When I got the bike, there was something wrong with the forks, in that they made a rather wierd hissing noise when depressed and seemed very notchy.
Looking at the fork components on the bench:
– the are 35mm diameter forks, not 38mm like some of the Jumbo’s
– there seemed to a lot less componentns than there should be
– the forks are in fact different.
Looking at the right hand fork (RH side in the picture), the bottom bush is not metal, but nylon and the bottom of the fork tube has been hammered over to hold it in place. A quick call to Martin Matthews confirmed that this is a little non-standard. The Nylon bush is an 16mm diameter hole for the bottom rod to pass though, which is a little tight. A dry-run assembly of the fork shows whilst the fork seems to have worked in the past, it now can’t be loaded.
The RH fork has some heavy corrossion around the area of the clamps, so replacing the tube with the bottom bush is a possibility.
The hissing noise is caused by the fork tops having their venting system not in place. Inside each top, there is a ball-bearing/spring arrangement to allow over air to escape if their is too much pressue. This is not in place.
Fitted to the new seals to the the fork bottoms, which were rubber backed unlike the original metal caged seals. These are 35mm inner diameter, 47mm outer and 10mm depth, double lipped.