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| Everything You Need to Know About Upgrading Your BMW E46 M3
The BMW E46 M3, considered by many to be the ‘best’ M3, also happens to be the car most often chosen by Turner Motorsport customers to drive, race, modify, or show. As the third iteration of the benchmark luxury performance car, BMW certainly knew their way around building a highly competitive street car from racing roots. In the E46 generation, the largest naturally aspirated straight-six engine was found between the strut towers, sporting gorgeous individual throttle bodies and that gorgeous //M badge, denoting it as the coveted S54. These engines and the cars which carried them have been heralded as one of the greatest platforms of all time, but that isn’t to say they can’t be improved upon, especially if you are working with a car that is now pushing into its teens. Today, we’re going to take a look at some of the best things you can do with your M3 to prepare it for aggressive street driving or some mild track use by walking you through what we would do had we just purchased an E46 M3.
If you are in the process of trying to find an E46 of your own, you may want to familiarize yourself with our E46 Buyer’s Guide, where we address many of the concerns of which you should be aware during the buying process. Here, we’re going to look at what next steps you can take once the E46 of your dreams is home in your garage. First and foremost, that means ensuring your M3 is in a good enough condition to handle aggressive suspension and performance upgrades for a hard afternoon around the track.
The first steps are obvious. While you should have scanned your M3 for codes before your purchase, it is equally important to go ahead and run through any faults that your M3 may have. With the Schwaben BMW Professional Scan Tool, you can systematically check all functions and see exactly what your car may need. Be that a sensor, a light, or catalytic converter, the scan tool will let you know what you need to replace. After addressing any faults you might have, the ever-important initial services are next.
Arguably, you can start with the basic maintenance, but running a scan to find anything you might not be able to observe will allow you to maximize your time by not having to take things apart twice. Either way, here are the biggest maintenance services you should perform: | | | | | | | | |
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With the basic maintenance performed, you’ll be ready to begin modifying your M3 to bring out its easily accessible capabilities hidden by parts that favor comfort over performance.
A well-versed E46 M3 aficionado will notice we left out a few things you may consider maintenance items like struts, shocks, tower mounts, brakes, reinforcement, and other items. Not to worry, we are just going to include these concerns with our upgrades. Two birds with one stone, right?
E46 M3s are unfortunately susceptible to cracked strut towers, shock towers, subframe mounts, and more. If you intend to drive your car regularly, especially on the track, we are going to almost require that you reinforce/fix these chassis issues before you continue. While the thought of a failed strut tower or subframe is terrifying, it can be prevented quite easily.
Reinforcement kits for your subframe mounts, front/rear subframes, shock towers, and strut towers are available to help distribute stress loads and further strengthen those areas prone to cracking and failure. Don’t skip this step if you like your chassis attached to your suspension. | | | You can further reinforce your chassis with a strut tower bar, which not only improves your chassis rigidity for better handling but distributes stress loads between the two strut towers, adding more strength and offering better protection against failure. Plus, they look cool. | | Now that your M3 won’t suffer from dreaded chassis failures, you can finally add some real performance. There are, of course, nearly infinite options when it comes to adding horsepower, everything from massive turbos to engine swaps. What we want to do is point out the places where you can make the biggest differences for performance with the fewest modifications so you can make your dollar go farther and your M3 behave more to your liking.
Let’s start with the (arguably) most interesting modifications: suspension, wheels, and brakes.
As you may have read in our Coilover Buyer’s Guide and technological breakdown, coilovers offer three main benefits: adjustability, simplicity, and handling. By offering ride height, compression, rebound, camber, and caster adjustability, coilovers allow you to dial in your suspension settings for the best look and handling characteristics to help you turn heads and corners more effectively. There are tons of manufacturers of high-quality coilovers for your M3, but we have highlighted some of the most widely regarded as top picks for you to choose between here at Turner. | |
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H&R Suspension
H&R has been a key player in suspension technology from DTM to weekend track days for decades. Their shock/spring package is less like a traditional coilover setup and more like a ‘cup kit’ that uses correctly valved shocks with height adjusters that lets you change your ride height by over an inch in the front and rear. Definitely not the most aggressive or adjustable, the H&R kit is an excellent choice for an out-of-the-box performer you can install, set the height, and rely upon to improve your handling and appearance. This kit is perfect for anyone looking for a visual upgrade without sacrificing ride quality or handling for primarily street driving, especially if you want a high-quality brand without paying out the nose for adjustability settings you won’t touch. | | TC Kline Suspension
TC Kline literally wrote the book on BMW suspension tuning. While it may not be the most readable piece of literature, his years of experience are a trusted resource for BMW drivers who want to fine-tune their suspension to perfection. That experience shows through in the coilover options by TC Kline for the E46 M3. First, the Street/Track Single Adjustable Coilover Kit offers a more affordable track capable setup. The SA kit features rebound-adjustable Koni dampers, interchangeable springs for free-height changes without changing ride height (just call us, we can help you find the right springs) and camber plates for better suspension setting adjustments. They can be set for comfortable street driving or aggressive track driving, which makes the SA kit a step above the H&R kit, but of course, that comes with a larger investment. If you are serious about track performance, the SA or its big brother, the Double Adjustable kit, are excellent choices for improving your handling dramatically. | | Bilstein Suspension
