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Discussion Starter #81
MFactory 1.5 Way LSD Installation

A couple updates ago I showed the MFactory 1.5-way LSD I had just bought for my car. I finally got around to installing it over the last week. When researching LSD options for my car there wasn’t much info out there other than “Just buy the diffsonline.com setup”. That’s great but they are crazy expensive and I prefer DIY so I can learn something along the way. MFactory has a decent reputation online so I took a chance with them. I couldn’t find any detailed reviews of the plate style LSD, only a few non BMW posts that said “works great!” I plan to use this space to show some details of the unit itself, chronicle the installation process, and give follow up reviews once I get it out on the street and track. In the future I may even do some diff tuning to see how the unit responds to preload and clutch pack adjustments.

A LSD is of no use on its own. It needs a diff carrier assembly to ride in. Before all the COVID-19 craziness I went to the local U Pull & Pay to buy a 3.46 diff carrier. I decided on the 3.46 for two reasons- 1) That’s the specified Spec E46 ratio, and 2) a slightly taller ratio will eliminate one or two shifts at my local tracks. I found a remarkably nice 2002 330xi with a clean looking diff and set about pulling it out. A diff from an AWD is good because the rear diff takes less load compared to an only RWD car. For the same mileage a xi should have less wear and tear on the gears and bearings. $75 later, plus some more for a few other parts (spare trunk, headlights, etc.), I was back home and throwing the carrier in the parts washer.





The biggest issue with an AWD diff is that the input flange doesn’t match the one on the RWD 330’s. The non-330 E46’s and the 330xi use a universal joint with a 4 bolt adapter. The 330i/ci use a 6 bolt CV joint. I found a CV input flange on eBay for just a few bucks and had it shipped to my house.



Before swapping the flanges I drained the 3.46 diff. The oil looked perfect, no metal flecks at all. I then measured the gear set backlash at .005”. It’s important to get this measurement before disassembly so you can confirm it after installing the LSD.



Next I pulled out the open diff and removed the ring gear and bearings. The bearings are pressed on and require a separator tool to remove them. Do not use a hammer to remove your bearings unless you have a new set to replace them. My bearings looked perfect so I reused them.



Before removing the input flange it is important to measure the pinion shaft bearing preload. This is done by using an in-lb dial torque wrench to measure the torque required to turn the pinion. I measured this torque at 4-5 in-lb, which is common for a broken-in setup. Removing the flange requires a thin wall 30mm socket. I took a regular one and turned down the diameter to fit in the recess for the pinion nut.





A quick hit with the impact gun and the nut popped off. I then used a puller to gently remove the flange.



The new CV flange slipped on and I torqued it down until I matched the 5 in-lb reading I measured before.



On to the LSD unit itself. It is packaged nicely and comes with extra hardware to change the spring preload.



According to the documentation it is assembled in the 1.5-way setting from the factory. I wanted to confirm this and the spring and plate stack settings before installation, so I took it all apart for inspection.



Here are some detail shots for those of you who want to see the guts up close. I was pleased with the fit, finish, and appearance of all the parts.









I confirmed the factory settings as 1.5 way, 6 springs and 4 active plates. According to their manual this should be about 55 ft-lb breakaway torque and 80% lockup. Previous experience shows that I (and most “smooth” drivers) prefer low static and high dynamic diff lock up. The factory settings should be in that ballpark. We’ll see if the E46 chassis likes this setup too.
Once I had the LSD reassembled I bolted on the ring gear and torqued it down. Then I pressed on the bearings.



I then reinstalled the differential into the housing. It barely fits due to the larger case size of the LSD. With the right combination of wiggling and turning it finally fell nicely into place. I put the outer bearing races into their original locations and then snapped in the retaining rings to their original places too.



A quick check of the backlash confirmed I kept the original .005” gear tooth clearance. I then smeared some gear marking compound on several teeth and checked the contact pattern between the ring and pinion. The results came out textbook perfect on the drive and coast sides of the gear.



