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Old 03-08-2012, 01:19 PM   #1
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E30/36 LSD into E46 Swap

Good morning fellow Fanatics. I'm hoping that this thread will go exactly as I have planned it. This is a continuation of where Raj left of here:


While brainstorming with Raj on how to do this correctly, I made contact with a differential guru that assured me that it can be done. He gave me fairly complete instructions which I will be sharing along the way. I don't have exact measurements, but I'll do my best to provide them as I go.

Disclaimer: I am NOT a differential expert. Contrary to popular belief, I'm not an expert on much of anything. I read a LOT. I generally only post when I'm fairly certain that I'm correct. That's why I'm generally right, hah. So, follow this thread with that in mind. My source is a busy man and I will do my best to not bother him during the course of this project. He has given me his blessing to share this hard earned information but as asked me to remain anonymous. We will refer to him as Mr. Wizard for the remainder of this thread.

So, let's start with what I know. The E46 non-M suffers from a serious case of one-wheel-peel. We'd all like to fix this, but our options are limited.

1. E46 M3 differential swap: This is possibly one of the least expensive options currently available. They are fairly easy to source. You'll need the entire M subframe, control arms, swaybar, halfshafts, and differential. Your stumbling blocks are going to be a) limited gear ratios (3.62 or 4.10) and b) connecting your existing transmission to the differential.

2. Kaaz: This is probably the next budget option available right now. I think the unit runs around $1000-1200 (last I checked). On top of that, you'll have to have it installed. This isn't the job for the average DIYer. If you have a friend or a hookup, this is probably good for you. The downside to this would be limited gearing options. My last search showed that the unit would only work in the 3.38 or 3.46.

3. Performance Gearing (Or whichever shop you prefer): Having Jim Blanton setup a differential perfectly matched to your needs is probably the way to go. You can choose from any ratio you like. I don't even think he charges a core charge. That means you have a spare unit in your garage just in case of any issues. Warranty. Very nice. The only downside to this unit - price. I'd love to have one, but $3000 is too steep for my budget right now.

4. That brings us to this option. Using an E36/E30 limited slip unit in the E46 housing. If all goes well, I see this as the cheapest option. Will it be the highest performing option? Probably not. This is a mass produced LS unit designed for spirited daily driving. You may be digging through salvage yards or fighting over these on bimmer forums. If this thread goes well, you may really be fighting. If the pursuit of a great performing daily driver with a budget LSD solution is what you want, this thread may help.

So, let's begin. Here's where you need to be to catch up.

Use SoloII///M's DIY to tear down your unit:


You do NOT need to remove your input shaft/pinion gear at this point. Pop out the output stubs, remove the seals, bla bla bla. He did the work, use his guide. Make sure you pay attention to which giant circlip goes on which side. I did NOT do this on my 2.93 that I will be testing this all on. I WILL do this on the 3.46 that will eventually get the transplant.

So here is what you should have handy:

On the left is the limited slip unit. On the right is the open unit from my 2.93. In the center is an output stub. We'll need all three of these to get going. Make sure the E46 bearings are in good shape. Mr. Wizard told me that E46 are not available for purchase. I'm going to double-check this with my local bearing supply, but I'd assume he knows what he's talking about. If yours are destroyed (either before beginning this project or during the next steps) this project can be tackled using E30 bearings. Your measurements will just be different to account for the difference in bearing height.

So, I'm going to leave you here. When we next meet, I'm hoping to have the bearings off of the units.

Last edited by aggieE46; 03-08-2012 at 03:05 PM.
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