Hi all,

I am looking to change the gears in 489 carrier from 3:91's to 3:55's besides the gears, what else do I need?


thanks!
Mike

someone who knows what they are doing. crush sleeve eliminator. ring gear gasket. gear lube. a nice chunk of hundreds for the bill. Are you sure you want to go thru that for just a slightly taller gear? you might be able to find a set of 3:55's then sell or stash the 3:91's or a taller tire might be an option. at least I would do the math on paper for the RPM change.

thanks Robert

Don't tear down 391's, stash or sell and build another housing up. It's like burning money.

Changing gears isn't that hard if you spend a few dollars on tools. Ratech makes a really nice tool for setting pinion depth that is around $25. They also have solid spacers to eliminate the crush sleeve. Dr. Diff has some nice installation kits too.

I too vote for leaving the 3.91 together. There's enough open center sections floating around to get one cheap and put your new gears/SG unit in.

They usually sell a gear instalation kit which should come with all you need like pinion and carrier bearings and the oil seal and so on. Ron

Leave the 3.91 intact. Use the opportunity to source a 3.55 pig with trak lock (clutch type) sure grip.

The install kit is definitely the way to go. You'll just need to know if you have the large carrier bearings or the small ones.

Lots of videos on-line on how to do the swap. Best to have an experienced tech do the job, but you can pull it off if you just take your time.

Yes, it is not really hard if you have the right tools, but it is tedious.

I sand the ID of the pinion bearings so they slip on and off. Makes setting the shim pack a ton easier.