4 speed gearbox capacity

[hdkeno]

I want to change the tranny lube on my 81,which is a 4 speed gearbox.

Anyone know the fluid capacity? Also should I go with the 80-90 or straight 90 weight stuff.

As always thanks for the help. Ken

 

[craig32]

Hey Ken,
You apparently asked the 'magical question'! I looked in the manual and it appears to be a typo. . .it says U.S. measure, 3L - 3 pts. impereal measure 2 1/2 pts. 3L is more like 3 QUARTS not pints! Not sure about the viscosity question, as all my cars are 'slush boxes' I think climate would determine that, in the northeast the lighter weight in cooler weather might be better. If you lived in the south, the heavy weight gear oil would make more sense. Hope this helps!
Craig

 

[srs244]

the capacity isn't as much as you would think it would be. 3 pints or so sounds about right. just don't be fooled and think the plug ON TOP of the gearbox is the fill plug. it should be located on the side of the case. if you make a mistake and fill it from the top, you will wind up with way too much gear oil in the case and you will only have to find the side case plug and drain it to that level anyway, lol.

 

[John Ulrich]

I've used Mobil 1 75-90 gear lube in mine for years. Also use it in my motorcycle transmissions and rear ends.
JU