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How to: 3rd Gen Aussie Locker Install

Ronin8002

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Year, Model & Trim Level
2008 XLT Ironman
Here it is! Just finished it up yesterday along with a front axle swap.

Many thanks to many people, especially RB and BigOne65 who were the first ones to do this and show that it works, as well as answering my questions on it. Thanks to Tyler92 and his writeup on removing the rear wheel bearings...great reference for me on how to disassemble the rear suspension. Also, many thanks to Pontisteve for providing a lot of helpful tips and answering all my questions about disassembling the rear driveline.

Background:
This writeup will show you how to install Aussie Locker part number XD-48831 in the IRS 8.8 differential. This writeup would also work for the 4th Gens I would think, since they have the same axle.

Update: Thanks to skysthelymyt, it appears that the Standard Gear Spartan Locker will also work for the 8.8 IRS:

http://www.explorerforum.com/forums/showthread.php?t=352259

Better yet, it is a direct fit, so you can eliminate step in this writeup where you modify the locker itself. The rest of the install steps here still apply.




Tools:
1/2” Drive breaker bar
3/8” drive breaker bar
1/2” drive Ratchet
5/16” box wrench or socket for cross shaft retaining bolt
Mini-sledge
1/2” drive 35mm deep socket for removing hub retainer nuts
1/2” drive Torque wrench
Hub removal tool
8” long cold chisel
Jack and jackstands
Something to chock the front wheels with
Small flat head screwdriver
Caliper Micrometer
Feeler gauges
Razor blade
Optional, but highly recommended: Air compressor, impact gun, and air chisel

Sockets:
12 point 12mm socket (1/2” drive) for the driveshaft flange bolts
1/2” drive to 3/4” socket adapter for the drain plug
10mm Socket for brake caliper bolts
18mm deep socket for pinch bolts on hub
18mm Socket for differential to crossmember bolts
15mm Socket for front isolator mounting bolt
18mm Socket for differential cover bolts

Fluids/Chemicals:
Assembly Lube or axle grease
2 quarts of 75W-140 gear oil
Super Black oil proof RTV silicone
Threadlocker
Brake cleaner spray
Penetrating oil spray
Anti-seize compound

Misc:
Large Zip ties or coathangers
12” long 1x1 piece of wood
Paint marker
Shop rags

First of all, I should say that you absolutely have to pull the rear axles and drop the rear differential to do this install. There’s no other way….you need room to be able to work on it and with the way its installed the diff has to come out, and of course the axles and rear suspension must be partially disassembled too.

1: Draining the differential:
-Using your 1/2” drive breaker bar, loosen (but don’t remove yet) the fill plug a bit to make sure it can come out before you try draining the fluid.
-Using your 3/4” drive adapter and breaker bar, loosen and remove the drain plug and let the fluid drain out.

CIMG0170-1.jpg


2: Removing the rear axles:

-Chock the front wheels, and jack up the rear of the truck and remove both rear wheels
CIMG0171-1.jpg


-Use your 35mm socket to remove the hub retainer nuts. Spray the threads and nut down with liquid wrench before doing this. I used an impact gun to remove mine. If you are using a breaker bar then you will need to either engage the parking brake and/or have a friend push on the brake pedal to hold the axles still while you do this.
CIMG0173-1.jpg

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-Using the 10mm socket, remove the brake calipers from both sides, taking care to not let them hang by the brake lines.
CIMG0175-1.jpg


- Carefully move them up and hang them securely from the coils with your coat hangers or zip ties so they are out of the way
CIMG0177.jpg


-Disconnect the parking brake cables from the cable guide mounted on the frame. This will give you some slack when you remove the hub.
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-Remove the nuts on the pinch bolts for the upper control arms (18mm deep socket)
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…and the toe links (18mm deep socket).
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-Use a hammer to tap the pinch bolts out of their holes and remove. These were very rusty so I had to use penetrating spray to help get them out.
CIMG0180.jpg


-Once the bolts are out, put your cold chisel in the slots (near where the pinch bolts were installed) and hammer it into the slot.
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This will open that slot up enough so that you can tap the upper control arms and toe links out of their holes.These will also tend to be very rusted in and stubborn. An Air Chisel is much better to use instead of a cold chisel if you have access to a compressor.

