Sprung vs Unsprung Weight
02-02-2009, 07:29 AM
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Sprung vs Unsprung Weight
How much sprung weight must you shave off to equvicate it to shaving off 1 pound of unsprung weight?
I have heard everything from 5 - 30 lbs of sprung weight to equal the equivalent performance gain of 1 lb of unsprung weight.
I have removed my spare tire and tools. I assume roughly 50 lbs of sprung weight. Anything else that can be removed to significantly reduce weight that is practical? (Meaning not ripping out the passanger seat).
I have heard everything from 5 - 30 lbs of sprung weight to equal the equivalent performance gain of 1 lb of unsprung weight.
I have removed my spare tire and tools. I assume roughly 50 lbs of sprung weight. Anything else that can be removed to significantly reduce weight that is practical? (Meaning not ripping out the passanger seat).
02-02-2009, 08:37 AM
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WAT?
what kind of performance gain are you talking about?? maybe you mean rotating mass, and acceleration?
i dont want to but i feel i should ask. how old are you?
what kind of performance gain are you talking about?? maybe you mean rotating mass, and acceleration?
i dont want to but i feel i should ask. how old are you?
02-02-2009, 08:48 AM
#3
These constant age questions are getting tiresome, other than in "I wrecked my Z" threads which are generally started by the youngsters.
02-02-2009, 09:08 AM
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Im 22
By performance gains, yes, I mean in general handling, better acceleration and so forth.
I beleive (correct me if im wrong) Unsprung weight is any weight below the suspension, such as wheels, tires, and brakes.
Sprung weight is anything above the suspension like a spare tire, seats, your fat ***, ect...
From what I have read about sprung and unsprung weight, it is really the weight you can shave off from below the suspension (unsprung) that gives major performance increases.
However shaving weight above the suspension does help but not to the same effect. I beleive there is a ratio to how many pounds of sprung weight is equal to shaving off 1 pound of unsprung weight. Why isn't this a legitamate question?
Your right the majority of people may have no idea this concept even exists, but the fact of the matter is... Some people on this forum could be considered for a car equivalent of mensa. I know someone has the answer
By performance gains, yes, I mean in general handling, better acceleration and so forth.
I beleive (correct me if im wrong) Unsprung weight is any weight below the suspension, such as wheels, tires, and brakes.
Sprung weight is anything above the suspension like a spare tire, seats, your fat ***, ect...
From what I have read about sprung and unsprung weight, it is really the weight you can shave off from below the suspension (unsprung) that gives major performance increases.
However shaving weight above the suspension does help but not to the same effect. I beleive there is a ratio to how many pounds of sprung weight is equal to shaving off 1 pound of unsprung weight. Why isn't this a legitamate question?
Your right the majority of people may have no idea this concept even exists, but the fact of the matter is... Some people on this forum could be considered for a car equivalent of mensa. I know someone has the answer
Last edited by Lento; 02-02-2009 at 09:13 AM.
02-02-2009, 09:16 AM
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There is no magical formula for spring vs. unsprung really. Things like large heavy wheels 19-20 inch and BBK's go way against this formula. For street driven cars it really doesn't make any difference. I wouldn't go out of my way to buy really heavy wheels (full chrome 22" lexani's kinda deal) but I'm not buying Magnesium and Carbon fiber wheels for $10,000 a set to save weight either.
If you are building a drag car, then 16" wheels and unvented rotors on all 4 corners with small aluminum calipers will help a lot in the unsprung weight department. However that is hardly an ideal street setup.
If you want to make your car faster losing weight is a great weight, however to make any difference you would need to remove 300+ lbs to even feel it. Taking out 300lbs comes down to cutting out the doors, changing glass to lexan, pulling A/C, race seats vs. power heated seats, no carpet headliner sound deadening, removing the heater core etc.. Basically the car will be a gutted piece of crap to save that weight. Then on a car with less than 300whp (normally aspirated 350z) still being likely over 3000lbs with driver you are still running 13's with a gutted, driver unfriendly car. Hardly worth it really.
So what I'm saying is, unless you are really hardcore racing, don't bother removing any weight at all it won't do you any good. Don't make the car heavy on purpose as wheels that are 50lbs plus tire will slow the car down, but you will not feel any difference between a 19" wheel thats 25lbs vs 22lbs on the street. You may gain in the 1/4 mile by 1/10th or so, but who cares? Whats the diff between 13.8 and 13.9 on your time slip? Going to a 16" slick from your 19" street tires will make a diff, but they won't look very nice on the street.
