Removing pulley wheel from alternator

[Bendy toy]

Im replacing my noisy Denso alternator with a used Denso. Same wiring same mounts. All good.
BUT the pulley wheels are different. The bike has a smaller wheel.
Does anyone know how to remove the retaining nut. I've tried holding the pulley in a vice (with an old belt for protection) breaker bar just pulls it out of the vice. Impact screwdriver (hit with hammer type) has no effect.

Any ideas?

 

[steadysteve]

I think steptoe answered a similar question, possibly 18months ago ish--- the alternator was on the bike though and involved holding the nut with the relevant socket and giving the starter button a quick prod, bingo

 

[ianboydsnr]

You need a proper impact gun, either electric or air

 

[SteveM]

Do you have access to a hot air gun or blow torch Bendy? I'd give that a go first, very often the shaft and the pulley will be made of different materials that expand at different rates, you know the rest.

 

[Bendy toy]

Engine in gear works for the drive pulley nut. It's easier with a ratchet tie down strap to pull the suspension up. It's not especially tight.

The alternator nut is solid.
I've had it to 120c with hot air gun (measured with IR thermometer). Daren't go hotter.
I've made a wood clamp with hole saw. Risked it metal to metal in a vice used a 2ft breaker bar taken tension and whacked with lump hammer.
It's not moved even slightly.
I've been more brutal with the larger wheel (not needed) still no luck.
WTF did the factory use?

 

[SteveM]

Are you sure its not a left hand thread

 

[roamer]

If you cant get access to a good impact gun,
Try a t bar that you get in socket sets on an impact socket ,
And hit it hard (2 Hander) about 4/5 inches along the bar, it will transfer the impact better,
The long bar will absorb too much energy, the t bar is soft enough not to shatter,
Roamer

 

[Bendy toy]

I don't believe so. The threads I can see are higher to the right. Also tried clouting it the other way. No change.
Scratch marks I made on nut and pulley show zero movement.
Next step drill the nuts to split and fit a new one.

 

[Bendy toy]

How hard can it be!!!!
https://alternatorparts.com/alternator-pulley-removal-installitation-instructions.html

I've just looked at Real OEM. The alternator shaft nut isn't listed.
http://www.realoem.com/bmw/enUS/sho...W-R_1200_GS_Adve_08_0380,0390_&diagId=12_2111

FECK!!! thats the drill it off option out the window. I'll have to pop it down the local garage and hope they can shift it

 

[kevingambrell]

Engine in gear works for the drive pulley nut. It's easier with a ratchet tie down strap to pull the suspension up. It's not especially tight.

The alternator nut is solid.
I've had it to 120c with hot air gun (measured with IR thermometer). Daren't go hotter.
I've made a wood clamp with hole saw. Risked it metal to metal in a vice used a 2ft breaker bar taken tension and whacked with lump hammer.
It's not moved even slightly.
I've been more brutal with the larger wheel (not needed) still no luck.
WTF did the factory use?

Bendy, 120 degrees isnt hot for a nut your not even close to removing any temper in the shaft its on.
Heat it cool it fast heat it again cool it again then heat it and try removing the nut. The previouse poster is right
an electric impact helps.

 

[Bendy toy]

Maybe I just need a longer Vee belt. The number for my bike (GSA) is 4PK582 (60A Denso). For a 2005 GS it's 4PK592 (40A Denso). I'm changing the pulleys because the one on my bike is smaller than the one on the "new" alternator.

Theres a problem with properly heating the nut is it's shrouded by the pulley. I used enough temperature to soften any threadlock, but no difference so its probably not thread locked.

Hitting the long breaker bar near the handle end is useless but near the hinge is the same effect as a smaller T bar but more pretension is possible and it's less risky. It didn't work with either.

If it was not an alternator I'd have run some arc weld on the nut which would soon shift it. But arc welds will almost certainly burn out the diode pack. Gas will put too much heat into the shaft and risk cooking the alternator windings.

A trip to the garage tomorrow should sort it.

Edit:

Just looked on Motorworks. The GSA belt is 582mm the GS belt is 611mm.

Feck! Should have thought of that !!!!

 

[Bendy toy]

I drove over To Ocean BMW in Plymouth and picked up a longer alternator belt. More money than MotorWorks but I need the bike.
The belt fitted fine and its all working boxed up and ready for a run to the Midlands tomorrow.
Top tip - If you are going either way between 40A and 60A alternators you also need the correct drive belt. 60A uses the shorter one.


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[Steptoe]

I drove over To Ocean BMW in Plymouth and picked up a longer alternator belt. More money than MotorWorks but I need the bike.
The belt fitted fine and its all working boxed up and ready for a run to the Midlands tomorrow.
Top tip - If you are going either way between 40A and 60A alternators you also need the correct drive belt. 60A uses the shorter one.


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Two belts for the 1200 - 582mm and 592mm.
The 611mm is for the 1100/1150.

 

[Bendy toy]

Update.

I never did get the pulleys removed - though a windy hammer gun probably would have shifted them. The 40A alternator uses a larger pulley and longer belt. New belt fitted and its all working again.

I went over to Ocean Plymouth and bought the longer 1200 belt. It was tight fit and kept snagging on the drive pulley. It's front face has a rib that flipped the belt. Sorted with some large washers.

Top tip. If the belt keeps flipping over as you try to wind it on, put a stack of large washers under the drive pulley nut. The belt them cant flip and will be on the bike in a couple of minutes. Remove the washers and torque the nut normally.

Job is done with bike in top gear on it's side stand. Pull down on the crash bar to lower the suspension and there's enough room for a torque wrench and socket fit. Left foot on foot brake and the bike can't move while you torque up the nut.