I had to hit the control arm on the side (not upward) to shock it loose before tapping it up and out. One thing that helped a lot also was using the wooden stick as a drift punch to pop the upper control arm upward out of its socket; this was also helpful with the toe link.

-If you plan on changing out the wheel bearings, you should also remove the bolt that attaches the hub to the lower control arm and follow this thread: http://www.explorerforum.com/forums/showthread.php?t=251915

Otherwise, move on to the next step:

-Attach your hub press tool to the lugs and press the knuckle off the axleshaft. I used an impact gun to turn it since without the brake calipers attached the hub will just spin. You might be able to hold it them with the parking brake set if you don’t have an impact gun.
CIMG0193.jpg


-Once you’ve pressed the axle out of the hub then you can pivot the knuckle over and rest it on a jackstand.
CIMG0197.jpg


After that’s done on both sides then you can work on getting the axles popped out of the diff.

-Use your wooden stick and mini-sledge again. You just need to position the wooden stick against the axle shaft as shown. Try to get it as in-line with the axis of the axle shaft as possible. A few good hits with the mini sledge on your wooden stick will pop the axle shafts out.
CIMG0196.jpg


-Once the axles are loose in the diff, pull them out, being very careful not to let the splines on the axles rub up against the oil seals in the diff. you don’t want to damage these because it will lead to gear oil leakage later.
CIMG0198.jpg


3: Removing the differential:

-Now you can disconnect the breather hose and ABS harness from the top of the diff.If you trace the gas filler tube down towards the tank the breather hose will split off from it and lead you to where it is plugged into the diff:
CIMG0203-1.jpg


-The ABS harness:
CIMG0199.jpg


-Next you need to remove the rear driveshaft from the diff. Before you do anything, take your paint marker and put a reference mark on the pinion flange and driveshaft flange so that you can line them both up when you reinstall.
CIMG0204.jpg


If you don’t do this you run the risk of having an out of balance driveshaft when you reinstall.

-Next tackle the bolts on the driveshaft flange. It’s a 12-point 12mm socket. I used an impact socket with a swivel so I could use my impact gun. If you don’t have an impact gun, you’ll have to put another breaker bar and 12mm socket on another one of the bolt heads and brace it against the frame so that the driveshaft won’t turn as you loosen the bolts.
CIMG0205.jpg


They have threadlocker on them so some heat might be helpful if they are stubborn.

-After removing the bolts run a coathanger or zip tie through the flange and loosely attach it to the swaybar which is above the driveshaft. Then take a prybar and put it in the slot shown on the side of the flange and pry it off the differential pinion flange.
CIMG0206.jpg


-Once it is loose, pull the driveshaft towards the front of the vehicle (it will compress the joint near the transfer case) and move it over the pinion nut and off to the driver’s side. Tighten the coathanger/ziptie as needed to hold it there so it doesn’t hang.
CIMG0207.jpg


-Put a jack under the diff to support it before you loosen the bolts that hold it on.
CIMG0210.jpg


-Then you can remove the 3 bolts that hold the diff in place; one is near the pinion flange (remove this first)
CIMG0209.jpg


-The other two of them are in the rear crossmember right up next to the spare tire (remove these next).
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-As you remove that last one support the diff with your hand so it doesn’t fall off the jack, then lower it down to the floor.
CIMG0213.jpg


4: Preparing the differential for the locker installation:

-Put the diff on a bench or on a piece of cardboard on the floor so you can work on it.
IMG_4965.jpg


-Remove the bolts that hold the diff cover on. Once they are out, use a screwdriver or prybar to pry here on the diff since the RTV sealant will still be holding the cover on.
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-With the cover off, now you can remove the cross shaft retaining bolt on the case. It is 5/16” in size. You might have to turn the pinion flange to get the case rotated around to the right angle. The retaining bolt has threadlocker on it from the factory so it may be tight. This bolt can break off if you use too much force so heat from a torch can help break down that threadlocker.
IMG_4970.jpg


If you use a torch make sure you clean up the excess oil inside the diff with brake cleaner before putting open flame in there.

