e30 Limited Slip Differential Swap.pdf - Brian David Bernard

Pelican Technical Article: BMW E30 3 Series Limited Slip Differential Swaphttp://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Sli...Page 1 of 68/21/2011Order Online or Call:888-280-7799Searchoursite:Enter Description or Part NumberView Cart | ProjectList | Order Status |HelpPelican Technical Article:GetFREEGroundShippingwith thepurchaseof $75 in qualifyingpartsTech Articles• ClutchReplacement• Time to Rebuild?• Control ArmReplacement• Reading InjectionFault Codes• Transmission FluidChange• more...Tech Forums• TechnicalQuestions• PerformanceModifications• General DiscussionClassifieds• Cars For Sale• Used Parts For SalePhotos• BMW Events• Owner's GalleryExtras• 2002 SalesLiterature• Events Calendar• Chat Room• Free Email• Free Web PagesDifficulty Level: 4Difficulty scale: Adding air to your tires is level oneRebuilding a BMW Motor is level tenBMW E30 3Series LimitedSlip DifferentialSwapJared FentonWant to get some more cornering acceleration out of your BMW? Do you want to add a limitedslip differential to your car? In both cases, the differential must be replaced. In this article I will goover the steps involved in swapping out differentials in the BMW E30 3 Series from 1984-91. Keepin mind that this tech article covers all 3 series models, including the BMW E36 318ti from 1995-99,as it uses the same rear end setup.What’s a limited slip differential? Simply put, a limited slip differential or L.S.D. is a differentialthat distributes power evenly to both rear wheels. Regular differentials only distribute power to onewheel. The real advantage of an L.S.D. is felt during cornering, as power distribution is splitbetween both wheels. Basically, the wheel with less resistance will receive more power then theother. A good way to explain this is when a car goes into a turn; the outboard wheel will bespinning faster than the inboard wheel. More resistance is placed on the inboard wheel, making itspin slower. Though a series of clutches or weights, the L.S.D. mechanically sends less power to theinboard wheel and more power to the outboard wheels. This helps to increase the stability of the carwhen coming out of turns at high speed, such as freeway on ramps or that high-banked turn at thetrack.The BMW E30 3 Series cars have an excellent reputation for handling and control, however ifyou wanted to go one step further, you would get an “is” model. The “is” models featured the L.S.D.as well as other handling upgrades. The nice thing about the design of these cars is that the L.S.D.can be easily swapped into cars that did not originally come with it.The first step is to get a hold of a L.S.D. These can usually be picked up on eBay in good shapefor around $250-300. I would be cautious if buying off eBay, as there is no guarantee of the age orcondition of the diff. Your best bet might be going to the junkyard to find one. Most majorjunkyards offer a limited warranty on items such as engines, transmissions and rear ends. So youhave a little piece of mind. They are easy to spot, as there is a large “S” stamped on the outsidecover. (For all of you out there interested in doing this, and you are not sure if it’s L.S.D. or not, Ican always check part numbers for you) If you are looking to have your current differentialupgraded to an L.S.D., there are several companies out there, such as Quaife, that can convertyour standard differential into an L.S.D. many times with custom lock-up rates far beyond what wasoffered stock on the “is” models. While these are great for track use, they don’t apply very much forthe street. So, in this article we will be assuming that the unit in question is a low-mile, stock usedunit picked up from the local junkyard.Now, let’s jack the car up. First, chock the front wheels to keep them from rolling while you havethe rear wheels jacked up. Next, loosen (but do not remove) the rear lug bolts. Now, use a floorjack and jack up the rear of the car. Be sure to jack the car up on a re-inforced part of the body,such as a crossmember or chassis beam. Be sure not to jack the car up on any other part, as youcould put a hole right through the bottom of the car. I have seen Porsches in the past where jacks

