Crankshaft Alternator Nut will not budge

Do not use any heat source beyond a good heat gun or a propane torch. Do not use a nut spliter as this is a specialized fastener, you will only make matters worse. Do not cut off the hex; this might allow you to remove the rotor, but the rest of the rotor nut will be much more difficult to remove and could move you into split the cases territory, cost you a crankshaft or some expensive machining.

I suggest that you purchase the tool that locks the clutch hub to the clutch basket or you can make one out of pair of clutch plates.



The upper picture is my "magnum", got it at a swap meet. The second is one I made for a Triumph, but can be easily made out of Norton clutch plates.

I suggest that you gently heat the rotor nut with a heat gun. With the clutch locked, one way or another, you work the stubborn rotor nut by alternatively applying tightening and loosening forces with increasing force, make sure that you engage the rotor nut squarely with a 6 point socket; the nut should give up before you do.

Be aware that the rotor magnets don't like excessive heat, so if you use a propane torch focus on the center of the rotor nut and heat in stages, applying force to the nut in between heating stages.

I also suggest that you resist the urge to put a pipe wrench on the rotor, assuming that you plan to replace it. I suspect that the rotor's center may break away before the rotor nut yields; I can't say this from experience; call it an "educated guess". If you get to this point a gram of C-4 would, probably, work as well...

Best.

Despite your justifiable frustration, I suggest you keep at it using the less dramatic methods that avoid damaging the nut the rotor and the shaft. I suspect (ok, "hope") it will eventually break loose. Good Luck!

Thanks, will retry

I have a engineer mate that has a much more powerful compressor, I think I shall retreat for tonight and take up the battle tomorrow! Thanks everyone for advice!

I also suggest that you resist the urge to put a pipe wrench on the rotor, assuming that you plan to replace it. I suspect that the rotor's center may break away before the rotor nut yields; I can't say this from experience; call it an "educated guess". If you get to this point a gram of C-4 would, probably, work as well...Best.[/QUOTE]
only a gram of C4 , we never asked you to blow the bl**dy doors off!!!!!

had same trouble with mine. with spanner on nut, kept heat on nut and tapped spanner. eventually came undone. took about an hr, hope this helps. don't leave heat too long. you'll expand the shaft too and defeat the object

Bernhard said:

only a gram of C4 , we never asked you to blow the bl**dy doors off!!!!!

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That powerful? I had no idea; emotions and passions are about the most powerful destructive devices I have had to deal with. I figured that if the OP got to a debilitating state using a real explosive might set the stage for another pastime. I have a lot of "static passion" when it comes to '60s and '70s British iron, hasn't become kinetic for a lot of years; not enough to remove over torqued fasteners, in any event, gotta use tools, however, my wife, who won't come near my shop, keeps on asking what I'll do when my arthritis overcomes my ability to wield tools. My answer is always the same: If I don't die with my hand on the throttle and can still think straight, I'll buy an ultralight and find a good crash site eventually...

Read "Big Sid's Vincati" if you'd like to understand what "kinetic passion" is.

Best

Before applying heat, cut a hole in two pieces of tin so that they just fit over the hexagon of the nut. This will act as a heat shield so you can really heat the nut up. An old oil can, cut up and opened out will be ok.

RoadScholar said:

That powerful? I had no idea; emotions and passions are about the most powerful destructive devices I have had to deal with. I figured that if the OP got to a debilitating state using a real explosive might set the stage for another pastime. I have a lot of "static passion" when it comes to '60s and '70s British iron, hasn't become kinetic for a lot of years; not enough to remove over torqued fasteners, in any event, gotta use tools, however, my wife, who won't come near my shop, keeps on asking what I'll do when my arthritis overcomes my ability to wield tools. My answer is always the same: If I don't die with my hand on the throttle and can still think straight, I'll buy an ultralight and find a good crash site eventually...

Read "Big Sid's Vincati" if you'd like to understand what "kinetic passion" is.

Best

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Roadscholar, The C 4 was not my post, but I get your drift.

dobba99 said:

Before applying heat, cut a hole in two pieces of tin so that they just fit over the hexagon of the nut. This will act as a heat shield so you can really heat the nut up. An old oil can, cut up and opened out will be ok.

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Yes, a good idea- except most of my cans are plastic now, the tin ones are collectors items. . .

Could a relief cut be made in the nut to then drive a punch or small chisel into?

Tornado said:

Could a relief cut be made in the nut to then drive a punch or small chisel into?

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I seriously doubt anything could apply more torque than an impact wrench.

maylar said:

I seriously doubt anything could apply more torque than an impact wrench.

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Not a matter of torque...a relief cut allows the nut threads to release it's clamping to the bolt/stud thread. Using a punch or chisel into the cut then helps to pry the nut open and fully release. It's a matter of whether there is sufficient clearance on the nut to make a cut without damaging underlying stud or surrounding parts. Sometimes drilling into the nut can have a similar benefit.

