Vorshlag BMW E46 M3 CSL - V8 Downforce Monster Track Car ("Chainsaw Massacre")

[Fair]

continued from above



It started out about 7 pounds heavier than the cast aluminum Cobra diff cover, which you can see above. But we needed thicker material to resist the torque of this LS motor, so the 1/4" thick steel unit was the right way to go. Buying a pre-made CNC laser cut and welded cover saved us a dozen hours of hand making this piece.



This bare steel cover was easy to modify to have "ears" attached that bolted to the E46 M3 rear subframe. Unlike the front, the rear mounting modifications were all done to the cover - nothing on the back of subframe was modified. Care was taken to maintain access for the rear cover mounting bolts as well as the existing fill plug.



The structure was set and plated, tack welded, then fully TIG welded to make a strong set of mounting ears on this 1/4" thick plate steel rear cover. Strong as an ox, yet compact. This cover came with a fill plug (threaded bung welded in, with a screw in plug) and we later added a drain plug as well.



The modified M3 rear subframe was also stitch welded to cover any gaps in the factory welds, just like the front. Then the rear subframe, the lower front mounting cross bar, and the reinforced front subframe were all powder coated gloss black.



So while the 210mm M3 diff housing might have worked, it was always going to be heavier, weaker, and have fewer & costlier options for gearing and LSDs. We would be having custom halfshafts built for either the 210mm BMW unit or the Ford 8.8", so that's a wash.



Aluminum subframe mounting bushings were installed into the shiny black M3 rear subframe. Instead of taking our chances with polyurethane or even Delrin, we're going "full stuff" on the rear diff and subframe mounts on this car.



We added a second threaded bung and plug to the diff cover before it was powder coated gloss black. This will allow us to run a dedicated diff fluid cooler, which will help keep the 8.8" unit happy under high torque abuse. The completed rear subframe - minus the diff housing - was installed in the car at this point to allow the rear suspension parts to be added.

continued below

[Fair]

continued from above

COMPETING IN NASA AND OPTIMA CLASSES

The customer who owns this build is an avid HPDE driver who is used to high powered RWD cars, and now has the Miata track trainer that we built to hone his skills before he jumps into this V8 M3. Before the build began we asked him, like we ask all customers, "What class do you want to build for". This is crucial, as even simple parts choices made early on can limit where you can run any car. We don't ever want to build a car "just for track use" and always encourage folks to at least have some class in mind for "down the road". It tends to make any race car more valuable if it is legal for some class or series.



Wheel to wheel racing was never in the cards for this car, so we looked at places where it can compete in Time Trial - which still has a competitive thrill, similar contingencies, but only a fraction of the crash danger of W2W racing. For a car approaching 4 pounds per hp, there is one class you build for in NASA Time Trial: TTU (aka: Unlimited class).

I'm not going to delve into the intricacies of NASA classing rules for TT, but there are basically a number of classes based strictly on power to weight ratio (TT1/2/3/4), then a few remaining TT Letter classes that are both points based and p-to-w limited (TTC/D/E/F). Basically TTU is fastest, followed by TT1 to TT4, then TTC to TTF are further down the line. TTU will be a tough class to compete in because things like ALMS prototypes and open wheeled race cars are allowed there... but typically TTU acts as a catch-all class for cars that exceed the limits of TT1 or don't have their classing sheets or dyno sheets in order. It is still a rather large class in Texas, most of the time won by Paul Costas' GT1 tube-framed Camaro.


Left: I'm using the #JankyStick to point out duct tape. Right: Costas setting the weekend's fastest lap at TWS

With numbers around 2700 pounds with driver, "over 500 hp", giant 14" wide slicks with functional aero its going to be pretty hard to beat this car with a unibody BMW coupe chassis with roll up windows, but TTU is just where this car fits. See, I've already got the excuses ready if we lose! Paul is a good friend of mine and I'm sure he won't mind the "class filler" we will be for him. With 5 in class, a win in TTU pays 2 tires per day if you are running Hoosiers, and with 7 in class pays 1 for 2nd - so even a runner up finish might take home some tires.



