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Vorshlag Track BMW E46 Development Thread

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  • #76
    continued from above


    We had a bit of a dead line for a "show and tell" meeting with a supplier in February 2020, who needed to see this race car. It was a good incentive for us to push harder and get more things done to the E46 - like installing an LS engine, installing suspension, having the cage mostly done, nose mounted, etc.

    We had the "backup" aluminum 5.3L long block up at HPR but brought it back and mounted a real road race style oil pan to the engine, then stuck it into the car.

    Of course we had a bunch of LS swap parts we sell to use for this, but luckily we had some early prototype headers, our original prototype mounts, and a few other leftovers to use. This Summit steel road race oil pan above fits with miles to spare - something we wanted to test on this E46 swap anyway.

    We built our shop 2015 Mustang #LS550 swap around this oil pan, and it seems to fit anywhere the 1998-02 Camaro pan or any of the Holley LS pan fit. We will test this in this road race setup on both the 5.3L and the 6.3L stroker that will go in later. With a wet sump oiling system and an Accusump, of course.

    Great fit on the kick-out style oil pan, so we'll keep that. The oil filter mount comes off for use with a remote filter and oil cooler, which we will show later. Found these tall LS valve covers with the "CHEVROLET" script, and we will use these with remote coil mounting.

    This is a Gen IV truck engine - which all come with DOD features we have to bypass. This requires a unique upper cover (ICT Billet, shown above), and Gen III style front cover, timing chain, cam shaft, and lifters. We're going to do initial testing with this 5.3L so we're getting it ready.

    Then we installed the Dorman "LS2" intake and a 90mm DBW throttle body. Then a set of our E46 stainless long tube headers.

    That's as far as we got for the show and tell - the motor has since been removed and then reinstalled with a new transmission.


    As I mentioned last time, we had a few 210mm M3 diff housings (which come with limited slip differentials from the factory) and two complete E46 M3 rear subframe assemblies, as shown below left. Everything on the E46 M3 version is stronger - the differential housing, trailing arms, rear brakes, and more. The E46 non-M rear subframe (see below right) has a number of disadvantages.

    In the long run it will be more cost effective for us to convert our 330Ci chassis to use the E46 M3 rear subframe and M3 diff than to convert the 188 mm Medium Case E46 housings to limited slip.

    Since none of the "non-M" E46 cars ever came with a limited slip, and many of those medium case housings have a ring gear welded to the diff case, it can get pretty costly to convert one to limited slip. I've done this conversion on non-M E46 cars a few times and it is always shocking how costly this is to do. The differential mounts on the non-M case are also different, and less than ideal (see above right). The available gear ratios on the larger M3 housing also work better for our V8 engine. We will be beefing up even the M3 bits, and will show the various steps below.


    We have a few complete E46 M3 rear subframe assemblies, brake to brake. We buy these when they come up for sale, and in one case we had a rusty version that was in a northern car that we picked up cheap. We took the ugliest of our available rear subframe assemblies apart to use for this project.

    This involved removing all of the subframe bushings, shown above left. This took a little work but they came out relatively uneventfully using our many BMW specific bushing tools.

    You can see the rusty surface of this subframe housing, above. It wasn't deep rusty, just ugly surface stuff. I took this and dropped it off to be bead blasted in November 2019. We got it back in mid December but didn't get a chance to work on it further until January 2020.


    While the subframe was coming apart we decided to test a new product we had found. The Rear Trailing Arm Bushing (RTAB) on the BMW E36 and E46 chassis is a complicated joint that has to pivot and rotate in 2 different axis.

    We don't use polyurethane in this joint, ever. Instead, for the past 16 years we've been in business, we press in an OEM rubber bushing + our RTAB "limiters", which we machine from UMHW for its self-lubricating properties - as shown above. This limits how much toe change can happen with full articulation of this rear trailing arm. A better solution for a race car is to use an aftermarket spherical metal bushing assembly here. The former works well on street and dual purpose cars, the latter not so much. A little road grit + rain will quickly wipe out an all metal bushing located so close to the ground.

