Hi there 4Runner Forum folks... I guess you could call this my first "Repair Thread"...

My 1998 4Runner SR5 has just over 160K miles, and to my knowledge I am the third owner. The truck has spent most of its life in the rust belt of the northeast where pavement is not black in the winter, but white with all of the road salt and calcium that the DOT dumps on them. Needless to say, this thread is for those of us that call this area home - and to show folks in the other areas of the country how lucky they have it...

To start off with, my 4Runner required rear axle seals - and props to BigFishAllDay for an excellent build thread sticky showing the details of this operation. I used this sticky as a jumping off point for what was to come next - the swap of the rear axle housing.

Please note - This is one expensive task that is forced upon some of us in the rust belt simply due to the fact that the rear differential "pumpkin" cover is not a bolt on item. Toyota in their infinite wisdom decided not only to not make this piece an integrated part of the axle housing, but to simply spot weld two brackets onto it as well - opening the door to two "salt shelves" that will corrode and eventually vibrate causing a hole for the gear oil to leak out of. The following information and the dollar signs will highlight more than anything why Toyota will likely NEVER issue a recall for these issues...

Just the parts:

A new rear axle housing from Toyota was over $1K...

Car Quest rear brake shoes, cylinders, and hardware kit was over $200...

Toyota axle bearings, seals, ABS rotors, retainers, spacers was over $400...

Stabilizer links and bushings for it and the lower control arms were over $200...

Plan on at least $100 in new hardware, and another $100 in consumables for cleaner, gear oil, penetrating oil...and all this is just to start with...more on that later...

First step - Locate the sticky for replacing rear axle seals on this site. Follow those directions for tear down, and buy the parts listed within that thread for reassembly later...

I will add to that sticky by saying that the ABS sensors are a PITA to remove, and at over $200each, one should take great care to not damage them. Unfortunately for us rust belt folks, it is not as simple as a flat blade screwdriver and a bit of prying... Remove the bolt, remove the three closest ABS wire clamps/mounts, hose down the sensor base with penetrating oil, and place a set of channel locks firmly at the base of the sensor. Begin to twist back and forth - rotating the sensor 1/4" in each direction to get it moving. Add additional oil every few rotations to aide the movement. Once you are able to rotate the sensor back and forth without a death grip on the channel locks, rotate so that the tab is above the pad it mounts to.

Use a small pry bar under the tab using the top of the axle housing for leverage to apply a little pressure while continuing to use the channel locks to wiggle the sensor back and forth. Feel free to use additional oil to aide in this process, but this was the only way I could remove my ABS sensors from my housing.

On to where the rear axle sticky ends...

**Plan on replacing almost all hardware, and just about everything else depending on the level of corrosion that your truck has, and how deep your pockets are***

-Begin draining the gear oil from the rear axle housing. Both the drain plug and the fill plug use the same socket size of 24mm. I was lucky and these came out with a little propane from the Bernzo...

-Disconnect the drive shaft from the 3rd member. I replaced all the U-joints and the drive shaft hardware a year ago, so I am unsure of the original bolt specs. The specs for the replacement hardware I used are:

4 Bolts: Stainless Steel M10 (1.00)pitch x 3cm
4 Split Washers: Stainless M10
4 Flat Washers: Stainless M10
4 Lock Nuts: Stainless M10 (1.00)pitch

If memory serves, both the original hardware, and the new hardware both are 14mm. However, it is a tight fit using a socket on the forward side, and only an open ended wrench will fit behind the flange of the 3rd member. NOTE - the bolts can't be much longer than 3cm as the flange for the 3rd member prevents anything much more than the lock nut to fit in there.

-Remove the 3rd member from the axle housing. There are 10 nuts that use threaded studs to secure the 3rd member to the axle housing. You will need a 12mm socket and some heat to remove these. Again, I got lucky and only sheared off two studs in this process - the others came out fairly easy, but most of the time the studs came out along with the nuts. I intend to simply use quality bolts instead of studs for the re-installation.

For whatever reason, my 3rd member was seized onto one of the studs that sheared off flush with it. This one was located in the upper right if you are looking at it from the drive shaft side. It took about an hour of penetrating oil, heating, hammering, and prying to finally free it from the housing.

Once it was out, I chipped off all loose surface rust, then bathed it in a good amount of brake cleaner both inside and out. I also took the opportunity to put a couple thick coats of primer on it before a couple coats of rubberized undercoating. Just be sure to tape off every part of the exposed gears, and keep the holes for the studs clear of what you are spraying...

