Tuesday, 22 November 2016

Exhaust Clamp

As I may have mentioned, when I ran the W/NG (for the second time in my care) a couple of weeks ago the exhaust detached itself at the cylinder head, due to the poor fit and inadequate clamp.You can see in this picture that the pipe is not quite aligned with the cylinder head stub - I am probably going to have to cut and shut the pipe to get it to fit. The rear stand also hits the silencer, so it may be that removing and refitting the exhaust will help but we have to start somewhere, and having the right bits is always a good place to start.

This is not the correct clamp, though it looks like some of the original brass parts are there. Here's the clamp illustrated in the 1940 parts book:

We can make one of these. First we will make a card template.

Clamped to a piece of 14 SWG cold rolled sheet ready for marking out

Cut & filed to shape

The clamp formed and ready for bending. The long centre section is now curved across it's width and the ends have been folded up

Bending the clamp - I'm doing this hot.

Fitting it for the first time reveals it is about 3/8" too short:

In principle the design is sound. I've run the bike with the clamp in place and the exhaust pipe joint doesn't leak.

We'll just have to make a longer one.

Here we go - use a similar pattern to mark out the clamp in 16 SWG cold rolled steel sheet, saw it out and file to shape. Bend up the lugs as before and dish the strap in the vice; this time I formed the curve around a short piece of scaffold pipe:

Final filing after bending up ensures the lugs are aligned and the slots are in the right places:

 For the bolt, I made a tee out of some 1/4" BDMS round bar, with a TIG fillet all round:

Cut to a suitable length, and cut a 1/4" BSC thread on the end. Excuse the wet paint!

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