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Author Topic: Help! Can't get magnet rotor off!  (Read 2377 times)

LarsBloodbeard

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Help! Can't get magnet rotor off!
« on: August 23, 2012, 02:20:59 AM »
Hello everyone!

First a little backstory... my little thumper (2003 Bullet 500 ES military) was used and abused when I bought it.  The original owner brought it over from India and changed the speedo, so I have no idea how many miles are on this thing.  It was in rough shape.  Barely ran, barely stopped, severely sun-beaten, rusted, etc.

One morning I jumped on it and got about a mile down the road when the bike stopped suddenly.  And by that I mean the engine halted and the rear tire locked up as I skidded down the road at 40MPH.  A quick grab of the clutch and I regained control.  I knew something major had gone wrong.  I tried the electric start and it would not turn over.  I flipped out the kick starter and it would not budge.  The piston seizing due to a bad oil pump wouldn't make much sense as I had only been riding for 5 minutes.  I figured maybe the rod broke and got lodged in there, or the crankshaft bearings came off. 

Well, when I started to dig into it, I discovered it was something I would have never guessed... The magnet rotor busted apart and lodged against the stator!  I basically had to break the stator to get it off.  The magnet rotor crumbled in my hands as I tried to remove it.  But there is an inner solid steel piece.  Once I got the stator off I was like "cool, I'll just slide the magnet rotor off and all is well."  Nope.  I tried pulling by hand at first, then I upgraded to tapping it with a rubber mallet, then I busted out a 3 arm puller and wrenched about as hard as I could.  Still nothing.  Anyone else encounter this before?  Is there some kind of trick to this year/model?  Any suggestions?

The Garbone

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Re: Help! Can't get magnet rotor off!
« Reply #1 on: August 23, 2012, 02:32:58 AM »
Hmm,  I think it torqued itself on the woodruff key and is affixed real solid.

Maybe you could lock the motor/trans up and put a big monkey wrench with a breaking bar on it and torque it backwards and pop it off the key.

Otherwise, I  imagine it would take a rather large bolt splitter,  maybe you could cut it with an angle grinder then put a wedge in it,  eeehhhh.

Freon and a heavy hammer would probably end badly.
Gary
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LarsBloodbeard

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Re: Help! Can't get magnet rotor off!
« Reply #2 on: August 23, 2012, 03:02:41 AM »
Hmm,  I think it torqued itself on the woodruff key and is affixed real solid.

That's kind of what I was thinking.  I've been torquing the puller and beating it with a framing hammer, hoping that it'll pop loose, but still nothing.  I'll try a big wrench and see if that'll help.

LarsBloodbeard

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Re: Help! Can't get magnet rotor off!
« Reply #3 on: August 23, 2012, 03:47:13 AM »
Hang on... I think I've discovered the problem.  Looking at a parts catalog it appears the nut holding it in place has a sleeve.  My nut does not... which leads me to believe the sleeve has broken off and is still inside that hub.

This does not bode well.  How on earth am I going to get that out?  I think my only option is going to be to cut into this thing...

http://www.hitchcocksmotorcycles.com/partsbooks/pages/1349/Alternator

Arizoni

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Re: Help! Can't get magnet rotor off!
« Reply #4 on: August 23, 2012, 04:05:24 AM »
From the looks of it in the Hitchcock drawing and you pictures, the "sleeve" is (was) a part of the nut.  That probably means it is threaded onto the crankshaft.

If I had this problem I think I would take a hack saw and cut down thru the hexagon part locating the cut about 1/4" (6.4mm) behind the face of what's left of the old nut.

I would try very hard to not cut deeper than the inside diameter of the hex part.

If I was lucky, and I had cut all the way around the hex part leaving just a very small amount between the bottom of the cut and the ID of the hex part I could then use a pair of wrenches to twist the hex part apart leaving about 1/4" of the old nut exposed.

Then with some careful filing I would cut a hexagon on the remainder of the old nut and hopefully be able to unscrew it with a box end wrench (spanner).

With that part unscrewed the rest of the hexagon part should pull off.  (fingers crossed).

I don't know if this plan will work but usually when I suggest something stupid, someone else comes along and tells us what the right way of doing this is.  ;D
Jim
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AgentX

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Re: Help! Can't get magnet rotor off!
« Reply #5 on: August 23, 2012, 10:57:05 AM »
If it was me, I'd probably try to use a Dremel wheel to cut a vertical slot into it until I just broke through to the sleeve from the nut.  (might have to use a hacksaw to take off some height from the remains of the rotor to accomplish this.) 

