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Silencer fastening

Technical help for all early models, A, B, C, LC, D, LD, E & F models

Silencer fastening

Postby bordercot196 » Mon May 11, 2020 11:53 am

I have a stripped thread on the stud located in a boss at the front of the crankcase, which is used as the lower fastening for the silencer. Have tried to unscrew the stud so I can replace it but, at the moment, it doesn't want to move. Looking down on the boss I can see the top end of the stud so am applying WD40 to this point in the hope it will ease stud removal. Before I do anything stupid am I right in thinking that the stud is not mechanically locked in place so should unscrew if the WD40 does its work.
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Re: Silencer fastening

Postby jbcollier » Mon May 11, 2020 2:42 pm

Could you post a photo just so we know for sure which fastener you mean?

If it is a stud and not a bolt, hitting the stud with a hammer to "shock" the threads can help loosen it up. Use a proper stud puller as well. Something like this:

https://www.amazon.ca/Performance-Tool- ... B0000AXFMG
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Re: Silencer fastening

Postby bordercot196 » Mon May 11, 2020 3:42 pm

Struggling to add an image, how do you do it ?
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Re: Silencer fastening

Postby Big Al » Mon May 11, 2020 6:51 pm

Is the stud screwed into the front end of the right side (as you sit on the scooter) engine pivot bolt lug ?
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Re: Silencer fastening

Postby bordercot196 » Tue May 12, 2020 1:44 pm

Yes, that's the one. It's used to secure the tab welded onto the silencer.
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Re: Silencer fastening

Postby Big Al » Tue May 12, 2020 5:25 pm

My stud is out at present but, to test it, I've just screwed in a 6mm hex head screw from the bottom, using a 10mm spanner.

The screw only goes up until it is level with the top end of the thread on mine - no further. It may be that someone has forced your stud up higher than it was intended to go, and stripped the thread.

Personally, I would be a bit cautious about hitting it with a hammer, as it might damage the lug.
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Re: Silencer fastening

Postby bordercot196 » Tue May 12, 2020 11:28 pm

Thanks Al, When I look down on the top of the boss I would say that the top of the stud is about 1/2 millimetre below the top of the boss - like yours I would think. That means it will have to come out of the bottom. The exposed stud threads where the silencer bracket and nuts and washers fit is in a pretty poor condition, such that on a run last Saturday the nut must have come off leaving the silencer to move about the cylinder connection point. Thats why I started this post as the stud is proving extremely difficult to unscrew and I don't want to damage the boss. In fact up to now, after no end of WD40, it won't budge. I tried a bit of tapping on the end of the stud but that hasn't freed it. So now I will have to try a bit of local heat on the boss to expand it away from the stud threads. I just wanted to make sure that these studs were never Loctited in, but I suppose in 1954 when the bike was built Loctite didn't exist.
Was your stud easy to remove ? I really don't want to try brute force or the stud may shear off.
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Re: Silencer fastening

Postby bordercot196 » Wed May 13, 2020 12:18 pm

Panic over !. Tried the little blighter this morning and it screwed out easily. Thread was wet so I can only assume that, contrary to my earlier thoughts, the WD40 had finally done its job. Exhaust/silencer now replaced using a Hex Hd 6mm screw screwed up from the bottom of the boss to which I've added a stiff nut on the top side of the boss, so that should keep things in place.
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Re: Silencer fastening

Postby Big Al » Wed May 13, 2020 4:38 pm

That's good news!
I think there must have been a hexhead screw and a washer in mine, holding the silencer on, before I stripped the scooter right down.
I would have left the stud in there otherwise.
Glad you found a solution, anyway.
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