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Old Aug 03, 2012, 05:53 AM
RC pilot by soul
Israel
Joined Apr 2005
2,485 Posts
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Changing bearings in AXI 4130/20

Hello guys,

I have an Axi 4130/20 with faulty bearings:
1. does anyone know whats the size of the bearings ?
2. any special specs for these bearings ?
3. whats the reommended way to change them myself ? heating/cooling of parts ?

thanks.
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Old Aug 03, 2012, 12:24 PM
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United States, FL, Pompano Beach
Joined Oct 2011
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Find a really good fitting 2mm Allen wrench as the Axi I have disassembled have lots of LocTite.
Heat the area around the screw as best you can. Heating the screw directly softens LT but expands the screw. Heating the ares helps expand the threaded hole. Remove the inny and outy "C' clip's that one retains a bearing. You can chase it or put the motor in a plastic bag when removing it. After all is loose carefully ( keep body parts out of pinch zone). I wash my hands and motor with alcohol to remove any lube. Grab the housings firmly as the a magnet snap can damage the motor or you. If this is the first disassemble there is LT on the shaft and that can take some force to pull apart. When removing the bell there will most likely be brass shim (a) washer(s) on the shaft or stuck to the inside of the bell, keep track of them. I take a long thin punch with sharp 90* on the tip and tap the bearings gently around the circumference a little at a time to walk the bearing out, trying to only touch the tool tip to the outer race. Even if the bearing is bad you want to walk it out so as not to damage it's bore
big bearing OD .631"/16.02mm X ID .232/5.94mm X .196"/4.98mm
small bearing X2 OD .472"/11.98mm X ID .232"/5.94mm X .157"/3.98mm
My caliper is good to .0005" so my measurement may not be exact but there close enough to find the bearings as there are limited sizes. Boca Bearing is very helpful and has a huge selection of quality.
Be patient, and use good fitting tools messing up the grub screw or bearing bore can open up a can of worms.
Keep the bell with magnets up. Facing the magnets down provides the opportunity for the magnets to grab stuff that you may not notice on reassemble. If there is trash when you turn the motor, especially under power there will very likely be bad damage. Make sure the magnets are clean before the bell gets near the stator. The bearings will push in with a finger tip, but if you fell the need to tap on them, ONLY tap the outer race so as not to brindle the bearing.
On reas use loctite and snug the screws down each a little at a time to bring to full torque. German torque is used "Gooten tight"
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Old Aug 03, 2012, 12:43 PM
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http://www.rcgroups.com/forums/showthread.php?t=1670086 Have you seen this?
http://http://www.rcgroups.com/forum....php?t=1633916
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Last edited by zeroback; Aug 03, 2012 at 12:53 PM.
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Old Aug 03, 2012, 05:21 PM
Dude, I do fly all day long!
rcalldaylong's Avatar
San Jose, California
Joined Dec 2007
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FYI - don't hit the bearing with anything...doing so you risk damaging the bearings. In this case you may not care since they are bad anyways.

Anyhow, instead, just heat it up and the bearings will fall out by itself.
same goes when you try putting the new bearings back in- Don't force it, heat up the stator and the bearings will just fit right in.
Do not heat up the can with the magnets...doing so will kill the magnets.


Bearing removal from a brushless motor without damaging motor (1 min 40 sec)
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Old Aug 04, 2012, 07:49 AM
RC pilot by soul
Israel
Joined Apr 2005
2,485 Posts
This method wotn work on the AXI motor because of the brass inner tube not allowing the ID of the bearing to protrude enough into the shaft hole in order to knock on it.

thats why i was asking the question.
in the Hacker its easy. with this brass tube seems like the best way is heat.

but im very afraid to ruin the coils by heating too much.
what kind of tempereature would you guys recommend ?

i can also use a heat gun but again, need to be very careful not to damage anything.
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Old Aug 04, 2012, 10:18 AM
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150* or so will be safe or hot enough that you really don't want to hold but it is not technically burning you 150* or less. Patients is a virtue.
Although I forgo the heat and gently tap them out every time no problem.
In the end it doesn't mater what technique works for you as long as it works. As well as not all techniques can be used on every motor. So now there a few tools in this box.
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Old Aug 04, 2012, 12:06 PM
RC pilot by soul
Israel
Joined Apr 2005
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150C or 150F degrees ?
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Old Aug 04, 2012, 04:49 PM
Dude, I do fly all day long!
rcalldaylong's Avatar
San Jose, California
Joined Dec 2007
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Depending on the bearing tube if it's very tight or loose, more heat may be needed. If very tight, the key is to let the stove get very hot before placing the stator and backplate on it. And place it on for only a very short period...say no more than 5-8 secs if very high heat. The windings are getting indirect heat, so in all my motor windings, they can take a good amount of heat before smoking (enamel is burning). Some motors need up to 500-700C and placing motor there for 5-8secs before bearings fall out. Some may need a slight tap even with some heat applied, but you should never tap it too hard.

You might want to try it on a cheap motor before doing it on the AXI.
I did about half a dozen motors before I got it right.
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Old Aug 04, 2012, 10:42 PM
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Quote:
Originally Posted by i3dm View Post
150C or 150F degrees ?
Fahrenheit
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