Axle Rebuild

Last September, we were making our way through the Kootenay region of British Columbia when our passenger side rear axle seal gave out, causing all of the rear differential fluid to leak out. This destroyed our wheel bearings and brakes and making it impossible to get home under our own power. A $500 tow later and we were back in Calgary with a very bitter taste in our mouth from the whole experience.

You can see the fluid splattered all over the tire as it leaked out of the axle

With the injured 4Runner sitting in the garage, it got me thinking; what would I do to fix it? Just replace the seals, bearings, brakes then call it a day? The rear axle was already very tired after 360,000 kilometres of abuse. It was time for a major rear end overhaul.

I contacted a local guy in Calgary who goes to the wrecking yards and pulls parts off these old vehicles for resale. I asked if he had a used axle I could purchase and sure enough, he had one in stock.

Now, it’s not the prettiest thing I had ever seen. In fact, it was down right ugly. By the time we got it home I was feeling a bit of buyers remorse, but I had a feeling there was some good metal under all that rust.

The used axle sat in the garage until spring time came around when I could get to work stripping it down to bare metal. First thing on the long to-do list was to remove all of the cables, wiring, brake assembly and pretty much anything that wasn’t the housing itself.

Here’s a photo of all the junk I pulled off of it.

Once everything was unbolted and taken off, I got to work getting it up on jack stands. Even with everything stripped off, it was still incredibly heavy to lift – definitely a two person job when it came to lifting and moving!

Looking a bit better, but still super crusty.

At this stage, it was time to start grinding and hope to god that there was some good metal under all the corrosion. I got out the trusty DeWALT angle grinder, attached an aggressive wire wheel and started the operation.

A few tedious hours of intricate grinding later and I’m pleased to announce my buyers remorse is gone!

Look at all that fresh metal to work with!

I was very pleased with the final product of grinding. However, it shouldn’t stay this way for long, otherwise it’ll turn into that piece of rusty junk I dragged home again. I decided to go with a paint product that is well known in the automotive industry when it comes to restoration projects. It’s a little something called POR-15. Ever heard of it? Well you should have. It’s great stuff! I’ve used it to coat the frame of my vehicle in the past to protect against that nasty road salt we get here in Calgary. To those of you who don’t live in the rust belt, consider yourself lucky.

At this time I also took the chance to remove and paint the third member, also known as the rear differential. The plan is to take it off to a shop by the name of KRave automotive and have them rebuild it for me.

I decided to stick with the OEM ring and pinion gears because the truck runs nicely with them and these ones are still in good condition. However, I did order a Nitro Gear and Axle master install kit which includes new bearings, oil seals and bolts as well as the cool yellow paint to show the contact points of the gears to freshen things up for this old differential.

I also took the opportunity to replace the axle seals in the axle housing. These seals keep the oil inside the housing and away from vital components such as the wheel bearings and brakes. If the oil gets past the seal, it will seep in to the wheel bearing and wash out all of the grease that allows it to turn. Without that grease, the bearing won’t turn. Therefore, your wheels don’t turn and you’ll be a sitting duck. Not a good situation to be in!

Old axle seal sitting inside the housing.

Along with the new axle seals, I had new wheel bearings backing plates, wheel cylinders, ABS rings and dust seals installed on the axle shafts. The axle shafts sit inside the housing and connect to the 3rd member. As the 3rd member turns, it rotates the axle shaft along with it. In turn, the rotating axle shaft comes out the end of the axle housing and connects to the wheel. The wheel bearing is pressed onto the end of the axle shaft with a hydraulic press.

I took both axle shafts to a friend who had a hydraulic press to fit up the new wheel bearings.

Here is a picture of everything put back together on the refurbished axle. At this point, it is ready to swap into the truck. Once the old axle comes out, it will be going in.

After a few hours of unbolting the old axle from the clutches of the 4Runner, out it came!

In addition to the new bearings and seals in the 3rd member and axle housing, I decided to upgrade the rear suspension, giving it an Old Man Emu 2861 coil spring lift and Bilstein 5100 33-187174 shocks. This will be a big upgrade from the Toytec Boss shocks and springs. Fun fact: These coil springs are made for the front end on an 80 series land cruiser! I did quite a bit of research and they will work on our 97 4Runner giving it about 5″ of lift in the rear. They are also supposed to be able to hold weight very well. I was always disappointed with the Toytec setup when we loaded up our camping equipment and the rear end would sag horribly.

With the added height of the new suspension, you will need extended bump stops. When the axle is flexed, bump stops stop the axle from compressing any further possibly damaging the shock absorbers. You can choose to buy specific bump stops from a company who sells them at a premium OR you could head to your local junk yard and take a set off of a 1995-2005 chevy blazer/S10/Oldsmobile Bravada for $15. These will give you a 3″ extension from stock.

Once the new axle was bolted up, the jack stands were removed, the wheels and tires were fitted up, 75W-90 gear oil was added into the new housing and the brake system was bled with DOT 3.