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Ray
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Hi all Roveros and I had a discussion last night about the different motors available and the magnetic down force and amount of brake that they provide.

It has been suggested that the bigger the magnets in the can the higher and mag effect and braking available which seem to make sense.

We race on two track with Magnabraid so the magnetic effect is not as strong as say on plastic track with steel rails but there is some advantage.

There are a range of motors available on the market offering the higher mag effect i.e. the green NSR 21k King, Slot.it Flat 6 etc. The question is has anyone tested these motors to provide a guide to the effectiveness of these? The Slot Car Motor list does provide some information. For instance it would be good to know what the difference in construction there is between say the NSR Red/Orange King 21k motors and the Green Magnetic Effect motor.

We raced a rally car race recently and one of the cars was using Spirit Sxxx motor which had a significant advantage due to it magnatraction. Does anyone know if there is a rating list on the magnetic effect?

regards

Ray
 

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There's two separate reasons why stronger magnets can give more brakes.

A stronger magnetic field round the armature means the motor will generate more braking torque.
This gives more brakes on non magnetic tracks just as it does in mag racing.

A stronger stray magnetic field from the motor gives more magnet attraction on "magnetic" tracks. This creates more drag and hence more brakes. This cannot work on non magnetic tracks.

("magnetic" tracks = tracks with steel pick up rails, magnabraid, magnetic paint etc.
non magnetic tracks = tracks with copper braid or track and without steel rails etc.)
 

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Lee Green
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It's not really magnetic force that does the breaking , it's the torque on the motors , for example the boxer2 and flat 6r , boxer has more torque and a lot more breaks yet the flat 6r has low torque and less breaking , yet they both have high magnetic force I think the flat 6r actually has more
 
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QUOTE (highbarn @ 12 May 2011, 08:51) <{POST_SNAPBACK}>Don't know of a list but some manufacturers quote magnetic pull, especially those that make motors aimed at rallying. Avant Slot and MSC both make motors with strong magnetic pull.
I think the MB Slot Dodo motor beat them all regarding magnetic downforce, I don't know if it breaks well, I didn't try one. I think the MB Slot Song La (long can) is a high downforce motor too. It's a bit odd that people claim to drive without magnets and then use motors with strong magnetic pull but I have no problems with that, most of the races I enter there is a restriction anyway. If there is a limit then a high magnetic downforce motor needs to be placed higher in the car. So a low magnetic downforce motor would give the possibility the use an offset motor mount thus bringing the whole COG down. That is why my SlotIt Nissan perform so well with a 20K Scaleauto motor (the blue one).

Breaking is a personal thing, some drive with full breaks and other prefer a car that "rolls" thru the corners. So it depends on personal style and the controller used since every type, brand of controller breaks differently.
 

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Jan Groosmuller
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So please do tell us how many motors and controllers did you break and in how many ways?

(tongue planted firmly in cheek, ever so sorry but I just could not resist this...
)
 

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QUOTE (Henk @ 12 May 2011, 08:46) <{POST_SNAPBACK}>Breaking is a personal thing, some drive with full breaks and other prefer a car that "rolls" thru the corners. So it depends on personal style and the controller used since every type, brand of controller breaks differently.
That's interesting - what difference have you found in braking between different types of controller?

I know those with adjustable brakes feel different depending on which setting they are turned to.
Some types need maintenance to keep the brakes working properly.
When adjusted to full brakes I've found that as long as they are correctly maintained, all the good ones feel quite similar.
But perhaps there's a differance that has escaped my notice?
 

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Rich Dumas
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4,328 Posts
If you exclude the controllers that have MOSFET braking any difference in the amount of braking that you will get between controllers has to be due to a difference in the resistance in the brake circuit. A high end controller usually has heavy wire and a seperate brake contact to minimize the brake circuit resistance. If there is a potentiometer in the brake circuit it could add a little resistance even if it is in the full brake position. I have a new Difalco Genesis controller that has the usual potentiometer brake control, however it also has a switchable brake relay that is located at the hookup end of the lead wires. With the brake selector switch in the on position the potentiometer and the wires that go up to the handle and back are bypassed for the minimum brake circuit resistance. If you have cars that just don't want to stop this controller would be worth considering.
 
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QUOTE (Race-Jan @ 12 May 2011, 15:57) <{POST_SNAPBACK}>So please do tell us how many motors and controllers did you break and in how many ways?