You guys have no idea. First undo the nut the correct way round , hold the crankshaft from turning and use an impact wrench [ also known as a torque multiplier in Kiwiland ] to get the bloody nut undone. Nut runners only work easily on an object which is locked solid. Take the bloody thing to a mechanic who knows what he is doing.
Maylar your on the right track. Thankyou. The rest. Go bury your heads in the sand.

Dereck

Ok. A torque Multiplier works like this. It has a massive spring in it, which when you pull the arm around in the direction specified, it gets to a point where the spring is tripped, and all that torque instantly smashes against the socket in the direction you are pulling. It will also smash anything not able to withstand the pressure. y only recommendation in this situation is to put the bike in top gear, jam on the foot brake and wind away. Nothing meant to be undone has a chance with this thing. Mine has a 3/4 square drive. I could add a photo of one if someone else emails me who can put it on the site.

A few years ago I had a similar problem with the same nut on a BSA B50. It laughed at my old impact gun. My buddy who sells tools brought over a new impact gun that was supposed to be good for 900 foot pounds. It laughed at that too. I tried heat and penetrating oil, nothing was budging it. Finally, I used my Dremel with a cutting disk and very carefully put four slots in the nut, getting as close as I dared to the crank threads without touching them. I then used a very sharp cold chisel and a hammer to separate the pieces of the nut. It still didn't come off until I had knocked half the nut off. A careful examination showed that there wasn't any Loctite. Someone had used a previous British thread nut with the same threads per inch but different pitch and had rattle gunned it on. I cleaned the crank threads with a thread file and bought 2 of the correct nuts. The first one I essentially used as a die with a little valve grinding compound. The second one then went on nice and clean and torqued right up. I don't know if you have the same problem or not, but if you have to get medieval on it, you might follow the same process. One thing that made it a bit easier for me was that the motor was out of the frame and I could lie it on its side to work on it.

Ed from NJ

The only advice I can offer is to be careful with force. Ten years ago I took my MKII to a so-called rebuilding expert. Found out he totally ruin the threads to the point of chipping off the end of the shaft due to applying a high powered impact wrench and other methods. Had to have the crank removed and repaired. Expensive.

kerinorton said:

You guys have no idea. First undo the nut the correct way round , hold the crankshaft from turning and use an impact wrench to get the bloody nut undone. Nut runners only work easily on an object which is locked solid. Take the bloody thing to a mechanic who knows what he is doing.
Maylar your on the right track. Thankyou. The rest. Go bury your heads in the sand.

Dereck

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The sleeve on the fastener in question is less than .100", if the resistance to removal is between the the bottom of the hex and the washer/rotor then a more powerful impact gun could be the solution. If the resistance is related to the threaded part of the sleeve, and/or an inappropriate LocTite product, or the ike, was used then a more powerful impact gun will quickly have the OP in deep shit.

I suggest that this situation be escalated in stages where using a heavy equipment impact gun is the last resort. I have 5 impact guns and 'am glad to say that they continue to gather dust.

Every time you escalate a solution the consequences become more expensive and time consuming.

Best.

From memory the nut in question is a sleeve nut, so the visible nut head is only a fraction of the threaded length of the nut, and cutting slots in that portion may not make much difference if it's truly locked into place. The same issue would probably reduce the effectiveness of heat, as the heat would dissipate into the rotor before it reached the far end of the nut. I think if it were me and even a powerful rattle gun (or torque multiplier if you can locate such a thing) wouldn't shift it, and you really are left to more invasive strategies, I'd buy a very good quality drill bit and drill a series of holes in the nut, just above the crankshaft thread and to the full depth of the sleeve nut, in the hope that that would decompress the thread enough to allow it to be undone. Alternatively, and if you don't trust your ability to drill straight (I'm lousy at it) the OPs thought of cutting the visible head off may also work if doing so allows you to then use your Dremel to cut a series of slots in the remaining sleeve. Ah, the joys of working on old pommy bikes!

I'll ask the OP here again if the rotor is made by Sparx. They come with the bore undersized and have to be reamed to fit the crank. The binding could well be the nut sleeve to rotor, not to the threads. If that's the case chopping the rotor off with an angle grinder cutoff wheel might be the least painful solution.

If it's a Lucas rotor.... nevermind.

johnny Lagdon said:

I am thinking of grinding the hex end off, so I can slip the rotor off, then deal with threaded sleeve part.
Thoughts?

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NO. put bike in gear run it up against a wall , try and find a driver for the socket you can hit with a club hammer as you apply heave ho to the extension over which you have slipped a length of scaffolding pole. Ie you fabricate a kind of impact spanner . Most breaker bars have a knuckle that you should not hit with a club hammer. I assume you have appled sufficent heat to break the loctite bond.
It maybe there is corrosion between the thread and the nut , You might try taking battery off the tank off etc so you can lie bikeon its side which would allow something like plus gas to soak into the thread..Failing all the above then a nut splitter..