E46 M3 Grassroots Motorsports Build (2010)

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E46 M3 Grassroots Motorsports Build (2010)

Last Update: 4/05/2021

In the late 2000s we built this E46 M3 as a dual-purpose street-track car for a customer. It was pristine inside and out, even with numerous annual track events. We even used it in ads and a poster. But after an incident in 2010 the insurance company totaled the car but offered it as a buyback. Not ones to waste a good S54 we tucked the car away to await the perfect opportunity. That time came when Grassroots Motorsport magazine held their annual Ultimate Track Car Challenge (UTCC) in our own backyard - Virginia International Raceway. We used this event as an exercise in building a E46 M3 track car with all of the essential components to compete but not spend an obscene amount of money doing it. Everyone expects a car with $100k of race parts thrown at it to be fast. But we wanted to surprise people with how fast we could go on short money. Oh yeah, we gave ourselves less than 1 month to complete.

Below is our photo journal of the initial build process as well as an update on what the car became. After the UTCC we made a pivot on the car's intended use - completing the transformation from mixed-use track/street car to full race car. At the bottom you will find an extensive list of parts that we used, which has been updated to reflect our current preferences. We didn't realize it at the time but this car would be a rolling canvas that spawned many M3 track upgrades such as aero pieces and exhaust.

This car has been featured in multiple places since we finished the build -

Visit E46 Fanatics for a more in-depth discussion of the build and parts used at the time.

Grassroots Motorsports also did a feature piece in their magazine which you can find here on their site.

This was a showpiece, but after an incident at Mid-Ohio, the insurance company put this car up for grabs. After a visit to Bassen Autobody, the car arrives ready for transformation.

First, sound deadening is removed for weight reduction and 4-point roll bar construction begins. A 4-point was necessary because we were using fixed-shell racing seats. For safety reasons during a rollover you should never use a non-folding racing seat without a roll bar.

Our roll bar construction and painting is completed. With a little modification, we are able to retain factory seatbelts which was necessary to maintain stock 3-point belts.

A few damaged items remaining from the wreck are repaired as engine and the first aero upgrades are installed.

The rear of this E46 M3 gets an overhaul, using Powerflex urethane bushings for suspension and subframe. There won’t be a better time than now to install the Moton double-adjustable dampers.

Original worn-out clutch and flywheel are out. Heavy-duty clutch and aluminum flywheel go in. New prototype MagnaFlow single-pipe exhaust goes on.

Motons are installed in the rear with Eibach springs and Ground Control upper and lower mounts.

Up front, brake ducting is installed to cool our PFC Direct Drive rotors and PFC race pads. The Motons are fitted in the front and wheel studs are installed. The factory engine fan, broken from the wreck, gets replaced with an all-electric SPAL 16″ puller fan.

Up top, the Motorsport carbon intake plenum is installed.

Before installing our front bumper cover, carbon brake ducts are mounted in place.

The interior gets more work with a little more stripping and Racetech 4009W seats installed. Outside, light weight wheels and Nitto-01 tires are mounted so we can align and roll the car around.

This car will retain the stock brake calipers, using solid brake guides. For the UTCC, we will be using sticky Hoosier slicks.

A quick and temporary splitter/undertray is fabricated and mounted.

Everything is coming together and our checklist is getting short!

The car gets an alignment, weighing in under 3,000 pounds. All that’s left is the dyno and decals for the UTCC.

James Clay finishes 8th in class at the UTCC behind a Viper, Porsche turbos, and Corvettes. He's the highest-finishing BMW in the event and most importantly he hit his target lap - 2:05 (in 2010).

After the UTCC is over the car begins a transition to a full race car, beginning with carbon upgrades for better aero and less weight.

The 4-point roll bar is expanded into a full roll cage. Also, an AiM MXL Pista dash is installed for real data analysis.

This M3 did not sit in the corner of a shop - it got a lot of exercise!

With help from Epic Motorsports and some parts being changed, this car is ready for NASA GTS-3 competition along with one of its twins.

E46 M3 Track Build Parts List (Updated)

Apex ARC8 18x9.5 ET35 Wheel Set - E46 M3

Square set of 18x9.5 of a strong, lightweight, flow-formed wheel in a classic design

Price: $1,475.96

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M12x1.5 75mm BimmerWorld Wheel Stud/Black Nut Package

75mm Bullet Nose stud and nut package - a great companion to street wheels!

Price: $149.99

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BimmerWorld E46 M3 Carbon Splitter/Undertray Kit

Increase frontal down force with our fully-functional, lightweight splitter

Price: $2,099.99

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Carbon Dive Planes - E46 M3

Add frontal downforce to reduce understeer and tire wear

Price: $349.99

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BimmerWorld E46 M3 Rear Diffuser

Functional and professional race-quality diffuser for track or street

Price: $1,199.99

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BimmerWorld Ultralight GT Carbon Race Wing

Professional-quality rear wing, 100% carbon element and components, incredibly light and effective

Price: $2,849.99

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BimmerWorld E46 Coupe Roll Cage Kit with X Door Bars

Precision-manufactured rollcage for Spec E46 and all other E46 Coupes

Price: $2,999.99

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BimmerWorld Billet Aluminum Seat Floor Mount Adapters - E30/E36/E46

Adapts fixed, universal-mount seats securely to factory mounting points - low seat positioning and lightweight

Price: $289.99

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Schroth Flexi 2x2 6-Point Harness (FIA 2016)

HANS/FHR compatible, 2" lap & shoulder, lap belt is pull up or pull down, snap-in ends, meets FIA 2016 regs

Price: $568.99

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Schroth Ratcheting Driver Net, Right - FIA Certified - SR 09575

Quick release ratcheting mechanism for a speedy exit

Price: $498.99

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Lifeline Zero 360 Novec 2.25kg Electric Fire System

Mid-high end electrical system with Novec gas

Price: $1,199.99

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OPTIMA D51R YELLOWTOP Lighter-Weight Battery (26lbs) - E30 E36 E46 E9X

AGM battery even lighter than the D35 and works in BMW track cars

Price: $289.99

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OPTIMA D51R Style 2 Battery Mount Kit - E46 Track/Race

Exclusive BimmerWorld aluminum mount for OPTIMA D51R batteries

Price: $169.99

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AiM PDM32 Power Module and Logger with 6" Road/Race Display

Consolidate electrical power and logging in one central module! Can display dash warning lights like a street car.

Price: $2,499.99

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AiM ECU Bridge with CAN/RS232 Open Leads (Hardwired)

Directly connects ECU to AiM dash or SmartyCam

Price: $237.99

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BimmerWorld E46 Rear Subframe/Chassis Reinforcement Kit (Expanded)

Solves a problem that plagues the E46 3-series - latest design has more coverage!

Price: $139.99

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