niznai - motor isnt allowed or able to be opened up. A new one is about £12 so no big deal

No drag in the transmission. Recently had a full strip, no grease in gears or bearings, just a slight coat of light oil. Runs as free as i can possibly make it which was why it was so fast to begin with and even for the 1st 1-2 laps of every hear it was very fast. This is why i think it was heat because it started off so well each time.

You're facing a typical brushed motor fatigue symptoms. If it can't be serviced and cheap to buy, replace it and don't forget to run them in. Use a new motor for the finals.

Well, before you bin it, perhaps it's worth having a look down the holes at the comm and brushes. If anything is discoloured, it's knackered. You can service it but it's involved and it's not going to come back fully.

Run the next one in a bit before chucking it in the car. There's plenty of info on the net about it, and a rather extensive thread you can look up here.

It's a technical term I can not disclose anymore about for fear of being thrown out of the brotherhood of old farts that play with toy cars.

what do you guys think would make a better on/offroad rally platform, an m03 or an m05?

Though with no practical experience, M03 I would think. Less stuff to clean...

M05. It has much less bump steer, especially over the large range of suspension travel that a rally car will experience. Also, the lower CG will help, since the rally setup will probably have a fairly substantial ride height.

Hi guys, went down the track last night. Ran 4 packs through 2 cars and it was only my car showing the symptom. Deffo not batteries.

Managed to sneek 10mins with my sons car. Once i had got used to how light his controller is i was shocked at how fast it it. Mine got 3rd A final. With his i would have been all over the top 2. Gutted i didnt say something earlier and either buy a new motor or sneekily swap ours over.

Another learning experience of how these things can go off without realising it. Heard about running a motor for hours connected to a AA battery just to bed it in. I know there is the water method but to be truthfull i would rather do it slow and steady than fast and in water.

Thanks for the help guys

In the time you've had your motor, have you done any maintenance???? A brushed motor requires constant attention to maintain peak performance. Your motor has many similarities to a Silvercan and is maintained in much the same way. The comm should be polished every run when racing. The motor should be removed from the car at the end of each day and cleaned. I don't like motor sprays for this but plain soap and water does a good job.

How to do this stuff????? There's a thread in this forum called Silvercan Motor Tips/tricks or something like that which is loaded with info. You'll find a lot of what you're looking for there.

I haven't touched my 21.5 in 6 months... ;)

The motor we're talking about is a brushed motor. It's quite different from your 21.5 B/L motor. For one thing, it has brushes and a commutator.

I know, but your always complaining about mini moving to brushless:lol:

You wont believe this but i did my first ever bit of maintenance a few days before the event. I think that may be what killed it.

1) Took motor out of car
2) Got AA battery and connected to motor
3) Dipped entire motor in clean water

Bits of crud came out then

4) Dried it off with paper towel
5) Sprayed with contact cleaner
6) Lubed bush at top and bottom with thin oil

I cant get inside the can so i cant see what more i can do.

I have access to high pressure air lines, would it be better to just give them a quick blast through with the air hose

You did nothing wrong. Granpa is talking about people who until a few weeks ago lived in a time warp and run silvercans, which is why they had to babysit them like the crown jewels. He has much good advice to give you if you listen (I usually don't).

I guess the wrongest thing you did was probably to dislodge all that crud and not wash it thoroughly. High pressure air might blow the brushes away, I would not use it. Low pressure, okay.

I used to blast the motors with motor spray 9which is just isopropylic alcohol) or just brake cleaner (same stuff), whichever comes cheaper. Don't be stingy. The crud you saw is very well disloged and comes out as a brown soup. Resist temptation and don't blast with WD40 because you're going to kill the comm.

Just be thorough.

Then you have to clean the comm. Not being able to dismantle the motor you have to get creative. I used a piece of flat metal to which I superglued a square piece of comm polishing stone (a very fine polishing stick) on the end which I bent at 90 degrees so it could reach inside the can and sit square on the comm. Now you need to turn the comm the normal way and press this thing evenly. This will polish the comm and bring it back to life.

When finished, clean crap again, dry, etc.

Running in is very important, keep it well lubed, use a Supernova if you have one so you can adjust voltage and have an RPM and current readout to compare.

Line up the bushings though before you do run it in. To do this you need to get a feel for how well it is aligned to begin with. Pull the rotor by hand and feel the play. Now pull and see if it returns on its own to some equilibrium position (this will happen because of the magnetic field of the magnets who want to keep it in a certain position and not others). There shouldn't be much play either (say 1mm or so, not more). If the rotor is free to get back to its natural resting position in the magnetic field then I would say leave it alone. If not, you need to tap the can lightly on the end and retest as above for freedom of rotor. If you have a Supernova and test after each step, it will tell you when you are spot on by the current it draws.

Run it in now.
I used to run them in at 2-3V dry and blow out the crap as explained above, then polish the comm, clean and lube.

One more thing. Your motors are as you said cheap. Hence there's going to be a lot of variation between motors. To spot a good one, you need to bench test all and select the best one when you have a good stash of data, so it may be worth buying a few at a time and comparing. Tuners of the past used to buy in bulk, select the best few and tune those. A dud is not worth tuning if all you're going to get out of it is the performance of a normal run of the mill one.

And yes, get a fan to keep it cool if you don't have one yet. This is perhaps more important than tuning.

Good luck and have fun!

Maybe you should listen. There are much easier ways to clean the comm. There several posted on the Silvercan thread. Nothing wrong with info in your post, but using a comm stick is really difficult for most. In fact seating the bushings, centering the armature, etc is all the on that thread. Our friend needs to do a bit of research, that's all.