I know the advantages of less wieght, but what about the consequences?

Someone told me once that weight reduced cars are less comfortable to ride in. Is this true? What's the logic behind it?

Someone else told me that weight reduced cars don't handle as well, even if the wieght distribution is not disturbed. He said that sprung/unsprung ratio usually turns less favorable with a lighter car. Is this true too? I thought that since the tires have less mass to move around, the lighter car would handle better. Who's right?

What other disadvantages might there be to reducing the wieght of my car? I'd like to be well informed before I randomly unbolt/saw/drill holes throughout my car.

Thanks

 

I wouldn't drill or saw anything on that already weak structure! That being said, several things can be done to intelligently reduce weight. A composite hood, aluminum heads, and other lightweight relacement parts can shave some pounds. Removal of the smog pump, AC equipment and catalytic converters also reduces the weight. You can probably take out the back seat as well. Hope this helps.

------------------
1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley AFPR, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Ruger P95DC, hot wife, new oil filter, thick rubber floormats, no cats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

AHAHAHAAAA... Remove all the seats except the driver! Of course it is more uncomfortable for hitchhikers, but... And maybe you'll lose some hearing if you pull all the carpet/panels/insulation, but I hardly think it is serious. Worth it? Not for me, but it may be for you.

Some people pull the front sway bar and run skinnys, but that is only at the track and is dangerous... duh! It is really just common sense here. A glass hood isn't any more/less safe than a stock hood, but it saves weight. Removing your front bumper might not be such a good idea in rush hour traffic...

------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...

-=ICON Motorsports=-

 

Generally yea, it will ride a little harder but with a thirdgen, it wont matter much. And worse handling? LOL thats funny.... I guess thats why Cart and Indy cars are such terrible handling cars.

 

well u can loose alot of weight swapping in a LT1

------------------
88' GTA 350 MODS---> air foil, K&N, Shift Kit, 180* therm, TB bypass

 

The key to making it ride the same after removing a lot of weight is to change the springs. Factory springs are designed to carry a specific amount of weight. If you lighten the car then there's not enough weight to compress the springs and the suspension feels too stiff. By putting in springs with a lighter spring weight, the handling will seem more like normal.

The best weight distribution is 50/50 front and rear wheels. Thirdgens are very nose heavy.

------------------
Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

all i know about weight reduction is for every 100 lb u lose off of your car, u gain a .10 of a second in the quarter. make sure your car is not to light in the rear, u obviously need weight for traction.

 

Thanks guys. I knew I was right.
mmmm, fiberglass....
mmmm, LT1....

 

The disadvantages? Worse handling, mainly. Friction is a product of (amongst things) how much weight is on said object.

Camaros and firebirds unfortunately suffer from poor weight distribution, with very little weight being on the rear of the car. Something you'll notice crusing at tripple-digit speeds.

------------------
89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Worse handling? Please! Where do people come up with this garbage? Why do you think roundy-round race teams have and do try so hard to violate the rules and run less weight? If more weight was better, nobody would be running at exactly the minimum weight, they would run heavier cars.

I really dont feel like getting into a physics discussion when practical example shows it so well. If you want me to I will, and I am pretty sure that the results will only back up what the race teams have been doing for years.

 

Is it true the LT1 weighs less?

------------------
1992 RS 3.1L Bone Stock

"Yeah, it's a V6 SO WHAT!?"

 

I doubt it weighs much less if anything at all.

 

Enkil, I'd have to agree with madmax about the handling...just remember the extra weight that holds you to the road is also against you with its momentum when you try to turn. It's a careful balance between center of gravity, weight, vehicle dimensions, spring rates, aerodynamic forces, damping and grip on the road that determines whether you break loose in a turn. Handling has to do with many dynamic factors, one of which is friction, one of which is weight, and others, and none of which I want to discuss anymore because it's already making my head hurt .

------------------
1990 IROC 350
Mods: Too busy trying to make it run right to mod it.
Airfoil, Dynomax cat-back, MSD coil, 180 t-stat, Bald Eagle tires,
Hypertech fan switch, Accel 23# injectors, Holley AFPR, ported plenum,
Ported Daytona Yellow stock base, Moroso valve covers, other stuff,
Ruger P95DC, hot wife, new oil filter, thick rubber floormats, no cats.
18.0 @ 85MPH since I'm one big-a$$ MF
"It's better to have and not need than to need and not have."

 

So let me see if I've got any of this right.

Sprung/unsprung wieght ratio is either a myth or it's less important for a street car than reducing overall wieght and front/back wieght ratio.

Reducing overall wieght is only good if it helps the wieght ratio (fiberglass hood is good, removing spare tire is bad. Aluminum LS1 good, iron big block bad).