Pelican Technical Article: BMW E30 3 Series Limited Slip Differential Swaphttp://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Sli...Page 2 of 68/21/2011have punctured the floorboards. A handy reference is Wayne’s article on jacking up your BMW. Thisarticle is specific to the E36 series, however, the same principles apply to the E30 as well.http://www.pelicanparts.com/bmw/techarticles/E36-Jacking_Up/E36-Jacking_Up.htmOnce the car is firmly secured on jack stands, the next step is to remove the lug bolts on therear wheels and take the wheels off. Now, look at where the drive axles are bolted onto thedifferential. We will need to separate the axle shafts from the differential in order to remove thedifferential. There are six internal Allen head bolts that hold each axle to the differential. Before youremove them, it’s a really good idea to clean them off to get any dirt of grease out of the boltheads. Any good brake cleaner should work perfectly. We don’t have to get them spotless, howeverjust enough to where we won’t have the Allen key from popping out. It’s also a good idea to hit thebolts with WD-40 or good penetrating oil. Typically, I like to let the spray sit overnight, to let the oilwork itself into the threads. This will make it much easier to remove the bolts, not to mentionpreventing stripping and seizing when you hit them with the wrench. Put the car in gear if it’s amanual gearbox. This will lock the rear end and allow you to loosen the bolts. Now remove all thebolts. The drive axles will now be free of the differential. Use a piece of rope or stiff wire to hang thedrive axles to the car and keep them from crashing downward.Now look at the front of the differential. You will see the mounting flange for the driveshaft.There are four bolts that hold the driveshaft to the mounting flange. Put the car in gear to lock thedriveshaft in place, and then use and open-end wrench to hold the nut on the end of each bolt. Nowremove the bolt. Put the car in neutral and rotate the driveshaft so that you have enough clearanceto remove the next bolt. Now put the car in gear again and repeat the procedure. Repeat thesesteps until all the bolts are removed. Now use some wire or rope to suspend the driveshaft in placeto prevent stress on the centering bearing.Now move towards the rear of the differential and remove the electrical connector from thespeedometer sensor. I forgot to do this one time and ended up ripping the wires off the ends of theconnector. Nothing was damaged to badly, but I did end up having to splice the wires backtogether.Now we have to remove the mounting bolts for the differential. I’ve found that using WD-40 oranother good penetrant spray on the bolt will help loosen things up. I’d recommend that you sprayit on all the differential mounting bolts and let it sit overnight to soak in. The next morning, itshould be a lot easier to get these loose. I have found that in some cases, using a torch to heat upthe bolts also helps to get the bolts turning. If you decide to do this, use EXTREME caution as youare directly in front of the fuel tank. Gas vapors and a torch = explosion. Just use enough flame toheat the bolt up slightly. This will cause the threads inside to expand and free up.Next, put a jack under the differential to support it’s weight. Trust me, you don’t want thedifferential falling on you while you are under the car. Now we have to remove the two rear uppermounting bolts. These are located at the top of the differential. You will need to use an open endwrench to get these off. You may also need to use a “cheater bar” to loosen the bolts. A cheater baris essentially a large piece of pipe fitted over the wrench. The extended length of the wrenchprovides you more leverage. Just like you learned in basic physics. A longer lever equals less forcerequired to move it.Now remove the two front mounting bolts. They are located at the very front of the differentialon either side of the driveshaft. Once again, you may have to use the cheater bar in order to getthem loose. Now remove these bolts. Lastly, remove the nut and bolt for the rubber mountingbushing. Use an open-end wrench on the nut to hold it in place while you loosen the bolt.Now we will be able to lower and remove the differential. Keep in mind that the differential isvery heavy, so use caution and while pulling the differential back, lower the jack. The differentialwill come out of the car.Once out, take the old differential off the jack and place the new L.S.D. differential on the jack.Now position the new diff in roughly the position it would fit in the car, but slightly to the rear. Wewill need to do this in order to angle the diff into position. Now start to raise the jack. As you bringthe diff into position, push it slightly forward to line the driveshaft up with the input flange on thefront of the differential. Once, there, slide a bolt through to hold it in place.Now, use the jack to carefully lift or lower the diff until the mounting holes line up. This maytake a few tries, as the diff is very heavy. Once you have it correctly positioned, slide the frontmounting bolts through the mounting holes and torque the bolts to 59ft/lbs. each. Now re-installthe rear upper mounting bolts and torque them to 59 ft./lbs.

