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s13 weight reduction demonstration

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Weight Reduction Part 1.



Interior trim was designed with the average consumers tastes and comfort in mind. While many people value the luxury and prestige of leather and polished wood interiors, we however, do not. It's not that we don't enjoy the finer points of interior decorating; we just have bigger and better plans for it, like ripping it out and throwing it on your garage floor.


In the quest for speed and improved handling, Newton's First Law and Inertia is your worst enemy. The law state (in slightly different terms) that your car will continue to go straight at a constant speed unless acted upon by on equal or opposite force. In fact, it is the natural tendency of your car to resist changes in their state of motion. This tendency to resist changes in their state of motion is called inertia.


So who cares? What does this mean for you? It means by reducing the weight of your ride, you can effectively reduce the amount of force required to slow down your car or, to change its direction. So you're reducing the inertia your car has by reducing the weight. Pretty cool eh? Grade 10 physics never looked so good. By decreasing inertia you also increase cornering speeds because your tires won't be loaded up trying to fight inertia, therefore allowing you to increase your corner speed without surpassing your tires lateral traction!


Sweet, so where do you start? Well for illustrative purposes we'll be using some shots of a 1989 (zenki) S13, for our weight reduction demonstration.


Now a stock 1989 240sx weighs 2,684 pounds, and its engine makes roughly 140hp. So if you divide the weight by the horsepower you get you get 19.2 so for every 19.2 pounds it will roughly translate to 1 hp.



Here are a few easy things to remove that aren't necessary but weight quite a bit *Note, weights are approximate*:


Passenger Seat (37 lbs) - Removing the passenger seat is a very easy and effective way to give your 240SX a small gain in power. The seat is only held in place by 4 bolts.


Rear Seat (29 lbs) - The rear seat is a little more complicated to remove than the passenger seat. The back rest of the seat is held in place by those two loop tabs, and the plate along the bottom where it pivots when you fold it down. The easiest way to remove this part is to pull up the loop tabs, unscrew the hinge from the seat and take the seat out. Then go back and remove the hinges. When removing just remember where everything goes some times matching identifying marks will help) and it should be easy to put back in place whenever needed.


Rear Seat Cushion (10 lbs) - The rear cushion should be removed after the back rest part is out.. It's held in place by little clip mechanism just below the seat, they are little black handles, pull them then pull the seat out.


Floor Mats/Front and Rear (6 lbs) - Pull them out.


Tire Floor Cover (3 lbs) - The tire floor cover is right underneath the rear trunk carpeting. It's made of a type of particle board/plywood/ whatever, it's useless take it out and use it for firewood.


Spare Tire and Jack (32 lbs) - Below the Tire Floor cover, unscrew the tire, pull it out, along with your jack and tire iron. This is only recommended for track use, if you have CAA, or a really good friend to bail you out every time you screw up. :


Rear Hatch Cover (6 lbs) - This can simply be removed whenever needed. Weight is close to 6 lbs.


Interior Panels (40 lbs) - Taking out your rear trim panels all around your trunk is a fairly easy thing to do. It doesn't require much finesse just pull until the clip gives. If you don't want to risk breaking the panels which tend to get a little brittle with age, cut the heads off clips. Remember not to forget your rear hatch panel and speak cover panels. Also removable are the door pads, they are typically held on by clips, so wedge in a screwdriver or something with similar characteristics, and pop the bottom and side clips out. Then lift upwards on the pad to clear the door sill. *Note* Removing door pads can be uncomfortable if you're the type who leans on it while driving. Before removing anything make sure it won't bother you immensely later.


Total Easy Weight Removal = 163lbs or about an 8.5 hp increase.


The above are the easiest ways to reduce weight in your car. For those of you, who need to loose some more weight or just love stripping cars, wait until the next segment, Weight Reduction Pt.2 of this little series for more advanced (and often pricey) upgrade to make your car lighter then ever.

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Weight Reduction Part 2 (Advanced).



With your newfound love for weight reduction, the moderate increase in performance and vehicle dynamics that comes with it, it's time to go on to the next level of stripping. In this stage with strip out unneeded interior and exterior weight, as well as replacing different stock pieces with lightweight alternatives. Unlike, Pt. 1 of this series, the modifications often come at the expense of comfort, and can even cause a hit to your pocket book as well. Typically these modifications are reserved for full race/drift cars, and or serious weekend warriors. With that being said, keep in mind some of these modifications may be irreversible, so it's imperative that you seriously think everything through before any removal is made. Also remember to mark everything taken out of the car with matching marks and list the parts, if you plan to put it back in. Doing all this will help you to make better choices and effectively save you time, money, and effort in the long run.


