Weight Reduction - a Comprehensive Guide

[Craftsman]

Originally posted by mranlet
Thanks.

Although, body weight is a worthwhile point - ever notice that the slow Hondas are the ones driven by big fat guys? They completely ruin the awesome P/W ratio.

I noticed that in my Honda...

Matt.

[mechaniac]

I'd like a guide on the adverse effect of weight reduction and suspension/chassis setup.

If you have the time.

[GRiDRaceTech]

Lightening a car excessively without utilizing the height adjustability of coilovers or even aftermarket spring/shock combination will result in a car which looks to be standing on tiptoe. This would obviously be detrimental to handling.

Also, the valving on any aftermarket non-adjustable shocks would be improper for the application, as they are assuming a stock-weight car. An adjustable shock would go quite far in compensating for the weight.

[Craftsman]

Here's some equations for you guys to optimize your setup...

First, you need to know your weights at each corner. Remember that this changes dynamically as you drive your car. Weight transfer happens during acceleration and deceleration (reverse acceleration). It occurs in turns also.

Your wn (natural frequency) is the square root of K (spring constant) / M (mass at each corner).

Your damping constant should be 2 * wn (natural frequency) * m (mass). I'm assuming that the damping ratio is one for critical damping... Remember to watch your units.

The only way to make sure you are at optimum is to put your dampers on a shock dyno.

Again, remember that the mass values change dynamically as you drive. You never want to be under damped as that means your car will bounce, and you do not want your car to be over damped as that means that your car will be too slow to return to the original ride height (slow response).

Enough control sytems from me

[Gingras]

wow that was a good write up on losin the weight

[mechaniac]

I was waiting for someone to say: "When reducing weight from the car, one must be cautious to not just start stripping everything out."

If you start to take everything out of the car and are not aware of the weight balance changing, you will end up with an off balanced car that will not handle as well as before the weight reduction. Race cars are stripped down to the bare metal and then built back up carefully placing components, and choosing the right components so that the total front and rear weight bias does not vary by much. Afterwards, the suspension is set up to the chassis and power of the car, not before.

This may not be apparent in the early levels of driving, such as slower speeds. But the more power you make, and faster you go, you will start to realize the car's handling characteristics change. Sometimes dramatically.

[gwilo_drifta]

This guide is hardcore, and cause of it, the back end of my celica is completly empty.

Thx man.

[GRiDRaceTech]

Now get a carbon fiber hood and eliminate more weight from the front of your car.

[gwilo_drifta]

I've only been in the game for awhile, not exactly sure where to get a carbon hood??

That probably is a good idea, but how much weight does it actually remove?

[GRiDRaceTech]

Originally posted by gwilo_drifta
I've only been in the game for awhile, not exactly sure where to get a carbon hood??

That probably is a good idea, but how much weight does it actually remove?

Yeah, it's really hard to find hoods, isn't it? It's not like you're on the internet with access to search engines or anything.

How much weight it removes is dependent on application.

[makai]

The sarcasm of your comment compliments your signature. lol.

That is really true. It is possible to find carbon fiber parts for almost any car. If you want it bad enough and you can't find it any where, you can get a custom one made.

[mranlet]

A friend ran across a write-up of a process that uses vaccumn bags to make pseudo-pre-preg carbon (like what is used for structural applications). If I can fnd it, I'll post it up here.

Even if you have to import a carbon hood from Japan, shipping isn't all that expensive since they weigh so little, but be prepared to wait a while.

I just bought a Legacy Wagon with full interior and goodies, and as I strip weight off (daily driver confort spec) I'll add pics and maybe show some illustrated how-to's for stuff like removing sound deadener or drilling bumper supports.

I'm really glad you folks like this write-up too!

