4 bolt rear install

This is the short version of the install, where you just replace the rear diff, axles, and axle retainer cups ("axle cups"). It is much faster than a complete suspension swap, and will save you a lot of money if you are buying your new rear from a junkyard, as they won't be selling you anywhere near as many parts. Just make SURE you get the axle cups, as they aren't cheap new, and shouldn't cost much used.

The first step is the get the car up on jackstands. Loosen the lugnuts on the rear wheels, then jack the car up using the rear suspension mounts (sorry, no picture, will add one next time I have my car in the air). Then put the jackstands under the body (you should probably pad the jackstand with some wood, cardboard, or towels). THIS IS VERY IMPORTANT - you want to support the car so that the suspension can drop, it is VERY important later.

Click on pics to get the larger versions.

Tools needed:

  

    NOT SHOWN - removing the yoke/driveshaft bolts. These are a pain to do, and I didn't get a pic (will try to add later). You need a 12mm open-end wrench and socket, or 2 wrenches.
  

    Loosen and remove the bolts holding the axles to the axle cups. This uses a 14mm box-end wrench and a 14mm socket.

    Once the rear of the car is up in the air (lift the body, not the suspension, you need the suspension to sag to give you room to access the top 2 rear diff bolts later), pull the rear wheels.

    Here is the "special" tool I made, which is just a long piece of 3/16" barstock (left over from making the crank tool for the Timing Belt VFAQ), with 1/2" holes drilled in it and a small arc carved out of it to fit around the center hub. It took about 10 minutes to make using a cordless 18V drill and a die grinder, and was well worth the $3 or so it cost. Bolt it down to the hub so that it will hit the ground when you go to loosen the axle cup retaining nut. Building this tool makes this swap a one person job. Without it, it can be a major pain. You can also do without the tool by having someone in the car stepping on the brake (it may be possible just using the emergency brake), but this tool was useful as a lever when one of the nuts would NOT come loose on my car - I propped the ratchet up against the shock and lifted the bar to crack the nut loose.

    Here is the back side view of the hub with the ratchet on the axle cup nut (27mm). Note that the axle is propped up on the suspension - if it doesn't stay there, tie it in place. Remove the nuts, and pull the axle cups off. Some slide off easily, some need to be carefully pried off.

    Chris Mejia notes that if the cups do not come off easily, a steering wheel puller works very well to remove them.

    Here's a front view of the axle cups off of the car. As you can see, the 4 bolt cups should be MUCH stronger than the 3 bolt cups.

    Back view of the axle cups.

    Axle cups overlaid on each other.

    Unbolt the lower shock mounts (circled - ignore the wrench, this pic is from the FULL rear swap). This is not TOTALLY necessary, but makes the job easier.

    Unbolting the side diff mount bolts. The diff mounts with 6 bolts - 2 top, 2 side, 2 back.
  

    NOT SHOWN - removing the top bolts. We couldn't get a decent pic of the area. THIS is where lifting the car by the body counts big time. If you lift it by the front suspension mounting points, it makes it near impossible to get the top bolts out. There are 2 17mm bolts up there, you will have to feel for them. You have to loosen both of them, then back them out as far as possible with the box-end of the wrench, then switch to the open end of the wrench. Note that one is shorter that the other for reassembly.
  

    Unbolting the back bolts. At this point, the diff is almost out of the car, so be careful. Some diffs drop down, some stay wedged in place, so be ready for it to drop. Lift the diff to finish removing the back bolts. As the diff drops, you can continue to remove the top bolts.

    Here are the 2 diffs out of the car. The 4 bolt is on top. Note the axles are obviously thicker. This is where some of the strength comes from. More importantly, the spline section going into the diff is thicker and stronger. Note that the axles configuration is different.

    Note that the outer end of the 4 bolt axle flange is much thinner than the 3 bolt axle flange.

    Note that the inner end of the 4 bolt axle flange is much thicker than the 3 bolt axle flange.

    A 22mm wrench up against the 4 bolt axle. Note that it doesn't come close to going over the axle.

    A 22mm wrench up against the 3 bolt axle. Note that it does come close to going over the axle. While the 4 bolt axles are only a millimeter or 2 thicker, it makes a difference.

THAT'S IT!

Reassembly:

I will TRY to add the torque values for various bolts and more pics soon.

Credits

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Last modified: Sep 24, 1999
Copyright 1997, Tom Stangl
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