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July 18 2024 [New Zealand] 
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Technical documents

Manx Front Forks - Featherbed 1951-1955

Author: Ken McIntosh

With the introduction of the long-stroke featherbed Manx at the 1951 IOM TT, the first version of the short' Roadholder fork was produced.

Although these had the same design alloy slider as the earlier fork, the stanchions were considerably shorter, and the yokes and internals were of a completely new type.

The internal dampers are shorter versions of the 1950 garden gate all alloy type.

The yokes were equal offset top and bottom, and have a smaller 13/16" diameter stem.

The bearings were originally angular contact ball thrust races, but are often replaced with taper roller bearings. The stem adjuster is unusual in that the bearing sits on the adjuster nut, not directly on the stem. This can cause problem if the thread is worn in this spot, causing what feels like loose head bearings.

These early yokes are almost the same as the early road model featherbed type, which were all 7" centres up to 1964. The bottom yoke on all road featherbed, and 1951-1957 Manxes, curve downwards. The 1957-1963 Manx lower yoke is straight, when viewed from the front.

The early featherbed top yoke is flat' in that the top boss faces are all level. They have two extra holes, which in the early road models are for rubber mounted handlebar mounts and in Manxes are often smaller diameter and serve no purpose

These type forks, with internal springs, have slightly less travel than the later, external spring Manx forks, but the ride height is almost the same. Their full extension is controlled by the damper, and provided the correct single-rate springs are fitted, they will work well. If the spring has too much pre-load, the forks will top out'

The oil quantity is 150ml of SAE 20.Hot or cold weather may require SAE15 or SAE 25 oil.

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