Wednesday, 30 March 2016

Rusty metal

While it doesn't look too bad from this angle, the battery tray on this MZ TS125 is falling apart due to acid damage. There is a crack from one of the hooks for the battery retaining strap which means that that tab, with the M5 hole for the side panel is quite floppy.

Since it was only going to cost me a few minutes, I tried to braze it up but in practice it is all too thin to have any strength, so the easiest thing to do is cut it off and make a new one. The bracket used to mount the battery tray on the frame is sound, so we can cut the tray away from it retaining as much as possible of the old tray to provide a pattern for a new one.

I have some 18 SWG cold rolled sheet in the shop, which is a good deal thicker than the original which looks like 22 SWG. You can see the extent of the damage in these pictures.

The new one is very simply folded from sheet, cut out with the jigsaw & hacksaw and with 5 mm holes drilled into the corners for clearance and drainage. We'll tack the corners together with the MIG welder.

Here's the hooks folded down and around the old strap.

So now I have transferred the side panel tab to the new tray, and brazed it in place in case I have to move it again. Next, to weld up the corners and finally weld the tray back to the frame:

Welding the outsite of corners is tricky if you are not to blow the material away completely; my welding needs a lot of dressing! Corners done, we'll tack it in place using the old one as a guide:

We'll need to fit some other parts around it to confirm that the side panel mount is in the correct location, and then we will complete those welds underneath. Removing it with those fully welded would probably destroy my new tray.

Just a little U-Pol etch primer to avoid rusting...

A few days later I have the cast aluminium rear mudguard and the coil bracket to mount up and test my new battery bracket. I'll put the lot in the vice and mount the rear end with some 10 mm pins, that are a close fit in the holes and don't allow any wobble:

You can see the three M6 mounting holes for the side panel - one in my battery bracket, one on the coil bracket and one in the mudguard. Here's the side panel mounted up:

Perfect! now we can weld up and apply some paint.

And that's it, ready to be returned to its owner.

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