Perhaps the oldest producer of damper technology, Bilstein is effectively synonymous with suspension, especially with German cars. That’s because they’ve been in business since the 1800s and have produced automotive parts for nearly 100 years. Bilstein PSS10 coilovers for the E46 M3 split the capabilities and cost of the two previously mentioned kits. With height and damper adjustability from more of a true coilover package, these upgraded coilovers have ten damping settings and more than an inch of ride height adjustability. The essentials are all there, which make setting your M3 up for success on the track is made simple with the Bilstein kit, but you do miss out on camber/caster adjustment and pillow ball spherical mounts. | | 
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FCABs/Camber Plates
For the control arms, we highly recommend replacing the rubber OEM front control arm bushings with either our Polyurethane bushings that use a Delrin insert or our Monoball spherical bearings. Both options significantly improve your turn-in response, eliminate deflection, and help with steering feel that can be the difference between a connected feeling steering experience and a quite muted one. The Polyurethane bushings are excellent to cut on cost, but they do wear out over time and don’t entirely eliminate deflection in the same way the spherical bearings do. You will find Turner Monoballs on the majority of Turner Motorsport employee cars, either commuters or street cars, because they are absolutely the best solution for FCABs. They are serviceable, which means they have an indefinite lifespan provided they are greased, and they have the biggest effect on your steering feel, responsiveness, and completely eliminate deflection at that point. | | Camber Plates
Camber plates, though commonly found on many coilover systems, are not always included. Our recommendations above included one kit with camber plates and two without. The benefits of buying coilovers with camber plates are that your install is all at once and out of the box you have camber/caster adjustability. However, you are limited to using the provided coilover’s camber plates unless you purchase different ones and the up-front cost is often higher on coilover kits that do provide camber plates. We have just released Turner Motorsport Track Camber/Caster plates for the E46 M3 developed on our Championship-winning E46 M3. These are the exact plates used on that car, now available to you. They offer a completely unique design that preserves the correct E46 M3 geometry, allows for separate camber and caster adjustment, provide a large surface area to help distribute stress forces, and work with all major strut manufacturers like the above mentioned H&R and Bilstein. These plates are the absolute best camber/caster plate solutions on the market and make buying coilover kits that do not come with camber plates an easy choice since you can add these later to gain even better capability than often doubly expensive coilover kits for less. | | Rear Camber
Traditionally, the rear camber of your E46 (and most BMWs) is not adjustable. When you lower your car, the camber angle becomes more severely negative and is not able to be pulled back within spec. We know, some folks like tilty wheels. For those of us with optimal performance in our sights, this just won’t do. That’s why we have the Street/Track Rear Adjustable Camber Arms. These arms are designed to let you pull your camber settings in the rear into spec and dial in the perfect settings for the best handling possible from your now lowered M3. They are lightweight, durable, and offer two bushing choices of either rubber or solid rod ends for street or track environments, whichever you prefer. We highly suggest including these with the purchase of any suspension upgrades that lower the car beyond its tolerance window.
With the suspension sorted and fresh new parts up under each corner, you can be confident the handling capabilities of your M3 are now back to their factory capabilities and beyond thanks to the upgraded coilovers, camber plates, dampers, springs, bushings, bearings, and camber arms. | | |
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Brakes
Moving outward towards your wheels, the brakes are your next important service and upgrade focus. M3s have excellent brakes from the factory, but if they are old and worn, they won’t help you much. Ideally, you have already flushed your brake fluid. If not, go ahead and do that now or install new calipers and fluid for an upgrade.
Refresh:
The stock brakes are excellent, but if you are in need of new rotors, just go ahead and upgrade to the BMW CSL Brake Kits. The two-piece floating rotor design and 345mmx28mm size make for both more surface area and better heat dissipation, which will mean more bite and less fade on under track conditions. The kit includes new caliper carrier brackets and front rotors. For the rear, stock replacements are fine. Make sure none of your calipers need to be replaced and change your pads to a more aggressive pad like Hawk HPS, StopTech, or EBC Yellow Stuff. Racing pads can be used for the track exclusively if you desire. | | 
| StopTech
If you are looking for an even more capable brake system, replacing the rotors, pads, and calipers with a StopTech Big Brake Kit is one of your best options. In the past, these kits were prohibitively expensive and left to the highest tiers of racing and most costly supercars. Now, companies like StopTech have made big brake kits affordable with the same performance capabilities. These extremely capable brakes are built with the specific vehicle dynamics of your M3 in mind to balance brake force and maximize efficiency at all four wheels, making the StopTech kit extremely tempting for anyone looking for peak brake performance. | | 
| Sparta Evolution
Like their competitors, Sparta has made Big Brake Kits affordable and accessible to a wide range of enthusiasts. Their tiered kits allow you to tailor your kit to your driving needs as well as meet your budget for a real big brake upgrade that gives you the best bang (or stop) for your buck. Two, four, or six-piston caliper options with their own Pegasus S-Groove rotors mean you can outfit your M3 with a BBK that is as aggressive or affordable as you need while still changing out all the brake components with brand new, durable, high-performance replacements. | | 
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