I have a 1980 900SD Darmah which still has a few minor niggles to iron out. However, one may not be too minor at all. There is a noticeable whine from 5th gear - especially on the over-run. All of the other gears seem quiet enough - at least I can't hear anything above the roar of the Conti pattern 'silencers', but in 5th I can definitely hear a pronounced whine. It sound like a bearing wearing out but, looking at the diagram of the gearbox, I can't see why it would only affect 5th gear and not the others on the same shaft which share a bearing. Anybody have any experience of anything like this?
Only one gear pinion is on the sleeve, which the sprocket attaches to. The other four gear pinions are on the mainshaft.
I think I can see what you mean. Are you saying the likely suspects are the two sets of needle rollers at either end of the sleeve? Or is it just that 5th is noisy due to that design?
Fifth gear is different from the others, although you would normally expect it to be less noisy since power is not passing via the layshaft gears.