    For this build we wanted to try a new "sealed" spherical bushing that Jason found. This should give us the best of both worlds. Water proofing a spherical bushing (like BMW does for some other rear suspension locations) would allow for full articulation in 2 axis, without the rattle and bang that worn sphericals give you in a short amount of street driving. Tim removed the M3 rear trailing arms (above left) from the subframe, then Myles and Jason pressed out the old bushings.

    We found an OEM replacement sealed spherical that was almost the right size and we made it work in this location. It wasn't easy, and it took some custom machine work and some other compromises. For now we're not releasing what we did or offering this as a kit to sell until we can test this car on track. With a little bit of work we think we can make this easier to install for the DIY crowd.

    We installed and fitted the bushings on the two sides two different ways, testing two methods. It was "more than a press fit" getting the spherical housing into the Rear Trailing Arm. Once we got the fit where we liked it, they were both pressed into the arms with the giant C-clamp bushing press shown.

    For now this isn't an easy "DIY" job but we're working on some other ways to make this work better. The articulation is perfect (above right) and should be the right solution for E36 and E46 chassis cars, once we can make the bushing more perfected for this application. More on this later.


    There were a number of things I wanted us to stitch weld as well as some reinforcements to make.

    Up first was a pair of brackets that held the rear swaybar. Nobody makes a reinforcement kit for the E46 M3 subframe so Myles drew up and CNC cut out these plates above.

    Likewise the two rear differential cover mounting brackets looked a little underwhelming, so I asked Myles to make the brackets above.

    After he made some cardboard templates and we discussed a number of tweaks it was time to turn them into CAD drawings then CNC cut them on the plasma table. After they are cleaned up and bent they fit these locations well. After showing the picture above a number of folks reached out and we have made this E46 M3 kit available.

    Myles TIG welded these reinforcements to the 4 locations we wanted to strengthen, then stitch welded a few spots that the factory skip weld. This is part of why we bead blasted the whole subframe - it makes for cleaner welds, shows any flaws hidden under the factory paint, etc.


    After we got the rear subframe back from powder coating it looks beautiful. We rounded up a set of Powerflex "race polyurethane bushings for the subframe (4) and differential mounts (3). Some might find our choice of poly unusual, as there are Delrin and even aluminum options for all of these locations. Well having done all of that before we knew that this option would give us the least NOISE while controlling any unwanted movement. Aluminum bushings in particular make for a lot of loud crashing and banging, which can be unsettling in an 8-24 hour race, over and over.

    Brad pressed in the bushings into the housing (above left), which had already been removed before blasting. The diff housing was then tackled with some special tools we have just for these 3 locations.

    Two of the bushings for the M3 housing are in "ears" that extend out from the aluminum rear cover. These are relatively easy to get to. The front bushing is near the pinion flange and goes in the right side - it is pressed into the subframe assembly, and is a little trickier to get to. The diff housing then bolts through this bushing to mount the front.

    With all of the bushings pressed into the subframe and diff housing it was time to joint them together, shown above and below.

    This selection of "harder" durometer polyurethane bushings should provide the control needed between these two pieces, which normally rock and roll around on very soft OEM rubber bushings. This movement, of both the diff to the subframe and the subframe to the chassis, is what causes so much flexing of the sheet metal tub - which leads to cracks that have to be repaired. We will fix this by adding reinforcements to our chassis in a later update, of course.


    One of my goals for this project it to develop new products - and one area we have been pushing into lately is seat brackets. I moved us into this arena reluctantly, but since many of the chassis-specific seat base bracket offerings out there are so terrible (too tall, too flexible, not safely built) that I felt we were doing the community a disservice by staying out of this area.

