How To: 240sx Open Differential to LSD Swap

So you’ve read this article: Fun With Legal LSD and decided you want to make the switch from your crappy open diff to an awesome limited slip diff. This article is meant to show you how to perform the most basic method of upgrading to a limited slip – swapping the “pumpkin”.

You’ll want to go online shopping or junkyard hopping to find one. What does it look like? I’ve always had a tough time finding a side by side visual comparison between the 2 S13 differentials (R200 vs R200V), so here it is:

The open diff (R200) is on the left, the limited slip unit (R200V) is on the right. I got the viscous limited-slip differential (VLSD) many years ago off Ebay (from Japan). They claimed it came out of a 180sx. At the time, it was the only one I could find that had the same half shafts as the diff I had (6 bolt, AKA “3 sets of 2” design).

To start, jack the rear of the car up (I put the jack under the diff) and support it on jack stands.

Next, locate the diff. Start by removing the 12 half shaft bolts (in the area of the hands in this picture). There are 6 per side. 12mm bolt head, 12mm nuts, and lock washers on all:

Before going any farther, you’ll probably notice that the output shafts are still pretty well stuck to the CV axles. I’ve tried beating them apart, and it can be done, but it’s a pain. Over the years, they get a little rust built up between the 2 parts, making it a royal pain to get apart. Get in the car, throw the E-brake on, start it up, put it in gear, and drop the clutch. It should bust one side free. Shut the car off, put a few bolts in the side that busted free (but don’t tighten them too tight), and repeat the process. This should bust the other side free. Remove the bolts you just re-installed, and continue on with dis-assembly.

If you have ABS, go ahead and disconnect the sensor now. It plugs into the diff near where the drive shaft comes in. Follow the line to the connector on top of the subframe and remove it from there.

Next up, remove the drive shaft bolts from the diff flange. Nissan likes to use the drive shaft itself to brace the bolt head side of things, so you don’t have to use a backup wrench. Just throw the car in gear to hold the shaft, loosen the nuts (14mm) and remove the bolts. Swing the drive shaft out of the way (you might have to push it forward a bit to get it to clear the differential flange).

In order to gain mobility once the diff is loose, remove the rear sway bar brackets. They are held by 14mm bolts. The sway bar wont completely come out (its still fastened to the knuckles), but it doesn’t have to.

Now is a good time to put the jack underneath the differential.

On the S13, there will be 4 studs (as seen in the pictures above) sticking out of the back of the diff that mount it to the rear sub-frame. The 2 bottom ones are “acorn” nuts, the top 2 are open. They are all 17mm. All that is left now, is the 2 main support bolts at the front of the diff. They too, are 17mm. Once those are out, the diff is loose.  I had to rotate and wrestle mine to get it to clear the CV axles. One guy handles the diff while the other manhandles the axles with a pry-bar.

Here you can see the 2 main mounts I was talking about earlier (17mm bolts), as well as a side-by-side comparison of an ABS equipped diff (left) vs a non-abs diff (right).  I disabled my ABS before doing this swap, and the car the open diff was going into doesn’t have ABS, so I just cut the ABS cable.

If you are swapping a like differential (ABS to ABS, or non-ABS to non-ABS), you can go ahead and install the diff in reverse of dis-assembly, crack a beer, and get on with life.

If you ARE changing the ABS gender, read on:

Reference the picture above. You can see the flange style is a little different. The distance on the casting for the ABS differential is a bit longer than the non-abs model.  Here is the ABS model:

and here is the non-ABS model:

So what does all this mean? Well, it means you have to do 1 of 3 things:

1. Either find and use a drive shaft for the differential and transmission you’re using (manual or automatic, ABS or non-ABS) – This requires you to unbolt the drive shaft from the carrier bearing (2 17mm bolts, which you can see in the original jack-point picture posted above).

2. Swap the rear portion of the drive shaft to the correct shaft for differential gender (transmission doesn’t matter at this point, and you don’t have to unbolt it at the carrier bearing):

3. Order a custom 1-piece drive shaft from shiftmasters.com

For more reference pictures and text, refer to the 240sx factory service manual.