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Forty Plus top nut removal?

Posted: Mon Jan 28, 2019 12:37 pm
by african imp
Guys, I have a 1974 Forty Plus here and even with a 350mm long shifter on the flywheel nut the thing will not move.

I have the crank shaft square in the vice, my fear is that if I use the shifter with too much force I will damage the crank?

Right now I am thinking about using some heat from a gas flame, to protect the plastic, I will place a wet towel on the plastic and a metal cover plate over that, this seems to be a best option.

Does anyone have another idea please?

Re: Forty Plus top nut removal?

Posted: Mon Jan 28, 2019 2:16 pm
by tambikeboy
You certainly pick the hard one's why not heat up as is and allow the wrench to protect plastic or if you have the square end of crank secured in the vise then how about your drill method me personally I've never had one that tight who knows might have been put on with the drill...

Re: Forty Plus top nut removal?

Posted: Mon Jan 28, 2019 3:20 pm
by haventaclue
My personal preferred method would be air impact hammer/wrench and socket set on it's lowest setting and let it rattle away,if no impact hammer/wrench,a sharp couple of taps on the top of the nut with a lump hammer to break the seal.Sharp taps not full on sledge swings :P

Re: Forty Plus top nut removal?

Posted: Mon Jan 28, 2019 3:54 pm
by african imp
haventaclue wrote:My personal preferred method would be air impact hammer/wrench and socket set on it's lowest setting and let it rattle away,if no impact hammer/wrench,a sharp couple of taps on the top of the nut with a lump hammer to break the seal.Sharp taps not full on sledge swings :P

Thanks,


I think my local tyre fitment shop will get a visit in the morning to ask them to use their impact hammer.

John at SOS says that they are easy to undo, as they are tourqued up to 20 pounds only.

He advised me to try a soft hammer, rubber was mentioned, with the flywheel gripped between your knees, hit the wrench or as I did the steel bar from the socket over the nut.

I used a one pound hammer with a copper face.

Nothing happend !

This motor belongs to a friend of mine and he has asked me to service and make it look better.

Re: Forty Plus top nut removal?

Posted: Mon Jan 28, 2019 9:28 pm
by Hugz
Personally l would prefer to use a ring spanner. Hit the end of the spanner (opposite end to nut) in the direction you wish the nut to move. The hit will be leveraged to maximise impact at nut. There is a thread on someone who had the exact same problem on a wipac magneto.

Re: Forty Plus top nut removal?

Posted: Tue Jan 29, 2019 5:33 am
by fleetingcontact
Hugz wrote: ... Hit the end of the spanner (opposite end to nut) ...
crying with laughter.png
crying with laughter.png (18 KiB) Viewed 805 times

I used one of these once. Never fails.

breaker bar.jpg

I was a bit worried it might distort the crank but when I finally got the flywheel off it was obvious it was already toast - very rusty.

Re: Forty Plus top nut removal?

Posted: Tue Jan 29, 2019 10:37 am
by african imp
haventaclue wrote:My personal preferred method would be air impact hammer/wrench and socket set on it's lowest setting and let it rattle away,if no impact hammer/wrench,a sharp couple of taps on the top of the nut with a lump hammer to break the seal.Sharp taps not full on sledge swings :P

Constructive information from forum members is always welcome.

I used your impact hammer idea and had a tyre fitment shop use their air gun and with the socket that I gave them for the job.

Thanks on the very good advice!

Re: Forty Plus top nut removal?

Posted: Tue Jan 29, 2019 10:42 am
by african imp
Hugz wrote:Personally l would prefer to use a ring spanner. Hit the end of the spanner (opposite end to nut) in the direction you wish the nut to move. The hit will be leveraged to maximise impact at nut. There is a thread on someone who had the exact same problem on a wipac magneto.
Thanks, yes I moved to a socket and a long bar, hitting the end of the bar with my one pound hammer with a copper face brought no results so I left it for a pro tyre shops impact hammer this morning, success was near instant but it still took a good go with the impact gun.