401 gearbox

RALPH M · #1 (**permalink**) 11-03-20, 09:00 AM

Refitting my 401 gearbox this week at long last. It is the early type and what is the advice regarding oil grade and type of oil? I also have a Laycock overdrive so again any advice on best oil choice?

RALPH M · #2 (**permalink**) 12-03-20, 08:40 PM

Well a bit disappointed at not receiving any views on oil grades so have done my own research and will be using Castro’s XXL which is straight40 grade in the gearbox and overdrive which shares the same oil anyway. I managed to get the box back in today with the help of my son in law and tomorrow will be bolting everything together. Looking forward to synchronised gear changes and smooth take offs. We shall see.

Geoff Kingston · #3 (**permalink**) 16-03-20, 03:10 PM

The 405 handbook suggests a an SAE30 for the gearbox and overdrive, I asked Brian at BCL what was best for my non overdrive box in the 401 and he suggested the same 20/50 oil we are using in the engine.
Castrol XXL is one of the oils recommended for the gearbox in the late 401's and 403's so I would have thought should be ok.

RALPH M · #4 (**permalink**) 12-04-20, 11:04 AM

Now I am grounded like us all, I am attending to several tidying up jobs on the Bristol as sick of gardening! I did take the 401 for a brief test drive before lock down with Castrol XXL 40 in the gearbox and overdrive and was very pleased that all the synchro worked and the gears shifted nicely. The change was a bit notchy so I have since slackened off the detent springs slightly but otherwise very pleased. The clutch is also now super smooth so clearly the minute skimming of the flywheel was just what was needed. Such a shame we are missing this weather but we fully support the stay home policy.