Manx Front Forks - Featherbed 1956-1963
|Author: Ken McIntosh
Because these forks are unique to late model Manxes, and very few components are the same as the road or earlier Manx, this often cause many questions.
The alloy sliders are the same design as previous and were originally forged. All the other components are new.
The most obvious is the use of outside springs. These are multi-rate, unlike the earlier, inside type, which were constant rate.
The purpose was to give a softer ride. I have found the standard springs to be much too soft for a rider of 80-90 kg, and bottoming under braking being far too common. I can supply a higher rate spring to fix this problem.
Because the ride height was not changed, multi rate springs need more pre-load. In order to do this the fork travel was increased to avoid topping-out.
This was achieved by increasing the damper travel to match all the available slider travel and the maximum movement is limited only by the bushes touching on full extension.
The result is that although the forks have more total travel, the ride height is much the same and the extra travel is only really more extension.
Because the old type bottom yoke curved downward, the space for the springs was limited, so a special, 'Manx only'straight bottom yoke was made. Although this grips the stanchion higher up, this causes no problems.
The lower, chrome covers, are recessed to support the springs.
The top yoke was also offset downwards (often referred to as a 'dropped top yoke'), and the bearing adjuster and the top nut made thinner. The purpose was to get a better view across the top of the forks, when the rider is 'getting down to it'
The fork stanchions are shorter than the earlier model, and the large and small damping holes drilled across the bottom of the stanchion are replaced with two smaller holes.
The dampers are now steel bodied, with alloy rods, and will not take the inside fork springs. The top cap has a hexagon, instead of two flats.
Because the springs are outside, the fork oil quantity is increased to 200ml of SAE20.
I have found that these forks work very well, and that any major problems with their performance is normally a mechanical fault. Although they appear quite crude in the design, the subtlety of the features often escapes the notice of mechanics.