5th Gen, front sprocket bolt stuck, advice?

Hello, I have lurked on the forums for a while, but now I am in need of help. The front drive sprocket bolt will not budge. I have tried my air impact wrench (it's a cheap model, but I expect this would have some effect), and also long bar, but using the long bar the head is starting to round off. I tried penetrating oil but looking at the diagram I don't think it will work into the threads.

I did try to use a blow torch on to heat it but a lot of smoke came off, which is either from the chain cover, but since seeing the diagram I think I may be melting the transmission seal behind-can this seal be replaced without removing the transmission shaft?

Should I continue to heat it, or will it need to be drilled. I haven't drilled a bolt before and am worried about damaging the threads, since a new transmission shaft is costly and long repair.

Oh and when trying to undo the bolt the rear wheel was moving when I applied the rear brake fully, is that normal? I have the spare pads but wanted to do the sprockets/chain first.  :unsure:

Thanks in advance.

Bike in gear, helper stands on rear brake, use large breaker bar, and a good socket.

Turn counterclockwise. Push push push. If you keep the sprocket still it should not be terribly hard to break the bolt loose.

Good luck.

What VFR4Lee said, good socket flat sides internally, hexagonal, not multi fit that rides on the edges, or you'll have to get one of those with the rounds on them that lock on the middle of flat section of the bolt. Seen them undoing even partially rounded bolts..

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Do you think a prior owner might have put thread locker on it?  If so, heating the bolt up might help.

Thanks for suggestions. I tried at it again today, I realised the impact sockets are 6 sided instead of 12 sided, but the air gun was useless. I ended up putting the impact socket on to my long torque wrench and put in gear and it did finally un do, after using some heat and oil.

I can definitely say cheap air tools are a waste of money! Now to fix the other parts of the bike....

Make sure you buy a new bolt.  The bolt drives the speedo sensor, so if it's rounded off it won't seat properly. 

Ciao,

16 minutes ago, JZH

Make sure you buy a new bolt.  The bolt drives the speedo sensor, so if it's rounded off it won't seat properly. 

Ciao,

Already ordered. And also I don't want rounded bolts anywhere near my bike, just makes the next time 100x more difficult (!)

7 hours ago, courtuk

Thanks for suggestions. I tried at it again today, I realised the impact sockets are 6 sided instead of 12 sided, but the air gun was useless. I ended up putting the impact socket on to my long torque wrench and put in gear and it did finally un do, after using some heat and oil.

I can definitely say cheap air tools are a waste of money! Now to fix the other parts of the bike....

Glad it worked out okay in the end.

FWIW, I have a Craftsman electric impact wrench that I use with cheap Harbor Freight impact sockets, and it has never let me down.