(tongue planted firmly in cheek, ever so sorry but I just could not resist this...
)

Oeps, that's what you get when you're replying when you should be working
 
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QUOTE (Gone Racin @ 12 May 2011, 16:12) <{POST_SNAPBACK}>That's interesting - what difference have you found in braking between different types of controller?
I found differences even amongst the same controllers, I don't know if this is just a feeling I have because the condition on the track differ as well. I didn't do a scientific research on this but maybe there someone on the forum that has the skills and time to look into this. IMHO some controllers just have a better brakes then others. Maybe they are better assembled? Currently I use a 3Rd Eye Technologies controller that has excellent braking maybe because it is a transitor type and not a PWM, I don't like PWM controllers but that's a personal opinion. The Italian Engage brand has a high end (and high price) controller with two controls for breaking, thus creating a kind of ABS (i was explained). I don't know how it works because I don't own one but some guys are very happy with it and they say it improved their driving with .1 or .2 secs a lap. So I guess a good controller is worth the money.
 

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Rich Dumas
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I believe that 3rd Eye controllers have MOSFET braking. As I undrestand it as soon as you release the trigger you get full braking. The adjustment affects how long the brakes stay on, once that time is over there is no braking. Most controllers with a brake adjustment just have a variable resistence in the brake circuit which limits the amount of dynamic braking that you get.
 

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QUOTE (Henk @ 13 May 2011, 09:28) <{POST_SNAPBACK}>I found differences even amongst the same controllers, I don't know if this is just a feeling I have because the condition on the track differ as well. I didn't do a scientific research on this .....
Could be the ones that brake less well are in need of some maintenance.
I've measured the contact resistance on controllers. Some controllers have measurably more contact resistance than other "identical" ones, but on closer observation the contacts are tarnished on the higher resistance ones. Polishing up the contacts usually restores them to the low resistance they should have.
 

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Lee Beswick
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1,212 Posts
Don't think anyone has mentioned the rear tyre size effect on magnetic force. Obviously the further from the track the motor is, the less magnetic effect it will have.

Rear tyre diameter can have a big effect on getting the motor as close to the braid as possible, optimising the magnetic force given out by the motor
 

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Premium Member
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I would imagine that the gearing on the model would affect the 'brakes' as well with the motor attempting to 'stall' under trigger 'off'. I'm not feeling smart enough this morning to work out which way higher or lower gearing would affect braking but, technically, there must be an effect. Overall tire diameter would also have an influence on the braking 'feel'.

Jules
 

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QUOTE (lee.bes @ 15 May 2011, 09:40) <{POST_SNAPBACK}>Don't think anyone has mentioned the rear tyre size effect on magnetic force. Obviously the further from the track the motor is, the less magnetic effect it will have.

Rear tyre diameter can have a big effect on getting the motor as close to the braid as possible, optimising the magnetic force given out by the motor
Any method of putting the magnet closer to the rails or "magnetic braid will increase the magnetic force, including mounting the magnet lower in the chassis and smaller tyres.

QUOTE (Pioneer @ 15 May 2011, 11:53) <{POST_SNAPBACK}>I would imagine that the gearing on the model would affect the 'brakes' as well with the motor attempting to 'stall' under trigger 'off'. I'm not feeling smart enough this morning to work out which way higher or lower gearing would affect braking but, technically, there must be an effect. Overall tire diameter would also have an influence on the braking 'feel'.

Jules
Yes it does.
More teeth on the crown wheel / spur or less teeth on the pinion gives more brakes.

Tyre diameter of the driven wheels is an equally important part of the effective gear ratio
Smaller diameter rear tyres have the same effect as more teeth on the crown wheel / spur or less teeth on the pinion.

Smaller diameter rear tyres also lower the c of g and on magnetic tracks put the magnet closer to the rails or "magnetic braid.
 

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Ray
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1,081 Posts
Hi all thanks for al of the great comments.

We are currently reviewing the rules at our club which has four tracks. Being a commercial track the owner is catering for a wide range of drivers from the casual to the club racer. Until recently all tracks were non magna braid however two tracks were converted which is the reason for this thread.

As you would all be aware in the Italian scene (as we understand it) they race mainly on large plastic tracks with steel rails (NINCO I believe but please correct me if this is incorrect). Several manufactures are now producing magnetic effect motors with open cans to increase the magnetic down force for non mag racing. Now the magnetic attraction of these motors does vary but there does not appear to be a definitive list which would be great for club racing. Thanks highbarn and Henk for the suggested motors.