For NASA TTU (and HPDE) the car will be run on 335/30/18 front and 345/35/18 rear Hoosier A7 tires, which we had exceptionally good results with in our TT3 car - this car was never beaten in class on these tires, and was easier to drive on than anything else we ever tested. These 345's are the widest DOT tires Hoosier makes, and should work well for this high powered car on the rear. We could possibly use a wider Hoosier 355mm racing slick, but I've found the DOT "A" Hoosier to be a bit friendlier, warm up quicker, and fall off later (more heat cycles) than dedicated racing slicks. I'd wager a very small amount of money that in the right conditions they are faster than similarly sized slicks. I might lose that bet, but in the first 1-2 laps of a TT session (the only traffic free opportunities) I've rarely seen any tire faster than A7s.



The more serious classing objective for this E46 CSL M3 is Optima's Search For the Ultimate Street Car series, run by the USCA organization. This is currently the biggest arena to showcase fast cars that have some smidgen of street car capabilities, with a massive variety of cars and a LOT of talented drivers and car builders. I have a lot of friends who compete in this series and missing the last 2 years of events is KILLING me.

We've had a modest amount of success in that series, where Amy and I have entered in Mustangs and Corvettes, and this BMW's owner ran a car at one event also - and enjoyed it a lot. I've always felt like they needed more BMW entrants in Optima, and I have been in contact with the series director to share our plans. Hopefully this hybrid BMW fits within their series parameters and gets as much TV time as our big heavy Mustang did.

Discussing the Optima series rules would take hours, but the basics are this: The USCA runs 8-10 qualifier events each year. There are 4 or 5 classes at these events, and the class winners from each qualifier get invited to Vegas for the "finale event" after SEMA, the Invitational. Here all of the classes get merged into one big shootout with 75-100 cars. Each qualifier and the Invitational are based on 5 competitions: autocross, speed stop, time trial, a road rally to test the streetability of all cars, and a judged car show section called "Design and Engineering". Winning a class at a qualifier is a big deal, as all of these events are televised. Winning the overall at the Invitational is a HUGE deal.



For this series the car has to run a 200 or higher treadwear tire, so we'll build around a 335mm front and 355mm rear street tire - which are the widest available/competitive tires. They won't be as sticky as the Hoosiers but we have some ideas to help manage that. We are building for the GTL class, but that's all I have to share about Optima classing with regards to this E46 M3 CSL clone at the moment. More soon!

WHAT'S NEXT?

In the next installment to this build thread we will show the electric assist steering we added along with the brake upgrades and suspension we have installed. Its all serious stuff that I am pretty happy with.



The max width tire and wheel testing will also be shown, which we used to order the first set of wheels. Then we will cover the unique rear seat mounted fuel cell and dry sump oil tank mounting we tackled for this build.

Thanks for reading,

[WSSix]

Phenomenal!

[preston]

Interested in your take on EPS which I know you have used before.

[Fair]

Project Update for June 20th, 2017: Another round of updates to the E46 M3 V8 monster project. In this installment we will show some unusual suspension/upright coatings, the brake parts we chose plus custom brake cooling, and most of the aftermarket suspension components being installed.


It took some time to get from tire mock-ups (at left) to making the final flares (at right)

The max width tire and wheel testing will also be shown, which we used to order the first set of wheels, which we are flaring around now (will be shown in more detail later). We also cover the electric assist steering upgrade, pedal box installation, and wrap it up.

NICKEL PLATED SUSPENSION PARTS

I mentioned this in my last update about the front spindles, but will expand on it here. This seems a bit over the top, but we didn't pitch the customer the idea of making show-car-like coatings on the remaining BMW suspension components (spindle, trailing arms, etc). We were actually building another E46 in 2015. The customer for this car saw what we did to make those parts look better than new and said "Do mine like that!", so we duplicated the effort on Chainsaw Massacre.



