I'm not very well up on bronzes or other non-ferrous metals come to that but I need to make a bush for the lay shaft in the Sturmey Archer gearbox for the Model A.
This bush lives inside the kickstart shaft and is grease lubricated. Can somebody help me with a recommendation for a suitable bronze?
Here's the shaft as it is currently - there's quite a bit of milling to do next!
Here's the one I'm copying. It's about 2" too long and the kickstart lever orientation is all wrong - it's for a horizontal box.
simon.holyfield wrote: Fri Feb 20, 2026 10:31 pmThis bush lives inside the kickstart shaft and is grease lubricated. Can somebody help me with a recommendation for a suitable bronze
For what it's worth, I used 544 (also known as C54400) phosphor bronze for the three bushes in the grease-lubricated Burman gearbox in my 1928 Ariel. Depending on temper, its tensile strength is in the range 50–60 ksi. However, "common" SAE 660 (923, or C93200) leaded tin bronze is a bit easier to machine, and I expect it would be fine for your bushes despite its slightly lower 35 ksi. I used 660 for the camshaft bushes and they showed no measurable wear or elongation after ~3500 miles.
What size do you need Simon ? I might have a bit of Aluminium bronze in the draw. Good wear resistance, normally used in harsh environments & grease lubricated. Great to machine, with very little cold welding on the cutting tool.
As an aside, when I rebuilt my 1928 Ariel (documented in my book 'The Ariel Chronicles') I added copies to my bespoke shop manual of the specifications of ever material I used. These ranged from various bronzes, steels, cast iron, Stellite, etc., to oils, greases, Hondabond, Loctite, etc. Having researched the materials at the time before I used them, this tabbed section of my shop manual subsequently saved considerable time when I've worked on my other motorcycles and needed materials for various purposes that I knew had performed well.
Bernie Blundell wrote: Sat Feb 21, 2026 4:02 pm
What size do you need Simon ? I might have a bit of Aluminium bronze in the draw. Good wear resistance, normally used in harsh environments & grease lubricated. Great to machine, with very little cold welding on the cutting tool.
I'm not certain to be honest. I have the grandkids right now so a visit to the workshop is a bit tricky!
I'd guess 1" OD x 1 1/2" at the most. The bore of the bush will be about 1/2" when it's all assembled and bored.
For what it's worth, Al-bronze wouldn't be my first choice for this purpose. Although it has better specifications than SAE 660 for high loads, high speeds, and high temperatures, none of those conditions will found in your gearbox. Despite its specifications, arguing against it are the fact it is much more likely to seize if there ever is inadequate lubrication, and it is more difficult to machine than 660. I would be especially concerned with proper lubrication throughout the bush in a gearbox that uses relatively high viscosity grease rather than oil.
Yes it's as tough as old boots to work with and get a good finish. I guess it depends on the Particular alloy . I used it on a marine drive shaft once.The Best alloy with copper is TIN making it a bronze . Phosphor Bronze is a good bearing metal. You don't want it too soft or it won't hold a Press fit. I've stuck to the Oilite porous Bearings like the originals and they are Flange Pinned and won't spin. With an oil filled gearbox and good seals, you can try something else. Having flanges precludes steel backed Copper lead which is the best High load material. Used in diesel small end bushes. I haven't had any luck with the extruded Bronzes (bar or Hollow Bar). I prefer the sand cast products to a specification. Brass is a complete no no. Copper-zinc. Duralumen works in Oil. Not affected by SCL gear oils. By the way Auto engine oils haven't met gearbox requirements since the Middle 70s as the required additives wreck the Catalytic Converters of road vehicles. Nev
Here's the bush I'll be replicating. It's held by an interference fit in the kickstart shaft, and the layshaft runs in it. I'll measure up when I get to the workshop.
