car tuning: weight reduction

The best way to increase performance of your vehicle is also arguably the cheapest. This performance upgrade: weight reduction. Reducing the weight of your car is incredibly easy—it’s as simple as taking the things out of your car that

aren’t strictly necessary. There is a drawback to performing your weight reduction without a plan: the weight distribution will be affected, making your car handle poorly. The name of the game in weight reduction is to add lightness in all the right places.

To appropriately reduce the weight in your car, the best place to start is by figuring out what your car’s weight distribution is. If you like the way that your car handles, you’ll want to try to preserve this distribution as much as you can while reducing the overall weight of your vehicle. The “ideal” for weight distribution has long been touted as 50/50—the front and rear of the car each having exactly 50% of the vehicles full weight. While a 50/50 weight distribution makes for good marketing, what really matters is whether your car’s handling feels good to you and whether your car’s weight distribution helps or hurts the handling of your car under acceleration and braking. Your car was engineered to work with its existing weight distribution, so any changes you make to this should be for your own preferences and not to reach someone else’s idea of an ideal.

Where to begin?

So, the first thing you need to do is know your weight distribution. But how? Sometimes the manufacturer will have this information available either in your owner’s manual or somewhere online. This isn’t often the case, so you’ll have to do a little bit of digging. If you have a somewhat more popular make or model of car, someone else has already gone through the process of getting their car weighed. Searching through your favorite make- or model-specific forum is a great way to find this information. If you’re not able to find this information, the most reliable way to find this information is by having your car weighed. A quick search online will help you find a shop that has this capability. Alternatively, you can purchase scales yourself. If you do buy your own scales (make sure they’re for weighing vehicles), you’ll place the scales under each of the tires and put those numbers together. Comparing the added weight from the front of the car to that of the back of the car will give you your weight distribution:

To start get the total weight of your car:

Front Right (FR) + Front Left (FL) + Rear Right (RR) + Rear Left (RL) = Total Weight

Then, add the front and rear weights separately and divide each by the total weight:

FR + FL / Total Weight = % of total weight in the front

RR + RL / Total weight = % of total weight in the rear

If you’ve done your math right, these two numbers will equal 100, but they will also give you your car’s weight distribution. Once you have your numbers, the easiest place to start your weight reduction adventure is in your interior.

Measure twice, cut once.

Whether you are going to keep the current weight distribution or you want to change it, reducing the weight of your car will work the same way: you’re removing weight from your car to make it lighter. When you’re removing weight, though, you need to make sure you know how much you’re removing. And if you’re trying to keep the current weight distribution, you need to remove it evenly. When you remove an item from your car you’ll need to weigh it, then remove an equivalent amount of weight from the other end of the car. If you’re looking to change the weight distribution of your car—bringing it closer to 50/50—you can reduce more weight from one end of the car than the other or shift weight within the car by moving the battery from the engine bay to the trunk. If you’ve purchased your own set of scales, you can also weight the car throughout the process to keep track of your progress and any changes in the weight distribution that you’ve made.

Ways to reduce weight

There are a wide variety of things you can do to reduce your car’s weight. (If you’re planning on racing your car, make sure that you’ve reviewed the associated rules for the organization you’ll be racing in.) Many of these options are cheap or free, since you’re just removing items from your car. Other methods can cost a decent amount of money. In the end, it’s up to you to decide what you’re going to do and how much you’re willing to spend.

Removing extra stuff

The first thing you can do to make your car lighter is to take out anything loose or extra in your car. This includes things like the jack and spare tire, tool kits supplied by the manufacturer, items you store in your car, floor mats, and any other accessory that came with your car or that you bought for it. Removing your spare tire and jack could easily reduce your car’s weight by 50 pounds! (You’ll want to leave your spare tire and jack in the car for everyday use—it’s a safety feature—but when you’re on the track, you won’t have any use for it.)

Another area you can remove ‘extra stuff’ from in your car is you, the driver. Maybe you’re working off those heavy holiday meals, or you’ve been indulging in a some extra snacks here and there. No matter what reason, if you have some extra weight on your body, that is a great place to start your weight removal process. (Just remember, if you don’t have extra weight you can lose, don’t go making yourself sick trying to lose weight. There are plenty of other places you can look to make your car lighter.)

Your interior

As long as it’s an allowed modification, removing parts of your interior can help reduce a lot of weight from your car. Back seats, door panels, carpeting, radio, and sun visors can all be removed relatively easily—usually with a couple of bolts or screws at most—and can reduce a lot of weight. Removing these items isn’t recommended for daily driven street cars, but for your race car, it’s a great way to get rid of unwanted weight.

Another way to reduce some weight inside your car is replacing the factory driver (and passenger) seat with a light-weight racing seat. The seats that come with your car are generally heavy and have added weight because of the mechanisms for sliding and reclining the seat. Racing seats that don’t recline are usually one piece and can reduce the weight in your car a lot. Just be prepared to spend a good amount of money for a decent set of seats.

In the engine bay

Apart from rebuilding your engine with aluminum components, there aren’t many things you can take off of the engine and have it continue running. One thing you can do, though, is remove the air conditioning components. Removing these components not only lighten the front of the car, it also helps reduce the parasitic power loss from A/C compressor.

Another option is to replace your battery with a smaller-sized battery. These batteries produce the same amount of power necessary to power your car, but it takes up less space and weight as little as half the weight of a standard battery. Additionally, if you’re looking to even out the weight distribution of your car you can move the battery to the rear of the car. This will require running longer, alternative battery cables, but this is a fairly standard practice in race cars.

Other areas

If you’ve done all of the above, you’re now following the old racing adage every ounce counts. 

The first place is your wheels and tires. You’re not likely to get a lot of weight removed by changing out the wheels and tires, but the weight reduction won’t hurt by any means. This part requires some planning about wheel and tire sizes as well as being incredibly concerned with the weights of the parts you’re replacing. It also isn’t going to be the cheapest endeavor as the lighter your wheels and tires, the more expensive they’re bound to be.

The next place to look for weight reduction is your windows. Depending on the ruleset you’re following—and whether you’re keeping things street legal—you can replace the side and rear glass in your car with a plastic alternative like Lexan. Glass isn’t exactly light, so replacing it will give you some mild reduction in weight. Just keep in mind that this might bump you into a class that you’re not otherwise prepared for, or might get you a ticket if you try to drive your plastic-windowed car daily.

Lastly there’s the car itself, or rather, the metal it’s made out of. There are a couple of different ways to handle this. The first is to go through your car and remove excess metal that while providing structure to the vehicle, but not explicitly necessary to its function. This can include internal parts of the doors, the supports for the dashboard, and the inside of the fenders and wheel well. Options for this can be cutting out pieces whole, or drilling holes in them to keep a portion of the structures while at the same time reducing their weights. One thing needs to be kept in mind when doing this: those structures are engineered to be there and likely play some role in the safety of the vehicle as a whole. If you are going to start cutting out metal in the car, make sure you have other safety features—like a roll cage—to make sure you survive a crash. (It’s never if you crash, but when.) The second way to handle lightening metal parts of your car is acid dipping. This takes the panels and, well, dips them in acid to remove some of the metal without cutting. This also will reduce the strength of the metal, so the same notes about safety apply to this process.

Whether you’re an autocrosser on a budget or are building a fully prepared race car, weight reduction is going to be your best bet for going faster without spending a lot of money. Just make sure that you’re taking your overall goals into account when removing weight so you don’t end up too uncomfortable on your daily commute. And, as always, be safe about the changes you’re making.

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