-After the retaining bolt is out, slide out the cross shaft.
IMG_4971.jpg


-Now turn the pinion flange by hand again and the 2 spider gears will fall out of the case and into the bottom of the diff. Remove these and make sure you retrieve the 2 thrust washers that were behind them…they sometimes stick to the inside of the case.
IMG_4974.jpg


-Now remove the larger side gears from the carrier, also retrieving the 2 thrust washers that were behind them. Hang onto those, you’ll need them for the install.
IMG_4975.jpg

IMG_4976.jpg


5: Modifying the Aussie Locker:

OK, the Aussie locker was designed for the solid axle 8.8 and not the IRS 8.8. Fortunately the internals of the 2 versions is the same, so it will work in the IRS 8.8 fine with some modification to the locker. The reason for this is the way the IRS axle shafts are designed. The solid axle 8.8 axle shafts taper down at the ends so that C-Clips can be installed to retain the axles. The IRS 8.8 axle shafts are not like this; they are the same diameter all the way to the end and are retained with circlips.
IMG_4977.jpg


So here’s what you need to do.

-The “axle gear spacers” as the installation manual calls them, must have the center hole machined out to 1.370 inches to allow the IRS axles to pass through the middle.
IMG_4978.jpg


The locker and its components are made from very hard steel. Pretty tough to do it yourself, I would think. So take it to a machine shop and let them deal with it.

6: Test fitting the Aussie Locker:

-With that done, install the Aussie locker in the differential as per the installation manual, but without any grease on the components (it can throw off your clearance measurements).
IMG_4980.jpg

IMG_4982.jpg


-You might find that you aren’t able to get the cross shaft in like I did.
IMG_4983.jpg


I have heard that this is common with a lot of the 8.8 Aussie locker installs. Some of the carriers were cast to different tolerances I think and they designed the locker based on those different tolerances, so it resulted in this little problem. (If you don’t run into this, then install the locker the rest of the way as per the installation manual and skip down to step 7: Sealing up the Differential)

So if your cross pin doesn’t go in, what do you do to fix this issue?

-One guy I read about fully assembled the locker, then to put in the cross shaft he got out a BFH and hammered the cross shaft into the case. If you do that then I would think it would be really hard if not impossible to get the thing back out if you need to remove it or fix something in it. It is also very unlikely that you’ll have proper clearances per the manual if you do that.

-Another guy I talked to (BigOne65) told me that he had the axle gear spacers machined down a bit on the flat side to allow the cross shaft to go in…I believe .010 off the flat surface of each axle gear spacer was what he told me. This fixes the cross shaft to spacer clearance problem, so you can install the locker, but it won’t make the center clearance be in specs as per the manual. His locker seemed to work just fine though I don’t know what all his clearance numbers ended up being…maybe he’ll chime in.

-Torq Masters (the company that makes the locker), KPSquared, and other people have told me that the problem of the center pin not going in is due to the thrust washers are too thick; they need to be thinner for the locker to fit and work right. Sometimes they’re not too thick and they are just “coned” up from wear and won’t offer a flat surface for the side gears. At any rate, you can’t leave out the thrust washers, they are there to prevent wear and tear on the carrier and if you try installing the locker without them you won’t have the clearances and it will likely fail prematurely. I took this advice and decided to go about fixing the problem by addressing the thrust washer thickness.

-To get an idea of what thrust washer thickness you need, use the steps in the installation manual to assemble the locker the rest of the way in the diff with all the springs and pins, but leave out the cross shaft for now.
IMG_4987.jpg


-Once you have it assembled, take your feeler guages and measure the clearance of the center gap as per the installation manual. I was sitting at about 0.124. Center clearance min spec is 0.145 according the manual.

-Write down the center clearance you measured and subtract that number from 0.145. In my case I came up with 0.019, which I rounded up to 0.020 to make things easier. So to get that 0.020 of additional clearance, I needed .010 less on the thickness of each thrust washer to achieve a 0.145 center clearance and to be able to fit the cross shaft in also.

-I removed the locker and then measured the thickness of my thrust washers with a micrometer caliper. My thrust washers were both 0.040 thick, so from what I figured out before, I needed to take 0.010 off the thickness of each one, resulting in a thrust washer thickness of 0.030.

