I've always wondered about the following warning issued in Haynes:

Depress clutch at speeds above 2000 rpm. If this precautionary measure is not taken, the synchromesh of the gearbox may be damaged.

WHY is the damage possible and HOW are the synchros damaged?

by being overloaded trying to match the gear speeds, without pressing the clutch the syncro is trying to slow down or speed up the engine by friction.

I've seen that warning written prior testing the centrifugal advance.

you got the engine at idle, then you just have to check the advance at certain speeds, up to 4200 rpm.

I really don't see what is breaking if you don't try to engage any gear...

we all revved the engine in neutral many times without depressing the clutch and without damaging the 'sensible' synchros up to the point of shifting hard in gear...

ahh i see you mean in neutral then yes?

ok the problem there is that the oil is pumped through the centre of the main shaft by the turning action of the diff. so lots of rpms in neutral means that the gears are all spinning on the mainshaft but have no oil apart from a bit of splashfeed.

the gears can (and i have seen it myself) seize to the shaft but the syncro's shouldn't be effected as they are not in contact while in neutral

I see... thank you.

so we can add this warning about synchros in neutral to the long list of Haynes crap.

see for yourself. the handbrake overkill warning blew my mind

why not dynamometer type harnesses too? jeez...

Edited 14 June, 201214 yr by masster