# E46 LSD...easier than you think...



## Ben Liaw (Nov 24, 2003)

Today, the RE E46 Project Wagon began with its E46 3.46 open diff and ended the day with a 3.62 LSD M-Differential.

Considering the cost of all of those "wannabe" E46 LSD options that are anywhere from $1500~$3000, I think our option was not only the most cost effective, but the EASIEST.

We've been on the lookout for a while now, for a complete E46 M3 rear end assembly. After much patience (and some luck), we were able to get one (which included everything from brake disc-to-brake disc, including the driveshaft) Shortly thereafter, a similar setup popped up on eBay, unsold at a rock bottom $750 complete. We recently came across the same exact setup, used, for $1000. The deals are out there...you just have to look for it.

So, after a few hours of work, the entire rear end of the wagon was completely disassembled. Removed half-shafts. Remove rear open diff. Remove rear brakes. Remove driveshaft. Disconnect all sensors and cables (including ebrake cables).

The funny thing...assembly is exactly reverse of disassebly! The entire rear end of the E46 M3 assembly was dismantled on the floor of the shop until just the subframe and control arms were left. This entire unit bolted RIGHT IN to the empty spot in the wagon floor. It's a slam dunk install. An alignment was required to check the rear specs, as the trailing arms are unbolted to the car without any real frame of referrence. After the alignment, turns out we were REALLY close, just by chance.

As an added bonus, the rear brakes went from the tiny 294mm stock sizes to the 328mm M3 rears.

Going from a 3.46 open diff to a 3.62 LSD is a nice change...more immediate power for sure. I can't wait to yank out the 3.62 LSD and install the 3.91 LSD we're waiting to be completed from the diff builder. For the moment, I'll just be content with the current gearing.

For those than don't have a transplanted S54 engine/tranny, a custom driveshaft would probably be required...to bolt up to the M differential setup. However, a custom driveshaft would only run around $200-$350.


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## Ben Liaw (Nov 24, 2003)

rumratt said:


> Cool. For the technically challenged among us.. What exactly does that include?
> 
> What would be a ballpark labor charge cost if we had someone install it?


The assembly we got included the following:
- Rear Subframe (including all required bushings and hardware)
- Rear Diff
- Rear control arms, trailing arms, lower control arms
- Rear hubs, axles, brake rotors, brake calipers, ebrake cables, etc.
- Rear swaybar
- Rear shocks! (they were too lazy to unbolt them, perhaps)
- Complete driveshaft with guibo

Of course, your results may vary with parts you are able to get from your local auto recycler (salvage yard). All the little things can add up (a guibo is $95 list!), so the more you get the better.

Approximately labor was about 5 hours, not including alignment. This included the planning of the disassembly of the factory setup and installation of the new setup. If we had a tranny jack, it would have been a little quicker (wouldn't have to take everything apart).


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## Dr. Phil (Dec 19, 2001)

Dibs on the 3.62 diff :bigpimp: :hi: 

Sounds like the wagon is coming along nicely. I guess you can get rid of those baby brakes in the rear now :tsk: :stickpoke


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## Kaz (Dec 21, 2001)

Ben, correct me if I'm wrong but this swap requires EVERYTHING that you just listed. I know, for example, that the diff housings , sways, brakes, etc. all separately will NOT bolt into a non-M; you need everything from the subframe on out. Meaning you still can't piecemeal just the bits you might want.


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## ClubSpec330i (Oct 22, 2003)

Ben,

Since you probably have no need for 3.46 diff, would you like to hand it over? Let me know if you would like to sell your 3.46.

thanks,

Mack


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## MicahO (Apr 19, 2004)

Hi Ben - back from the road and ready to order that clutch arm. After the past 2400 miles and two ferry trips piloting the wife's Argo (her Quest), I'm ready for some decent seat time in the 330.

I'm very interested in getting an LSD into my ZHP, and I've spent a good amount of time thinking about the available options for that swap. I'm not in any way shilling for any of the people making e46 LSD's available at the moment, but I do have to comment on your described transplant.

While you've gotten a great rear into your wagon, and brought along some Brake goodies in the process, I couldn't agree less about your rear swap being the easiest route to an e46 LSD. It's not at all a simple swap, unless you are a shop that does this work on a regular basis and are able spend the large amount of time it takes to cruise various salvage yards looking for an entire rear end. The amount of time involved in the parts search alone is large (I'll leave that lowercase for now), and if/when you find it, you're getting parts from a salvage yard - no guarantee on history and no help if something $hit's the bed.

As for the 'wannabe' comment, just because it's not a factory LSD doesn't make it a 'wannabe' part. Brett's LSD's are hand-assembled and come with Brett's considerable reputation behind them. He can dial up as much or as little lock as you desire, which is a far cry better than the factory LSD, and they bolt right in - no custom driveshaft needed. The parts from Diffs Online are using Kazz LSD units, which are very well known in the racing world. Again, the diff will come with some guarantee of quality, they bolt right in, and the level of lock is chosen by you, the purchaser, not the folks at BMW who have to make a compromise between performance and driveability for the mass-market.

The real deal-breaker seems to be the custom driveshaft that you did not need for your M3 powered ///Monster. I'd love to see a shop like yours begin a regular search for the parts needed for this kind of swap. Doing that would require keeping an inventory of M3 assemblies, sourcing those custom shafts, and providing the user with some guarantee of quality or parts-use lifetime. Passing these costs along to a consumer would have to be included - you are a business, not a charity. Doing all of what you describe, for a consumer, and staying below a price-point of +/-$3K would probably place you squarely in the 'charity' category.

If you could publish prices for an end-to-end swap, people like me who want to move to an LSD (and wouldn't mind the brake upgrade in the process) would be able to plan something. The reality is that most of us don't have the time for an extended parts search, or an S54 powertrain, so this option is neither easy, nor inexpensive.


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## Ben Liaw (Nov 24, 2003)

Kaz said:


> Ben, correct me if I'm wrong but this swap requires EVERYTHING that you just listed. I know, for example, that the diff housings , sways, brakes, etc. all separately will NOT bolt into a non-M; you need everything from the subframe on out. Meaning you still can't piecemeal just the bits you might want.


Kaz, you are correct...you need everything. Nothing from a non-M E46 fits.

I guess that's the beauty of the swap...all of the E46 M3 parts bolt RIGHT IN. There is no fabrication, whatsoever.

The "V" brace, however, does not fit, since there are not accomodations in the chassis to bolt it into. I'll be looking into that in the future.

Whereas it's rather excessive, to get an LSD in this manner (vs. the relatively expensive methods known), I was interested in using more factory parts. For example, the E46 M3 rear end uses ring/pinion parts that are much larger than the standard E46 diff (which is fine for current non-M powerplants). Additionally, there are more gearing options for me, since it's S54 powered. With a 3.91 being built, that should satisfy my craving for more immediate torque.

Blanton does build another custom unit for the E46s, entirely out of billet chromoly. It uses standard E36 M3 ring/pinions and clutch packs, which means you can determine lockup amount (25%-100%) as well as being completely rebuildable. Ratios from as low as 2.79 all the way to 4.45s are available in those ring/pinion size as well. Last time I checked it was around $3500. This would be a serious consideration, since it does use more traditional parts in the built (which means most other diff builders would be able to service it at some point).

FWIW. LSD is nice to have again. It's been a year since the E36 was sold and almost forgot what it was like.


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