnets can weaken over time, but will never degenerate to the degree you state in a few runs. I do agree with your observations about overheated motors going slower. I just don't agree that it was due to weakened magnets
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Old 09-18-2008, 03:45 PM   #1062
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Gauss meter says differently.

And then once rezapped the motor is back and stronger than before. So I'm not sure I can agree about the magnets

As far as burning brushes and the arm...yes, I've seen that ruin motors too. But they tend to run slower and are very hard to bring back to life. A weakend motor that has weak magnets from being run too hot repeatedly will be returned to it's glory days via zapping most of the time..as long as everything else is taken care of. I've got some 4 slotters that were crap...once zapped and run a few times have shown HUGE improvements over previous performance. And they were checked on a gauss meter before and after zapping. And it's very noticeable on track. So yes, the magnetic strength does weaken. Science doesn't fib.
I'll have to concede the point, since you measured with a gauss or tesla meter. Do not have one as a good one was more expensive than my budget allowed. For my own information, how much weakening percentage wise did you notice and how hot did the motors get. Have a few more ??? so I'll send you a PM rather than boring anyone else
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Old 09-18-2008, 08:39 PM   #1063
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for info, what kind or brand zapper do you use for silvercans??????
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Old 09-18-2008, 11:41 PM   #1064
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I've got a brand new "Red Dot" silver can Johnson motor from Doc (rccardr) that I just don't need. It's still in the box and has never been run. Pics and more info here:

http://www.rctech.net/forum/r-c-item...cardr-doc.html
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Old 09-28-2008, 07:07 PM   #1065
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Any word yet on making black can's/sport tuned motors quicker?
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