-I wasn’t able to find thinner thrust washers of the same type anywhere, so I thought I might sand the factory ones down. They were flat and not “coned” like other people have seen. Anyway, I took some emery cloth and started sanding down the thrust washers but I quickly realized that this would take a loooooong time by hand and be very tedious…though it will work if you want to do it this way.

-What I did to speed things up was buy a pair of carrier shims from a Limited Slip diff that were 0.030 in thickness…which is 0.010 less than my factory ones.

-The inside diameter of these was a little bigger than my factory thrust washers, but this wasn’t an problem since they still fit on the side gears of the locker just fine. The only issue was that the outside diameter of them was also larger than the stock thrust washers and won’t sit flat in the sides of the carrier of the diff. So, I used a drill with a sanding disc and sanded around the outside edges of them until they were small enough in outside diameter to fit in there and lay flat against the sides of the carrier. It only took about 20 minutes to do this. Make sure to clean them off when you are done and deburr the edges with emery cloth.

-With that done I reinstalled the locker with the new modified washers….everything fit this time, including the cross shaft. My axle gear spacer to cross shaft clearance ended up being .006 and my center clearance was right between 0.144 and 0.145…from what I understand that will be fine for the 8.8 Aussie locker to work. If it’s a lot narrower than that then I am told it might or might not be able to unlock properly. You won’t know for sure until you do the function test (“spin test”) after the install is complete and the axle is back in the truck. After all the work it took to do that I wasn’t going to take any chances

-So with the clearances good, I took the locker out one last time, put assembly lube on all the surfaces that rub together and reinstalled it. This time when you put the cross shaft in you can put the cross shaft retaining bolt in all the way. Make sure to put some threadlocker the threads of it; you don’t want that thing backing out because it could cause some big problems if it does!
IMG_4988.jpg


7: Sealing up the differential:

-Now take your razor blade and get to work cleaning all the old RTV off of the cover and diff mating surfaces. After it’s all off, spray the surfaces with brake cleaner to get it all clean. If you want you can also wipe all of the old gear oil and residue out of the diff with rags and brake cleaner, just make sure not to leave any bits of rag in there.

-Lay a about a ¼”wide bead of RTV on the cover in the groove of the cover. Before reinstalling the cover, put a couple of bolts through the holes to guide you to the right holes on the diff and get them hand tight.
Put in all the other bolts and tighten them all down in a cross pattern.

8: Reinstallation of all driveline components:

-Reinstall the diff and driveshaft.

-Guide the axles into the diff carefully, then give them a few good shoves once they're in the diff. You'll feel them lock into place. Check underneath and make sure they're fully inserted.

-Now reinstall the hubs, control arms, and trailing links, brakes, and wheels. Put anti-seize on the splines of the axle shaft where they go into the axle hubs. that will let you press the hub on by hand, then you can tighten the axle nut down. Also, I recommend busting the rust off of the control arm and toe link studs and coating them with anti-seize before assembly. You'll be able to tap those components in with a hammer and less effort than it took to get them out.Don’t forget to reattach the vent hose and ABS sensor harness to the diff!

Torque Specs:
-Axle hub retainer nut 203 lb/ft
-Upper control arm and toe link pinch bolts 59 lb/ft
-Brake caliper bolts 24 lb/ft
-Driveshaft flange bolts: 83 lb/ft

9: Testing the Aussie Locker for correct operation:

-Re-install the tires and conduct the “Spin Test” as per the Aussie Locker installation manual.

-If it passes the test, then you’re good to go!

10: Final steps:

-Make sure the drain plug is screwed in…you can a little Teflon tape or RTV on the threads of it to make sure it doesn’t leak.

-Let the RTV sealant on the cover and drain plug dry, then fill the diff with gear oil up to the bottom edge of the fill plug hole (I used 75W140 synthetic as per the updated Ford recommendation). Put a little bit of RTV on the fill plug threads and reinstall.

-Test drive your setup as per the installation manual and have fun!
 



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SWEET!!! That looked pretty easy, you didn't have to remove the main gears or anything:D

Edit: This is a great addition!!! It'll be a sticky soon!
 






Must sticky this!!!! Im next im next! How have the testdrives gone??? Sweet
 






SWEET!!! That looked pretty easy, you didn't have to remove the main gears or anything:D

Edit: This is a great addition!!! It'll be a sticky soon!