Pelican Technical Article: BMW E30 3 Series Limited Slip Differential Swaphttp://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Sli...Page 3 of 68/21/2011We now need to re-install the driveshaft mounting bolts. Take the car out of gear and rotate thedriveshaft until the mounting holes line up. Now re-install the rest of the bolts. It’s a good idea touse new self-locking nuts on the ends of these bolts. These nuts will not come off once torqued. Usean open-end wrench to hold the nut in place and torque all the mounting bolts to 53ft./lbs. Nowattach the sender for the speedometer on the rear of the diff.Now we need to re-install the axle shafts to the new differential. Before you start, make sure toclean the mounting bolts. They must be clean and free of grease before you install them. Now,make sure the car is out of gear and rotate the flanges on the side of the differential until the boltholes line up with the ends of the drive axles. Thread the 6 bolts into the flanges and put the carback in gear. Having the car in gear will lock the diff and help you torque the mounting bolts. Thereare two different sizes of bolts used on these cars, M8 and M10 Torx. If you have M8 bolts, torquethem to 47 ft./lbs. If you have M10 bolts, torque them to 74 ft./lbs.It’s a good idea to change the diff oil while you are under the car. Look under the diff, you willsee a hex-head plug. This is the differential drain plug. In order to drain the old oil, we will need toremove this plug. Slide a drain tray under this plug. Now, look at the back of the diff. You will see asimilar plug on the rear face of the differential. This plug is the fill port for the new differential oil.Now, remove the fill plug first. Use a 14mm Allen key or socket to remove the two plugs. Thiswill help relieve any vacuum built up inside the diff and make it easier to drain the old fluid out.Next, remove the drain plug from the bottom.Immediately, the differential oil will pour out. It should take a few minutes for all the fluid to drainout.Once all the old fluid is out, re-install the drain plug and tighten. Next you will want to measureout the correct amount of fluid for the differential. For 4 cylinder cars, you will want to measure out1.2 quarts of oil. For 6 Cylinder models, you will want to measure out 1.8 quarts of oil. BMWrecommends you use BMW SAF-XO Synthetic Oil for differentials without limited slip, or use BMWSAF-XLS Synthetic Oil for differentials with limited slip. In my personal experience, I have foundthat Swepco Lubricants work equally as well in the differential. However I would use BMWrecommended fluids in cars still under warranty.Now, use a siphon or pump to get the new fluid into the fill port on the rear of the differential.When the fluid starts to pour out of the top of the fill port, the differential is full. Remove thepump/siphon, and re-install the fill port plug and tighten using a 14mm Allen key.Lastly, re-mount the tires and snug up the lug bolts. Now lower the car and tighten the lug boltsusing a criss-cross pattern.Well, there you have it - it's really not too difficult at all. If you would like to see more technicalarticles like this one, please continue to support Pelican Parts with all your parts needs. If you likewhat you see here, then please visit our online BMW catalog and help support the collection andcreating of new and informative technical articles like this one. Your continued support directlyaffects the expansion and existence of this site and technical articles like this one. As always, if youhave any questions or comments about this helpful article, please drop us a line.Comments and Suggestions:njemtrnJuly 28, 2011Comments: I have a '91 318i with a 4.10 diff that needs to be replaced.the only diff i can find by "diff" i mean the whole assembly, with thecase and all internals is a 3.91 ratio. would i need to anything besidesthe diff to swap ratios like axle or sensors?nickJune 20, 2011Tiago SilvaMarch 6, 2011Comments: of what model diferential can i put to my e30 318is????thanksComments: I'm in the process of installing an LSD for my E36 325imedium case diff. I want to change only the inner parts not a completeswap. Is there any way i could find info about the installation of theLSD. I know there is some precision tools and tolerances involved in theprocess so I'm searching for a good guidance to try and do that, andwhile at it, change my final drive ring a pinion from 3.15 to 3.45 or 3.91since the car is mostly for going sideways.Thanks and great site.