Then force it apart by wedging a thin chisel or flat-blade screwdriver into the slot, then spray some penetrating lube into the slot to work its way around the sleeve.

Then pull or push it off by any means necessary.

I can possibly see where the Dremel might not be able to cut through the bottom of the nut closest to the crankshaft sprocket, but I still think it might work despite that remaining bit of metal.

The Garbone

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Re: Help! Can't get magnet rotor off!
« Reply #6 on: August 23, 2012, 01:12:00 PM »
You could use a small drill and drill to holes/notches  into the end of the sleeve at every 90 degrees and use a spanner socket, if you can find one the correct size.

Example---     http://www.ebay.com/itm/Honda-Clutch-Lock-20mm-24mm-Nut-Combo-Spanner-Socket-Tool-GL-1200-1984-85-86-/110919867093?pt=Motors_Automotive_Tools&hash=item19d356dad5&vxp=mtr
Gary
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barenekd

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Re: Help! Can't get magnet rotor off!
« Reply #7 on: August 23, 2012, 08:10:24 PM »
The rotor is a taper fit so it doesn't have to move very far to release it.
I would try, first some penetrating fluid, then tapping the stuck piece from the side. If that won't pop it off, I'd heat it with a torch and tap some more. Try not to heat the crankshaft end but just localize it on the rotor. Heated, the Three prong puller may take it off.
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LarsBloodbeard

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Re: Help! Can't get magnet rotor off!
« Reply #8 on: August 23, 2012, 09:21:56 PM »
You could use a small drill and drill to holes/notches  into the end of the sleeve at every 90 degrees and use a spanner socket, if you can find one the correct size.

I thought about that, but I'm not sure I could do it without damaging the threads.  Might be the easiest solution though.  If the threads get damaged I'll have to replace the crankshaft, right?  :(

The Garbone

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Re: Help! Can't get magnet rotor off!
« Reply #9 on: August 23, 2012, 11:59:33 PM »
It may be best to buy a replacement bolt and compair it to the bit you have to figure out how deep that sleeve goes.  Mark the rotor leavings and cut into it with an angle grinder until you can get a chisel in there and split it off the threads.   

I am sure there is an easier solution,  just need a good machinist to clue us in...
Gary
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95 RE Ace Clubman 535
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mrunderhill1975a

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Re: Help! Can't get magnet rotor off!
« Reply #10 on: August 24, 2012, 03:15:31 AM »
All good suggestions.  Do you have a narrow steel punch that would fit between the threads and the inside of the rotor?  If so, you could soak the shaft in penetrating oil, then try to tap the remaining ring out using the narrow punch.  You would need to be very careful not to bung the threads on the shaft.

mikail gransee

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Re: Help! Can't get magnet rotor off!
« Reply #11 on: August 24, 2012, 10:01:27 PM »
Hello everyone!  Any suggestions?

Seen that pic before....your rotor core is "fused" to the crank shaft due to heat transfer and the sleeved "missing" part is still screwed on the crank shaft. Arizoni has the best advice...or you got a good machine shop near give them a shout.   Good luck!
This is the second rotor failure....wonder how many others? Seems like it is around the early 2000 years since I ran a check on the number I found on my "second hand NOT new" dealer installed rotor/stator.
« Last Edit: August 24, 2012, 10:13:15 PM by mikail gransee »
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AgentX

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Re: Help! Can't get magnet rotor off!
« Reply #12 on: August 25, 2012, 10:04:44 AM »
Hm.  If the rotor remains are fused to the broken sleeve from the retaining nut, couldn't you just immobilize the crankshaft and use a big wrench on the flats of the rotor core to turn the sucker off there?  It'd either screw off the whole thing in one shot, or break the connection between the rotor and nut...either of which is a good outcome.

Conversely, if the sleeve nut is fused to the crankshaft, aren't you kind of screwed?  Full rebuild of the crank is in order then, right?

The Garbone

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Re: Help! Can't get magnet rotor off!
« Reply #13 on: August 25, 2012, 10:20:11 AM »
Don't forget you have the woodruff key under the rotor so spinning the rotor probably will not work.  Might be a good place to cut as it will give you a bit more clearance.
Gary
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AgentX

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Re: Help! Can't get magnet rotor off!
« Reply #14 on: August 25, 2012, 11:44:28 AM »
Of course you do.  See, I'm capable of making any situation worse!