# Problem trading rotors: Bonded to Sintered



## Buff (Dec 9, 2002)

I posted this question on another site, but haven't gotten a response yet, so I thought I'd get some people's opinions here. The motors I speak of on this post are all new LRP Vector X-11's that haven't been run yet. What I was wanting to do was take the sintered rotor out of the 4.5t X-11, and install it in my 5.5t and use the bonded rotor that came with the 5.5t, and put it in the 4.5t. (The 4.5 is the only X-11 motor that comes with a sintered rotor)...
Here goes:

I'm VERY confused..... I just got done switching rotors.....I took the *sintered rotor out of the X-11 4.5t,* and installed it into my X-11 5.5t *for which I took the bonded rotor that was in the 5.5, and installed it into the 4.5..... Everything went together without a hitch....*
** Realizing that (without any knowledge of how to tear down a brushless motor) all it took to remove the rotors from each motor were three screws on the bottom of the can where the pinion mounts....surprisingly easy, as there were NO shims or anything to fall out witch I was hoping wouldn't happen even though I wasn't sure!!* *

Ok, now here's what confuses me.....both motors are now assembled fine, everything lined back up perfectly because I marked the endbell, can, everything so that I made *SURE* I put each motor back together exactly as they were, including the timing which I never changed either. SO, the 5.5t which now contains the *sintered rotor, still feels like it did before when it had the standard bonded rotor in it!!* :blink: I thought that sintered rotors/magnets were much stronger, hoping to spin the rotor in the can having it feel like it did when it was in the 4.5 can.....but it spun VERY freely as it did with the *bonded* rotor.... :huh: :\ 

Why is this??? And vice versa: *Now the 4.5t CAN has the BONDED rotor*, yet it feels like it did with the SINTERED rotor that originally came with it, by feeling like the magnets were much stronger, more like a brushed motor without the brushes installed and with strong magnets.... (in other words, I figured that the 4.5 can would now feel like the 5.5 did because of the bonded rotor it now has in it???) :blink: :S 

*In Summary:*
*So to make a long story short.....both motors feel exactly the same as if I never changed rotors, even though I did. 4.5 now has bonded....5.5 now has sintered....yet they feel exactly the same as they did before the switch when spun by hand inside the can!! I mean, it's VERY VERY easy to tell the difference as the 4.5 STILL stops MUCH faster, while the 5.5 STILL spins almost freely like there are no magnets (as it did before the switch) *

My question, *WHY????* Does it have something to do with the windings inside the can or did I assemble something wrong??? I made sure I assembled everything EXACTLY as it was because these things are precious and I paid a good amount of money for them and didn't want to ruin them before I even got to run them. 

Anybody know what's up?? Will the 5.5 still have more torque though?


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## FishRC (Sep 28, 2001)

Part of the issue might be is the airgap between the rotor and the can. From what I have read that is part of the diferance. The other big thing is without the power applied to a brushless, they will basicaly free spin (Not compleatly, but far less than with the brushed motor.) If the 4.5 is stopping very quicky as you say, I'd look to see if either of the bearings are dirty or worn out. That would more likely explaine the differance.


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## Buff (Dec 9, 2002)

They're definitely not worn.....all my X-11 are BRAND NEW and haven't been installed in a car yet.

But literally, it seems with the 4.5t, it doesn't matter what rotor is in it, the magnets are strong and it's a tiny bit difficult to spin the rotor in the motor by hand....and vice versa with the 5.5 cans....even with the sintered rotor installed in the 5.5t (took it out of the 4.5) it feels as if it still has the bonded rotor in it because it spins very easily, exactly as it did when it had the 5.5 bonded rotor that came in it. 

I thought the magnets came on the rotor with brushless, but even though i've switched rotors to different cans, it's made the feel, by spinning with my hand, that nothing has changed. The difference between the 4.5 motor (which is supposed to be sintered) and the 5.5 (which is supposed to be bonded) is very noticeable so it's not even close to tell which one has the stronger magnets....

This is what's confusing me....does this have something to do with how many turns each can has in it??? 

