Help with a Reedy quad spec 19t

[damian]

Hi
I have a reedy quad spec 19t in a b4. the comm is in a terrible state after about twenty minutes running. i have standard wheels and a 23t pinion on an 81t spur. the battery is a 2 cell 5000mah and the esc is an lrp ipc v6.
I have attached a picture of the comm. It was in good shape to start with and I polished the comm up to a proper shine.
Is this a very high maintenance motor?
please don't tell me to buy a brushless system. I paid 35 euro for this car, motor and esc and I am not afraid of maintaining things but this seems a bit much.
Any help is greatly appreciated.

[Jay Dub]

Well, the com needs to be turned, and brushes replaced. The problem I remember with the Reedy Quad Mag design is the gearing is extremely finicky. I cant help with a recommended ratio, but 20min of continuous runhning is a little much for most brushed motors with a proper rebuild. THe problem isn't only the surface finish of the comm, but the concentricity. AS the com is run it becomes clover shaped (where the grooves are), and causes brush bounce and arcing. This causes the comm to erode more quickly and the cycle becomes quicker and worse. -Jeff

[damian]

it just occurred to me that the problem is possibly more apparent after i put a shottky diode on the motor. is this a possibility or am i imagining the timing of when i put the diode on?
the motor was run for twenty minutes over about four days so not all together.
what are some things which cause increased wear?
could the springs be too strong?
could my gearing be too high? i believe the stock gear is a 23t? i read that this motor likes to be geared higher then normal so i should be okay there?
i knocked up a shonky comm lathe this morning and the comm looks good now but i don't want to put it back in until i find a way of reducing the wear.

[Jay Dub]

There actually allot of things that can cause comm wear. Typicaly heavier springs is not one of them, as they reduce brush bounce. Overheating is the biggest issue, with lack of maintenance the second. THis is of course with a motor that is properly tuned and geared, and has the correct brushes. I would start with a low silver or low copper brush, set the timing in the proper place, make sure the springs are not too soft, and then rebuild the motor as ofted as possible. Then the motor will last as long as possible. -Jeff

[MIKE VALENTINE]

Another issue you will have is the lay down brush, they were meant for racing. Maximum performance on the track, not back yard running. Take a small file and narrow the brush face that is wrapping around the commutater. This will reduce the amount of time the coils are energized and also reduce arcing. You should be able to find some articles on this if you search the internet.

[dldiaz]

Also be sure to align the brush hoods, check that the brushes are not getting stuck inside the hoods, and fully seat the ball bearings at both ends of the motor.

I have several of those Reedy Quad mags, they are very good motors.

[damian]

thanks for all the helpful replies.

i did a couple of things and i think it's going a bit better.

i went to a 21t pinion (standard spur).

i cut the brushes down a bit.

and i polished the comm to a mega shine.

seems to be lasting a bit longer now and not looking so completely destroyed like before.

i wish i had a proper lathe because the motor is plenty powerful on 2s but a lathe costs a much as a cheap brushless system which seems like a better spend.

[Lonestar]

this is the drawback of brushed motors... if you don't have a lathe, maintenance becomes an issue. In the days when there was no choice and BL was not available (cheap), you had to bear with it - but on the other hand the batteries were not allowing you to run enough to overheat (I'm simplifying). But now, brushed + hi-cap lipos without a lathe is a recipe for disaster...good you got one, and you seem to have done a good job too

If your motor drew THAT much current to become this worn out in just 20 minutes of (non-continuous, if I read right use), I would check the overall transmission, remove pinion and push the car around your living room, it should roll very freely. Also make sure your pinion/spur is not too tight. If both are ok, then check if the comm moves freely in the can (shimmed to tight? Bearings not aligned???). If all this is ok, then try new brushes. If it still does it after that, then I don't know what to do !!!

Paul

[damian]

both motor and trans spin really well and the gear mesh looks perfect.
it could be a combo of lipo with the grip of new tyres on grass.
im gonna keep using my makeshift lathe for now.
re. vintage cars. no not really. i have not had an rc car since a tamiya mad fighter years ago. ive been keeping my self going with homebrew gliders and hovercrafts and recently i picked up a b4 and a losi street weapon. im trying to get them going on the cheap. just for fooling around no racing. i reckon the losi may count as vintage.

[Jay Dub]

Grass = bad. -Jeff

[slotcarrod]

Your going to need new brushes as those will be burnt with no lube in them remaining! I have found that some very high silver content brushes will cause accelerated wear! I had some high dollar GM brushes that did that in one run! Anyway, follow all the above suggestions but my belief is you had high gearing and high silver brushes!

[damian]

i have since done a bit more reading and all the references to this motor liking a high gearing are on touring car forums. maybe that is the difference. mine is certainly happier on 21/81. i polished the comm to a mirror finish and i stick some earbuds (q-tips) in my pockets when i go out so i can stick one in the endbell and clean the comm every now and then. this seems to be making a difference. i also have some new brushes and a 19t pinion in the post so i will try those out soon.
i know the grip on grass is not helping but the combo of high grip and hardly and tyre wear is hard to ignore. these days tyres are more expensive than motors.

[teman]

I prefer to use a com cleaner stick as opposed to a qtip. Like this...