pinion swap

[WiSDoM]

hello guys,

I am will be doing my 4.77 gear upgrade soon so I need help putting a parts list together for Merlin and any install advice you guys could muster would be appreciated.
I also have to replace my driver side half shaft due to a little inner cv boot tear. so I would like some advice with that too and any other things I should change while I have it all apart. I hope to be making up some drop diff brackets too.
Thankful for any advice you can give.. :p

[ZEUS]

Hey, left ya hangin there for a while! This might come in useful: http://www.vehicross.info/modules/Downloads/userfile.php?id=15


Otherwise, here is the best explanation and advice I can come up with.

I strongly suggest taking your 3rds to a reputable shop to have them check the setup before installing them in your housings. You don't want to be in my situation a few months down the road. If they need shimming or adjusting, now is the time. This step will give as much longevity as possible to your bearings and should keep the gear whine at bay. I will be getting into my front axle reinstall soon. I figure I might as well fab up some drop brackets while I am at it as well. I will post pics of my progress.

For now, you need these parts for the front end:
Outer Pinion Bearing
Crush Collar
Oil Seal
Dust Shield (to use as a tool to help install the new oil seal - you will thank me for suggesting you buy this $3 part - trust me)
Pinion Nut

Basic Front-end Disassembly:

Lube every nut and bolt you can in advance. I use a 1-3/16" socket and a slide bar I got at Sears for the pinion nut - I forget the metric size. Mark the f/r drive shaft flanges at each end to ensure you install the drive shafts on the yokes the same way they were from the factory, to minimize vibration. Drain the diffs. Remove the front drive shaft and loosen the pinion nut before removing the axle shafts. This makes it much easier to remove the VX yoke you will be swapping onto the new front 3rd. Jack up and secure the VX. Remove the tires, brakes, shocks, sway bar links, and tie rods. [If you want to install stainless brakelines, sway bar disconnects, HD tie rods, and/or greasy sway bar bushings, now is a good time.] All these parts are removed to guard against ripping your CV boots. Remove anything that may be in your way. Be careful with the ABS sensor wires - they can be overextended and pull out of the sensor at the spindle. Support the lower A-arm with a floor jack so you can remove the spindle. [If you want to install new ball joints and perform the flip, now is the opportune time.] Remove the axle shafts. Remove the cross member under the 3rd member. Remove the axle housing. Don't forget to disconnect the breather hose coming of the long axle tube. Remove the 3rd from the housing.

Reassembly:

I mounted the 4.77 3rd on the housing at this point and then set down on the concrete floor before me..... DUN-TADA.... my BIG VISE (which is mounted to a large heavy stand) to hold the yoke still while I removed the pinion nut from the 4.77 3rd. I did this so I could work on it away from the VX. You could also install the new 3rd onto the housing, and then remove the yoke after you put the axle assembly back in the VX and it's on it's tires again. I have done it both ways; I find it easier to do it on the ground, personally (sounds kinky huh :rolleyes: ). Use a magnet pen and screwdriver or a pair of strong fishing hooks with the tips cut off to remove the old bearing. Leave the race in the 3rd and remove the old crush collar. Install the new parts I listed onto the new 3rd, including the VX yoke. Put everything (excluding the driveshafts) back together on your VX again in opposite order.

Now - for the oil seal. Here is what I came up with. Place the rubber lip of the oil seal into the recess of the dust shield. Slide the two over the pinion shaft until they are up against the housing. Slide the yoke over the shaft and tighten everything down using a rachet on the pinion nut and washer. Remove the yoke and the dust shield - the oil seal should be inside the 3rd member now. Lightly tap the seal in the rest of the way with a brass hammer until it seats. I found this method keeps the outer wall of the seal from deforming, giving a nice tight, leakless seal, quickly and easily.

As posted by Swordy:

"OK,,
The Torque specs for the front pinion nut/crush collar is:
177-275 Nm (130-230 lbs/ft)

The Torque specs for the rear pinion nut/crush collar is:
245-294 Nm (181-217 lbs/ft)

Be sure to stake the pinion nut afterwards to keep it from un-adjusting itself.
Piece of cake :)"

Staking the pinion nut is done with a chisel (or heavy screwdriver) and hammer. You just deflect the nut into the shaft to keep it from loosening - locktite would probly work as well - your choice.

The rear is cake. Remove the driveshaft, brakes, and backing plates, slide out the axle shafts, unbolt the 3rd. Put in new 3rd, slide in the axle shafts, replace backing plates and brakes.

Put fluid in the diffs wait a half hour or so and watch for leakage - no leakage... Install the driveshafts, lining up the marks you made before removing them.

Post pics if you get to work before I do! We'll see if we can build I nice how-to guide with pics...

[WiSDoM]

Thanks Zeus,

Where is a go shop to go an have them check the new 3rds for defects? a dealership?
I will be getting all my parts together over the next couple of weeks to maybe install the second week in Aug.

[ZEUS]

Just start calling auto repair shops if you can't find any drivetrain specialty shops. I think any good shop that would work on such things would have access to an archive for the Isuzu tolerances, backlash, etc. See that they have useable numbers yourself - don't just let them say, "Yeah, we know the tolerances." A lot of people just use GM torque specs and stuff on everything from engine rebuilds to hinges! Maybe you could call St Charles and get the gear setup numbers from someone there, or find them online, and give those numbers to the shop you choose? I am going to take my front end to a mechanic friend next weekend. I guess you could also ship out your 3rd's to a good drivetrain shop if you can't find something local.