And my most important question....will there be any performance gain at all with the 5.5 now that it has the sintered rotor in it???????
---*(even though by spinning the rotors of each motor by hand, feeling absolutely no difference from how it was stock even though I swapped their rotors) * 

And again, vice versa.....will there be any *loss* in performance with the 4.5 because it now has the bonded rotor in it??????
---*(even though by spinning the rotor of the 4.5 motor by hand, feeling again no difference from how it was in stock form, even with the 5.5's bonded rotor installed in it, the magnetic strength felt very strong and pretty much identical to how it felt with the sintered rotor that came with it. *

I assume the amount of turns each can has, may have something to do with it???? But, I thought that Brent (MX51 on RC10B4.com) told me he wanted to run a 6.5t in his cars with the sintered rotor because it supplied more torque and mid-range power.....

I'm so lost..... and am wondering if I should just switch the rotors back to the cans they came in??


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## OvalTrucker (Dec 14, 2003)

My experience with sintered and bonded rotors has been solely with the Novak motors. 
The 4300 guys swear that the sintered rotor is a worthwhile upgrade. And I'm sure it is too. But, the difference is minimal and probably not very noticeable unless your chassis/gearing is darn near perfect already.

I race the 13.5 class and I have experimented with at sintered rotor in that motor. I can't say that my chassis was perfect, but it is pretty darn good. What I noticed with a sintered rotor was increased braking and lower operating temps. No huge difference in torque. Although I'm not sure I had the right gear on it. Gearing changes significantly with the sintered rotor.
The sintered rotor feels way more 'coggy' that the bonded rotor. Hence, the increased braking.

I can't explain the feel you are experiencing by turning the motors by hand. I can feel a definite difference between the two rotors in the same 13.5 can.

I can't tell you if any of what I've said will relate to your X-11's. Just thought I'd add my 2 cents, based on what I experienced.


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## kevinm (Jan 16, 2002)

I've noticed that many of my brushless motors seem to have the "cogging" feel of a brushed motor BEFORE I run them, but it goes away afterward. I suspect that while the motor just sitting around in it's package before you buy it (or even while sitting in your toolbox), the strong magnet in the rotor temporarily magnetizes the steel in the stator (windings). It'll probably go away after you run it a bit.


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## Andy Olson (Feb 23, 2007)

its my understanding of these type motors that the rotor or armature " moving part " isnt magnetised at all. the only magnetic field is in the windings. there maybe some residual magnatism in a rotor but as has been said , its probubly not going to last long sintered or no. nor is it likely to be desireable anyway.


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## OvalTrucker (Dec 14, 2003)

The "moving part/rotor" is the magnet. The windings are in the can and that is what actually determines the performance differences between the motors.


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## Buff (Dec 9, 2002)

OvalTrucker said:


> The "moving part/rotor" is the magnet.


Yeah, that's what I thought. Here's another post I made on another site which may help explain what I'm having trouble understanding and what I experimented doing:

Maybe I'm not explaining myself correctly of what I'm trying to figure out.... Ok, I"ll put it this way, the ONLY thing I'm looking for is magnet strength and wondering why it is not different when I change rotors from a brushless motor can to another.

I completely understand the windings are in each can now, so you can't change what the motor is without completely changing the cans since the windings are INSIDE the can.....however, the ROTOR is what I'm trying to figure out, and it's strength between sintered rotors and bonded rotors.....bonded supposed to be the standard, sintered being much stronger, allowing the motors to run more efficient, have more torque (more magnetic stregnth).....

The ONLY problem I don't understand.....ok, ALL 3 of my brushless motors right now are LRP Vector X-11's, and they are brand new. One is a 4.5 sintered rotor/magnets (which is the only X-11 that comes with a sintered rotor) and two 5.5t both with bonded rotors/magnets. 

Ok, I decided that the 4.5 (with sintered rotor) was going to be too much power for anything but touring car (which I later learned AFTER I had already got the motor) and by learning what people were telling me and (Brent and Coach and many others, sorry if I didn't mention your names, you know who you are!! :rockon: ) I had learned that I eventually wanted to run a 5.5 (which come with bonded rotors) but wanted to take the sintered rotor OUT of the 4.5 and install it into the 5.5 and race it that way in my BJ4 W.E.... 

