Gearbox Identification and which oil?

[arceye]

Hi chaps,

Just fitted a replacement gearbox and a new clutch on a Morris Minor 1098 traveller for a chap I do a few bits for.

He supplied the gearbox which is a rib cased type that looks identical to the Minors and fitted without problems. I notice however that this box has a reverse light switch fitted which I don't think any Minor boxes had,

So, is it more likely a Midget / Spridget box, and if so what oil should it run? Currently have it filled with 20/50 engine oil, it works ok but is quite whiny in all but fourth. Probably a bit worn as it was an unknown quantity and had apparently been laid around for a few years.

Just wondered if perhaps it should / could run a different oil.

Cheers

[JPB]

20w50 engine oil is correct, only A-series RWD car that runs gear oil in its gearbox is the 1300cc Marina with its Triumph gearbox.

[arceye]

Cheers John,

Much appreciated

[Wicksy]

Hi arceye, my last MGB was a bit noisy just like you describe and engine oil is the recomended brew for the box. I put 80 HP in and it quietened it right down but the downside was that it made the change a bit stiffer when cold - no difference when warmed up or in the summer (That is for about a week)

[JPB]

Hi arceye, my last MGB was a bit noisy just like you describe and engine oil is the recomended brew for the box. I put 80 HP in and it quietened it right down but the downside was that it made the change a bit stiffer when cold - no difference when warmed up or in the summer (That is for about a week)

It's the EP additive that renders gear oil unsuitable for these boxes, not the viscosity, so if anyone should decide to experiment with 80 weight (or 140 weight in the case of the almost terminally sloppy ribbed case gearbox in a certain MK2 A40 Farina ) in a gearbox designed to run on engine oil, please don't use one with the extreme pressure additive as that can attack yellow metals, particularly the phosphor bronze used in Oillite bushes which, being absorbent, will suffer like a brick that's split through lime present having absorbed water. This is also why trunnions must be lubricated with straight, non-EP oil (or a suitably liquide grease but this isn't intended to kick off that particular debate again ).

The above is probably a side effect of my office being too close to the tribology department at work, nice people but they only know about tribology, maybe this is why they're all single and childless?