The locker install itself wasn't hard. Obviously most of the time and effort is spent on removing/reinstalling the diff.

Fortunately there's no need to mess with the ring and pinion, even with 4.10 gears installed.
 






Must sticky this!!!! Im next im next! How have the testdrives gone??? Sweet

Spin test passed no problem, so it will definitely unlock on turns. Here's a video of how to do it without a helper:

http://youtu.be/jmmBCdKYkV0

I haven't driven it yet...need to put some gear oil in the front axle and I was too tired to do it last night. Will do that and take it for a drive this afternoon.

It will be a bit before I can really put the locker to a serious test...gotta break in the new gears for 500 miles before I can offroad.

I have a month long trip for work starting this week so all I will have time for right now is an initial break in. I'll finish breaking em in when I get back in early July.
 












Onya mate!!! Awesome write up, it doesn't get anymore comprehensive than that. Brilliant!!!!
 












Took it out for another drive this evening to continue breaking in the new ring and pinion gears.

You really can't tell the locker is back there when driving on the road or making turns from a roll.

It only clicks when I am going at very slow speeds and turning, like in a parking lot. It's audible inside the truck but no big deal...lets you know it's working. I am told that it will quiet down a bit after a few hundred miles.

I am very happy with how it behaves on the street. Can't wait to take it offroad!
 






sweet!!! im putting money away right now!
 






Nice write up ronin! :thumbsup: Definately needs to become a sticky for this section!
 






hate to ask, but, what was the total cost start to finish, including the limited slip shims?

great work by the way!
 






Thanks Kazer!

For just the Aussie install in your factory differential:

Aussie Locker XD-48831 - $280
Machining on spacers - $60
0.030 LS Carrier Shims - $4
2 Quarts of Mobil 1 75W140 Synthetic - $38
1 Tube of RTV Sealant - $4
1 Tube of Anti-Seize - $7
1 Tube of threadlocker - $3

So about $400 if you have all the tools and other stuff you need in the list above, a little less if you already have the last 3 things. You could sand down your stock thrust washers if you have a better way of doing it than I did and save some money there too...I just did it to save time.
 












very nice mod for the money. i have access to a jig grinder, so ill save some money there. ive never been one to tackle big projects, any ideas on roughly how much a shop would charge if i took them the modified aussie part and have them install everything?

how are the 4.10s? is there a noticeable difference from stock 3.55s?
 












No idea on the labor to have a shop do it. It took me a couple of afternoons during the week and most of a Saturday but I was also taking notes and pics. If I had to do it again I could get it done in a day since I now know what tools I need, socket sizes, tricks, etc.

Really the worst part of it was getting the control arm and toe link out of the knuckle on each side. If yours are as rusty as mine were it would definitely add time to the install. Main thing with that is that you should use that wooden stick and a mini sledge to pop them out instead of trying to bang on them all day with a hammer. The angle and space is just too hard to do it that way and it took me a bit to figure that out :D Air tools help a lot but it's do-able with hand tools. Having a buddy there would also help a lot too.

I've taken it really easy on the 4.10 gears until they break in so I won't be able to fully appreciate the difference yet, but even with driving carefully I can already tell that they help a LOT with the bigger tires. The truck doesn't have to downshift as much to go up hills and it just climbs right up them with a lot less gas pedal. Kind of like how it drove with stock tires and gears. Off the top of my head I think the 265/75/16 tire / 4.10 gear combo is pretty much like having stock tires and 3.73 gears from a numbers standpoint.
 






you think it would be just as easy with 4.56 gears intalled ?
 






Only thing might be that you would have to notch the corner of one of the ring gear teeth to allow the cross shaft to slide out....the 4.56 ring gears for the 8.8 are pretty big. Not a big deal people do it all the time. Just don't notch the cross shaft...that weakens it.
 



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well after looking at the aussie locker and my neck of the woods, i think ill be going with a Detroit electrac for the 8.8. my only issue is that im not sure if it can be modified to fit the irs pig. the reason im not going with the aussie is because ive heard they can be difficult driving in snow and ice and in michigan theres only two seasons, winter and construction so a selectable will be nice. decided against arb air locker because its pricey and i dont need onboard air
 






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