Before I made the switch, I made a crude physical comparison, by hand, of magnet strength by simply spinning the rotors inside each motor. Naturally, the 4.5 with the sintered rotor felt VERY strong and is slightly difficult to turn in the can because of it's magnet strength. The I then spun the 5.5 with bonded rotor, and it spun VERY easy because of it's BONDED rotor which isn't nearly as strong. 

So, I THOUGHT that if I switched rotors by taking the sintered rotor out of the 4.5, and putting it in a 5.5 can (I would take the bonded rotor out of the 5.5 and actually put it in the 4.5) that the 5.5 can would now have a sintered rotor, that it would have really good magnet strength that it did when when it was in the 4.5....but NO. It (the NEW 5.5 with sintered rotor in it) does NOT have the same strength it did when it was in the 4.5 can, and as a matter of fact, it feels EXACTLY the same as it did with the bonded rotor that was in it. :blink: :S 

THIS is what confuses me. Switching rotors didn't do any good for either motor....but especially the 5.5.... and even more strange, the BONDED rotor that is now in the 4.5 STILL FEELS STRONG like it did when the sintered rotor was in it.... :huh: :wacko: 

Does anybody understand now what I"m trying to do? The only reason I was thinking it's not working was maybe in the 5.5 can, the spacing between the rotor and windings is further apart than inside the 4.5 can?

Coach? Brent????

Even though this "trade" doesn't feel, by hand, any different when spinning the rotor in each can, will there be any performance gain with the 5.5 with sintered rotor even though it doesn't feel any different magnet strength-wise?????


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## KOZ (Mar 8, 2002)

Question?Have you run the motors on the track? checked lap times?checked runtime?checked temp? You can bench test stuff all you want, it's the on track difference that you see between a bonded rotor vs a sintered rotor..


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## Buff (Dec 9, 2002)

That's not what I'm looking to find out right now, regardless.......what I'm trying to figure out is the question "why" to the question I stated above. I'm figuring somebody knows out there, eventually I'll find out.

It's strange that two motors would still feel the same magnet wise, even though the magnets have been completely swapped from one motor to another. 

So in other words, the one motor that had the sintered rotor to start, now has a bonded rotor and should spin freely right?? No....it's still the same, which feels pretty strong as it did to begin with....ok, strange to me. Again, in other words, the rotor is very hard to spin, and stops almost as soon as you spin it by hand.

Now, the other motor that started out with the bonded rotor, now has the sintered rotor in it....it should now be more difficult to spin due to the stronger magnets/sintered rotor right??...No. It still spins freely like it did with the bonded rotor that was in it....it will now spin for several seconds before stopping.

Does anybody understand this???? These motors have to have some type of different performance due to two completely different types of rotors, and I figure if they're switched, they would make another motor perform differently.....and they have to if you can physically feel the difference between magnetic strength just in your hands.....it's not even close, it's like night and day. 

I'd just like for somebody to give me an explanation why this is, or what has caused the motors to "feel" the same as they did before trading rotors/magnets. 

Doesn't any of this seem strange at all??????? 

*Both motors are also the same brand... Vector X-11's.*


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## signman501 (Apr 10, 2006)

I don't know much about this, but what about the bearings it the motors? I have only done nitro stuff to this point, just getting into electric using brushless, and bearings can make a big difference.


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## Buff (Dec 9, 2002)

Exact same bearings, and the motors are new, so the bearings can't be bad....they don't feel bad because I spun them when I had the rotors removed to check them. 

I've about give up on trying to find out why they are the way they are.....so I'm just going to run them this weekend and see what happens. I'll probably swap back rotors again to see if anything changes too.


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## cheatr71 (Dec 1, 2006)

I wish I could help ya buddy, but at the roar race in GB I swapped a Novak 13.5 can for a 4300 can but retained the 13.5 rotor/magnet. My lap times before the swap was 4.3 to 4.5 consistently, after the swap laps went down to 4.0 to 4.2 now explain that. I finally figured out that everybody else is cheating. I ended finishing 11 out of 21 guys but was within 1 lap of making A-main, so handling was not that far off. I ran a Ass.10l40 and beat half the field with a car everybody says to junk. I don't get it,all those other cars are pretty much copy cats of an associated. That opens another can of worms!!!!!! But its true, they all resemble one another.


