Stuck Alternator Rotor

[Superexcellent]

I have a problem in trying to remove the Bosch alternator Rotor from my V50 II. It has been in place for 40 years and the taper will not release it. I have tightened the extraction bolt as much as I dare and tried tapping the end of it to no avail.
The purpose is to check the static ignition timing as a stroboscopic gun I used gave 20 Deg static and 55 Deg fully advanced. The bike runs well and I suspect the strobe is giving me a false reading as I do not believe the factory setting has been altered.
Is there another way of removing the rotor? I do not want to destroy it

[Guzzistajohn]

There is a hardened steel pin of a VERY specific length that goes in front of the bolt and pushes the ALT off the taper. Anyway, that's what Mike Harper of Harper's Moto Guzzi told me years ago.

[moto-uno]

  The term "tapping" is probably way too gentle , tapers (if they're any good ) are pretty damn tight .
  A sharper blow with maybe a smaller hammer , well centered should do it .  Peter

[dxhall]

I tried everything on a taper-mounted armature on an Aermacchi a few weeks ago.  After deciding that I would probably have to destroy the thing to get it off the crankshaft taper anyway, I tightened up the puller and then hit the forcing screw with a 3/8 impact wrench.  The armature jumped off the taper and hit me in the stomach.  If you want a last resort, the impact is probably it.

[Tom H]

Are you using an extraction tool, or just threading a bolt in? If just a bolt, you need a hardened rod in the hole first, then the bolt. Then tighten and smack it with a hammer standard carpentry size.

If that fails, maybe some penetrating oil and/or a heat gun while the tool is tight.

dxhall, Were you using an extraction tool or like a 3 arm puller? Doing what you did could have messed things up if you were using the tool or a suitable substitute. Glad it worked out!!!!

Tom

[John A]

If you don’t use a hardened pin you will regret it.

[Moparnut72]

I collect and work on vintage outboard motors. Pulling flywheels off these old motors can be a real problem. An impact tool works quite well for this task. One caution, don't hit it at full strength, start low and work up. The shocks from the impact tend to break the fit to the tapered shaft. It is kind of scary especially when it lets go with a bang, makes you think something broke. But all is good.
kk

[Antietam Classic Cycle]

I prefer to use the special made tool, not a bolt and pin no matter how hard.
https://www.euromotoelectrics.com/product-p/boalt-rotor642tool.htm

I suspect Superexcellent is using something similar.

[jwinwi]

I prefer to use the special made tool, not a bolt and pin no matter how hard.
https://www.euromotoelectrics.com/product-p/boalt-rotor642tool.htm

I suspect Superexcellent is using something similar.

I don't know Charlie... It's kinda spendy (Guzzi Content!) 

Thank you for posting. I've always used The Hardened Pin but am concerned about rounding out the internal hex in the alternator bolt. This tool will take care of that.

[John A]

I prefer to use the special made tool, not a bolt and pin no matter how hard.
https://www.euromotoelectrics.com/product-p/boalt-rotor642tool.htm

I suspect Superexcellent is using something similar.

I like that one and 10.9 tensile should be enough

[berniebee]

I would add one more thing to rodekyll's post: Make sure you have soft bed underneath the alternator for when it suddenly jumps to the floor.

I sacrificed an Allen (hex) key from an old incomplete set to substitute as a removal pin. That's what I had around the garage that day. You'll know it's hard enough if you can't cut it with a hacksaw. I used a Dremel tool.

BTW in Guzziology, Richardson tells us the diameter of the removal pin tool is 5mm x 2 inches long.
He writes: With very little torque, the rotor usually pops off. If reluctant give the bolt head a sharp, direct but not too hard rap with a metal hamer, preferably brass.

In my case, it took four or five cautious hits to free the alternator.
 

[Chuck in Indiana]

Yep, tighten the bolt until you are sure you don't want to tighten it any more..  Give it a good rap with a copper hammer and prepare to catch the rotor before it hits the floor.

[Scout63]

When I went through my v50ii last year it just wouldn’t come off with an extraction pin and rapping it, heat, impact driver, etc.  I ended up drilling and tapping the rotor on two sides, cutting off the nose of the rotor with a dremel cut off wheel and using a bearing puller threaded into the rotor with the center against the now exposed crank nose.  My big block and all of my BMW’s have always just popped off.  That rotor was not reused.

[Superexcellent]

My rotor is really tight. I can get a second hand one so I may have to sacrifice the original one. I am worried that if I hit the extraction bolt too hard I will damage the crank or crankcase as there has to be a something stopping the crank moving backwards.
I will keep you posted. It will now have to wait until next week.

[paulbricey]

I just removed mine this morning (650 engine) due to big oil leak from front crank seal (front face of seal was split). I used standard tool £6.60 from Gutsibits to avoid jamming hardened pins in the crank nose.....It was harder 'fitted' than my 500 engine one was so needed to progressively tighten the 13mm bolt through a series of twist/hammer cycles but released with a loud pop on third go......patience grasshopper !

BTW instead of proper seal fit tool, I fitted oil seal initially (flush) with large washer tapped using big 30mm socket, then drift the new seal in to just past crank step up with the old seal using the same 30mm socket pulled in using the old rotor bolt

[dxhall]

I was using an extraction tool which threads into the armature with an 18mm left handed thread.  The forcing screw threads into the tool, not the crankshaft.  I figured i’d risk the tool.  Which is a bad risk because the tool is unfindable and my lathe won’t cut an 18mm thread. 

[Superexcellent]

I finally got it off!

 The extract bolt had been tightened up as much as I dare against the pin and had been like that for three days whilst I hit the end of the bolt, an axial force a few times. This got me nowhere so yesterday I decided to hit the rotor with a drift on one of the iron poles. This was a radial force and after the second hit it came off. The pin came out of the crank easily and the extraction bolt came out of the rotor so job done. I checked the resistance of the rotor and that was within spec. So very luckily nothing had been damaged. I can now at last check the static timing.

  I now realise I should have bought the Gutsibits tool as it is one piece and a better material.

[Chuck in Indiana]

 

I didn't want to mention that you could hit the rotor itself with your copper hammer because it seems most don't have them. That is the standard way of removing a toolholder stuck in a tapered spindle.

[moto-uno]

  If possible , you might want to put the rotor ends in a couple of "V" blocks and just check
to make sure the 2 rotor halves spin true . Pretty easy check . Peter

[Superexcellent]

I finally was able to check the static timing. It was spot on. I think that I was the first person to do this as the screws holding the cover plate for the pick ups were unmarked. After putting all the various bits back together I was very relieved to find that the alternator was still charging and the engine firing on both cylinders. I marked the flywheel at 35 Deg BTDC for both cylinders, 9 teeth on the flywheel, and found the full advance was correct too.

I still need to discover why there is a lack of power above 75 mph. It now is either a restricted pattern exhaust or the carbs. Compression test is 170 psi on both cylinders. I shall check the carbs next although I have balanced them with a mercury gauge.

Many thanks for all your help.

[Scout63]

Good luck super excellent. I pulled the stock ei and installed a Sachse crank mounted system.  It is great.  I was trying to solve intermittent loss of spark on the right cylinder.  After a complete tear down I realized that I had left out the idle jet in the right carb, flooding the cylinder. For the want of a nail, the horse was almost lost.