The best way to get a gain is take out the easy weight, about 100lbs, and add power at the same time (intake, manifold spacer, exhaust, chip etc) that kind of thing. Otherwise a turbo kit or nitrous is your best bet to make a difference you can feel.
If you are building a drag car, then 16" wheels and unvented rotors on all 4 corners with small aluminum calipers will help a lot in the unsprung weight department. However that is hardly an ideal street setup.
If you want to make your car faster losing weight is a great weight, however to make any difference you would need to remove 300+ lbs to even feel it. Taking out 300lbs comes down to cutting out the doors, changing glass to lexan, pulling A/C, race seats vs. power heated seats, no carpet headliner sound deadening, removing the heater core etc.. Basically the car will be a gutted piece of crap to save that weight. Then on a car with less than 300whp (normally aspirated 350z) still being likely over 3000lbs with driver you are still running 13's with a gutted, driver unfriendly car. Hardly worth it really.
So what I'm saying is, unless you are really hardcore racing, don't bother removing any weight at all it won't do you any good. Don't make the car heavy on purpose as wheels that are 50lbs plus tire will slow the car down, but you will not feel any difference between a 19" wheel thats 25lbs vs 22lbs on the street. You may gain in the 1/4 mile by 1/10th or so, but who cares? Whats the diff between 13.8 and 13.9 on your time slip? Going to a 16" slick from your 19" street tires will make a diff, but they won't look very nice on the street.
The best way to get a gain is take out the easy weight, about 100lbs, and add power at the same time (intake, manifold spacer, exhaust, chip etc) that kind of thing. Otherwise a turbo kit or nitrous is your best bet to make a difference you can feel.
Last edited by 350z-Jim; 02-02-2009 at 09:21 AM.
02-02-2009, 09:29 AM
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There is no magical formula for spring vs. unsprung really. Things like large heavy wheels 19-20 inch and BBK's go way against this formula. For street driven cars it really doesn't make any difference. I wouldn't go out of my way to buy really heavy wheels (full chrome 22" lexani's kinda deal) but I'm not buying Magnesium and Carbon fiber wheels for $10,000 a set to save weight either.
If you are building a drag car, then 16" wheels and unvented rotors on all 4 corners with small aluminum calipers will help a lot in the unsprung weight department. However that is hardly an ideal street setup.
If you want to make your car faster losing weight is a great weight, however to make any difference you would need to remove 300+ lbs to even feel it. Taking out 300lbs comes down to cutting out the doors, changing glass to lexan, pulling A/C, race seats vs. power heated seats, no carpet headliner sound deadening, removing the heater core etc.. Basically the car will be a gutted piece of crap to save that weight. Then on a car with less than 300whp (normally aspirated 350z) still being likely over 3000lbs with driver you are still running 13's with a gutted, driver unfriendly car. Hardly worth it really.
So what I'm saying is, unless you are really hardcore racing, don't bother removing any weight at all it won't do you any good. Don't make the car heavy on purpose as wheels that are 50lbs plus tire will slow the car down, but you will not feel any difference between a 19" wheel thats 25lbs vs 22lbs on the street. You may gain in the 1/4 mile by 1/10th or so, but who cares? Whats the diff between 13.8 and 13.9 on your time slip? Going to a 16" slick from your 19" street tires will make a diff, but they won't look very nice on the street.
The best way to get a gain is take out the easy weight, about 100lbs, and add power at the same time (intake, manifold spacer, exhaust, chip etc) that kind of thing. Otherwise a turbo kit or nitrous is your best bet to make a difference you can feel.
If you are building a drag car, then 16" wheels and unvented rotors on all 4 corners with small aluminum calipers will help a lot in the unsprung weight department. However that is hardly an ideal street setup.
If you want to make your car faster losing weight is a great weight, however to make any difference you would need to remove 300+ lbs to even feel it. Taking out 300lbs comes down to cutting out the doors, changing glass to lexan, pulling A/C, race seats vs. power heated seats, no carpet headliner sound deadening, removing the heater core etc.. Basically the car will be a gutted piece of crap to save that weight. Then on a car with less than 300whp (normally aspirated 350z) still being likely over 3000lbs with driver you are still running 13's with a gutted, driver unfriendly car. Hardly worth it really.
