Any thoughts on this gearbox fault

[Partyvan]

Hi all

On my E46 M3 manual, 2nd and 4th gear are sometimes difficult to select. When the car was SMG, it sometimes skipped these gears or crunched going into fourth. Now it's manual converted, they are difficult to physically select.

I'm also getting a sound coming from the gearbox area when in those gears. It's best described as the sound you'd get from putting the tip of a stick against spinning bike wheel spokes. Like a fast tinkling sound.

It's not particularly loud and only happens under acceleration load.

Any thoughts on the most likely culprit? To be honest I'm fairly resigned to the fact the gearbox has to come off.

Thanks

[GreenV8S]

I'm not familiar with that gearbox but on a typical H pattern manual box those gears wouldn't be on a common selector. However, they would both be at the same side of the 'H'. Are you sure you're getting full travel on the linkage without any preload on the selector when it is in gear?

[Partyvan]

I'm confident the linkage is good, as all gears select perfectly when the engine is off.

[dhutch]

Presumably when converted to manual it's a whole new box, so any issues with the SMG are unrelated?

Six speed box or five speed?

Daniel

[Partyvan]

dhutch said:

Presumably when converted to manual it's a whole new box, so any issues with the SMG are unrelated?

Six speed box or five speed?

Daniel

It's the same box, just converted to manual without the box being removed.

[Partyvan]

dhutch said:

Six speed boxl

6 speed. Was originally SMG, it's now a manual (same box)

[GreenV8S]

Partyvan said:

I'm confident the linkage is good, as all gears select perfectly when the engine is off.

And presumably the funny noises stop too. That doesn't prove the linkage is okay.

[Partyvan]

The linkage is brand new and there's no adjustment to it, it's just a short piece of bar with a nylon bush. I'm confident it's okay.

[GreenV8S]

Could the sound be coming from part of the external mechanism hitting resonance rather than the 'box internals?

[Partyvan]

GreenV8S said:

Could the sound be coming from part of the external mechanism hitting resonance rather than the 'box internals?

That's what I'm hoping!

[Partyvan]

I'm going to try an oil change with Royal Purple (the best, apparently!)

[PositronicRay]

While you're at it check the flex discs, carefully.