B400 - gear box oil - modern equivalent

[Geoff Dowdle]

Bela ,
Do you know the history of this gearbox .
Was the gear lever and top of case changed at one time . What lever is fitted?
What is the gear box number stamped on the right hand side of the case?

I had a similar problem with a gearbox that had a remote shift top fitted to
a long lever box . On the bench it changed perfectly but after use when the box reached operating temperature I had trouble moving the gear lever .
The three piece gear case during manufacture has the three selector rod holes either line bored or reamed to give a perfect fit for the selector rods.
Changing the top will mean that they are unlikely to be in alignment .

A change of grade of oil will not fix the problem .
For non overdrive boxes I use a 10W/30 mineral oil (SAE30 was recommended originally) .
I have used a thicker oil 20W/60 in the past and found the syncros slow until the box and oil warmed to operating temperature.
I'm not sure of the recommended oil for your overdrive. Get advice from the person you bought the overdrive from .

Geoff