[jayballash]

newbie here, but i saw this thread, so i had to register and post.
one of the cheapest and seemingly obvious ways to shave pounds off is one of the most overlooked. my buddy was obsessive about reducing the weight of his car, stripping almost everything down to bare bones. he asked me if there was anything else that he could do to reduce the weight for his races. i told him to lose 50 pounds. he is an exceedingly overweight person. if you are serious about racing, than your physique should definitely be an issue. granted it takes a little more time to acheive than just throwing the back seat out, but as we all know, every ounce counts. when was the last time you've seen a fat jockey riding a horse in the kentucky derby? well, why should car racing be any different? i bet most of the people who read this could stand to lose a few pounds, and guess what? this takes pounds off of the total weight! i just thought this was funny, because he cared so much about stripping out wiring, and carpet, and nuts and bolts, and he could have just dropped a couple lbs, and kept it all in his car! think of it as a personal weight reduction.

[otakugt4]

Tho I think it was implied, one should not only watch the f/r weight balance WITH DRIVER but also the right to left. It's a pain to do but I have my FB down below 2200lbs now, last weighed in at 2210lbs (2400lbs w/ me) and a nice 49 front / 51 rear balance, and side to side seems nice but I haven't found some one w/ 4 little scales I could use.

Note: Stock weight for my car was ~2450lbs.

[Mike Peters]

wow you must have been bored.

keep it grindhouse.

[the puppet man]

god damn there is so much *Censored**Censored**Censored**Censored* involved in drifting. well i drive a 1990 Z32 2+2 which weighs in stock at about 3550. now i know a lot of you people hate z's and will tell me that it is way too heavy to drift, but i dont car ive seen it done, my friend has a Z31 that is pretty close to stock(weighs 3163lbs), and drifts like mad. before i start my real question i want to say that i will never buy a 240 or a 200sx for the sole reason being that everyone and their mama drifts in one. so please dont tell me to buy a damn 240.

ok so i was wondering if any1 knew how much a z32 could lose just through fiberglass hoods, trunks, front end, rear end, possibly carbion fiber doors. cuz ive noticed that almost everything on the car is extremely heavy compared to most cars. and i want the car to be able to drift, as well as be a daily driver

[purpleDrifter]

Lighter drive train parts usually result in weaker parts. Nothing is as strong and reliable as steel. I replaced my aluminum block with a heavier cast iron one after it cracked. I replaced my aluminum drive shaft with a steel one after it twisted in two. I replaced my control arms after they bent. I replaced my torque arm after it bent. I replaced my solid OEM axle housing and went with a much heavier housing after it twisted and bent (it bent by over 2 inches). I replaced my panhard bar with a stronger, heavier one after it bent. I replaced my shock absorbers with ones with bigger shafts after they bent. So, I do not think a lighter drive train may be the best way to go, unless you like to be constantly replacing parts!

Also, I would not take out inside lights. THere is nothing more frustrating than being at the track after it gets dark and not being able to see the schedule inside your cockpit. However, the rules do not prohibit cutting away inside metal. With a sturdy roll cage, lots of weight can be taken off by cutting out your inside metal panels and just leaving the outside skins.

To be honest, lightening a car for racing is a much better idea then boosting the power of the car. and I quote Colin Chapman:"blah blah blah...added lightness...blah blah"

The thing is, most people can not afford a second car for the track to race or drift in. They have to build a kind of race car/daily driver hybrid. Loosing weight is good, but it has to be within reason. Lightening your car can also raise your fuel economy. So in my opinion, it is a good idea for everyone to do this.

The back seats of a 2+2 is not for people to sit in, most 2+2 sports cars have back seats that can not fit your backpack. They are just for lowering insurance rates on sports cars. It is just a waste of interior space and extra ballast, So you can remove the back seats without having any remorse afterwards(unless you are planning to sell the car, then you shouldn't remove anything).

The rear window can be replaced with perspex, but I don't know about the legality of this in D1 or Formula D.

The spare tire should be at home in your garage, for emergency, just bring a puncture repair kit or call AAA.

Don't have any junk in your car, don't keep your whole wardrobe or golf bag in the car when you are going to school or work.

Removing the AC on a daily driver is a bad idea, as demonstrated in this trip across Europe with James May in his Aston Martin V8 Vantage N24 stripped out GTR racer.
http://www.youtube.com/watch?v=QApgl...eature=related

[INFO]

Weight Reductions Guide & Tips
http://www.importtuner.com/features/...ips/index.html