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Old 03-13-2007, 06:03 PM   #1
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Default HELP! wearing armature shaft

Hi all,

Im hoping I can get some answers and a conclusion to why is the shaft on the motor armature (pinion end) keeps wearing down (around the bushing) every motor I run (Stock 27 turn in an XRAY fk05).

This problem has been going on for at least 3 to 4 months now and Im going through motors after motors trying different things to fix the wear but no luck.
A brand new motor (armature) will last me roughly 2 to 3 race meets before its unusable, meaning their ends up being to much play on the pinion end through the shaft wearing (the wear appears to be uneven around the shaft meaning its deeper on one side than the other) which causes excessive heat, very bad performance and OH...the motor starts to sounds like a coffee grinder, this is progressive the more I run the motor, but after about 6 to 10 runs Im having to replace it with a new motor which is killing my hobby budget. PLEASE HELP!

Ive asked a few people in my club and all have never seen or heard of this problem before, and Im stumped to figure out whats causing the shaft to wear like this and to every motor

Ive tried....
-Replacing the bushings...Im convinced this is not whats causing the shaft to wear, cause it happens to every motor, though with a worn shaft the bushing wears with it more.

-Different spur to pinion mesh, its not this as Ive had other drivers at my club check if its a good mesh and they say it looks and feels good. And its the same mash Ive used when I started racing roughly over a year ago.

-I usually add a small amount of bushing oil (Muchmore) before a run, though again Im not convinced its a lubricating issue as Ive been lubing the bushings the same way as when I had started racing and never had this problem, though when I think its time for a motor rebuild and complete clean their seems to be a considerable amount of dirty oil/gunk on the inside of the bushing in the can, now this dirt build up could be causing a little wear to both the shaft and bushing though not in the way the shaft is wearing.

- Ive replaced the the middle diff and the spur gear where the 2 belts meet thinking it may have been bent causing this and to eliminate probable cause.

- Motor mount screws are always tight as this isnt causing the problem.

-Armature is properly shimmed with correct play in the can, again not the problem as it occurs to every motor I put in.


The only conclusion I can think of is maybe the rear bulkhead is bent or their is a considerable amount of tweak around the rear bulkhead causing all shafts to wear like this, but checking the chassis for tweak I found their is very little, though not enough to convince me its this, Im not sure though it could of been caused by an accident/crash I had on the track, though I have never been in such a crash that has caused any parts to break (knock on wood) apart from the rear body mount.

Im confused and frustrated and would love to get back to the enjoyment of RC racing.

Any help, advise, assistance, cure, remedy, support would be much appreciated as its become very confusing and frustrating as I and would love to get back to the enjoyment of RC racing.

Thankyou for your time.
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Old 03-13-2007, 06:18 PM   #2
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a quik way to check if you have a bent bulkhead other then romoving it and checking it on a flat surface is I would take some white grease and smear it on your spur and turn the gears by hand see if the grease smears evenly on the pinion to see if they have an even contact across the face of the gear teeth if the dont you may have a bent rear bulkhead also if all the grease is squished of the gear you have the mesh to tight there should be a small even film across the gear teeth.. Even so I cant imagine this would cause wear on the arm shaft if the mesh was set correctly. something I would check is your pinion gear see if it is warped from excessive overtightening of the set screw this will over time make a gear out of round and the harmonic vibration can without a doubt take out a bushing or shaft.

Last edited by Jmccormick; 03-13-2007 at 08:05 PM.
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Old 03-13-2007, 06:22 PM   #3
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what car do u run? IT is possible if you dont have a square motor moutn that you are hitting your spur/pinion gear on a slight angle? That woudl put added pressure on the armature and wear on the pushing... But you would think you would see this wear show up on the spur or pinion gear.

Maybe post a detail picuture of your chassis. Hi res of you motor mount,motor and gear mesh. Maybe it would be easier to see your problem with a photo
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Old 03-13-2007, 06:28 PM   #4
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Quote:
Originally Posted by Joel Lagace
what car do u run? IT is possible if you dont have a square motor moutn that you are hitting your spur/pinion gear on a slight angle? That woudl put added pressure on the armature and wear on the pushing... But you would think you would see this wear show up on the spur or pinion gear.

