Rear Diff questions.. Swap info.

[Markus Johnson]

I have a 3 bolt open auto rear diff and a 4 bolt LSD 5 spd rear diff. Is it possible to combine them to = a 4 bolt auto rear?

[Jason Swan]

my first thought is different gears ... so iffy.  very iffy.

[Marke Bailey]

no. the gear ratio's are different and using the wrong one will burn up the viscous coupler or transfer case. use the one intended for your drivetrain. If you need a 4 bolt auto rear, I can sell you one.

[Markus Johnson]

I figured it was a long shot, I was hoping there was some way to change the internals over from the lsd 4bolt while maintaining the auto rear ratios.

[Phil Maki]

i'm betting you'd be able to swap the auto ring and pinion over to the 4 bolt diff.

[Marke Bailey]

i'm betting you'd be able to swap the auto ring and pinion over to the 4 bolt diff.

I started to wonder that myself after I posted.

In truth the 3/4 bolt thing has nothing to do with the diff. Its the axles-trailing arms that you are concerned about. If you can swap the ring and pinion from the open auto to the LSD then you would have a 3 bolt auto LSD.

I have everything you need for sale, If you want to go 4 bolt. why not just sell what you have and buy the correct unit? $250 for auto LSD diff, axles, and sub frame!

[John Hartman]

buy Markes.

Doing a ring and pinion swap is tricky as you have to set a couple of critical clearances.  If you frig it up, its gonna be noisy at best, and possibly you will break it.

And its not just like a torque spec, its more of an art kinda thing.  I've done a few, and a couple at school, and I still feel super leary when I have to do them.  I've seen experienced guys have whiny diffs after rebuilds.