Whiny CP gearbox

[Pete.Silson]

When under load 2nd gear in my CP gearbox has become embarrassingly whiny (to the extent that a rider behind me commented on it). On disassembly I found the 2nd gear cog to be very slack on the lay-shaft...

2nd Gear Layshaft Bush 1a.mp4

(1001.08 KiB) Downloaded 4 times

...and the teeth on the lay-shaft cog and on the main-shaft sliding gear badly worn.

Clearly I need to replace the bronze bushes on the layshaft, the layshaft 2nd gear and main shaft sliding gear but can anybody suggest a cause of this type of wear i.e. did worn bronze bushes cause the tooth damage or did something damage the teeth that caused the wear on the bronze bushes.

The first gear is worn similarly albeit not so severely but the 3rd gear and output gears appear fine.

Any thoughts welcome. Pete

[Roger Gwynn]

The wear on the teeth will cause the whine, I like it, my VA whines in 3rd. I have no idea why it would affect some gears and not others apart from some gears may be worked harder than others, usually 3rd as it will usually see more use and is held longer than 1st and 2nd. It doesn't look like damage from a foreign object but from wear.

[Pete.Silson]

The wear on the teeth will cause the whine, I like it, my VA whines in 3rd.

Roger,

I wouldn't normally worry about a bit of a whine from a 75 year gearbox but this one has got past that stage. When crawling up a gravelly 1-in-5 windy back lane I would describe the sound more like wailing Banshee than a gentle whine.

Since it is mostly 2nd, and to a lesser degree 1st, gear that is noisy, I was wondering if the worn bushes allowed the layshaft gears to wobble and increase the wear on the teeth. Either way I think I need to quieten it down a bit.

Today I made some new layshaft bushes and will now go on the hunt for some less worn cogs.

Pete

[will_curry]

The banshee wail from my 1929 Q box - silent in top - was the sleeve gear bush.

Presumably replaced at some stage with something inappropriate it was dry as a bone
at the clutch end with bits of bearing dust all over the final drive sprocket.

A new sleeve bearing from the club and much spanner-work to fit it quietened things down.

Both the gears pictured above are far from happy and are the worst I've seen from
a Burman 'box. The gear in the first picture looks like those I often see from BSA
'boxes where the case hardening is breaking up and flaking off.

[nevhunter]

They are worn out. Any deformation of the tooth profile will make Noise. Worn bushes affect the Meshing and increase WEAR. Use the best Lubricant you can and keep the Level correct. A noisy gearbox takes the fun out of it. TOP is not using any of the gears and should never make any noises as no gears are loaded. Nev