Pelican Technical Article: BMW E30 3 Series Limited Slip Differential Swaphttp://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Sli...Page 4 of 68/21/2011Followup from the Pelican Staff: Rebuilding differentials is not alwaysstraightforward. I'm not sure about the BMWs, but on the Porsches, youneed some special tools to set the clearances on the ring and pinion. Iwould really just recommend that you do a swap of a completedifferential unit with another. If I understand you correctly, you soundlike you want to swap the internals of an LSD into a regular differential,which I'm not even sure is possible. - Wayne at Pelican PartsTheOneFebruary 19, 2011e30 for lifeFebruary 16, 2011318tiDylanJanuary 19, 2011funcrewDecember 10, 2010driveandtractionDecember 6, 2010backdocMay 21, 2010Comments: I own a 91' 318is. I am not sure if it has an l.s.d, ia friendtold me only one wheel would spin during a burn out. Could this behappening because the diff might need a tune up?Followup from the Pelican Staff: If one wheel is planted firmly on theground, and the other is spinning, then you most likely have an opendifferential, not an LSD. - Wayne at Pelican PartsComments: I have a 86 325 with 2.93 gears and also have 93 325iwith 3.91 and limited slip, want to put 3.25 ratio in the 86 325 withlimited slip can i reuse the limited slip from the 93 325i and do you sellring gears? building an e30 with s50/s52 with SD5Followup from the Pelican Staff: Hmmm, I'm not sure that wouldwork - I think the E30 and E36 diffs are different, but I'll freely admit, Ijust don't know. I'll post this on the forums, and perhaps someone therehas done this swap previously? - Wayne at Pelican PartsComments: I just bought a 3.93 LSD from an e30 and I plan on puttingit into my 318ti. I read on a few forums that I need to get e30 halfshaftsand I also read on other forums that I do not need them. Is itpossible with my stock ti ones? I really do not want to buy e30 ones.Followup from the Pelican Staff: The rear of the 318ti uses a lot ofcomponents recycled from the E30 world. I do believe that you can swapin the E30 differential into the 318ti with a minimal amount of partsreplacement. I think the half-shafts are the same as on the E30 and Ithink it will work well, but I'm not 100% sure. - Wayne at Pelican PartsComments: Thanks for the writeup! A couple issues - One, I don't seewhy the road wheels need to be removed. Two, why didn't you fill thenew diff with oil while it was out of the car?Comments: For 188mm and 168mm LSD clutch plates Check out mywebpage at driveandtraction.blogspot.comComments: Hi All,I have a similar problem as Ant. Bought a 98 M3 auto sedan for my sonlast Dec'09 and has been trying to figure out a vibration problem whenaccelerating. The vibration ocuurs as I pass 25mph and goes away asspeed picks up, no vibration when coasting down or very slowacceleration.The vibration used to occur at 35 mph, then I replaced engine & transmounts, guibo, csb, then the vib is more noticable and shifted down to25 mph. Since then I've had the CV joints rebuilt, changed diff mounts,RTAB, all rear susp bushings with no help. When I support the rear atthe RTA and run the engine, put it in R or D, I hear a crucnhing noise &vibration coming from the diff area. Sounds & feels like something iscatching, grinding, crunching. This is the reason I had the CV jointsrebuilt last time because when I diconnected the drive axles, thecrunching went away. I was so sure the CV jts were bad, but since I'drebuilt the CV jts, put the car back together, it wasn't the CV jts afterall.Is there a better way to diagnose where the problem is coming from? Isit from the diff, drive shaft or auto trans. I also replaced all the fluidsauto trans, diff, engine when I got the car.Followup from the Pelican Staff: Hmm, you've tried all of the toughstuff so far, perhaps the solution is the easy stuff? Try rotating the tirescorner to corner or having the balance checked. Make sure the rotorsare okay and not dragging. Sometimes the system will have a naturalfrequency that is only triggered under load. Driveline components would