    I wrote this forum thread last year explaining the "what, why and how" of our unique form of seat brackets. We have made these for 5 different chassis now and will be offering the E46 versions soon after I post this. We make these to bolt to the chassis, have mounting holes for lap and anti-sub belt anchors, and leave a swatch of metal that the end user drills and bolts their side brackets (fixed) or sliders to. All of these designs are minimally tall and have reinforcing ribs underneath, and we make them 100% in-house with CNC cut parts, TIG welding them on production fixtures.

    We normally take manual measurements of each chassis' four factory mounting holes, but this time we were willing to try some new technology - 3D scanning. A helpful sales tech came by to demo his scanning products and used this chassis for the test. What it gave us was a point cloud that we could then translate into a CAD design. Don't know if it really saved much time, but it was cool watching this tool being used.

    Myles turned that into a working prototype, which he CNC cut and we tested in the car (above left). The E46 chassis is pretty narrow and what he realized pretty quickly when this prototype was placed in the car is - we usually offset a racing seat pretty far towards the tunnel. The factory steering wheel isn't even centered on the factory BMW seat. So I worked with him on version 2, which has this offset built in, that he cut, tested, then welded in the reinforcing ribs for (above right).

    Tim worked on the sliders and side brackets, which were tested on the seat, then the holes were transferred to the bracket (above right) and the sliders + brackets were bolted into the car. So we have one seat mounted. As soon as we make the passenger side version (they are sometimes mirror images of the driver's side, sometimes now) we will release this as a bracket to sell.


    For the past several months our E46 had been up on jack stands and stuck in this cramped work bay. This was because we had removed all of the OEM suspension and had only mocked up up one front corner with a strut/spring/top mount. This let us work on the big brake kit there but we needed to get this car down on the ground and mount up some wheels and tires to move forward in the build. This meant we needed a set of coilover shocks.

    We had put out the ask for a little while, and MCS came through in a big way. Getting triple adjustable MCS dampers for this car was the culmination of a lot of hard work, a long record of MCS sales and race wins using their parts, and a little begging.

    Normally we will stretch our budget to go for internal doubles (TT2) or remote double (RR2) adjustables on our shop owned cars - which tend to be focused on Time Trial and autocross competitions. My S550 Mustang has RR2s, as does my wife's Optima entry, an LS powered 86. But MCS felt that the triple adjustables were worth it on this endurance road race car.

    The triple adjustables give us low speed Rebound, low speed Compression and high speed Compression adjustments. This is especially helpful on a Wheel to Wheel race car where "defending your line" means using a bit more curbing than you would in a TT or HPDE car. The rear shocks are setup to run as a coilover, which we normally don't do for various reasons on the E46 or especially E36 chassis BMWs.

    We got to work quickly installing these onto our E46. The front was a simple bolt-on affair with springs we had on hand. We needed that end on to be able to spec the front wheels - which we try to keep as far inboard and as close to the strut as possible.

    continued below
    Terry Fair -
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev


    • #77
      continued from above

      Out back was a bit trickier. MCS wanted us to run their inverted, eye-to-eye style rear shock with a 22mm shaft and coilover spring mounting, using a dual / helper spring setup to keep the tire loaded - even at full droop.

      This required the use of the MCS "eye" upper shock mount, which bolts into the stock shock tower (see below). Brad mounted that and I was happy with how much inboard wheel clearance we still had. Whew!

      This type of spring mounting can sometimes compromise inboard wheel room - a coilover rear on the E36 chassis absolutely will eat up tire room, but the E46 chassis does not suffer from this space constraint. We will need to reinforce the rear shock tower to take full suspension loads, instead of just damper loads, however. We have some ideas and will share that work in a future update.

      Brad handled this MCS install in early February 2020, which let us mount the 17x10" wheels and roll the car out of that back bay for the first time in months. Big step, seeing the car down on 4 wheels and rolling again!


      Shortly after getting the suspension installed we were able to get the E46 over to a 2-post lift and up in the air.

      I asked Brad to temporarily tape the Clinched flares (we showed last time) to the car at both ends on the driver's side. These are made to be "trimmed to fit" the contours of your car, and this is where the look and fit of these will improve. For now we're just taping them in place.

