A Strip of the Old Bike 4

While I’m working on the old girl I’ll take the chance and make a couple of upgrades.

The first is the rear brake pull rod. The current rod is original to the frame and is over 50 years old. The adjuster nut is beginning to jump the thread so I’ll make up and fit a new rod while I have the chance, it’s been intended for a while so the materials are to hand, a clevis and a length of 6mm rod.

First step was to thread the end of the rod to take the clevis, with this in place the rod was cut to the same length as the old one and the free end threaded to match the old.

Next is the adjuster nut. The original is a brass wing nut so you don’t need tools to adjust it. The idea is good but proximity of the silencer makes it awkward so a new one made from a bit of brass hexagon rod is indicated. This can be adjusted using a deep socket and extension bar or an old-fashioned box spanner (tube spanner for those in the colonies).

Manufacture is simply just a case of drill and tap it 6mm, turn part of the length down to about 10mm diameter and cut to length. A bit of work with a file to shape the end to a saddle for on the lever roller and that’s it.

The other is the link in the gear-change train.

The original link here is a length of steel rod with a 90º bend at either end.

I’ve always found that this puts the lever a bit too high and have been meaning to change it for long enough. I’m doing it sophisticated like though, using a pair of rose joints and a threaded bar.

I’m being really posh though and having the rose joints left and right hand threaded so the final position of the pedal can be easily trimmed to suit, just means I need to get a left-handed 6mm die up from Tracy Tools.

The bike’s gear levers each have a 5mm clearance hole for the original rod while the rose joint mounting studs are 6mm thread. Tapping size for 6mm however is 5mm so rather than just open them out a bit I’ll run a 6mm tap through the levers, screw the rose joints into place and fit a lock nut as a “belt and braces” to secure them in place. I could have just done this using clevis joints on the rod ends but the rose joints are a neater answer.

I’m now nearly at the point where I can start the re-assembly, there’s just the rear swinging fork to repaint. Once that’s done I’ll refit it temporarily and take the opportunity to properly centre the rear mudguard.

At the moment it has been done by eye, the original position needed altering due to having a car tyre fitted at the rear end.

Normally on a BMW the wheel runs biased towards the right side of the swing fork. This allows space to remove the wheel so, while the wheel may be centred in the frame, the swing fork is not.

Using the wider car tyre meant that the wheel had to be shifted over a bit as the right side of the tyre was fouling on the swing fork so the mudguard was no longer centred on the wheel and had to be moved over as well.

While the guard was moved across a bit it was not quite enough as at full bump the left side of the tyre rubs a bit on the inside of the guard. It only happens on full bump though so I’ve been living with it but I’ll take the chance of fixing it while I have it, if I shift it by 10mm that should do it but any more and I’ll foul the other side.

A downside of using the fatter tyre is that to take the wheel out now means that I have to remove the final drive as well, but this is more than compensated for by the increased tyre life.

I’ve already checked the tyre against the rear mudguard and there is clearance, but not much so a future project will be to make up a wider guard.

UPDATE

I’ve just refitted the mudguard to measure up to find that the problem was not that I had not moved it far enough over the first time, the top of the guard was centred on the tyre.

The problem was that I had not moved the bottom front mount over as well, the front of the guard was still on the original mounting so the guard was twisted!.

All that was needed was to reposition the front mount and the job was done!.

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