my wagon is 3.900 final drive ratio. whats different between 3.700 or so?

my wagon is 3.900 final drive ratio. whats different between 3.700 or so?

 

The ring and pinion gears.

 

If you have a 3.7 ratio LSD you can pull the centre out of this, remove the ring gear. Then get your 3.9 ratio diff and pull the centre out of the diff. Remove the 39 tooth ring gear and bolt it back onto the LSD centre, replace in the same casing it came from - no need to worry about back lash etc.

 

Seal and top up with LSD gear oil, replace in the back of your subi and you're good to go.

 

Another thing that is good to do is place several washers on each spring of the LSD to increase the amount of pressure on the clutch packs if it's one of the older (and some say better) units. If it's viscous just drop it straight in

 

Cheers

 

Bennie