We started with this extra M3 rear subframe I purchased brake-to-brake for a good price. Normally we get parts from Texas and there's never a hint of rust or corrosion - we're very spoiled here - but the pallet came from the mid-Atlantic area and it had just the hint of some signs of salt corrosion. I abhor rust in even the smallest traces, so it was time to blow the entire rear subframe apart, bead blast all of the steel and aluminum parts, and re-coat everything with a more durable and corrosion resistant plating.



Our guys got all of the parts stripped down, then pressed out all bushings. Next the taped up any surfaces we didn't want to blast - machined bearing surfaces (the acid wash process before nickel plating would clean any remaining paint off without giving these surfaces a "blasted" finish). Upper rear control arms, lower trailing arms, RTAB cassette buckets, rear hubs, rear caliper brackets, rear uprights, front spindles, even the rear diff cover were all glass bead blasted.



After seeing what salted roads can do to metal coatings and platings, about a decade ago I switched the plating we specified on steel camber plate parts from zinc chromate ("yellow zinc", shown above left) to electroless nickel ("e-nickel), shown at right. It costs about 4x as much but lasts a helluva lot better on steel than anything else, and the added thickness is nominal so it doesn't mess up bearing tolerances. This is why I wanted to re-plate the steel suspension arms and spindles with nickel.

A local blaster did the honors and got the parts perfectly down to bare metal. I picked up the pallet from there and took them right to our plater (except the front and rear subframes, which we had powder coated after reinforcement).



Then another vendor we use double nickel plated the parts. This was the first time we tried this. This started with the electroless nickel process we already use, which flows into every nook and cranny. The Rear trailing arms are hollow and the E-nickel can get up inside there. Then on top of that we had them electroplate another layer of nickel - called "Bright nickel". Electroplating only grabs onto the outer surfaces of the metal part but it gives a shinier finish. This double plating worked out better than I had hoped. It was several hundred dollars of work but on a build like this the results were worth it.



So that is why we had to blast/plate these parts, and once you see these in person it looks so shiny and sparkly its hard to say no. But for Optima there is a "car show" component that cannot be ignored, and additional tasks like this only help.

BRAKE SYSTEM - ROTORS, CALIPERS, & COOLING

The nickel plated E46 M3 spindles from above are now being fitted with new wheel bearings and brakes in this step.



If you follow our build threads you will notice that in the last 2 years we have begun working with a new Motorsports brake company out of South Africa called Powerbrake. They machine their calipers, brackets and rotors in-house and the quality and construction rival the highest cost iron based brake kits in the world. I always say "you get what you pay for" but due to a strong US Dollar relative to SA's currency, we can get these kits for a good bit less than other brands.

continued below

[Fair]

continued from above



I have been using their 4 piston BBK on our E46 330 since early 2016 and right off I was amazed at the difference in feel, confidence, heat resistance, and stopping power these had over good pads/fluid/lines. We've since worked with them on getting measurements and testers for a number of new fitments: FRS, C6 Corvette (above left), S197 Mustang (above right), and SN95 Mustang (AJ Hartmans's AI Mustang).



I've driven all but one of these on track already and all I can say is I don't know how I didn't move to Motorsport style calipers and rotors sooner! "Being cheap" catches up with me again, I guess? And that's what's funny. We put the Powerbrake kit on my E46 in the middle of 2016 and I'm still on the same rotors and pads, and the pads are still at 3/4 depth. And I drive like such a tool I tend to murder brakes. So in the end the total running costs per lap will be lower, even with the higher initial BBK cost.



They make a lot of different brake kits for the E46. On my 330 we used a large 4-piston caliper on a 330 mm rotor (to fit under 17" wheels). With Powerbrake's help we picked the 350mm front 6-piston brake and 350mm 4 piston rear caliper for this M3 project. This all easily fits under 18" wheels and should be more than adequate for this ~2600 pound car.



All serious cars used for track use need some sort of brake cooling, especially for the fronts. This is where you take high pressure air through an inlet, route it through tube/hose to the back of the hub, then force it into the rotor and pump it through the rotor itself. This helps keep the brake rotor cool, but also cools the hub, caliper, pads, and of course the fluid. We have made ducted brake backing plates for a number of cars and sometimes inlet duct kits as well. Super important for track use - extends the life of the pads, rotors and fluid, and could potentially save you from a crash.