Lowering a car is good for handling as long as the suspension geometry is not distorted too much. Will lowering a car for cornering diminish its ability to launch?

The LT1 is an iron block--not appreciably lighter than a Gen I small block. The LS1 is aluminum and would be lighter.

The fourth gen handles better than the thirdgen because the track is wider and the engine is behind the front wheels. LS1 models enjoy even better weight distribution (I've heard that Corvettes even have the transmission located in the rear end for wieght distribution's sake).

I'm sorry if I'm irritating anyone, I'm just trying to learn something that I guess is pretty basic to a lot of people by now. I've posted what I know so people don't have to guess what I'm thinking or where I'm going wrong.
Thanks,
Homer

 

Umm...worse handleing....well, look at the viper, theres a car that is more engine than weight...ever try and drive one...fast? It's scary! They will try and lose it on ya! As Enkin said friction is based on the weight, called the "Normal Force". The exact formula escapes me but I think it was as simple as N*coefficient of friction where in this case, N is the weight of the car/4 wheels (well, you gotta account for weight distrobution, but thats simple)
So why in the hell do cart and others try and remove weight? Well 1st off they are pro drivers used to a squirrley rear end, but they do try and keep it from doing so. Well, did you ever hear how high pitched those motors are? Well that says to me they are running high rpms (duh!) so that means they have horsepower cars, not low end torque cars. Torque is the force the friction from the tires is trying to fight, that fight produces linear motion of the car. So if they are running fairly (I say fairly in comparison to some other race cars) low torque motors, they don't have to worry so much about keeping the wheels from spinning right? So they don't need the weight. Where do they need it though? In the handleing, but since handleing doesn't put as much force on the tires as the torque of a big beefy 454 with all the mods, the tires can take it, even with a lower normal force. They have such incredible suspensions that they can get away with having more HP than a viper, and weighing less than a viper, and go faster, and handle better. (Not to downplay the viper as it is a very bad@$$ car, and has been kicking @$$ at races like lemans Had enough? You mean you actually read this much, I'm impressed!
Will the 3rd gen suffer from worse handling, well, depends on what else you do, beef up your suspension to compensate, nope, you'll get better handling. And honestly, if you shave off 200 lbs, you probably won't notice it, that's like having a friend or 2 (depending on size) in the car with you. Jsut remember if you get the
Fiberglass hood
Fiberglass body panels
Fiberglass notchback conversion (to get rid of all that weight in glass!)
Aluminum Block
Aluminum Heads
ALuminum Driveshaft
etc
remember to work over your suspension too, it's gonna need it!
Corry

EDIT: spelling mistakes


[This message has been edited by Corry (edited August 27, 2001).]

 

I don't have the numbers to back it up but im pretty sure the LT1 is lighter than the L98. LT1 heads are aluminum. L98 heads are Iron. And judgning by the fact that the LT1 pretty much can bolt into an L98 eninge bay tells me that they are very similar in size. So by this logic, if the LT1 is not significantly lighter than the L98, than anyone buying aluiminum heads for an L98 for weight savings is wasting their money. Correct me if im wrong but an aluminum headed LT1 has got to weigh alot less than the L98. Does anyone really know how much these things way?

------------------
"Though I cruise through the valley of Rice I shall fear no turbo, for torque art with me."
--Cullan Hooley
-----
1985 IROC-Z w/T-tops, 305 out and 350 L98 TPI engine in, Hooker Super Comp Headers, 3" Hooker Super Comp Cat-Back, Dropped Cat, Rebuilt TH700R4 with Shift kit, 2,800RPM Torque Converter, 3.73 Richmond gears, Auburn differential, Accell SuperCoil, Accell 8mm racing wires, BBK AFPR, Homemade Ram-Air (thanks to askulte), MAF screens removed, Dropped A/C, Dropped A.I.R, TB coolant bypass, Hurst Dual-Gate Shifter, SLP Air Foil, K&N filters, Holley performance fuel pump, Spohn Subframe Connectors, Re-located Spohn Lower Control arms, and more to come.

 

Just to clarify...im not saying that the only reason to buy aluminum heads would be weight savings. But it is a factor in considering heads.

 

Prolly about 60lbs less factoring the aluminum heads and lack of the cast water pump. Not much... try LS1

 

Actually I do believe I misread that. LOL oh well.

[This message has been edited by madmax (edited August 28, 2001).]