-Remove all E-Brake, and brake line bolts. These can all be removed with a 12mm socket, and a bit of heat... I saved the clamps for the brake lines, and luckily the rubber brake hose to the axle T was in good shape, and the metal lines came out with a little oil - but I was planning to replace the metal lines so I was not concerned with them breaking.

The only bolt that did not come free was the one holding the E-Brake Guide to the bracket in the center of the differential cover... Go figure... I knew if it was rusty enough to cause the cover to leak gear oil, it was likely fall to pieces in the attempt to remove the bolt that was secured to it.

At this point everything but the suspension components should be removed and/or free from the axle housing.

-Remove the lower Shock bolts. I replaced the shocks a year ago, so the bolts came out without any heat with just a 17mm socket.

-Remove Stabilizer (sway) Bar. Here is another instance of the rust problems I encountered. I began with the links that attach at the frame rail brackets. The bushings were cracked and dry rotted, and the nut was rusted solid to the link. Even using a small 12mm wrench for the nut, and a small 14mm wrench for the link, both links snapped after applying moderate force. In contrast, the four bolts holding the bushings on the axle housing came out easily using a 12mm socket and a bit of heat.

About this time, I expected what little compression the springs had left to force the axle housing down enough to simply pull them out. Unfortunately, this was not the case - I went to Advanced Auto Parts and rented a set of coil spring compressors and started with the passenger side spring.

-Remove coil springs. Once the passenger side spring was compressed quite a bit, I had a helper stand on the axle housing end to allow the spring to come out the forward side of the axle. I quickly realized that the driver's side spring is a bit more difficult to get the compressors on, due to the lateral control arm bracket being on the rearward side, and the gas tank being so close on the forward side. I got the tools on, and compressed the spring enough so that it would move, but not enough to be applying pressure on the axle housing. Once the rest of the suspension components were removed, the spring could easily be removed once the housing was down.

-Cut off all control arm nuts. Again, here is where the project will get even more expensive fast. Besides the stabilizer bar, the only bushings that Toyota offers as replaceable are the ones for the lower control arms. That means that if any of the other bushings are rotted, damaged by trying to burn off the bolts, or simply damaged by the heat used to free up the hardware...you get stuck buying the entire piece. Both upper control arms are over $100each, and so is the lateral one. If you plan to replace these three pieces, or are forced to, I would be stumped to think of why you would NOT replace the hardware anyways...

For me, this project was on a finite timeline and getting too expensive real quick. So I opted to just cut the nuts at the axle housing end for the upper and lateral control arms, and replace the lower control arm bushings all around. While I had the stabilizer bar and lower control arms out I chose to clean them up a bit as well - priming and undercoating with the same as the 3rd member. This also will help me remember what I have replaced, and what I have not, if I ever do need to replace the remaining control arms with included bushings...

By cutting only the axle housing end of the upper and lateral control arm hardware, this also was a great starting point for the new axle housing to be hung in place.

Once the bolts for the control arms were removed, the axle housing was able to be taken out, along with the driver's side spring.

I chose to prime, and use some pretty heavy duty paint-on bed liner material to coat the new axle housing all around the differential cover and those pesky spot welded brackets. The rest of the old housing was in pretty good shape, so I focused on slathering this center section of the new housing.

This is the point where I am at today. More updates on the installation of the new housing to follow, but in the mean time here is a hardware list of what this project has included, along with extra parts for the items I do not intend to completely remove unless I have to:

2: ABS Sensor Bolts - M6 (1.0) x 1.6cm - 10mm socket

4: Brake Cylinder Bolts - M6 (1.0) x 1.0cm - 10mm socket

8: Axle Nuts - M10 (1.25) - 14mm socket

10: 3rd Member Replacement Bolts - M8 (1.25) x 3cm - 12mm socket

2: Lower Shock Bolts - M12 (1.25) x 2cm - 17mm socket

5: Brake Line Clamp Bolts - M8 (1.25) x 1.6cm - 12mm socket

2: Lower Shock Bolts - M12 (1.25) x 2cm - 17mm socket

4: Stabilizer Bar Axle Bolts - M8 (1.25) x 1.6cm - 12mm socket

3: E-Brake Tube Guide and Passenger Housing End Bolts - M8 (1.25) x 2cm - 12mm socket

4: Lower Control Arm Bolts - M12 (1.25) x 10cm - 19mm socket

4: Lower Control Arm Nuts - M12 (1.25) - 19mm socket

2: Lateral Control Arm Bolts - M12 (1.25) x 7.5cm - 19mm socket

2: Lateral Control Arm Nuts - M12 (1.25) - 19mm socket

4: Upper Control Arm Bolts - M10 (1.25) x 9cm - 17mm socket

4: Upper Control Arm Nuts - M10 (1.25) - 17mm socket

-I did not look up what the specs for E-Brake arm bolt (Driver's side axle housing end) was as I re-used this...

