Annoying brushed motor problem.
 

I've got this 11x3 peak racing carera motor that was bought from new.

It hasn't been used much and the brushes are in good condition (as they are new and used only a few runs).

The comm has been skimmed, but still the motor refuses to start up.

If I give it a spin (or the car a push) the motor will engage and run.

It's currently on a motor break in and I can hear it speeding up and slowing down all the time.

Any ideas what's up?

Check your motor springs make sure they are in good condition not bent make sure there is no crap in the brush tubes.

A

Has the motor been really hot? Coz you can get burnt stuff on the brush tubes which can bugger things up.

Are the windings soldered to the arm stack or just crimped down. I suspect it's not contacting properly.

You could have one of the winds broken on the armature so its only running on 2 winds. that may be why it works on a "jump start" only.

I think we are on the same track here Dan

Thanks for the replies everyone.

I can't see anything wrong with the arm...it looks newish...much like any other. No visibly broken copper strands....all soldered to the top of the comm as expected.

I have tried loads tonight, but to no avial.

I've tried the arm in two different cans, one with the same brushes (by just swapping the end bell onto a different can with the same arm) and one other can with different brushes. Nothing made any difference and the bugger refuses to start properly.

I also skimmed it and cleaned up the brushes (which are relatively new) with a comm stick and motor spray...no joy still.

The only thing left is to try some new upright brushes...which seem to be quite rare compared to laydowns these days.

I don't hold out much hope for this working though because the arm exhibited the same behavior in two different cans with the same brushes and different ones which I know work.

I don't suppose anyone else has any further ideas....other than to jsut smash it to bits! :( :confused:

Its thrown a wind.. May i ask what motor it is???

A

Ashley
When a motor throws a wind it means that the copper wire starts unwinding itself, and jams between the arm and the magnets.

It definitely has not thrown a wind....on top of what tyreman said (ne'er a truer word spoken) there would typically be solder and all sorts of crap inside the can if it had thrown a wind (most likely due to extreme heat).

Plus it would probably take quite a tug to get the arm out of the can due the wire being jammed between the magnet and the arm.

The motor is a Peak Racing Carrera 11x3 Modified (with adjustable timing), old style (V1?) endbell, standup brushes....quite old tech really, but new when I bought it not too long ago.

Have you checked the vibration spring at the base of the brush hood, as this can cause friction if not moving properly.
Has it got the surface mounted capacitors? as if one of these has gone that could cause your problem. Take both of them out and replace them with 3 standard 102K capacitors that you solder on.

How old are the brushes as the lubricant may have dried up causing the fluctuation in power.
Where have you got the timing set?
If you look at the timing marks on the motor, you want to be on the 3rd timing mark to the right.

Whats it called then when the wire doesnt come off and jam beween the magnets im not very good at technical language:confused:. But the copper does come disconnected from the com??? meaning one wind doesnt work??

I had the same happen to my 14 armature it was a peak v2 and i had only run it for 3 meetings wasnt happy I think i may contact horrizon.

A

throw a wind ash, chris and kev already suggested that

The way i would check if the arm has lost a coil (electrically) is put a pinion on so you can use the grub screw as a datum and make it easy to turn by hand. Then check whether the motor starts from every position by rotating then applying power, rotating then applying power, and so on. If there are only 2 coils working, I think it will start in some positions and not in others.

Work through the rotation a few times so you can see if it stops working in the same place consistently

I'm not saying this is definately your problem, but it might be worth at try.

Knackered :p

It sounds like a bad/dry joint somwhere on the arm, normally they do this when they've got too hot and thrown the solder off the joint between the windings and the comm. There's not a lot you can do about it usually, you just need to replace the arm :(

To check for it I would measure the electrical resistance between each comm segment with a meter, that should give you some idea where the problem is on the armature.

I remember this motor got very hot once when used a Bury and it was then that the trouble started I think.

The damn thing started changing speeds on me on the straight (fast, slow, fast, slow) - very disconcerting...especially when trying to judge brake points or being launched into full speed when you don't want it!!

I've got some new brushes on the way so I'll try them.

Failing that I'll just bin it.

Thanks for your help.