First we needed to refresh the front hub bearings and install some wheel studs (I hate lug bolts). The shiny plated spindles worked great and the microscopic thickness added on the bearing surfaces didn't amount to any clearance problems with the new bearings.



On this M3 we're going to custom make backing plates to fit this Powerbrake 350mm setup that bolt to the E46 spindles both front and rear. Looking to get a 4" ducted hose for the fronts first so we will build around an 4" oval duct on the backing plate. The E46 uses a brake dust backing plate that is a funky shape and completely encircles the spindle - so to use a proper backing plate the OEM dust cover is not used.



With the 335mm tire mocked up, the calipers and rotor mounted, and the bare backing plate bolted on the spindle (above left) it was easy to see where the ducted hose flange needed to be added. This 4" oval tubing was made on the bead roller, welded up, marked, cut, and welded to the backing plate (above right).

continued below

[Fair]

continued from above



We will show the work on the front inlet ducting and the hoses in a later post - we have a good place for that on the 1M style front bumper cover that the customer chose.



Out back the nickel plated trailing arm got new bearings, plated hubs, and AKG spherical bearing kit in place of the RTAB bushing. I always say that the RTAB bushing needs to pivot freely in 2 axis and won't do polyurethane here - only the OEM rubber bushing + limiter OR a spherical bearing like this. Anything else is just asking for suspension bind. The spherical bushing kit needed a hair of clearancing to press into the trailing arm, and the entire setup was held in place by both a press fit + a little bearing retaining compound (above right).



The rear ducted backing plate was a little trickier. With the rear hub installed (its a bear to remove) we noted that a 2piece backing plate made more sense. So a backing plate was made that fit close to the Powerbrake 4 piston caliper and rotor. With the rear suspension assembled a 3" oval ducting inlet was added to clear the control arm. Its usually pretty difficult to route hoses to rear brakes, but again - with a car like this its worth the effort.

SUSPENSION PARTS INSTALLED

Since we ended with the brakes out back we'll start with the suspension there also. The rear control arms are all mounted in spherical bearings - a mix of OEM sealed rubber versions (where the factory included those) and aftermarket spherical bearings elsewhere. We also sourced all brand new rear suspension bolts from BMW - cheap insurance.



The reinforced and powder coated rear subframe (detailed in my last update) was installed with AKG aluminum chassis mount bushings and bolted to the reinforced mounting holes using the new BMW bolts. Then the rear suspension was bolted in with the plated aluminum upper arms and SPL Parts adjustable length, spherical bushed, lateral lower arms. The plated and spherical bushed trailing arms were also bolted in place.



That wraps up the rear suspension - well other than the shocks/springs. We went with MCS Remote Reservoir 2 way adjustable dampers on this car (RR2) along with a firm set of springs - rates which might change later due to aero and lateral loads (track testing will sort this out). Vorshlag spherical rear shock mounts were installed as well.


MCS RR2 dampers installed on this E46 M3

Up front we used the M3 version of our E46 camber/caster plates along with the RR2 front struts. We were working pretty quickly around this time and the suspension went on, ride heights were quickly set, and then wheels went on before I could get good pictures of the suspension installed. I'll make a point to get shoot these with the wheels off soon.



We haven't mounted the reservoirs yet but they have hoses long enough to keep them mounted underhood for easy access to the compression knobs. The rebound knobs are on the top of the strut, which makes them easy to access. The camber-caster plates bolt into the reinforced E46 strut towers - which may receive further reinforcement with bracing to either the chassis and/or the cage.

continued from above

For most track E46 builds we'd put in a new pair of Lemforder lower control arms, Powerflex 2-piece LCA bushings, and fresh tie rods. This isn't the typical track car - its spherical or nothing.



continued below

[Fair]

continued from above

So for now the front control arms are still stock to let the car roll around, but we have plans for something good. We sent the OEM lower control arms/chassis mounts to SPL parts down in Austin and they are working on a new set of adjustable spherical control arms for the E46 M3 chassis, based on the test parts we sent them.