 

The friction force (static please, we dont want kinetic) is f=µN. So lets say the coefficient is .3 (taking a wild guess, I dont remember the exact number) and lets say the car weighs 4000lbs and has perfect distribution, so call it 1000lbs on that tire, which you are claiming to be the normal force. Fine. So the actual friction force (*ideal**theory**ideal**theory**ideal**theory*) the tire can handle is 300lbs. Now lets say you apply the max weight on the tire sideways, 300lbs. If you change the weight of the car to less, there will be less weight applied sideways as well, so the numbers will cancel out either way. Where the problem comes in is the force is not applied at the ground, but rather somewhere above the center of the tire, IIRC its around 22ish" on a thirdgen. That force is not accounted for by the tire, if you apply the force at another place beside the bottom (put a tall empty glass on a table, and apply the force at the top of the glass) the friction force no longer matters, the glass tries to tip over. This is what the entire car tries to do, it wants to tip over. The more weight you have being applied above the friction point (see glass example) the more tendency the car will have to tip over. How do you add more force, just add more weight to the car... F=ma right? Same acceleration, more weight... more force. I, for one, do not want more weight for that reason alone, I dont wanna be upside-down. The other reason is, the car has 4 tires. The 2 inside tires will be unloaded and the outside tires loaded. The only way to balance the applied weight, and hence the normal load, is to use stiffer springs that dont allow the car to tip over, and to use stiffer swaybars to transfer the weight to the unloaded tires. This, like everything else in life, is far from an ideal transfer. The weight of the car ends up being transferred to 2 tires rather than 4, I suppose you can guess which one will corner better... and as it so happens handle better. Handling can also encompass transitioning from a right turn to a left turn. I tell you what, you take 1000lbs mounted on a rigid pole and swing it in a circle, and then suddenly reverse your direction and see how that feels compared to doing it with 1lb. The tires dont like that much either.

So, to recap the questions:

Sprung/unsprung weight ratio is either a myth or it's less important for a street car than reducing overall weight and front/back weight ratio.
Its not worth the cost difference.


Reducing overall weight is only good if it helps the weight ratio (fiberglass hood is good, removing spare tire is bad. Aluminum LS1 good, iron big block bad).
Well, you dont really want to take weight off the back of the car, weight reduction in general is a good idea.

Lowering a car is good for handling as long as the suspension geometry is not distorted too much. Will lowering a car for cornering diminish its ability to launch?
Yea, it will. I lower my cars anyway, if you dont go too much the suspension geometry doesnt change so much that it cant be corrected by an alignment. Small errors that some people will argue about all day long are great if you want to argue about theory, but in reality it doesnt make much of a difference in speed.


The LT1 is an iron block--not appreciably lighter than a Gen I small block. The LS1 is aluminum and would be lighter.
Yup.


The fourth gen handles better than the thirdgen because the track is wider and the engine is behind the front wheels. LS1 models enjoy even better weight distribution (I've heard that Corvettes even have the transmission located in the rear end for wieght distribution's sake).
IMO the 4thgens handle worse, their transition into turns and from right to left is absolutely terrible, and I place the blame on the rack+pinion in them. I drove a new SS at a GM test drive a couple years ago, and it was downright scary, it sat there and thought about turning after you had already moved the wheel.


I'm sorry if I'm irritating anyone, I'm just trying to learn something that I guess is pretty basic to a lot of people by now. I've posted what I know so people don't have to guess what I'm thinking or where I'm going wrong.
Nothing is basic, its just varying degrees of who knows more about something than others.

 

I have to agree with madmaxx here. There are many other factors. Someone stated the normal force (which opposes the gravitational force) and how it relates to the friction of the tires. Thats good thinking, but while more mass means more of a normal force, it also means more weight (force of gravity). These two forces cancel each other out (for the most part) in the VERTICAL direction. They will always cancel each other no matter how much mass the car has, this is why they don't float away or sink into the ground (usually ). In regards to cornering, more mass means that when you take a corner (esp. at a high speed) it requires more centripetal force in the HORIZONTAL direction to change the velocity (read: speed AND direction) than it would in a less massive car because Force (centripetal) = MASS x acceleration (read: change in speed AND/OR direction). And the centripetal force I'm talking about is mostly the force of friction between the road and the tires. So, It is a lot easier to keep a car that has less mass in a turn with similar tires and suspension than it is to keep a more massive one in that same turn. Now, to answer the first post, the only disadvantage I can think of is that many other american cars are much more massive (SUV's) and in a collision, momentum is conserved so the SUV wins (but that'll happen regardless of if you add or if you subtract a few hundred pounds)
John

P.S.
Just to clarify about the acceraltion Im talking about: even if you keep the same SPEED in turn, you are changing the DIRECTION and therefore the velocity is changing (acceleration). I love physics!

