Since I pulled the rear drum wheel it made sense to take a peak at the rear axle. As I expected since the frame is 3/4″ wider than all MK models from 1962 to present the rear axle is also 3/4″ wider. So that makes it 10″ long by 5/8″ in diameter.
The axle came out real easy despite the rust. The spacer on the left is what retains the rear brake drum dust cover in place against the frame fork. I was surprised to see R10-2RS bearings instead of the wider 1623-2RS bearings used in MK1, MK2 and MK3 15″ drumwheel bikes. It was bent by about 1/16″ right where it came out of the bearing on the brake drum side. I used a 2 ton arbor press to straighten it. I did not have to lay into the press very much so I suspect this longer unsupported axle is a weak spot. If it bends again I will look into upgrading to 3/4″ axles. I put cheap wheel barrow grade bearings and a 3/4″ axle in my good MK1 4 years ago and they are still holding up quite well.
The rust cleaned up on my ScotchBrite wheel. The original R10 bearings were good enough to re use but I stuck in new R10s that are about 1/3rd times as loose. The bolts are 3/8-24 UNF and drilled for safety wire although none was used. Both of my MK1s have all 4 axle bolts drilled for safety wire. The chain tension spacers are identical to all models up to present. There is no spacer to keep the drum from rubbing the frame on the non brake drum side. No doubt this is part of the reason why the bike squeaks so much. I will have to take a good look at this as it goes back together. I am thinking a 1/32″ thick spacer is a good idea.