Pelican Technical Article: BMW E30 3 Series Limited Slip Differential Swaphttp://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Sli...Page 5 of 68/21/2011theoretically be immune from the actual speed of the vehicle, unlessthey are internal to the transmission. I.E. you would feel the vibrationsat a certain RPM, not a certain speed. Hope this helps... - Wayne atPelican PartsTRUEBLUEApril 12, 2010Comments: HI I AM LOOKING FOR LIMITED SLIP DIFF CLUTCH PLATESFOR BMW LIMITED SLIP DIAMETER OF PLATES ARE 88MM. CAN ANYONEHELP ME.THANKS TREVOR.Mark Comments: I have then same problem as ANT with my 88 325ic -172,000 miles. A couple years ago, a mechanic replaced the carrierbearing non-oem and it solved the problem - for a while - now it's back.I started as a vibration coming from right rear, now it's a thump. Oncethe car is moving, its fine. Also confirmed its not the CV joint, doesn'tsound like a bearing problem. I have decided to replace differential,assuming the carrier bearing is a part of that?April 7, 2010Der Bart84January 29, 2010scorpionJanuary 18, 2010suveNovember 23, 2009JANovember 16, 2009MuleSeptember 30, 2009AntJuly 29, 2009Comments: Thanks for this article! The Pelican articles were already ofgreat help to me. I would like to ask you the following: can I swap myEuro e36 325i differential with a differential with a lower end gear ratioand still keep a correct value on the speedometer? Thanks in advance,BartComments: i have a 93 325is i want to swap the differential can ireplace it with a newer bmw differential or what other recomendetionsyou guys recomend.....Comments: i am looking diff lsd for my e30 89 325i. in what car i canfind 3.92 and 4.10 ratio?Comments: This is an excellent article. First time changing a differentialand it went without a hitch. Thanks.Comments: i'm looking into a diff out of a wrecked M3 for my 325icoupe. i've heard the output shafts need to be swapped. will the onesfrom my current diff fit the M3 diff and if so do they pull out and swapeasily?Followup from the Pelican Staff: Good question, but I don't know theanswer. One thing though - you really don't need an LSD for the street,and in reality it will not help you too much with non-track driving. -Wayne at Pelican PartsComments: Appreciate the insight. Fairly certain it is the diffy. Iexperienced this problem previously in a different vehicle. It feels verysimilar. However, I will verify that the driveshaft couplings are in goodshape.Any comments on the fluid/additive selection?Can you offer any info on the significance of the "M" designation for thismodel? Haven't found anything very specific online. Again, mostappreciated.AntoniFollowup from the Pelican Staff: Yes, try Swepco 201 - all thePorsche guys swear by it for the 915 transmissions. I've had good luckwith it too and I recommend it in my books. We sell it here on the site.-Wayne at Pelican PartsAnt Comments: I purchased a 1989 M535i with LSD suspect the M-designation is a European one, but not sure - 4 speed auto/3.5L "bigsix" B30 for dirt money. It exhibits sort of a thumping sound duringacceleration from a stop, which is transmitted through the car enough tofeel, but is otherwise quiet past 5-10 mph. I switched out the differentialfluid and replaced with Mobil 75W90 synthetic and added 200 ml of aTrans-Ex friction modifier LSD additive total volume = 1.8L; 1.6L fluid +0.2L additive. However, this has not remedied the thumping situation.What would you recommend? I heard Red Line is the diffy fluid ofchoice, but I also heard some conflicting accounts and since I trust Mobil

Pelican Technical Article: BMW E30 3 Series Limited Slip Differential Swaphttp://www.pelicanparts.com/bmw/techarticles/JF-Tech/BMW_E30_3_Series_Limited_Sli...Page 6 of 68/21/2011July 27, 2009Synthetic, I went for that instead. Possible that the friction modifiersucks? Or does it sound like the diffy has to be dismantled and manuallycleaned to free the mechanism? Look forward to your response. Thanksin advance for any assistance you might be able to provide. AntFollowup from the Pelican Staff: Problems like these are tough todiagnose. I would take a closer look at the driveshaft, and also thewheel bearings and CV joints too. They often exhibit problems like theseat times. - Wayne at Pelican PartsWrite a Comment:Comments:(2,500 characters max)Your nickname:Your email:Upload a Photo:Email Optional - so that we can notify you when a staffmember responds to your question. Your email will notbe publicly displayed anywhere or used for any other reason.Browse...* I have read and agree to abide by the Comment Submission Guidelines.SubmitGot more questions? Join us in our BMW Technical ForumMessage Board, and ask a question to one of our manyautomotive experts.Search our site: Enter Description or Part Number View Cart & CheckOut | Project List | Order Status | HelpRecommend this page to a friend...[Home] [Customer Service] [Shopping Cart] [Privacy Statement][Contact Us] [About Us] [Shipping] [Map to our Location]Copyright © 2008 Pelican Parts Inc.