------------------

• 84 Firebird w/ T/A gfx
• 350 4bbl (LM1)
• Automatic
• Non-leaking T-Tops (new rubber all around)
• Working headlights (new parts)

Mods: 14" K&N open element, 180* stat, ram-air hood, Accel cap & rotor, MSD Super Conductor Wires, 24mm solid rear & 36mm hollow front sway bar w/ PST polygraphite bushings & endlinks, Spohn SFCs, WS6 springs, SLP 1 3/4" Jet-hot coated headers, Hooker 3" cat-back, Catco high-flow cat, Comp Cams High Energy 268 cam, AFR 190 heads, Weiand Action+ intake, Comp Pro Magnum 1.6:1 Steel Roller Rockers, Moroso Oil Pan with trap doors, windage tray and crankshaft scraper, poly graphite motor mounts, K&N oil filter and Mobil 1 synthetic.

http://www.homepagez.com/350thirdgen/

[This message has been edited by johns84bird (edited August 28, 2001).]

 

Yeah, it's in posts like this that i appreciate my understanding of physics, and at the same time, marvel how some people who have no grasp whatsoever can still feel a need to argue and reveal the depths of their lack of understanding of the world around them.

 

The basic formula used in Mechanical Engineering is this.
F=MA
Force (torque normally) = Mass * Acceleration
This changes with a simple algebra to:
F/M = A
So as mass is decreased and force remains constant then acceleration increases. Obviously this is a very simple and not accounting for traction but with lower mass there is less force pushing outward.
Anyway just remember F=MA and less M equals more A!

------------------
84 Z28 383
Stripped w/Cage back halved w/ladder bars and coil overs and 9 inch
700R-4 3.73
I would have a time by now if I could ever get my car back from the shop!!

 

I know about the centripetal accelleration, yes, more mass = higher moment of inertia, =more force to turn. But, I also know there is a very small area, where *ALL* force goes, and thats your tires. You *NEED* friction! So what do you have to do to make your car handle better? (I am sure there is someone out there who has already done this) You need to engineer the whole system. I am sorry, I had forgotton the center of mass problem and the car tipping problem, anther area that say cart accells at, all their mass is VERY close to the ground = less tipping=more even force distribution to the ground. Their low mas makes for a low centripetal accelleraction making them turn easier. (less force required) and softer rubber compounds make more friction. Can you get the same handling as a cart with a 3rd gen? probably not, at least, not without modifying it to the point it is no longer a thirdgen! Also remember, in that torque of the body changing direction (turns) Torque is needed, and therefore the car has a moment of intertia, ideally even weight distrobution, you could say it is close to the straight bar example, since the car is going to pivot on or near the rear wheels, it is close to a bar rotating on it's end. Since the equation for moment of inertia of a bar includes an L component (length) wheelbase is also going to affect turning ability, and of course, Carts have a fairly short wheelbase.. Now that I believe all ideal dituations have been discussed, will reducing weight help? probably some...if I get really bored, I will go ahead and either work all the calulations by hand, or if I get really really bored, I'll write a little windows program to do it, and distribute it Just remember, there is only so much that calculations like that can do though. I can get the coefficient of friction for rubber on asphault but that won't hold for all asphaults, or cement, or either with contaminents (such as oil) or rainwater, so it will still be an ideal case.
or I might be too busy with school to do so We'll see, if I do, I'll post all calcs, and results, so all the other physics nuts here can check it, and we can get a really accurate handling setup for everyone (I eventually wanted to do this anyways, since I like good handling

Corry

 

Why's everyone still talkin'? I thought I explained everything as truthfully and vaguely as possible several posts back .

 

ohhh ohhh ohhhh. i got the aluminum everything!! moved battery to the spare tire hole! and took all the other stuff out of the engine bay! (heater/ac ,smog pump,power steering, crapy radiator,mainfolds{obviously},uhhh wiper motor? , and put in all light weight bottom end parts. will i have a traction problem? yeah i will, will i wheelie? i hope so! do i know anything about the whole advantages/disadvantages?
i know less weight is better for acceleration, lower center of gravity is better for conering, and i need new springs cuz my front end is about 4 " higher than its supposed to be!!
HAVE A NICE DAY!!!

------------------
87 z28 bowtie aluminum 420small block dry sump crower lt. wt. knife edged crank oliver lt wt rods brodix track 1's super ram intake slp 1 3/4 headers accel dfi art carr 700 r4 3.42 gears ssm sub frame/ladder bars.....other parts on the way ,soon to be finished!! couple more weeks!!!

http://people.ne.mediaone.net/gdm

 

I changed one of my reverse lights today.

 

hahah i guess i could see how someone may think that more weight = more traction.. but, that lasted no more than a second, and then i was thinking wtf? why is harwood wasting time making light hoods.. well nevermind, im sounding quite silly after madmax and group's explanations. mkthx g'by



------------------
83 Z28--not a pretty site, sold thank goodness

74 Z28-- 383/400, green on black. pretty clean. FOR SALE!!!