So what I'm saying is, unless you are really hardcore racing, don't bother removing any weight at all it won't do you any good. Don't make the car heavy on purpose as wheels that are 50lbs plus tire will slow the car down, but you will not feel any difference between a 19" wheel thats 25lbs vs 22lbs on the street. You may gain in the 1/4 mile by 1/10th or so, but who cares? Whats the diff between 13.8 and 13.9 on your time slip? Going to a 16" slick from your 19" street tires will make a diff, but they won't look very nice on the street.
The best way to get a gain is take out the easy weight, about 100lbs, and add power at the same time (intake, manifold spacer, exhaust, chip etc) that kind of thing. Otherwise a turbo kit or nitrous is your best bet to make a difference you can feel.
Right now I run without the spare and tools and in the summer I usually only keep a quarter - half tank of gas.
I have yet to weigh it but I figure the spare, tool, and 6-7 gallons less of fluid may be about 75 lbs or so saved.
02-02-2009, 09:44 AM
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You can figure it out by calculating the moment of inertia. Too lazy to do it, so here's an example:
http://www.audiworld.com/tech/wheel13.shtml
http://www.audiworld.com/tech/wheel13.shtml
Last edited by zettahertz; 02-02-2009 at 10:00 AM.
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02-02-2009, 09:59 AM
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unsprung weight affects how a suspension reacts to bumps. ex: control arm and brake caliper weight, inverted shock designs
rotating/moving mass plays a bigger role in acceleration than static mass. ex: flywheel, driveshaft, wheels, tires, rotors
moving mass can also be unsprung weight. ex: wheels and tires
rotating/moving mass plays a bigger role in acceleration than static mass. ex: flywheel, driveshaft, wheels, tires, rotors
moving mass can also be unsprung weight. ex: wheels and tires
02-02-2009, 10:32 AM
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02-02-2009, 10:50 AM
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Remember Japanese cars are designed assumming each occupant weights 145 pounds or less.
Also suspension components are half and half: half the weight of suspension arms, shocks, springs, roll bars is unsprung. Why manufacturers had to go to aluminum arms to offset wheel weight when they bumped up from 14-15" [G20] to heavy 17" much less 19".
Also suspension components are half and half: half the weight of suspension arms, shocks, springs, roll bars is unsprung. Why manufacturers had to go to aluminum arms to offset wheel weight when they bumped up from 14-15" [G20] to heavy 17" much less 19".
02-02-2009, 11:08 AM
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But... That is pretty freakin cool
And I rhyme!
02-02-2009, 07:06 PM
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Generally speaking, reduction of unsprung weight improves handling, while reduction of rotating weight improves acceleration (and deacceleration, otherwise known as braking). Of course, the reduction of any and all weight generally improves both handling and acceleration. There are several good threads concerning reducing weight, including "have you lightened your Z". I'm sure you noticed the performance improvement from the weight you've taken off, and it also shows up in miles per gallon as well. I particularly noticed a big difference in going to lighter wheels, that was one of the best mods I've done. Look your car over carefully, and you will notice little ways to reduce weight that will not affect the look or utility of the car.
02-03-2009, 08:32 AM
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i may have been a bit harsh but we have been getting so many fast and furious questions of late i instantly pictured someone buying lighter lug nuts to and then bragging about how much faster it made the car.
like Jim said there is no real quantifiable coloration between performance of sprung and un-sprung weight. mostly cause there is no good way to measure handling except horizontal Gs or speed on a slalom coarse. Also the fact that the only time sprung and unsprung weight come into play is when you are going over bumps
rotating mass does make a big difference mostly because it makes the tires a lot easier to spin up. so while getting wheels that weight 10lbs less will not make your drag times noticeably different, the car will feel noticeably faster
like Jim said there is no real quantifiable coloration between performance of sprung and un-sprung weight. mostly cause there is no good way to measure handling except horizontal Gs or speed on a slalom coarse. Also the fact that the only time sprung and unsprung weight come into play is when you are going over bumps
rotating mass does make a big difference mostly because it makes the tires a lot easier to spin up. so while getting wheels that weight 10lbs less will not make your drag times noticeably different, the car will feel noticeably faster
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