      This let Jason come out and inspect the clearance inboard, outboard, and relative to the flares. These flares are going to be big enough for our 18x11" wheel and 315/30/18 (or thereabouts) 200 treadware tire package.

      The test wheels shown here are NOT our final race wheels, and they are already 10" wide. We're looking to add another inch of wheel width and a good bit more tire. The "stock vs flared" pictures above should show how much room we gain with these flares. Jason was able to spec the wheels so that the same set can be used front and rear (fewer spares needed, and they can rotate) with a 12mm spacer up front, which is normal for most BMW wheels. These wheels were ordered from Forgestar before their additional bespoke wheel charge came into effect, which was a bit of a surprise in March 2020 when that came down.


      We had been debating head lights to use and how to mount them. The factory "radiator core support" (shown below) is the easiest way to mount the headlights, but it has a bunch of structure we don't need. We have bought a number of these over the years from the import suppliers and they all worked just fine. Looking through our pile of spares we had another brand new one in stock, so we decided to splurge the $55 already spent and use it.

      Our car didn't come with one, as it had been in a front end hit. These are pretty common to replace after any small accident, and BMW keeps them painted black no matter what color E46 they made. It didn't take Evan more than a few minutes to bolt this in place, then we started looking at the extra plastic clips and mounts needed to bolt the headlights in place.

      Instead of ordering a half dozen special clips from Germany we decided to add nutserts into those square holes in the core instead. Evan drilled the square holes round, then installed some M5 rivnuts. We used some old headlights to make sure they lined up and they did.

      The radiator support was then cut up quite a bit - looking for room to fit the radiator. Our goal was to open up a narrow spot and then shove a wider than stock radiator and roll it forward into all of this area we added by making a tubular bumper beam. Unfortunately the headlights themselves are wide and we don't gain a lot of room between the lights to roll the radiator into. But we did remove a lot of structure that was blocking airflow.

      The "mock-up" headlights we had on hand were fitted in place when the rivnuts were being added. These looked rough, and were some old OEM units we had leftover from a customer's build when we installed new headlights and turn signal housings on his M3. Tim wondered - can we clean these up and use them? I was doubtful...

      Now for headlights I was ready to spend a few hundred on some nice aftermarket replacements but these aren't really needed on this race car. The halos, the smoked turn signals, not really worth it. These are some I purchased for another E46 we covered in this same thread, years ago.

      Brad brought out his headlight polishing kit and got started wet sanding and polishing the lenses...

      They cleaned up pretty well, surprisingly. Enough to not be an eye sore for our "show and tell". I still might buy some new lenses later (they are amazingly inexpensive) and we can install those with some very bright LED bulbs from Diode Dynamics. Possibly even some yellow XPEL film to protect the new lenses. Will show more here another time.


      Many months of work and a bit of a thrash in January and February came to a head when we got the car on the ground, on MCS dampers, with an LS engine and headers installed, wheels and tires on and rolling, headlights, M3 bumper cover, bumper beam, and the red steel hood installed.

      Since we had the car on the lift we installed one of the Sparco race seats, a radiator, stuck both doors in the back, the heater box (which I haven't showed yet) was set inside, and the electric steering column (also not shown much) was bolted in place. This car has both front 14" rotors and one of the Brembo calipers, and the E46 M3 rear rotors are installed. All of the tubes from the cage kit were inside the car, if not welded in place already. Still has the old non-M subframe and diff, for now. We even loaded the clutch, flywheel and pressure place inside. A Mishimoto radiator was set on top of the engine, and a 22 circuit wiring harness was placed into the trunk, too. Then we got this weight.

      2112 pounds was lower than any of us guessed, but a decent amount. We're still missing the the transmission + bellhousing, windshield, driveshaft, swaybars, plumbing, fuel tank + fluids, and the larger E46 M3 diff housing is going to be heavier than the medium case in the car now. But the steel hood and trunk are being replaced with carbon, which will save a little. So we're off by 200-300 pounds. Still, it was a very encouraging number.