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## Buff (Dec 9, 2002)

Yeah, I know what you mean there.....I guess the only way I'm going to find out is to run it and switch rotors between runs to see what happens. Switching rotors between cans is a matter of about 15 seconds, so that's nice!! Three screws, pull rotor out, slip in other rotor, re-install 3 screws, done. 

I think different types of rotors should be made for motor tuning....different weights maybe, or drilled, something....different types of magnets, sizes, whatever, because it is VERY easy to take rotors out. I didn't know what to expect when I first pulled it apart, but was VERY shocked and pleasantly surprised how easy it really was. 

Would also be nice if they made a universal rotor that fit all brushless motors, just different brands and types to change performance that fit all motors.... I just LOVE NOT messing around with stankin' a$$ brushes and comms AND expensive freakin' lathes with 100$ bits that only last so long. 

Looks like I've got a Twister lathe to sell, and several brushed motors...lol. I believe I'm brushless fo life and I haven't even ran them yet.... :dude:


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## KOZ (Mar 8, 2002)

Putting a rotor out of a 13.5 motor into a 10.5\4300 is flat out cheating,it's the windings in the motor can that make the difference between motors not the rotors..

As far as an AE car being JUNK, ae cars Dominated the Snowbirds in the 3 fastest classes...


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## McLin (Dec 5, 2001)

KOZ is right, what you did was go from a 13.5 to a 4300 LOL


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## Porksalot4L (Nov 4, 2002)

the best part of that was seeing that he got 11 out of 21 running a cheater motor  classic


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## parrott88 (Jul 2, 2002)

Lap times are easy to explain... you went from a 13.5 to a 4300.


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## cheatr71 (Dec 1, 2006)

I don't get what you think is so funny, ya I cheated but that was only so I could run with them better, I was leading the B-main till somebody thought it should turn into a demo derby. The general consensus around southern wisconsin is that associated cars are junk and the best chassis are KSG, Leading edge, or someother chassis. I dont understand how these guys are running almost .5 second faster, the car is not that far off on handling. Any ways I don't plan on leaving the motors that way, it was just an experiment that paid off, but roar is rumored to be allowing the sintered rotor so i guess i'll buy that next.


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## Porksalot4L (Nov 4, 2002)

cheatr71 i really hope you figure it out. maybe a local that you respect maybe will give you some help on the car and motor situation. i doubt the 10 guys that beat you are cheating but who knows. thats pretty bad tech


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## OvalTrucker (Dec 14, 2003)

Associated cars are definitely not junk. 
The advantages of some of the other chassis is adjustability. But, if you don't what adjustments to make it won't matter which chassis you have. I ran an AE car for a while with minimal success. It wasn't the fault of the chassis. I switched to LE because I was able to get help from a few of the best LE drivers out there. They are great guys and fun to race with. The changes they suggested translated directly to my car, so they worked. Sometimes a spring change on one chassis won't yield the same results on a different chassis. 
Talk to the fastest AE driver at your track.

I don't think you will find a .5 second lap gain from your motor. Nor will putting a sintered rotor in your 13.5. You'll get a little, but only if your chassis is real good and you get the gearing right. You can gear up with the sintered rotor.

I understand that your handling isn't that far off. But with brushless a little off is a lot at the end of the day.


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## Mayhem (May 5, 2002)

And on and on, here we go again. As long as motor manufacturers make motors that can be tampered with and opened, little johnney will always sit there at his bench and say,,HMMMMM I wonder what will happen if I swap this with this?

The whole idea of rebuildable motors was to allow easier tech inspection, therefore reducing cheating. What is has done, in my opinion, is made cheating easier. Race directors still dont, for whatever reason, open motor cans any more often than when they were sealed. I hope this doesnt become a problem with brushless, I was hoping that while the R/C world got used to the switch, the manufacturers would adress those issues and make different class motors less compatable. The solution is to SEAL these freakin motors! With brushless' lack of maintenance I think it makes sense.


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## Buff (Dec 9, 2002)

Mayhem said:


> Race directors still dont, for whatever reason, open motor cans any more often than when they were sealed.


I would say because usually if someone is cheating, it's obvious or will be apparent that somebody is, or has a history of it, making it easier to catch them. I don't think that with racing be so competitive these days, if someone is cheating (with motors) it wouldn't matter any way because at the end of the day, the best driver with the best car setup will take home the hardware.

