The nice thing about the 50 year old bike is that there is loads of aluminium to polish. I love aluminium, probably due to a life spent repairing aircraft made from the stuff. But aluminium has its place and that is not everywhere.
The 31mm fork tubes on the bike are made of steel, as one would expect, as they need to be strong. The top yoke is made of an aluminium alloy casting and that is also strong enough for the forces involved on that item. But the plugs that attach the two parts together are also aluminium and they have a screw thread that screws into the steel fork tops, never a good idea. This is where they are fitted. In this picture the one on the right is the new one, more later.
These pictures show the problems with aluminium alloy fork plugs.
As can be seen, the 12mm allen key holes have been damaged by a previous owner who probably needed to take them out but did not possess a 12mm allen key, but even worse the threads have been ripped off the alloy by the steel threads of the forks. I have no idea if this is due to over tightening or just wear and tear over the last 50 years. The reason that the top four threads are not damaged is that these do not screw into the fork tubes, but sit inside the top yokes.
The answer is a set of steel plugs. This arrived today in the post:
On opening I found this.
Which was kind of amusing. The manufacturer of these stainless steel fork plugs obviously has a fantastic quality control system which involves the local medical laboratory or he has reused a box, made me laugh anyway.
The packaging was superb!
This is the old and the new on my desk with the correct removal tool above them. This picture illustrates the lack of thread left on the old one. If you now go back to the first picture you will see that a new stainless steel one is fitted to the right hand side and the old alloy one on the left. They are both steel now.
The threads on the new ones were slightly rough on the skin, nothing to worry about, but being a perfectionist, I rubbed them over with some 4,000 grade micromesh just to polish the edges slightly before a quick wash off with degreasant, refitting of the o-ring and fitting to the bike. This procedure was overkill as they can be used out of the box.
The new plugs were bought over the internet from www.eurojamb.com and I will let you browse their website to find the price, but be assured that for the quality they are well worth that price. Joe at eurojamb is also a star, he is quite willing to answer emails promptly, even ones from people like me who try to avoid ordering anything from the US. Thanks Joe.