      Due to this latest weight check we have a good idea of where we will end up now, and this is helping us make smarter decisions as we wrap up the build. We will of course keep taking weights and posting them, even if the car is incomplete. These data points have been helpful to some.


      On March 3rd I was working late and a freight truck arrived at 7 pm, in the dark, while raining. I had to scramble a bit to get the fork lift hooked up and unload this big pallet of carbon fiber parts. I dubbed it "The Carboning!" and was as excited as a kid on Christmas.

      We unloaded the pallet the next day and unboxed all of he Anderson Composites and Seibon parts. These are two sides of the same company, with Anderson being their domestic car arm and Seibon the import car arm. For our S550 Mustang I received a carbon trunk and carbon doors, shown above.

      For our BMW E46 project we got a carbon hood and a carbon trunk. The quality and finish on all of these was great. These Seibon pieces are not "dry carbon" motorsports parts (which they also make) but their more affordable carbon-over-fiberglass / shiny gel coat versions. Still lighter than stock, but not as light as you could see.

      Of course we took weights on everything. On the trunk we went from a 27.7 pound steel unit to a 15.6 pound carbon unit. That's a 12.1 pound drop, or a savings of 43%.

      The steel 330 hood was 44.5 pounds, and the carbon version was 24.2 - for a drop of 20,3 pounds and a savings of 46%.

      In addition the new hood is the "bulged" M3 style and includes a set of carbon grills (which are removable) as well as four massive, carbon vent panels (also removable). The outside carbon surfaces are very glossy and the weave is laid out nicely.

      Brad installed the Seibon trunk in about a half hour, just needing to shim the hinges a bit to get the body lines perfect. This required zero sanding or trimming of the actual part, which is pretty rare for composite parts.

      Jason and I spent about an hour and a half fitting the hood. This was mostly due to the poorly aligned front fenders, which had huge gaps to the steel hood. We slotted some of the mounting holes there and got the body lines pretty darned good, too. Really looks good with this carbon installed, of course.


      This car was missing anything and everything of value, and that included the pedals. After getting a loaner set that I had to give back I broke down and ordered a clutch/brake pedal assembly for $102 shipped from eBay. Tim got those installed on a work night pretty quickly. Installing those allowed us to bolt on the E46 brake booster we had, on the other side of the firewall.

      We found an SSR fiberglass sunroof panel that I had ordered back in 2015 for another E46 coupe, and this will be used on this car now.

      Another missing part on this chassis were the rear tail light housings, along with the trunk mounted reflectors. I bought a set of the brighter LED versions for this E46 coupe.

      Tim installed these into the carbon trunk in early March - nothing tricky here, just a straight bolt-in. As we have done before, we will "direct wire" these around the CAN network that normally controls these brake/tail/turn/reverse lights. We're replacing the entire wiring harness on this chassis.

      This set of LED tails + carbon trunk really set off the back of the car. We have a new, fake, custom license plate we will add and show next time, too.

      WHAT'S NEXT?

      That's a big chunk of work to cover this time. We have other work that has been completed but we're not ready to show all of that just yet - like a brand new crossmember to support a new transmission for this E46 LS swap. Lots of parts have arrived for the front suspension, too.

      New inner/outer tie rods, Lower Control Arms, and these LCA bushings from Whiteline with a 2-piece bushing (that allows for proper articulation). We're using this car as a test bed, remember - and this is a new part to us. Rear subframe reinforcement work needs to be done, exhaust needs to be built, and more.

      At the same time as this E46 endurance car update was written we also posted an update on our GMT800 shop truck build thread, which went through a ton of changes. You can read that here.

      Until next time... thanks for reading!
      Last edited by Fair!; 03-24-2020, 07:49 AM.
      Terry Fair -
      2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
      EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev