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Both my Mk2 Escorts have RX-41s despite what the SCX website says.

Anyway the RX-42B gives a higher top speed than the RX-41, but the RX-41 has more midrange power, for a rally car I think the RX-41 is better, but for a track with long straights and wider corners the RX-42B is better.
 

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One petunia in a field of onions
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Although the numbers don't show much difference, there is significant difference between the original and the B spec motor when you put it on the track. I have RX-41,RX-41B and RX-42B in rally cars. Actually the 42B is in an Escort.

The Slot Car News list has figures on them all, I think.

Embs
 

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Tore
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1,760 Posts
The RX-4, RX-41, RX-42 and the 4WD versions RX-8 and RX-81 plus the older F1 motors are "16.000 RPM" motors, while all the RX motors that end with a "B" (RX-41B. RX-42B and RX-81B) are "19.000 RPM" motors.

You can often compare the performance of the 16.000 RPM motors with Ninco NC-1 motors, while the 19.000 RPM "B" motors are competitive with standard Scalextric and FLY motors.

In theory the motor in your Escort should be much faster than the Renault 8, but SCX motors often perform below their spec when new and are known to be inconsistent in performance from the factory so it's not uncommon to not notice the difference at first. The SCX motors need a long "run-in" period to seat the large motor-brushes, so the more you use them the more free revving they become and you will start to notice the difference better. The newer releases, and especially the RX motors with red lettering seem to be better assembled and balanced than the older motors, so they run better from factory.

As Julian points out the RX-41 can be the faster motor on a smaller track. The RX-42B does have more torque but on a tight track you might not get enough speed to get into the "comfort zone" of the motor, and sometimes the RX-41 just suits the grip level of the small classic cars better and give you better control and faster lap-times.
 

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Alexis Gaitanis
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2,438 Posts
The things that change SCX cars radically are:
-Running in motors .In ironing water not tap water,at 3-6-9 volts 1 hour each,oiling in between segments,then 5 min @12 volts in alcohol.
-Running in gears.Using toothpaste,15 min,good rinsing afterwards,oiling.
This is what i do with all my SCX cars,the difference is huge.
 

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Circuit Owner
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Ironing water is actually distilled water - usually distilled by boiling and condensing the steam. This tends to remove impurities such as calcium which would "furr" up the iron.

I can see that removing such impurities might help or hinder running-in depending on what you believe the water does inside the motor!

Distilled water is NOT de-ionised.

De-ionised water is non-conductive or at least a lot less conductive than ordinary water.

By the way you can put distilled water through the deionisation process (it's a filtration process through expensive resins) to get "ultra-pure" water which is a very aggressive solvent and will corrode stainless steel and even attack glass!!!

Probably not a good idea to put that in the motors then!!!
 

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Alexis Gaitanis
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The ironing water sold in super markets,in Athens at least, is advertised as de-ionised i wouldn't really know if it is or not.This is what i use and have had no problems so far for over 2 years and not only with SCX motors.This process is not my invention,i read about it some place,most probably in this forum,i'm just stating my experience with it.Probably running the motor in alcohol after running in water protects from potential damage.
 

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Rich Dumas
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I am a retired chemist that worked in the lab for 42 years. Distilled water is effectivly de-ionized because any inorganic dissolved material is removed when you boil water and condense the steam. Distillation is a very expenseive way to purify water and it may not remove organic impurities, such as solvents. Our labs used reverse osmosis systems to purify water and those can remove all impurities. Pure water does not conduct electricity. Water that has a significant amount of inorganic material dissolved in it will be a good conductor. In most cases it will be safe to break in motors using ordinary tap water. Purified water is not more corrosive than tap water, it is more "hungry" than tap water because it has more space available to dissolve things that are easily ionized. As an example it is not recommended that you fill a concrete swimming pool with deionized water. Running in a motor in water or some other liquid is faster than a dry break-in because the brush material floats away rathey than getting trapped and the water keeps the commutator from getting very hot.
 

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Circuit Owner
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Fair enough.

This is where I got my info from.

Distilled water vs. deionised water

Go get 'em Rich!

Surely by running a motor in deionised water provides the "hungry" water with more inorganic material (dirt and charged carbon particles from the brushes) so it must re-ionise quite quickly.

Is this why you only run the motor for a short time?

People run the motor in alcohol after water to clear the water out and prevent corrosion. If the main aim of the liquid is to provide cooling and facilitate the floating away of debris - why not just run the motor in alcohol and skip the water? Or does it heat up to the point the alcohol would evaporate away?

This is interesting - wasn't that bothered to start with but it's drawn me in now.
 

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Tore
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1,760 Posts
I think the fear of running in motors in water is a bit over dramatized.

