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Rider400

Do old brushed motors get weak?

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I wired up an older brushed motor and installed it but it doesnt seem to have much power. Forward will move the car somewhat but reverse not at all with wheels on the ground.

Do these things just lose power over the years/decades?

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Yes they can lose power if they are not properly cleaned and maintained at least every couple of years... The armature/brush face where the brushes make contact with the armature will get dirty and corrode a bit along with the brushes themselves  IF it is a serviceable can you can open it up and clean the brushes and the armature/brush face off with a bit of very fine steel wool or use 400 grit or finer sandpaper then fully reassemble it and should be just fine again

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I used to clean mine with some kind of motor spray back in the day, and all sorts of filth or carbon would come flowing out.  I would spray the motor until the fluid leaking out was coming out clean or cleaner.

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Thanks guys. I did put a volt meter to it ad am getting 7+ volts fwd and rev at the wires but only half that in reverse on the motor itself. Could be a ******* solder job on my part. Will see about cleaning it up some.

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Is this a rebuildable motor or silvercan?

I've had some Super Stocks which I bought secondhand which needed the comm skimmed on them.  They just wouldn't run before this was done, now they're like new.  My LHS was able to do it for me since I don't have a comm lathe, and don't intend to get one given I don't generally use brushed motors.

I've worn out some kit motors, silvercans and torque tuned, and while the performance dropped off a bit, the most noticable thing was excessive heat.  They got so hot and then stopped working.  Wish I had known that before taking diffs apart etc to check for what was causing the heat.  It looks like kit motors last a decent amount of time, but not forever, so they do wear out.  The 2 that have worn out for me have both seen a lot of run time, I suspect far more than most Tamiya's would see.

Hobbyking sell some cheap replacements which are about $7 each so it wasn't all bad.

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4 minutes ago, Jonathon Gillham said:

Is this a rebuildable motor or silvercan?

I've had some Super Stocks which I bought secondhand which needed the comm skimmed on them.  They just wouldn't run before this was done, now they're like new.  My LHS was able to do it for me since I don't have a comm lathe, and don't intend to get one given I don't generally use brushed motors.

I've worn out some kit motors, silvercans and torque tuned, and while the performance dropped off a bit, the most noticable thing was excessive heat.  They got so hot and then stopped working.  Wish I had known that before taking diffs apart etc to check for what was causing the heat.  It looks like kit motors last a decent amount of time, but not forever, so they do wear out.  The 2 that have worn out for me have both seen a lot of run time, I suspect far more than most Tamiya's would see.

Hobbyking sell some cheap replacements which are about $7 each so it wasn't all bad.

This one is an aftermarket Trinity brushed motor. Im not sure of its rebuildable or can even be cracked open.

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3 hours ago, Fabia130vRS said:

All of them can be opened.

Its the putting back together that can be problematic particularly on those where the endbell is held into the can with the pressed in metal prongs. Ive opened one before on a knackered old motor but in doing so the prongs were so mangled they would never go back into the slots to hold the end in so it went in the bin.

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5 hours ago, Superluminal said:

Its the putting back together that can be problematic particularly on those where the endbell is held into the can with the pressed in metal prongs. Ive opened one before on a knackered old motor but in doing so the prongs were so mangled they would never go back into the slots to hold the end in so it went in the bin.

Could be a one and only case. I have managed to open all such cans and close them again. I know it could be difficult but never had such problems on 5-6 motors.

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If the motor is being operated via the old mechanical speed control you may have bad/dirty  contacts on that.  Also if not set properly you may not be getting past the second resistor point on the speed control hence slower running

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2 hours ago, Toolmaker72 said:

If the motor is being operated via the old mechanical speed control you may have bad/dirty  contacts on that.  Also if not set properly you may not be getting past the second resistor point on the speed control hence slower running

Good tip. In this case it is an ESC.

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3 hours ago, Fabia130vRS said:

Could be a one and only case. I have managed to open all such cans and close them again. I know it could be difficult but never had such problems on 5-6 motors.

What do you use to remove the prong? I tried needle nosed pliers which just bent it back on itself when pulling it out and when i tried to put it back together i couldnt then get the prong to go through the slot in the end bell with out it being loose. If i tried more than a couple of times it felt like the prong would snap off.

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17 hours ago, Rider400 said:

I wired up an older brushed motor and installed it but it doesnt seem to have much power. Forward will move the car somewhat but reverse not at all with wheels on the ground.

Do these things just lose power over the years/decades?

It can, based on how oxidized your commutator surface is and possibly weakened magnet from heat or getting dropped.   Carbon brushes can use some cleaning too probably.  

But if stored well, I have motors from near 40 yrs ago with like-new power.   

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1 hour ago, Willy iine said:

It can, based on how oxidized your commutator surface is and possibly weakened magnet from heat or getting dropped.   Carbon brushes can use some cleaning too probably.  

But if stored well, I have motors from near 40 yrs ago with like-new power.   

Any way to test it with a meter?

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38 minutes ago, Rider400 said:

Any way to test it with a meter?

Sure, if you remove the brush hoods or the entire endbell, you can put a multimeter on 2 segments of the commutator to check whether you get resistance in the wires. I just measured one of mine (an old 27T stock that I know works fine) and it was 22.4 ohms on all three poles.

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1 hour ago, Rider400 said:

Any way to test it with a meter?

You are talking about like a load test without taking the motor apart right?   Might be difficult.   Usually I don’t open up permanently crimped silver can motors so I’d just get a new one once worn.   I suppose you could do a water submerged cleaning if you want to try that as a last resort.

If this is a motor where you can remove the endbell and remove the armature, then I’d just get a comm lathe and cut it and install new brushes and springs. 

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9 hours ago, Superluminal said:

What do you use to remove the prong? I tried needle nosed pliers which just bent it back on itself when pulling it out and when i tried to put it back together i couldnt then get the prong to go through the slot in the end bell with out it being loose. If i tried more than a couple of times it felt like the prong would snap off.

I have a small flat screw driver… same as on the picture from Unior.

thumb_d_gallery_base_52ffcaed.jpg
 Thats usually enough for taking it apart. With nose pliers 

 

when putting it back, I use a workbench vice and a small hammer with this small screw driver.

but of corse the often you bend the pronge it could get weak, but never move the pronge more then necessary. Just enought to get the end bell loose

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8 hours ago, Rider400 said:

Any way to test it with a meter?

Yes, every motor is also a generator. Spin the shaft fast enough and you'll be able to measure output via the power wires... you might be able to get away with clamping the shaft in the chuck of an electric drill but you'd want to make sure everything was axis-aligned properly, you'd want to clamp down the motor somehow.

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I'm surprised no body mentioned this, but the main power loss with old motors is due to loss of spring tension when the brushes are worn down.   Putting new brushes that have full length will create more tension on the spring and allow the motor to generate more torque.   Cleaning the commutator is  a good idea as well.

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the main power loss will be that the magnets are losing their magnetism over time. Any old Motor will have that problem.

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Before brushless motors were common, I had to skim each motor after every race, until the comm wore out and had to be replaced. Most motors are rebuildable, if it has two screws in the end bell. If it has screws and markings on the end, the timing is also adjustable. I have never had to mess about with pliers to take one apart, just loosen the screws a few turns and twist the end 1/4 turn, I used to mark where the timing was set with a sharp point along the end and down the side of the motor. The main cause of power loss was either worn brushes, burnt comm, weak springs or bad connection on the brushes to end bell, which is why I used to solder them with the wires.

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