-There are also two pins for attaching the E-Brake U-Brackets to the arms on the axle backing plates...

-Lock Washers for all M6, M8, M10, M12 Nuts...

-Flat Washers for all M8, M10, M12 Nuts and Bolts...

I chose to go with Stainless Steel for everything that I could find. The only items I did not get Stainless (mainly due to availability) was the M10 and M12 bolts for the suspension components.

Pictures to follow as well...

That's alot of text with no pics... I have done this swap and I got confused reading through it.

The socket list is a great item, and a more detailed materials list would be useful.

In my opinion, you include too much of your own specific experience with rust. I didn't have to cut off the control arms bolts, but was able to reuse them, in fact cutting them off would have been silly and more costly despite me having TONS of rust.

There is alot more detail that can go into the section on locating a used axle housing or assembly. Your current description makes it sounds way more expensive than it needs to be. Same goes for the other hardware. You can probably pick up new LCA's and UCA's cheap at a salvage yard.

I am sure if someone has the time, and is willing to spend the effort, they can find all of these items used at a salvage yard - perhaps one out west where the parts are actually SALVAGEABLE... However, I personally did not have the time, or want to spend the effort to tear apart two sets of rusty components only to question how long the "new" rusty components would last - the original metal control arms are fine - the non-replaceable bushings are the problem. My time is valuable, and the last thing I wanted was to do this job more than once.

Unfortunately, the dealer is the only place you can go for these parts new, that means spending this kind of cash for the convenience of having them two days later...

The pictures I am about to upload will show the rot I speak of...and as luck would have it, the control arm bolts did free up with the BFH, and a bit of elbow grease...but compared to the cost of the rest of this project, I am still going to replace the hardware...

PLEASE, if someone out there has a better method for any of the things I have had to do on this project, please post for all to know. I am not a mechanic by trade, but do have a degree in autobody repair.

Whoo-Hoo...Pictures!

Here is the culprit for the axle seals blowing... If you haven't already, plan to replace your axle breathers. They are inexpensive, and a relocation kit is a great idea if you don't want to replace or check these on a regular basis... If it looks like this part came from a shipwreck, it is because it has been exposed to same elements... (Cold, Water, Salt, Oxygen, Time)

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This is the pumpkin cover on my original axle housing. I took this picture after I removed the housing from the truck to get better pictures.

You can see how bad the rot is on this around what used to be the E-Brake bracket.

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In an effort to prevent this ever happening again, you can see the bed liner I applied to the new housing. I made sure to sand the OEM finish that came on the new housing, and apply two heavy coats of primer before using the bed liner material...don't want this coming off...

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In this picture you can see the inside of the new axle housing. Those four dots up the center of the differential cover are the spot welds for the brackets on the outside.

If there were to be a re-design, a simple fix would be to simply put another 3rd Member bolt ring around the back side of the housing. Then a replaceable cover could bolt onto that... If this cover would have replaceable, this job (axle seals and diff leak) would have only taken a couple of days instead of a week and cost WAY less...

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Stabilizer link bushing rot... See for yourself, no amount of massaging would bring these bushings back to life - and that nut is rusted solid... These came out easy - they snapped off... The axle housing bushings turned out not to be this bad, but are being replaced anyways just to be sure.

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Lower control arm rot... Thankfully, these bushings are the ones that are able to be replaced without replacing the entire arm. However, as you will see in the next few pictures, the process of removing bushings this bad takes time and plenty of effort. UPDATE - The hardware for these, as well as the rest of the control arms did come out without the use of a cutting tool. Had to bash it with a BFH, and get out the 3/4" ratchet and an impact socket. Again, compared to the rest of this project, the cost of new hardware is minimal - so they are going to be replaced anyways...

I took this time to install a wire brush wheel in my angle grinder and give the stabilizer bar, and two lower control arms a good cleaning to remove all rust. Once the old bushings were removed, I coated them with primer, and rubberized undercoat... Hindsight, I would have bed lined these instead...I still may...

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Here you can see how I elected to get the old bushings out. In my tool box I had a set of 3/4" sockets. For the socket wall thickness of my sockets the right sizes were 1" and 1 5/8". The smaller socket's outside diameter fit just inside the control arm end, while the larger socket's internal facets were just smaller than the outside bushing diameter.

Put everything in a big friggin' vise, apply flame to the outside of the control arm end (all the way around) and begin cranking down...