The following are some advanced weight reducing tips. *Note* weights are approximate:


Air Conditioning (40 lbs) - Removing the air conditioning will net you a reduction of about 40lbs. Be sure to remove everything from the engine (compressor and hoses etc.) as well as behind the dash (piping, A/C unit etc.). A Factory Service Manual or another form of manual for your vehicle can be extremely useful in the disassembly of the A/C parts. *CAUTION* The refrigerant in the A/C lines is compressed and releases into the atmosphere at -2 F (-19C), and will freeze any surface it comes into contact with, including your eyes. The safest way to release the refrigerant out of the system is to take it to a shop to do it for you, explain that it must be completely empty because you will be removing it. It is illegal to release R-12 refrigerant into the atmosphere so try to avoid it.

Once the refrigerant is released start ripping those useless parts out and shed those unwanted pounds. :


Front Hood (50 lbs) - Replacing the front hood with a lightweight fiberglass or carbon fiber hood is a good way to kill some weight from around the front end of the car. Weight saving are around 50lbs give or take, depending on the type of hood you have. If you don't intend on replacing the entire front hood you could also remove the sound deadening on the inside of the hood.

Stock Wheels (22 lbs each/replacement weight from 11lbs each) - Replacing the wheels is an option, however keep in mind, drifting hurts wheels big time (like when you hit a curb). You may find it more cost effective to stay with some steelies at first as they are easy to replace. If you do choose to go with aftermarket wheels there are a WIDE variety of models and brands to choose from. It's a good idea to look for lightweight wheels because that the whole point of this article. Replacing your wheels with lightweight wheels will dramatically increase your cars acceleration. We suggest not going over 17 inches if maximum performance is what you want to achieve, however more powerful cars wear 18 inch wheels very nicely. *Note* With wheel size increase, the price of tires increase, especially from 17 to 18 inches. For tons of good wheel weight information check out this site here: http://www.wheelweights.net/


Front Drivers Seat (40 lbs/replacement weight from 14lbs) - The front drivers seat on most cars can easily be replaced with a much lighter aftermarket seat. A lightweight racing seat will save you considerable weight and will also provide more lateral support and stability then its stock predecessor.

Stock Flywheel (13 lbs) - Can be replaced with lightweight aluminum flywheels. Machining stock flywheels down is not recommended due to lack of structural integrity after machining. It can be very dangerous if a flywheel breaks up, and rips through the bell housing of your transmission and into your legs.


Stock Steering Wheel (3 lbs) - Can be replaced with lighter performance steering wheel with no airbag. Check local laws for information on the legality of this upgrade.


Stock Speakers (2 lbs ea.) - These can also be easily removed.

Replace Stock Exhaust (Varies) - The stock S13 exhaust weighs considerably more than some of the aluminum aftermarket exhausts. There are many to choose from, that are made of different alloys and metals. It doesn't hurt to shoot off an email or make a phone call to a manufacturer and ask them for the weight of their exhaust systems.

Carpet (40 lbs) - Removing the carpet as well as the carpet lining will net you a pretty good amount of weight.


Excess Wires, Brackets, and Bolts (10 lbs) - Removing excess wiring and bolts and brackets will also net you a reduction of close to 10lbs. Remember any bolts that expose straight through holes to the outside atmosphere (holes that you can look through and see the road etc.) are required to be filled or your car will not pass safety. It's easier just to replace those critical bolts back into the holes. This will also prevent rust.

Fiberglass Reinforced Plastic, Carbon Fiber, Fiberglass (Varies) - These materials if made into fenders, bumpers, rear trunks or hatches, will greatly reduce the weight of your vehicle, but are extremely expensive.


Sound Deadening Tar (35-40 lbs) - This is all that textured stuff under your carpet all over the car. This stuff is can be a real pain to chip off with a hammer and a screwdriver. Thankfully there is an easier way. Buy a bag of dry ice from wherever it may be sold and dump it onto the sound deadening. Let it sit for a few minutes to let it get nice and cold, then whack it with a hammer, and it will shatter into pieces and come out in huge chunks. Any residue left over use an adhesive remover (gasoline) and a chisel or flat head screwdriver to chip it out.


Carbon Fiber Driveshaft (varies) - Less rotational (unsprung) weight through your drive train is an excellent way to improve your cars performance. Unfortunately it costs a lot to purchase.


Total Advanced Weight Removal = 269 lbs not including variables which roughly equates to a 14hp gain.


Not bad considering there is still room for improvement in lighter body panels and Lexan windows. So there you have it, increasing your performance though alleviating the weight in and on your car. Thanks for reading.

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