Front fork 1 1/4 G3LS bearing solution

[rudelan_LAPSED]

Hello, is there a closed bearing or something else to replace part 012620 (race ball)
on the 1955 G3LS heavyweight front fork?

[ajscomboman]

There used to be but not anymore as the manufacturers have retired. Now the club stock the new taper roller bearing similar to the original set-up.

[rudelan_LAPSED]

I looked through the list, but I can't find...

[ajscomboman]

Sorry stupid me I was thinking of a completely different part. No there is no off the shelf replacement, some owners have carried out a taper roller conversion but it's not straight forward and personally I don't see the reason for swapping the original set up.

[rudelan_LAPSED]

Ok, well, thanks anyway for taking the time to answer me.

[mdt-son]

No there is no off the shelf replacement, some owners have carried out a taper roller conversion but it's not straight forward and personally I don't see the reason for swapping the original set up.

A taper roller conversion is not required. Suitable angular bearings are smaller and will require less modifications, in addition they mimic the orignal design. There are good reasons to perform a headstock race modification:

* The design of #012620 features an outer spherical seat, which is convenient for manufacturing ("self-aligning"), but a bugger design for sure-footed driving characteristics, especially for heavyweight twins, as the bearing seat will slop around in the headstock. This affects roadster frames up to 1963.
* Fixing the oem races by a termoset resin may work for a short time. I doubt it's a viable long-term solution.
viewtopic.php?f=17&t=20823&hilit=fork+bearing
* Headstocks were not well designed (or had casting flaws in some instances), providing bearing foundations of ridiculus low stiffness, aggrevating the first point.
* Races are not particularly hard, which means balls will create indents within a short time if bike is ridden hard, compromising the design.
* Using loose bearing races, one in the handlebar lug and one in the frame, means the bearing is very vulnerable to moisture and thus rapid wear. A recessed bearing is easier to protect.

* I have a faint recollection the factory made some heavy duty races. Can someone fill in?
* As I have no bearing set in front of me, can someone measure these bearings, please? I tried searching for information and I am sure someone has measured them. ID, OD, and thickness including balls would be great info.

At this time (March 2022) the races 000805 & 000806 are not available with AMOC Spares; new stock is is expected soon according to them.

- Knut