Time for our favourite game… ‘what’s this noise?’

[hysteric]

My experience with the three rail gearbox in normal use (that doesn't include use in a racing car) is that any wear in the gearbox casing apertures where the layshaft slides in is not significant enough to cause any issues. I've never seen one worn to the extent where the layshaft rattles around in the casing bores. If the clearance was such that the layshaft was rattling around in the casing bore it would become worse very rapidly - imagine a hammer bashing around inside the bore because that's the effect. Any gear miss alignment resulting from this would also be detectable through increased gear whine noise from the gearbox in the intermediate gears.

This really is one of those situations where it is very difficult to do a remote diagnosis. These gearboxes are generally very reliable. Most of the issues are caused by people not assembling them correctly.

Hi mate, yes this is exactly what a local gearbox specialist said after taking a look for himself. Following that sanity check on the gearbox I started working from the exhaust back up to the engine tightening and nipping up everything I could see.

This has really helped with the noise which has significantly reduced. The problem now is that I’m into the root cause analysis rabbit hole and will probably get the timing chain sorted next just to safe.

Maybe some festive tinkering!