The diff cover then was bolted on with a thin smear of silicone gasket maker. One the silicone dried I filled the diff with a quart of Redline 75W-110 gear oil.



Lastly I pulled out the old 3.38 open diff carrier and bolted in the new 3.46 LSD carrier. The process takes about an hour on jack stands. This is where thinking ahead on my exhaust design saved time. I was able to quickly remove the center section of the exhaust with two V-band clamps and then have all the access I needed to the CV joints and diff bolts. I didn’t get any pics of this process, sorry.

So that’s it. Not too hard of an install. You just need some special tools and a little knowledge to be successful. I have now built differentials for Ford, Jeep, Mazda, Toyota, and now BMW. They are all basically the same with minor variations to the process. The car is still up in the air while I work on the splitter so I’ll write up my break-in and street driving impressions soon.
 

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Gold

This last thread is gold to anyone who wants to install an LSD.

I have learned all your steps the hard way. It cost me one burned diff (rear cover got loose, oil went out) and two others that started whining like hell shortly after installing. I also tried installing all new bearings, but then getting the contact pattern right turned out to be difficult, when the only adjustment available is in the lock rings.

Had I seen this thread 3 years ago, I would have saved a bunch of money and a lot of time!
So.. thanks, I guess :D:thanks::bawling:
 

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Discussion Starter #83
This last thread is gold to anyone who wants to install an LSD.

I have learned all your steps the hard way. It cost me one burned diff (rear cover got loose, oil went out) and two others that started whining like hell shortly after installing. I also tried installing all new bearings, but then getting the contact pattern right turned out to be difficult, when the only adjustment available is in the lock rings.

Had I seen this thread 3 years ago, I would have saved a bunch of money and a lot of time!
So.. thanks, I guess :D:thanks::bawling:
Thanks! Always better to learn from someone else's mistakes, I say.
 

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Discussion Starter #85
Such an epic build thread dude. So much so I made an account just to say nice work !
Thanks, I appreciate it! I promise to keep the updates coming. I finished up my splitter build and should have that update posted soon. I am currently working on the wing fab and installation so look for that update soon too.
 

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Discussion Starter #86
Splitter and Air Dam Build, Part 1

I previously teased my idea for a quickly detachable and adjustable splitter. I finally got around to making it. Like other E46 designs I’ve searched, my concept uses three points to attach the splitter assembly to the chassis- The front edge of the aluminum undertray and the two frame spar/bumper mounts.

The rear mount is a simple piece of ½”x.120 U-channel that was cut to length and had three holes drilled to line up with the OEM plastic undertray screw holes. I counterbored the bolt heads so no hardware protrudes. This gives me a deep slot for the splitter’s rear edge to slide into and align laterally on the bolt heads.




For the splitter template I used a large sheet of cardboard I saved from the hood packaging. I slipped it into the U-channel and supported the front with jack stands.




I then used a 4” machinists square to transfer the vertical outline of the bumper on to the cardboard. NASA TT5 rules require a splitter that protrudes no farther than 4” from the vertical projection of the OEM bumper. I cut the template oversize so I could make the final marks and cut once the splitter was mounted and the air dam was in place. I then transferred the template to a sheet of ½” birch plywood and cut it out.






The front frame mounts are made from 1.25”x.125” aluminum structural tubing. I attached them to the outer bumper damper bolts on each frame spar. This spot is perfect because it is a straight down drop to the floor pan without getting in the way of the brake ducts, air filter, or headlights. To get my adjustment I slotted the holes ½” either side of level so I can make final splitter angle adjustments once the car is on the ground at race weight.



The front splitter mounts are made from a combination of aluminum square tubing and angles. The center piece is a 1.5”x.125” tube that slips over the 1.25” frame mount tubes. The inner and outer tubes are connected by a quick release pin that I’ll show later. I attached the center tube to the two sections of angle with an 8mm bolt. This arrangement allows some angle and position adjustment just in case it’s needed later. Final weight of each mount came out to just .65lb.






