The following is provided for information only. Driving or riding can be a dangerous activity, what you do on your own time with your own vehicle is up to you. Always drive / ride safe and never do anything that would endanger pedestrians or other motorists. The roads belong to everyone; make sure that you, and everyone you pass, makes it home safely. By using this site you agree to release lateralg.org from any liability resulting from your actions.
If you are the kind of driver who finds this site interesting, chances are you have made modifications to your car or are currently planning to. If done properly, upgrades and modifications can drasticaly improve the handling and performance of your vehicle. Care should be taken, though, in deciding what to upgrade and how to install. Having a back alley shop perform the work on your vehicle may save you money at the start, but if a poor installation job fails during high-speed cornering in a canyon it could mean a big repair bill or even time in the hospital.
When planning upgrades, make sure you know what your ultimate goal with your vehicle is. If you are upgrading for appearance, quality and safety are no where near as important than when you are upgrading for performance. Remember, if you drive hard in the canyons or desert you are trusting your health and safety, and that of the other people on the road, to your car. Make sure it is up to the task.
Whether your car is stock or highly modified, make sure you have critical components like brakes, steering, tie rods, and tires checked on a regular basis. Never underestimate the consequenses of poor planning or judgement.
Tires are the most important upgrade you can make to your car's handling. Suspension, wheels, brakes, sway bars all help, but nothing will give you the most "bang for the buck" as a good set of ultra-high performance tires.
Unless you drove off the dealer's lot in a 911 or Ferrari, chances are your tires are not the top of the line. When a car manufacturer choses a type of tire for a given vehicle, they have to weigh many factors including road noise, safety, price, and the number of miles the tire will last. If your main concern is performance, a little more road noise an tires that don't last quite as long are not a big price to pay. A set of Pirelli P-Zero's or Yokahama AVS tires will increase the grip and cornering ability of your car more than you might believe.
One thing to keep in mind; if you just paid a lot of money for some new performance tires, you might want to refrain from donuts and burnouts in the parking lot. No reason to turn those expensive pieces of rubber into smoke.
Increasing your wheel size is done for several reasons. One; to allow the fitment of bigger brake systems (see below). Two; to allow the fitment of larger and wider tires. You may also want to fit wheels that have a larger surface opening to allow better brake cooling (see below). But the biggest reason to change your wheels from the original factory set, from a performance point of view, is to decrease unsprung weight.
The wheel on the left (brake dust and all), is mine. They aren't my favorite style, but they only weight 17lbs each which removed roughly 5lbs per corner from my car. By decreasing the weight of the wheel, the car is able to maintain higher levels of grip when cornering on rough or uneven pavement. The wheel on the right, a Dub Spinner, may have more style but weighs a lot more. This is a bad thing when it comes to performance driving.
Your car's suspension has to do two thing when you drive; keep the car level and keep the tires on the ground. The more weight you have on the corner that the suspension has work to keep on the ground (unsprung weight) makes it harder for the suspension to keep the car level. Think of it this way; when your tire hits a bump in the road it is pushed into the air. The more weight it has from the brakes, bearings, wheel, tire, etc., the harder the suspension has to work to push it back to the ground. The less weight, the easier it is for your suspension to do it's job, and the better you can corner because your tires spend more time in contact with the road.
I also chose to stay with the original size wheels for two reasons; BMW knew what they were doing when they designed the car and I didn' want to risk upsetting the driving dynamics by randomly picking a different size tire; and larger diameter wheels weren't any wider, so all I was doing was increasing the cost of the tire and wheel, adding weight, and not increasing the contact patch (and thereby grip) at all.
At one of my BMW LA club meetings a representative from Stoptech stopped by to give us a little information on brakes, upgrades, etc. While bigger calipers, rotors, and pads will improve braking performance, they will also increase unsprung weight (see above) and of course can run you a lot of money.
The cheapest and best upgrade you can do for your brakes is cooling. If you have ever watched a NASCAR race and seen a close-up shot of their brake systems, you will notice large ducts channeling cold air from the front of the vehicle to the brakes, and another set allowing the heated air to escape. Large, open face wheels also help, as air is drawn from below the car, around the brakes, and out through the wheels. The Dub Spinners pictured above provide absolutely no cooling ability for your brakes, while my wheels on the left allow a lot of air to flow through.
There are two more cheap and easy upgrades you can make. The first is to install some high-performance brake pads. Racing pads are not advisable because they are designed to work at temperatures greater than what you would normally achieve on the road. If you're pads are cool and you hit the brakes, don't plan on stopping anytime soon. But high-performance pads can really make a difference and are relatively cheap and easy to install. You can also remove the dust shield from the inside of your brake assembly. This is designed to keep dirt, rocks, and water off of your rotors; but in Southern California those really aren't issues. With a little care when driving through large puddles of water in the rainy season, you can remove these and allow your brakes to cool faster by removing what is essentially a wind-break for your rotors.
PERFORMANCE vs. AESTHETICS
As I touched on briefly in the wheels section, upgrades and modifications that look great may not be a good idea for canyon or high-speed desert driving. I've seen cars with wheels so big that they couldn't turn to full lock because the tires rubbed the wheel well. I've also seen many cars that were lowered so much that the chassis would scrape on just about any bump, and the suspension components no longer had enough travel to do their job properly. These cars looked great, but really had low levels of performance.
Another issue to keep in mind is the appearance of your car. While bright paint schemes and intricate graphics might win at the auto shows, they aren't always a great idea for the kind of driving discussed by this site. Let's face it, high speed driving is not exactly legal on every road, so it helps to have a car that gets as little notice as possible. A row of 10 sports cars with racing graphics passes a cop car, even at the speed limit, and that officer is immediately going to suspect them of breaking the law. Sometimes, having a sleeper car that doesn't get much notice can be the better vehicle for back-roads driving.