Let people cheat....they will eventually get caught....and if you go out and practice and dial in your car setup and beat the guy who's cheating, it'll just make him look more stupid, and you, will gain that much more pride to beat someone who's trying to gain an unfair advantage by not following the rules. 

On the other hand, a lot of times, fast drivers are accused of cheating as well when they're not. I personally just wouldn't worry about someone else unless it's blatantly obvious that someone is passing every other car on the straightaway with ease. 

If it's not that obvious, that would just make me want to beat the guy that much more since he has some kind of horsepower advantage, but a better driver with a slower car will still win any day. 

But, this is another reason I run mod too....don't have to worry about cheaters!! lol.


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## Porksalot4L (Nov 4, 2002)

ever hear the saying "that guy must be cheating, cuase i am and he still beats me!"

lol thanks Dirk for that one


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## yuk17bandit (Nov 23, 2005)

*wow*

Wow, it's not about buying sintered motors or better batteries to be competitive, not with brushless, set-up set-up set-up, just because it's easy to drive don't mean its fast. I’ve never taken my motor apart, I’ve never tried to "adjust the timing" , my best run in GB got me qualified 3rd in the A, and was done with my oldest battery pack. I bet if we traded chassis your car wouldn’t be noticeably faster. Tires -SIDE SHOCK ALIGHNMENT- chamber- caster - how much pre-load - how far out/in are your wheels shimmed - how your body is mounted- tire size - rear shocks - RIDE HIGHT - stagger - chassis rake- set-up set-up ,, if all I just said is right, then you might see a minor improvement in lap times with sinter rotor,-better batts, motor cooler - chassis.


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## MIKE VALENTINE (Mar 12, 2002)

Buff, Your thinking about the swaping of rotors (magnet) the wrong way. A magnet needs an object to pull/oppose against for you to feel the cogging effect in the motor. Since brushless motors aren't built the same way as brushed motors you won't get that heavy cogging when you turn the rotor. Since the entire can is almost completly filled with wire, the rotor won't feel any different when turning due to the fact almost equal force is being apply from the magnet to the can in pulling and repeling forces. I hope that made sense, I know is a simple way to explain what is happening but I figure using any other technical explaination would be harder to understand.


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## kevinm (Jan 16, 2002)

Enough analyzing, already! GO OUT AND RACE IT!


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## OvalTrucker (Dec 14, 2003)

kevinm said:


> Enough analyzing, already! GO OUT AND RACE IT!


What? I'm not sure this horse is dead yet. Kick it again.


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## cheatr71 (Dec 1, 2006)

*Problem trading rotors*

Well since you put it that way, I apologize to the 10 other drivers that showed up for the event and my cheating ways. So maybe my car isn't 100% perfect on handling, but changing that can sure made a lot of difference. If the 10l4 is that far off on handling than that motor swap should not have made that big of difference. But anyways, I've already given myself a bad image and didn't do the sport anygood either, the motor has been swapped back since and put on the self till next year, time to play with the big oval car were people don't know you cheat(I mean stretch the rules).


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## Buff (Dec 9, 2002)

MIKE VALENTINE said:


> Buff, Your thinking about the swaping of rotors (magnet) the wrong way. A magnet needs an object to pull/oppose against for you to feel the cogging effect in the motor. Since brushless motors aren't built the same way as brushed motors you won't get that heavy cogging when you turn the rotor. Since the entire can is almost completly filled with wire, the rotor won't feel any different when turning due to the fact almost equal force is being apply from the magnet to the can in pulling and repeling forces. I hope that made sense, I know is a simple way to explain what is happening but I figure using any other technical explaination would be harder to understand.


Well even though I'm still not quite understanding, it seems finally someone gets what I'm trying to figure out. I think I get what you're saying though....If I have to, I'll run them out in the street to find out! lol.

Didn't race today because it looked as if we were going to get a bunch of more snow, but ended up stopping. Oh well. There's always next weekend, and the "testing strip" or street.  

Right now, I have the 5.5 with sintered rotor (which still spins freely almost) in my BJ4 W.E. and I'll give her a whirl tomorrow if it's dry outside and see what happens then swap back to a standard 5.5 (bonded rotor), and then maybe for fun, I'll try the 4.5!! THAT should be fun.....


