diff answers for dummy please

[IFC.58]

hey all
i have a fc wagon

i want lower the revs on the highway
its all standard
now i have done some seaching and heres what i found
the fc diff  has 3.888 to 1
the eh diff has 3.36 to 1
the widths of both diffs are the same
now

can i put the eh centre into the fc housing
or
do i have to put the whole diff in

thankyou for you info in advance
terry

[I958GM]

Pretty sure you have to change the diff housing as well? Could be wrong but l dont think so.

[IFC.58]

cool man
seems to be the same answer from every where i have checked

thanks has anybody else tryed this
or know for sure

[customFC]

Hey Terry.
You only have to change the center and the rear uni.
A 3.55 ratio is also available and might be a better compromise.
Regards
Alex

[FB_MAD]

Yep, Alex is right, change the rear uni joint to a red motor uni joint ( around $30 or so, and easy to fit to the tailshaft ) and the 3.36 centre bolts straight into the FC diff housing.Axles will fit as well but make sure you only get a course spline diff centre as the fine spline centres that came out in HX Holdens ?? won't fit as is.

3.08 and 2.78 diff cenres had two longer bolts which makes them a bit different to the other ratios.To fit these ratios you also need these two longer bolts but they would probably be too tall for a grey motor to handle if thats what you are running in your car.

Only other thing you will need is the red motor uni joint "U" bolts to fit the rear uni to the pinion flange.

Cheers,

Another Terry.