Examples of SPL Parts front control arm (at left) and rear control arms (at right) made for another chassis

Of course other people "already make spherical/adjustable arms" for this chassis, we know. But we know the SPL guys from NASA racing and they build everything here in Texas, top quality stuff, super strong and of course - spherical and adjustable. We trust that they can add something to their version that will make them worth building. They supplied the rear lateral arms and this FLCA setup is a logical next product for them for the E46 chassis.

TIRE MOCK-UP FOR WHEEL MEASUREMENTS

You may have seen the 18x13" wheels we have on the car now (below) in teaser pics on social media, but getting to the proper offsets and sizes was some work. We are trying to tuck the wheels as far inboard as possible to minimize the amount of flare needed - which is still going to be huge. To do this we started out with the correct sized front tire, mounted it to a wheel mock-up tool, and tested it on the front suspension...



To even get to this point for tire fitment testing we needed the car's suspension in place, camber set within about a degree or so, and with the brakes and hubs installed. That took a lot of parts spec'ing, ordering, and installation. This tire test was done early in the project because we knew the custom wheels would take a while to be built. We didn't think it would be 4.5 months, but it was...



We tested the 335/30/18 on the front and a 345/35/18 on the rear, at ride height, full droop and full bump travel. Then the front was swung lock to lock. This visual testing with the correct sized tire gave us an idea of how much body modification would be needed as well as the offsets we should order for the 18x13" front and 18x14" rear wheels.



This Forgestar M14 wheel is a 2-piece version of their popular F14 wheel, which comes in 18" diameters from 8" to 15" wide. We worked with the customer on color schemes early on, and made a lot of photoshopped pictures of this wheel with various colors and finishes. He settled on a satin black center and anodized red outer lips, shown below. So we ordered the wheels. And waited. And waited... We were stuck. We needed wheels and tires + the car at ride height to be able to tackle many other tasks.



Over a third of a year later when the wheels arrived they looked beautiful, except for one thing we noticed right away. They are all 18x13" wheels. To make these 2-piece wheels inner and outer rim halves are mixed and matched - plus the backs of the centers are machined - to get the width and offset we needed. This was done to clear the brakes, fit the biggest tires we had planned (335F/345R), and give us the most inboard offset to minimize the flare needs. After the issue was noticed I had a "spirited" phone call with the manufacturer, and we could have sent them back for a full refund. But the thought of waiting another 4.5 months (or even a few weeks) for correct rear wheels would wreck our timeline. The project was at a standstill until we could put it on the ground with the right tire sizes mounted. So we talked to the customer, mounted up the 335/345 Hoosiers, and bolted them up.



I saw them on the car and wanted to be mad, but they looked good and fit really well. We realized this car might need as many as 3 different sets of wheels - for differing classes/uses - so we decided to keep this 18x13" set. The 345mm tire fits on an 18x13" wheel well enough, but the 14" width would have been better - yet I ran these tires for 2 seasons on an 18x12" wheel. They were a tick squeezed on the 12s but we won every event we entered on the big tires, so it wasn't that bad.



Ryan started the clearing work to the unibody and structure up front to clear the 335s at full lock and then flare mock-ups, but I'll show more of this next time.

ELECTRIC POWER ASSIST STEERING: COLUMN + RACK MODS

If you have driven a modern car built in the past 10 years you may have known that the OEMs have almost completely dropped hydraulic power steering in favor of electric assist. They have done this for many reasons, but for Motorsports use it is good because it deletes a residual power drag (power steering pump) as well as removes the largest cause of underhood fires: leaking hydraulic fluid. With the added costs of the (racing modified) power steering pump, cooler, and lines it is almost a wash on costs. It wasn't hard to convince the customer that this was the right way to go.