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The metal sleeve that is left was a real PITA to get out... Chisels, BFH, penetrating oil, and lots of elbow grease is how I got it done... I welcome any better suggestions...this sucked...

Today the dealer bushings, and my hardware order should all be in...then it is on to assembly... More updates and pictures to come...

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Woof, that is bad rust. You should edit your first post to include all those pics (make a nice walkthrough). Did you happen to take pics while you did your swap? That is something I didn't do when I did mine. I started late one night and was mostly stressed about getting it done and didn't take pics.

As far as the time and effort to find these at salvage yards, I disagree with your assessment of the difficulty of finding parts. I live in Mass, even farther into rust belt than PA, and I still managed to find one, though albeit I had to have it shipped up here from florida. You drive a couple hours south from PA and you are out of the rust belt and should be able to find a pick a part yard and get one for super cheap. I admittedly spent a while looking, but if you troll for a while, it really isn't that much effort or time invested (10 minutes a day to check the forums and searching a couple yards).

Here are some other things that I did differently (pretty much all to save money):

1. Did not replace the bushing in the LCA's and UCA's - There parts are very expensive (since you have 4 of each). These are a PITA to replace and the rubber is not as affected by the salt as the metal is. I cleaned up the metal, and the rubber was totally acceptable. AS long as it isn't cracked and breaking apart, they are fine. Also, the LCA's and UCA's are easy to remove later if you choose to do these later.

2. Did not replace the brakes. These had a nice coating of brake dust and grease on them so they weren't nearly as rusted as the housing was.

3. Did not replace the bearings, seals, ABS rotors, etc... Rusty housing doesn't mean your bearings are shot, so don't change them unless you absolutely have to, and it is a separate issue than the housing leak. They are very expensive to replace too as the parts have to be pressed on.

4. Didn't replace hardly any of the bolts. They are huge bolts, and despite all the rust I had, they were salvageable.

I ended up paying $725 including shipping for a complete axle to axle assembly, including e-locked diff, not including brakes. Add to that about $15 for a brake hardware kit from advance, a can of POR-15, a couple small bolts for the brake line mounting points, and some new stock bolts for the drive shaft, and that was pretty much it. Around $800, and that included not just a housing, but diff and axles as well, and shipping of the axle. Not sure I could have handled the $2k+ spec'd out in the first post. I have seen multiple guys here that have done this for significantly less than I did, so it can absolutely be done for much less.

Even here in Morgantown, they dont use salt on the roads. Now all the silt does chip your windshield, but that is a different story.

WHOA! That's a ton of rust

Yesterday's progress... New parts arrived!

I drove to the nearest Toyota dealer and picked up the new bushings that I had ordered a few days ago... New Stabilizer Bar pillow bushings, end links, and the bushings/hardware needed for the new links.

See the picture of the diagram that I uploaded...
As far as part numbers, QTY, and cost...the dealer took mercy on my and gave me shop cost...

4: Lower Control Arm Bushings - Toyota part #48702-35070 at $30.21each (pricey, but needed)
2: Stabilizer Pillow Bushings - Toyota part #48815-10090 at $9.82each
2: Stabilizer End Links - Toyota part #48830-35020 at $69.41each (pricey, but needed)
4: Link Cushion Retainers (Upper and Lower) - Toyota part #90948-02126 at $4.32each
4: Link Cushions (Upper and Lower) - Toyota part #48817-30020 at $2.84each
2: Link Cushion Retainers (above lower cushion) - Toyota part #90948-02127 at $3.33each
2: Link Lock Nuts (to frame assembly) - Toyota part #94183-00831 at $0.72each
2: Link Nuts (to stabilizer bar) - Toyota part #90179-12141 at $1.01each
Grand Total after tax - $337.14 (the bulk of wich were the two links, and the four LCA bushings)

I also got my order of new stainless hardware from McMaster-Carr... For those of you wanting new hardware, most good hardware stores like Worth Smith will have everything you need for this kind of replacement project and would be much cheaper than a McMaster-Carr order (they have minimum QTY purchases for most items...) For this job, I was not anywhere close to a good hardware store...so I had to order the parts I needed... See my first post in this thread for specs on this hardware - I updated a few things in it today...

Turns out that I have neither the proper tool, or the muscle to properly press in the new Lower Control Arm bushings. I attempted to heat the control arm by putting it on top of a wood stove, while placing the bushings in a deep freezer. An hour later I used the socket/vise method and only got a fraction of the first bushing pressed in... So this work is being given to the shop that pressed in my axle bearings for me...

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