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## katf1sh (Jan 17, 2002)

correct me if i'm wrong but... the 2007 snowbirds was dominated by silva cars not AE cars. i don't think many people use a box stock AE car anymore.

me thinks cheater is trolling...look at his handle....


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## Buff (Dec 9, 2002)

Well, I'm glad that my thread has helped find a cheater and all, but I just wish somebody knew where I was coming from and could give an easy answer to because it just bothers me and pretty honestly confuses the h e l l out of me too.

Has anyone else even tried this or encountered it??


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## KOZ (Mar 8, 2002)

What were cochran and ziggy on at the birds?


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## OvalTrucker (Dec 14, 2003)

Buff,
Have you raced your two motors yet? That is where the answer is. As it was stated earlier in this thread, the difference if any will be on the track. Make sure your chassis and driving skills are spot on. That is when the difference shows up with a Novak motor that has had a sintered rotor put in it.

It would appear that nobody know's why you don't feel a difference in the feel of it by spinning it by hand after you've swapped around your rotors. So go see what happens on the track.

Let us know what you learn. I for one am interested in what you find out.


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## cneyedog (Jan 22, 2002)

KOZ said:


> What were cochran and ziggy on at the birds?


Koz, If I'm not mistaken both were Silva cars ......... they are in fact listed as X-Factor Factory drivers on the silva's website.


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## AJS (Mar 21, 2002)

The one that I have a picture of is a solid chassis, not a slider either. All their cars were very fast and smooth, and of course they are both super drivers.


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## rj14 (Nov 4, 2006)

someone touched on it before- the sintered rotor was initially developed to help w/ the thermaling issues. It may have only helped gain a very minimal amount of power, maybe something that is hardly noticeable. But look at it from another point of view. The sintered rotor has become another means of stimulating the sales. If you ran a bonded rotor and never had a problem with thermaling, why buy the sintered if all it does is reduce the temps to help it keep from thermaling. And then in the process of testing the motor at the factory they found it increased power by .00035%. Does the average and above average racer know how to utilize that power gain? Probably not. Maybe the top 3% of the racers in the world could. But if they advertized that the new rotor would decrease temps and reduce thermaling, plus gave added power (.00035% more than a bonded rotor) then they weren't lying. Granted they weren't exactly being truthfull, you would see that and buy it, plus they could raise the price of the new units. Either way you have been seperated from your money for the hype.

now chew on that one for a bit


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## Buff (Dec 9, 2002)

Ovaltrucker.....I think i'll try and find out tomorrow night if I'm able to go to the track....they're racing on Wednesday nights, so I may try it out then. 

*(speaking of all motors are all the new Vector X-11's)*
I'll try the 4.5 with bonded rotor (originally came with the sintered rotor), and I'll also try the 5.5 with the sintered rotor (originally came with the bonded rotor) which is what I have in the car now, and then I have another brand new 5.5 that has it's original bonded rotor that has had NOTHING swapped out of it, and I'll try it too. I'll probably swap rotors back to the cans they originally came in also to see what happens as well. 

According to readouts, the original 4.5 (which comes with sintered rotor) compared to the 5.5 (which comes with bonded rotor) the 4.5 actually has less rpm across the board, but a LOT more wattage and torque compared to the 5.5....the 5.5 turns in, again according to LRP's readouts, a lot more rpm's through it's range with much less wattage (which I believe with brushless motors is a basic rating of overall power). The 4.5S pulled around 530 watts of power, while the 5.5B pulled somewhere around 360 watts of power....quite a difference in overall wattage/power, but the 5.5B had the more rpm's throughout it's range.

rj14....appreciate that info....interesting. Things like this is helping me understand more.


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## ICEMAN96 (Nov 17, 2005)

*Inductance Meter*

Use A Inductance Meter To Tech Brushless That Is About The Only Way.it Will Tell You Exactly What Motor Your Running.


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## teamductape (Nov 29, 2002)

hey buff my brother ran into a problem similar to yours he installed new wires(the three main power wires to the motor) on his 5800 and had a little piece of solder touching two of the wires togather on the bottom of the esc basically putting the brakes on 

i don't know if this helps in your case but i figured i would throw it out there


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