We have been investigating aftermarket or "OEM adaptations" of an EPAS system for the past 4-5 years, and I loved the EPAS unit in my 2011 Mustang (once we swapped it for a Ford Racing version). Our Scion FRS has electric assist also.

continued below

[Fair]

continued from above



Jason and I talked to a lot of vendors that make these kits at the PRI show in December 2016, with an eye on working with this M3. After weighing all of the options (DCE and EPAS), home built vs aftermarket, we went with the EPAS Performance kit shown above.


Ford Racing EPAS unit for 2011-14 Mustangs

There are generally two ways electric assist is used (outside of the early systems which used an electrically powered hydraulic pump with traditional lines and hydraulic assist) on OEM cars these days: the electric assist is built into the steering rack (shown above) or it is built into the column. The latter is what most of the aftermarket is using and frankly its easier to integrate into a car that came with hydraulic assist.



Of course integration with a motorsports steering column would be even easier, but for a number of reasons we wanted to keep the OEM steering column intact on this car - for a working turn signal stalk and some other bits. This BMW steering column was cut apart, modified, and the motor assembly was merged with it.



There are a lot of steps that this "merging of columns" that I'm skipping. Frankly he did it quickly and we didn't get pictures of each step. But it was possible to get the two columns to work together - with some cutting, custom machine work, TIG welding, and careful measuring.



This is the final E46 M3 column with the EPAS system integrated. There are separate controllers and two heat sinks that keep the electronics cool, and a knob that will go on the dash to control the amount of assist, from heavy to light, based on your need. Autocross will likely have a heavier assist, track use less so.



The column was mocked up in the car to get the height and tilt close, then a mounting bracket was built and welded to the cage dash bar to set it in place. The factory tilt is still operational but the telescoping is gone due to the massive changes to the column that were needed. The seat can move fore-aft so that's not an issue.



Below the column a 2-piece steering shaft was built using our BMW-specific U-joints and some DD shafts to connect to the steering rack - we've built and sold hundreds of motorsport steering shafts for BMWs. A column mount bushing and plate to cover the large hole in the firewall will be added later. Now it was time to modify the M3's power steering rack...

continued below

[Fair]

continued from above



The guts were removed and the shuttle valve was modified to work without hydraulic assist. The "power assist" will be upstream inside the column. The interior cavities of the rack were filled with grease and the pressure and return hose ports were capped.



New inner+outer tie rods were ordered and installed, as were a new set of steering rack bellows and rubber caps. The rack was tidied up and reinstalled into the subframe.



People that have seen the picture above left have asked "Is it in the way of your feet?" The answer is no. The picture above right shows the EPAS motor buried up under the dash. It will be all but invisible - to the eye and with respect to steering feel - once the dash is back in place and the car is on the road.

OBP PEDAL BOX ASSEMBLY

This is the last section for this update - the OBP pedal box. Early in the build we had decided on the EPAS steering and Ryan felt that the motor might be difficult to package under the dash using the stock pedal box, which is hung from the firewall and the dash mounting structure.



We also decided to gut the inner workings from behind the dash skin and go with an digital dash display and custom HVAC (Motorsport heater core/blower) to save weight. This meant the heavy, clunky OEM dash bar would go away and be replaced with a horizontal cage bar, to which we could mount the steering column and possibly the pedals.



Instead of a set of traditional "hung" pedals the packaging of the EPAS and other bits dictated a floor mount set of pedals. And instead of building this from scratch we chose this kit from OBP. It comes with a mounting plate, spots for all 3 pedals and 3 brake master cylinder mounts, and it has a balance bar.



Due to some changes to the floor structure, seat location, and other tweaks we have made, the pedal box bracket needed to be tweaked a bit to fit the contours of the remaining section of floor.



But with very little rework this OBP kit bolted into the chassis and gave plenty of room above for the EPAS and other dash bits.

WHAT'S NEXT?

There's still plenty of work to show before we are "caught up to real time". Custom fuel cell + fuel fill + enclosure, oil tank + enclosure, carbon hood and 1M front bumper cover install, and much more. And flares.



Until next time,