Diff Centre Ratio

[FCman]

G/day all.
I am looking to improve driveability of my FC on the highway (lowering the revs) can someone recommend the best diff ratio.Also will it match up to my current standard diff housing and axles?

FCman

[freddyc]

Gday FCman I just put 3.55 into my FC on saturday, works well. I think 3.36s, would be better. Dont make the same mistake as me, check the splines first, before you install. You will have to get new universal bolts too ?. $7.00 from holden.   

[Sheriff]

Am having a 3.55 put into my car tomorrow, to lower the cruising revs.    I believed that you had to change the universal, not just the bolts.     If its only the bolts it will save me some dough, as I have asked the workshop to get a new uni from a red motor model Holden to replace my old one.      Mike.

[FB_MAD]

  You have to change the rear grey motor uni joint for a red motor uni joint and also use the red motor uni joint "U" bolts when installing a red motor diff centre into grey axle housing.

 Original axles will fit the red motor centre provided they are course spline axles.


Fine spline axles came out around HX Holden ??  or so and they won't fit.

No other mods are required unless it's a 3.08 or 2.78 centre which use two longer bolts.

[freddyc]

sheriff, 3.55 did not lower my revs that much, i am running standard everything. About 10% lower ?

[Sheriff]

Freddy,  I have 185/70 radials on my car which I think are a smaller diameter than the 6.40x13 originals which add to my revs.   Mike.