Installing a DSM 4 Bolt Rear End

Installing a DSM 4 Bolt Rear End


The trio of turbocharged 4 cylinder vehicles commonly termed “DSMS” are some of the more popular sport compact cars from the mid 90s. With the robust 4G63 and available all wheel drive, it made for an easily tweakable machine capable of reaching 300 whp without many upgrades.

While the motor was way ahead of it’s time, many other features of the vehicles left things to be desired. Once such area is in the 1st generation of these vehicles, where the rear end is a 3 bolt / weaker version than the one found in later models.

Today we’ll be installing a DSM 4 Bolt Rear End to upgrade this first generation Eclipse GSX and improving it’s powertrain and reliability.
Installation time: 1-3 hours

This swap is for people who have either broken their 3 bolt rear ends, or want something stronger. In order to complete the installation of a 4 bolt rear end into a car previously equipped with a 3 bolt, you will need the following:

  • (1) Rear diff
  • (2) Axles
  • (2) Axle retainer cups
  • (8) Nuts, bolts, washers
  • (1) Quart rear end gear fluid. We used Synergyn.


  • 12mm socket with ratchet and extensions
  • 14mm socket with ratchet and extensions
  • (2) 14mm wrench
  • (2) 12mm wrench
  • 27mm socket
  • Crowbar
  • Flat screwdriver

We have the luxury of a lift, so the pictures are of the car on a lift. The same premise applies to installs using a jack, just make sure when you use jack stands, you don’t place them in a place that keeps the rear end up. You want the rear end to be fully uncompressed. Try to jack up the car a couple of feet for ample room.





Here is a DSM 4 Bolt Rear End from our friends at Attarco Motors, our local wrecking yard. This particular unit has not been drained, so we’ll be doing that first and cleaning up the pumpkin in preparation of install.



Here you can see why these rear ends are called “4 bolt”. The axles are also slightly thicker.



We’re now going to begin the process of swapping the rear end. Here is the car on the lift. First you will need to remove your catback. This should be pretty straight forward. Remove the two bolts holding it to the catalytic converter or testpipe, and slide it off the hangers.



You’ll want to start by draining the fluid out of your rear end. If you don’t care about keeping your old rear end, you can leave the fluid in here, and not pull the axles out. We recommend draining the rear end, and pulling out the axles to prevent the axle boots from tearing when the axles hang during removal.



Make sure you have a container to catch at least one quart of oil.



Here are the bolts holding your axles to the axle retainer cups. As you can see there are 3 of them, which is why this rear end is a 3 bolt. You will need two 14mm wrenches to get these off. Put one wrench on the nut, and one on the bolt. If a bolt/nut is hard to reach, just rotate the wheel slowly to give you enough room. In order to remove these without the wheel spinning, you will need to put your ebrake up.



Here is a picture of us removing the axle retainer cup bolts. To remove the actual retainer cup, you will need to use something to break them free, or a steering wheel puller. They sometimes do not come off easy.



With the axle retainer cups off, you will see this nut. This holds the cups to the suspension. It’s a 27mm nut. If your ebrake isn’t strong enough to hold the wheel while you are loosening this, you may need to use power tools.



This is where the driveshaft attaches to the rear end. We saw the bolts were rusted, so we added some WD40 to all the bolts. These are 12mm, and you will have to take these off same as you removed the axle retainer cups.



These are 2 of 4 bolts that hold the rear end to the frame. These are 17mm. When you remove these, and the two side bolts (pictured below) you will need to be sure you have a jackstand under your rear end, because the rear end will want to drop at least 6 inches or more. Be careful, it’s heavy!



The last two bolts holding the rear to the frame. These are 17mm.



Now for the two bolts last bolts shown below.



The tricky part is removing the two bolts up top. There are two 17mm bolts. Note when they come off which is longer or shorter, as you will need to remember this for reassembly.



With the rear end removed, you can now begin the process of putting your 4 bolt in. Just reverse the process, and you will be set.



Here are the new 4 bolt axle retainer cups on the car. Ahh…!



During reassembly, we had a hard time lining up the rear end with the frame plate that holds the rear end in place. We found by removing the two nuts on either end above, that we were able to move that plate around, and connect everything easily. Remember to jack up the rear end so that bolting back those two nuts will be easier.



Here is our DSM 4 Bolt Rear End installed on the car.

Happy Launching!