I've been running in SCX motors for years in tap water and then flushed them out in either alcohol or WD40 without any issues. Lately I've just squirted some WD40 into the brushes to run them in and then just flushed them out quickly in water and again in WD40 to get the water out, before taking the brushes out to heat them in a soldering iron to burn off any residue from the WD40.

Using this method together with gently adjusting the brush holders to advance timing, and a small metal file to true the armature stack, I'm getting 17.000 RPM out of the RX-41/RX-42 and 20.000 RPM out of the "B" motors (at 12 volt). The "extra" 1000 RPM is usually from the armature stack truing which also greatly reduce vibrations from the motor, improving smoothness and handling in the car.

Tore
 

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Nobby Berkshire
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2,015 Posts
Please do not ruin your motor by shortening its life running it in water, or anything at all. They do not need this treatment.

The RX41 has smaller wire winding and lower rpm, but they are fairly responsive if you do not bog your performance down with too much magnetism or added weight. The standard magnets SCX use these days are far too powerful for this motor so it does not perform that well. But reduce the drage and they are cool. I have one SCX rally car with an RX41 that out performs Pioneer Mustangs.

The B range just give you a bit more rpm. They are more like standard Scalex motors as performers.
 

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Discussion Starter · #13 ·
Thanks to everyone for their reply. I always felt the RX41 was slower but it was difficult to tell as the Renault doesn't handle as well as the Escort.
I'll try swapping the motors over and see how the Escort goes with the RX41 motor in it. Generally I've been very happy with SCX motors and I agree
they work better after a bit of running, mine if left for a week or so seem to lose some punch and need a few minutes of track time before they get their speed back.

Regards,

Alan
 

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Ray
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Hi Tore 356Speedster I am interested in the how you advance the timing any chance of a quick description and some phots. I have only breifely played around with thesae motrs with some tips from Rick1778 but admit to not real knowing what to do with these motors. Some of you club members have been playing around with the timing but don't let too much out of the bag.

Have tried the heating of the brushes with a soldering iron makes a difference sometimes. I have also been told two options with the brush springs one to reduce the tension the other to increase the tension which is the recommended way to go?

I also understand that the Gold Dust brushes make a difference over the standard ones ant comment?

Regards

Ray
 

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Rat,

The best Ive gotten out of a SCX 42B without openning the can is 20600 rpm at 12V. If youre doing better than this ya dont need any help from me or anyone else for that matter Rat. Lenny is pretty cluey on these motors, you should ask him, or isnt he letting on??

cheers
rick1776
 

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Ray
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He Rick I have had some conflicting comments on the spring tension from memory you like to reduce the tension others are saying increase it.

Ray
Team Thunderbird
 

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Registered
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It really depends on how concentric the com is. If its really bad you need to increase the brush tension. If it really good you need to decrease it. You got a optical tacho so it should be an easy thing to test. I suspect that you would have at least 10 motors to choose from so start with the best motor and start jigging this around to see the increase you get.

Now if you could figure a way to lathe the com without openning the can up then decreasing the tension is the way to go. Im sure its possible but you may destroy a few motors before finding out how to do it. Dont worry you got at least 7 months to figure out how to make these motors sing without breaking the rules (as they are written).

Whats the best rpm you got at the moment?? Id also tell jazz to rewrite the rules about the gear that you can run. It says only 9T pinions but doesnt say anything about the crown gears. Is it supposed to be 27T of is this free as long as its an SCX gear? Bit vague at the moment.

cheers
rick1776
 

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Ray
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Hey Rick I only have a couple of SCX motors so not a lot to play with that are working but a couple of dead ones that I am playing with just to get up to your level of knowledge. Will try the Tacho trial with a coupole of spring settings. No worried about the Scale Nationals at this stage the motors will need to stock as there will be some tests carried out at scruteneering so my NASCARS will be the pick of a couple of out of the box motors.

I am currently setting up a couple of rally cars but will probably not use an SCX motored car this time round. I am building up a new MSC Subaru with the Yellow motor looks promising but has not been on the track yet. I had a pplay with my SCX Rally car last night and dropped in a new SCX 42B motor but this car will probalby not be up with the MSC rally car. Did not reve check it but put it on my speed checker only got to 28k the MSC got to 35k.

Don't have a comm lathe would rather by 20 motors and use the pick the bunch probably cheeper.

I thnk that Shane is on a cruse at the moment have not heard from him for a week or so. The rules are mainly being set to the National Standard which was set for this year event and Shane is tweeking the new class rules, the only other change (that I am aware of) is the use of NINCO Prorce parts and lightning bodies.

Chris is having a new track constructed for the 2012 Scale Nationals, 6 laner glass to 1/24 standards similar design the the current Lowndes track but more open and sweeping turns.

Regareds

Ray
 
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