How to replace rear differential

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06/10/2009, 01:30 PM
LittleBeast

How to replace rear differential

This is how I replaced my stock 4.30 rear differential with the new 4.78 gears:

1st you must drain as much of the diff fluid you can out of the drain plug, then jack up the rear end and support with multiple jack stands for safety, always have backups, never trust one thing to hold the weight of the VX, I always engage the 4xlow and make sure the VX is in park and make sure front tires cannot move:
http://www.vehicross.info/gallery/data/515/110.JPG

Then afte you have removed the wheels, you will remove the 2 bolts holding the brake caliper in place and then remove the 4 bolts holding the axle housings in place:
http://www.vehicross.info/gallery/data/515/28.JPG

http://www.vehicross.info/gallery/data/515/315.JPG

Then remove the ABS sensor:
http://www.vehicross.info/gallery/data/515/45.JPG

http://www.vehicross.info/gallery/data/515/54.JPG

Then remove the emergency brake bracket:
http://www.vehicross.info/gallery/data/500/61.JPG

Then pull out the axle half:
http://www.vehicross.info/gallery/data/500/72.JPG

Then remove the 4 bolts connecting the driveline to the 3rd member:
http://www.vehicross.info/gallery/data/500/8.JPG

http://www.vehicross.info/gallery/data/500/91.JPG

Then remove all 10 bolts holding the rear 3rd member in place:
http://www.vehicross.info/gallery/data/500/108.JPG

http://www.vehicross.info/gallery/data/515/111.JPG

http://www.vehicross.info/gallery/data/515/123.JPG

I had the stock Limited Slip unit taken out of this stock 4.30 gears and put into the new 4.78 gears:
http://www.vehicross.info/gallery/data/515/131.JPG

http://www.vehicross.info/gallery/data/515/141.JPG

This is after I had Houston Ring and Pinion professionally set-up the new 4.78 gears with the stock LSD:
http://www.vehicross.info/gallery/data/515/151.JPG

Then you need to use some RTV black silicone gasket maker to form a continual bead of silicone sealer around the edge of the new diff going back in:
http://www.vehicross.info/gallery/data/515/161.JPG

Then you might need to use a jack to raise the new diff up into place and tighten bolts, I did not use a jack but it was pretty heavy, make sure to not over tighten bolts or all the sealer will be pressed out:
http://www.vehicross.info/gallery/data/515/172.JPG

http://www.vehicross.info/gallery/data/515/181.JPG

While I had the brake rotors removed I repainted the old rusted out center with some silver brake caliper metal paint, this is definitely optional:
http://www.vehicross.info/gallery/data/515/192.JPG

http://www.vehicross.info/gallery/data/515/201.JPG

After this you just put everything back together the same way you took it off. Reconnect the driveline to the 4 bolt flange on the new 3rd member. Then slide axles back in and tighten the 4 bolts that hold them in place. Then reinstall the brake rotor and caliper using the 2 bolts you removed. Then replace the emergency brake bracket and then ABS sensor. Then make sure everything is tight, put the wheels back on lower it down to the ground and fill it back up with fluid (NOTE: normally the RTV silicone gasket sealer calls for at least a full 24 hours to dry before filling back up, but absolutely do not forget to fill diff back up). I would use cheap normal gear oil at first ($10 a gallon) and then once you have confirmed you have no leaks you can drain the normal stuff and put in some synthetic stuff ($10 a quart). Rear end should hold just over 2 quarts. Hope this helps.
06/10/2009, 01:45 PM
Marlin

So how much of a difference have you noticed in acceleration?

Awesome write up by the way...how long did it take ya? With pics and info like this, it makes it seem like something I could do, if I ever go bigger than 33s.
06/10/2009, 02:04 PM
Triathlete

Yep, the back is the easy one...have fun with the front!:bwgy:
That is the nive thing about the Zu 12 bolt, 9 inchers, and Toy axles. You can just remove and replace the third members.:thumbup:

Marlin...the 478's are ideal for 33ish tires on the VX. And unfortunately are about your only option if running the stock 10 bolt front end. For 36ish tires 538's are probably better...but that would require a solid axle up front.
06/10/2009, 02:11 PM
kodiak

Very cool write up! Driver
06/10/2009, 02:16 PM
lasturbo

How about replacing the rear wheel bearing that are on the axle shafts. Does it require special ZuZoo tools? When we replaced my rear diff for howling finally, I was going to do the bearings and hubs and precautionary but we could not get those bearings to free.
06/10/2009, 02:17 PM
LittleBeast

Quote:

Originally Posted by Marlin

So how much of a difference have you noticed in acceleration?

Awesome write up by the way...how long did it take ya? With pics and info like this, it makes it seem like something I could do, if I ever go bigger than 33s.

It is definitely a difference, but really I would say it only "feels" like an increase of 10-20hp, but it is a nice step up in performance, my speedo is WAY off right now :)

Back took me 1-2 nights (4-5 hours) each night. With a write up like this or if I had known exactly what I was doing I could've done it in one night easily.