Hi Julian Boolean this is becoming a fact of life , we may now, like others have done may need to acquire a Magnet Marshal and state a maximum allowed magnetic down force or limit the motors used on these two tracks (we race non magnet but this is becoming an issue). Also as you would know there is quite a difference between the magnetic effect on steel railed tracks vs. magna braided tracks.

It was interesting to see James May's Toy Storey and the mag/non mag comparisons and the trade off between cornering speed and top speed a must see for any slotter.

Lee. bes yes you are correct we have been playing around with this variable and low profile smaller diameter wheels make a huge difference even on magna braid. The lower the better.

Race_Jan yes controllers do make a difference Roveos and I have been playing around with controllers and motors i.e. Professor Motor, NSR, DeFalco and 3rd Eye as well as the various chips that come with some of these. For instance the 3rd Eye has a lot more braking than the Professor Motor with the same car and track. 300SLR we have also been looking at some of the brake bypass switches etc on the various controllers particularly the 3rd Eye.

Gone Racing yes the magnet does impact braking for sure(but nowhere as much on magna braided tracks) but on non magna braided tracks so does the motor braking of the various motors as does the amount of grip that a track develops during a race.

Pioneer gearing is also crucial we run a standard gear on Tuesday Nights and open gearing on a Friday Night it is amazing how much difference one of two teeth on a gear makes to braking.

Thanks all for the comments keep them coming.

Regards

Ray
 
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QUOTE (RichD @ 14 May 2011, 15:56) <{POST_SNAPBACK}>I believe that 3rd Eye controllers have MOSFET braking. As I undrestand it as soon as you release the trigger you get full braking. The adjustment affects how long the brakes stay on, once that time is over there is no braking. Most controllers with a brake adjustment just have a variable resistence in the brake circuit which limits the amount of dynamic braking that you get.

I have a third eye and knew that it had Moffset brakes but had no idea what the difference was compared to other controllers but now i know so thanks for the explanation. I just know it brakes better and thats probably all that matters really. Braking is caused by a number of factors gearing motor torque etc. One other is the available grip. We run five minute heats at a club where treated tyres are allowed and sometimes a car will "grip up" a minute or two into a heat and the breaking distance is definately reduced when this happens.

The magnetic pull of a motor is a bit of an issue and some motors definately have a bit of pull. The king evo MB song na spirit sxxx have some the flat 6 r does to. Interestingly from what i have read anglewinder long can cars have a massive advantage over inlines as the magnetic field is dispersed over a greater catchment area. An inline doesn't get anywhere near the same benefit and maybe on magnabraid compared to steel rails the effect would be negligible.
 

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QUOTE (roveros @ 17 May 2011, 15:04) <{POST_SNAPBACK}>Braking is caused by a number of factors gearing motor torque etc. One other is the available grip. We run five minute heats at a club where treated tyres are allowed and sometimes a car will "grip up" a minute or two into a heat and the breaking distance is definately reduced when this happens.
Agreed you can brake later into a corner when there's more grip. Two factors are in play
1 With more grip the car goes round corners faster, so you don't need to slow down as much.
2 More grip means the car can brake harder without the wheels starting to lock up. Unless the car has enough braking torque to get to the "starting to lock up under braking" zone, it's doubtful that this second factor can make much difference.

Sometimes wheels start to lock up under braking (for example when the track is a bit dusty at the beginning of a clubnight) This makes the car behave inconsistently, it's usually better to turn the brakes down to stay clear of the "starting to lock up under braking" zone.
 

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Nobby Berkshire
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I've always been doubtful of whether motor magnets create any real magnetic pull to the track surface as they'd need to be almost touching it to do that at about 0.5mm distance.

I suppose they could cause some kind of internal drag on the inside of the motor, but who knows? If they did, then that drag would actually slow the spinning motor down during normal running so you'd end up with slower lap times. It'd be swings and roundabouts!

It could just be another slotcar myth that motor magnets do anything other than operate the internal motor, I think. But if you test it for yourself and notice a difference in lap times then that's the only fact of the matter you'll ever find. The lack of folks posting actual differences in laptimes in this thread seems to indicate that few have tried to test the theory.

As people have already written; if you want magnetic downforce and drag then use magnets. If you want better brakes then use different gear ratios.
 
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