The first of the GL1000s (1975 and some in 1976) suffered from a wear problem of the sliding spline joint or coupling at the final drive and propellor shaft. There was no external means of greasing this joint and, unless the owner was concientious enough to take off the final drive and re-grease the splines occasionally, this meant severe wear would occurr with occassional total failure!.
Here area couple of pictures to illustrate what can happen.
Note the complete lack of any lubricant and the wear on both sets of splines. This drive would have failed completely in fairly short order had the owner not investigated a 'clunking noise' coming from the drive line.
At first thought to be the universal joint failing ( common on the early 1000s), when he pulled off the final drive it revealed this horror.
As you can see from the last pic, no way of getting grease to the joint. Honda reacted quickly to rectify this by providing a grease zerk / nipple on the end of the swing arm directed at the joint, and a large grease seal to stop the grease migrating away from the joint into the swing arm.
Early arm on the left, later one in the two right pictures. Old style swing arm could be changed for a later one, but the modification is relatively simple.
The only problem could be the aquisition of the seal 91267-371-003. Discontinued by Honda, they are sometimes very difficult to find, but NOS turns up fairly regularly at vintage part dealers.
Here you can see the way the grease seal fits aroung the coupling, keeping the grease in and preventing it from disappearing into the swing arm. If you are doing this mod and having difficulty finding one, contact me as I have a wide range of dealers all over the world to call on and sometimes have these in stock myself.
Although you will see advice on different forums that says any grease will do the job (and certainly any grease is far better than none!), this is an area of very high sliding pressure for which Honda specify a 60% Molybdenum Disulphide (MoS2) grease.
I have not found a source of grease with this high a molybdenum content other than Honda's own.
more to come on drilling and fitting the zerk when I have time