Quote:

Originally Posted by Triathlete

Yep, the back is the easy one...have fun with the front!:bwgy:
That is the nive thing about the Zu 12 bolt, 9 inchers, and Toy axles. You can just remove and replace the third members.:thumbup:

Marlin...the 478's are ideal for 33ish tires on the VX. And unfortunately are about your only option if running the stock 10 bolt front end. For 36ish tires 538's are probably better...but that would require a solid axle up front.

Yeah but I didn't really find the front that difficult either, it was just the center link ball joint and the lower ball joints that were giving me problems, which if you are careful and know what you are doing you really do not need to remove them. I will write all of this up when I get around to doing the how to for the front, but yes the front is MUCH more complicated, and I will probably have at least 30 photos for that how to thread.

Oh and Independent 4x has sold multiple 5.38 gears for our front end but I am not sure of their availability as of now, I am pretty sure they are sold out as of now, but they are out there somewhere.
06/10/2009, 02:20 PM
JoFotoz

AWESOME write up.....:clap::clap::thumbup::clap::clap:

jo
06/10/2009, 02:45 PM
tom4bren

Great write up.

I can certainly vouch for the difficulty in removing the ball joints on the center link.
06/10/2009, 03:40 PM
tom4bren

"the off the line punch is more pronounced with the gear swap if you don't have a free-flowing exhaust. The lack of back-pressure takes away from the torque aspect. ...at least in my experience with it all."

Don't you gain all that back tho if you install a 'lectric fan?
06/10/2009, 05:23 PM
Triathlete

Quote:

Originally Posted by tom4bren

"the off the line punch is more pronounced with the gear swap if you don't have a free-flowing exhaust. The lack of back-pressure takes away from the torque aspect. ...at least in my experience with it all."

Don't you gain all that back tho if you install a 'lectric fan?

Or you can just punch some "speed holes" in the hood and fenders!:bwgy:
06/10/2009, 05:54 PM
tomdietrying

I'll say it again......Great write up! BTW - Did you also install your drop differential bracket while you swap the gears?
Peace.
Tom
06/11/2009, 06:36 AM
LittleBeast

Quote:

Originally Posted by tomdietrying

I'll say it again......Great write up! BTW - Did you also install your drop differential bracket while you swap the gears?
Peace.
Tom

Of course!!!!! I will post pics with a write up for that shortly as well. You are wanting to do the drop as well huh? Sounds like I need to make a trip to Dallas soon :)

Quote:

Originally Posted by ZEUS

WTH? Why in the world would you reinstall your LSD?!?! :( I mean, come on, only people who want traction would do that! :p

Great write-up! I am not sure how big of a deal it is, but to my understanding it is best to mark the driveshafts before you remove them so that you can put them back the same way they came out to minimize the chance of developing a vibration.

...I wish I would have thrown in a lunchbox while I was swapping gears but I don't think they were even available at the time.

Did you get your front pinion seal in without leaks?

Oh, and BTW, the off the line punch is more pronounced with the gear swap if you don't have a free-flowing exhaust. The lack of back-pressure takes away from the torque aspect. ...at least in my experience with it all.

As far as the driveshafts go I was having all kinds of whine from the driveline post lift so I wanted to try to change it up, and now it is as quiet as a sleepy baby :)

As far as the "lunchbox" goes, I just had them take out the stock one and install it in the new 4.78 when they were setting it up, they didn't charge me anymore for this just a simple $200 set-up.

As far as athe front pinion seal, yes I had the ring and pinion shop here in Houston do it for $50, I know it is super easy and I could've definitely done it myself, but in case of any mishaps (leaks) I did not want to be the one to blame (fix).

The off the line punch is quite a bit better, but I have found that the rolling take off is almost too good for the brakes now ;)

Quote:

Originally Posted by lasturbo

How about replacing the rear wheel bearing that are on the axle shafts. Does it require special ZuZoo tools? When we replaced my rear diff for howling finally, I was going to do the bearings and hubs and precautionary but we could not get those bearings to free.

I am not sure. I got the front bearings free pretty easily on each side, as I had to do the Diff Drop and had to remove the old brackets and install the new ones. I will do a write up on that pretty soon, what all did you try to get them free? The ones on the front are held in by a couple of C clips, one before the bearing and then one before the seal.
06/11/2009, 06:44 AM
Ldub

Top Notch!!!

GREAT write up Ryan...:_wrench:...:thumbup:
06/11/2009, 10:33 AM
lasturbo

Quote:

Originally Posted by LittleBeast

I am not sure. I got the front bearings free pretty easily on each side, as I had to do the Diff Drop and had to remove the old brackets and install the new ones. I will do a write up on that pretty soon, what all did you try to get them free? The ones on the front are held in by a couple of C clips, one before the bearing and then one before the seal.

Thanks, it seems to be the consensus as I started a separate thread on this and it has been quiet. I should have done it in the first place since this was a differential R&R thread. BTW. Great job on it!!:bgwg:

Link to rear wheel bearing question thread:
http://www.vehicross.info/forums/sho...threadid=15867
06/11/2009, 10:34 AM
nfpgasmask

Nice write up. I will likely end up doing something similar with my Trooper down the road...

Bart
06/11/2009, 11:47 AM
tomdietrying

Ryan,
Yeah, come on up to Dallas anytime. Shoot you never know. I might be in your neck of the woods this summer. I'd love to see you and the Beast in person again.
Peace.
Tom