Connecting the two sides is another aluminum angle that spans the center of the splitter. This part provides a lot of strength and stiffness across the middle section. I had to notch the mounts and the stiffener so everything would continue to sit flat when bolted down.




A small notch was needed in the bottom rear edge of the bumper cover to clear the mounts. You can’t see this cut unless you’re under the car. I also had to notch the fender liner pieces too.




Here you can see how the splitter mounts are attached and put together using a quick release pin.

 

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Discussion Starter #87
Splitter & Air Dam, Part 2

I want to be able to install and remove the splitter without taking the bumper off. This way I can load the car into my trailer easier with the splitter off and then take a couple minutes at the track to pop it back on. Plus I don’t have to give up any street driving ground clearance like I would with a permanently mounted splitter. With this in mind, a while ago I removed the front fog lights and filled the openings where the lights were with a thin sheet of plastic. The fog light bezels are made to remove from the outside very easily, and they happen to be big enough for me to fit my arm into when removed. This is how I install and remove the pins that hold the splitter in place.






With the splitter mounted and level I then traced the outline of the bumper directly to the wood surface using the same 4” square.




My splitter came out to 3.25” off the ground, which should be a good height for balancing performance potential and prevent bottoming out too much.




To fill the gap between the splitter and the bumper I am making and airdam out of .070” HDPE sheet. The airdam is mounted to the splitter surface with a length of .75” x .062” aluminum angle. I cut numerous slits into the angle so it could be shaped to follow the contour of the bumper outline. It is attached with #8 wide head wood screws. The part is made as two pieces so I formed and joined them in the middle with a rivet.






With the airdam mount in place I marked the splitter at 4” projection and trimmed the splitter to final shape.




The airdam material is soft and easy to cut but also very durable and lightweight. I carefully measured, cut, and riveted the HDPE sheet to the aluminum angle forming a perfect gap filling piece that stays permanently attached to the splitter.






With the fabrication finished I took everything apart and scrubbed the aluminum pieces with a red Scotch Brite pad and painted the splitter wood with truck bed liner to seal and protect it. You can also see the finished rear mounts and braces in these pictures. I am using two pieces of 3/16” aluminum that protrude from the back of the splitter. These slot into the U-channel bolted to the undertray providing a sturdy metal to metal junction. Braces were also added to connect the front mount angle brackets to the rear mounts. These braces added a lot of strength for their half pound weight penalty. Final weight of the splitter assembly is 15.5lb. If I change to ¼” Alumalite I should be able to drop another 3-4lb.








Before I reassembled the parts I traced the splitter outline onto the rest of my 4x8 sheet so I can cut and prepare a spare to keep in the trailer.




The underside of the splitter is perfectly flat other than a 1/16” lip and button head fasteners at the back edge. I used ¼” ribbed elevator bolts to attach the wood to the aluminum mounts. These have a very wide head that sucks up into the soft wood when you tighten the nuts down.




One last thing to show is the leading edge of the splitter. It is important to put a nice radius on this edge to reduce aero pitch sensitivity and help prevent catching on things in the paddock and on the track. Plus it just looks more finished.




Lastly, here are pictures of the finished product on the car. Looking mean! I can’t wait to get out on the track and see how it feels combined with my new rear wing (currently in process). I am hoping for a 1-1.5 second improvement at High Plains Raceway due to the aero improvements.



 

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Tim I've just read through the whole thread and I loved every bit of it, keep up the great work with the car.

I also wanted to do the Fortune Auto Coilovers and the MFactory upgrades down the line, and with your reviews I'm more confident with my decision
 

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Tim I've just read through the whole thread and I loved every bit of it, keep up the great work with the car.

I also wanted to do the Fortune Auto Coilovers and the MFactory upgrades down the line, and with your reviews I'm more confident with my decision
Thanks! Just trying to give back to the community a little bit.
 
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