Maybe post a detail picuture of your chassis. Hi res of you motor mount,motor and gear mesh. Maybe it would be easier to see your problem with a photo
He said he had an fk05 in the first paragraph..
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Old 03-13-2007, 06:36 PM   #5
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the more I think about it I realy would try a diffrent pinion if you havnt already. I remember a few years back when I was running my TC4 I had a motor that ate bushings and it did end up being a bad pinion gear the gear where the teeth are where fine but the are where the setscrew is was egg shaped not to mention it was a cheap heavy gear I replaced it with a PRS gear and whalahh
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Old 03-13-2007, 07:22 PM   #6
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One more idea to throw into the mix with the ovalled pinion...are you setting proper lash(gear mesh)...too tight and you will wear the bushing out as well.
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Old 03-13-2007, 08:07 PM   #7
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I'll have an even closer look at the 21 pinion I usually use, and try the grease trick, though the mesh seems quite even right around when I check it by hand.
Thanks its another angle and Im definitely buying a new pinion to eliminate probable cause.
I will hopefully/eventually find the cause to this problem, Im hoping soon before I go broke.
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Old 03-13-2007, 08:14 PM   #8
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I have seen that EXACT issue before, I am not the one that is experiencing this issue but the owner (he is also a racer) of a local hobbyshop near our track.

He as Several armature that are worn Exactly as described, he is also the only person that I know of that this has happend to. I have been racing RC for 10+ years and that as not yet happened to any of my motors. strangest thing is : he is also running an FK05. and that only happends on Stock motors of is (obviously).

I got a bag full of Fubar armatures from him not to long ago, ill take a picture if I can and post it.

Matt
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Old 03-13-2007, 08:19 PM   #9
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Quote:
Originally Posted by MATTS
I have seen that EXACT issue before, I am not the one that is experiencing this issue but the owner (he is also a racer) of a local hobbyshop near our track.

He as Several armature that are worn Exactly as described, he is also the only person that I know of that this has happend to. I have been racing RC for 10+ years and that as not yet happened to any of my motors. strangest thing is : he is also running an FK05. and that only happends on Stock motors of is (obviously).

I got a bag full of Fubar armatures from him not to long ago, ill take a picture if I can and post it.

Matt
Great that would be appreciated, as Ive only every run stock, very strange that it only happens to his stock motors
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Old 03-13-2007, 08:43 PM   #10
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Here is a picture.
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HELP! wearing armature shaft-dsc00837-large-.jpg   HELP! wearing armature shaft-dsc00838-large-.jpg  
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Old 03-13-2007, 08:45 PM   #11
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I dont know why this is happening to is motors. all mine are fine.. I am even using a 4 year old P2K2 and it still works great.

Matt
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Old 03-13-2007, 08:54 PM   #12
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Quote:
Originally Posted by MATTS
Here is a picture.
Thanks Matts this is exactly whats happening to my shafts, though after last nights racing it looked much worse than these pictures.
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Old 03-13-2007, 09:23 PM   #13
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new car
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Old 03-13-2007, 09:33 PM   #14
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Quote:
Originally Posted by masta-racah
new car
Yeh considering. will see.
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Old 03-13-2007, 10:05 PM   #15
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one more thing is how tight are you running your belt?? I ran a Fk05 with a stock motor with no issues it is still a very good car so dont give up!!! but I have been told that a tight belt will cause this to. One other thing to check on the 05 is the shaft bearings for the spur gear along with the entire drive train its funny but a bad bearing can cause the motor to wear out bushings because of the excess torque required to move the gears etc if there is resistance on the drive train at all the spur gear wont want to move easily and the pinion will try to climb the gear to counter act the force of the motor turning and of course there is no give as the motor is solidly bolted and the bushings and shaft take the full force of this reaction...
heres what I would do.....
1)check ALL bearings shafts etc drivetrain should spin nice and smooth and free
2)use a new pinion preferably a light weight one from robinson or PRS
3)gear mesh you should be able to rock the spur back and forth slightly
4) belt tension important for stock I would have the belt as loose as possible without it skipping
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