Sunday, 9 February 2014

Bantam part 3: BlunderSprint!

I've got the bike in one piece now!

After getting the head bearings in, the swing arm went on. This was the reason I didn't MOT it, it had a lot of free play. Thankfully, the new bushes I put in 4 years ago weren't buggered, either I'd not shimmed up the end float right or the bushes moved sideways a bit. Anyway, for reference: the thick shim (25 thou if I remember right) goes on the left, chain side. Push the swing arm pin through the left bush, the shim, then into the lug in the frame. Tap it thhrough with a soft mallet until it is most of the way through the lug, but not so the end comes out yet. You might want to put a bolt in the end to protect the thread, don't use the ones you want to fit as you'll bend them.
Now, buy a load of different thickness shims, and fit one that only just fits in the right hand side. Or measure the gap with slips and machine one up to suit.
You now need to tap the pin all the way through, but also hold the right shim in place, and avoid trapping it. To do this, push in your old swing arm pin in from the right, so it just goes in the lug, and therefore holds the shim in place. Carry on thrashing the new pin in, it should push the old one out and slip neatly through the shim.

Yes, I forgot to take photos again.

The next area of attention was this dowel. It attaches the rear subframe at the top, and has a bolt going through that both holds it all together and attaches the tank. On some bikes it also attaches the horn, the tax disc, some panniers, spare slippers and a sidecar-a hell of a job for one bolt! Of course, any looseness here will give you a lovely hinge in the middle of your frame. Mine was no exception, the pin had about 10 thou clearance. I put a suitable sized (i.e. found one that fits) reamer down all 3 holes to get them the same, then made a new dowel that is a tight fit in the frame, and close but free fit round the bolt. You can almost feel the handling returning.

So, I had this:

The above object is a location for both the fork spring and rubber gaiter. In standard trim, the spring butts up to the bottom yoke and the gaiter goes on the headlamp ears. I'm binning the ears, so made this replacement. It also has a bit to keep the end of the spring off the stanchion, similar to my previous post.

Last bit on the forks for now. I found that the top bolts were leaking oil whilst riding, so I machined a groove in them for an O ring. Problem solved. This is yet another design flaw they all seem to suffer from.

Gratuitous shot of it coming together.

I'm also trying to hide all the electrics, which will let me do away with the side panels completely. The coil fitted neatly under the tank.

The fuses and key switch in the seat hump

And the reg/rect unit underneath, out in a cooling airflow.

Onward to the engine. The holes in the front mount were worn and a strange size, so I made the top hat washers. Hard to see, but there is a small diameter that fits in the frame hole and bushes it out.

All was going swimmingly well, until someone threw a spanner in the works.

"I'm going to watch Thundersprint this year"

"Why don't you enter your bantam?"

So I did. To begin, I made new lock wirable gearbox drain and filler plugs. The filler has provision to fit a breather hose.

So, having thrown brass swarf everywhere, and got a few kilos in my hands, I went to bed. Night all.