unsprung weight

brucelidat

I've been talked out of the SC.

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DEpointfive0

Oh. Well then... Just do whatever makes you happy. I don't understand the rat race to have the best really...
You should want the best for yourself, yes, but AFTER what makes you happy.
You want 20's with a big àss lip that's chrome, do it, while 18" TE37's with PSS will weigh less and your car will be "n" seconds or "n" percent faster is good and dandy, but if you don't like TE37's, then who cares? Someone will always be faster and happier than you with THEIR set-up, Taylor make your car to what you enjoy while you have it.


And going back to your other threads and thoughts on making the car faster, if you have the money, and you want it faster for YOURSELF, just buy the headers, don't wait on other dynos, just do it, it will be better than stock. And at the same time, know that the 4.08 gears on the auto negates, or is worth a LOT more in the way of acceleration than many of the mods you CAN do. I bet 50lbs of unsprung weight is about the same as the jump in gear ratio.

But yeah, unsprung weight is the final frontier.


And brother, I kind of fear that you'll forever fall into the trap of wanting faster, and at the end of the day, the 370Z is NOT the fastest car you can buy, not even for the money. I don't think it's worth the effort to keep trying to make it better with no end or not being happy with it.





Sorry for the long post, maybe I'm retarded and sorry if I'm being redundant.

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brucelidat

I don't want to be the fastest. I want fun that I can feel which is why i am asking if the reduction in unsprung weight makes a difference that a DD driven car can actually feel. But its a little hard to buy something that you know will actually be detrimental to your performance even if you might not notice it.

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DEpointfive0

DETRIMENTAL is a bit strong, and that contradicted itself IMO. Isn't it a little hard to drive a car you don't enjoy 100%.
You put spacers on because it LOOKS nicer, it "technically" lowered the performance of your car. How much do you care?

If you're going from 28lbs to 45lbs a piece, ok, sure. I see a valid complaint, or reason to think about it. But from 28 to 30? I don't see any concern.

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brucelidat

If it makes a difference I can feel in terms of accel, braking nimbleness, then the heavier wheels aren't happening. That is what I am trying to learn here. I've heard some really big and hard to believe weight equivalencies thrown around so I am trying to figure out what si actually more accurate. Just want to know as much info as possible before making decisions.

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critical

I dropped around 11lbs in the wheels over all and the difference was huge in terms of feeling. Totally worth it. It probably feels about 165lbs lighter to me.

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brucelidat

I didn't know anything about unsprung weight or anything when I installed the spacers. I did it purely for looks, yes. Wheels are a bigger investment than spacers though. Also, some people are saying it makes a big difference which is why I am asking, to find out if it really does. So like I said, I am trying to figure out if there is a significant enough difference that I would feel it. According to Critical, he felt a difference from 11lbs. If I get slightly lighter wheels and drop the spacers, that'll be more like 15lbs or more. And if I switch to PSS on my next set of tires, it would be even more, like 30+ lbs overall. So I am just trying to get info.

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Chuck33079

You'll definitely feel 30+lbs. You'll feel it in the acceleration, braking, steering and handling. The car will feel livelier.

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Amuse370z

I can't seem to find the weight for the 2013 18" base wheels.

But I bought 19" TE37SLs and I'm expecting quite a difference performance wise when I put them on.

Read T

I dropped my car's rotating weight by drilling holes in my tires. Like you guys have said, it does detract from ride quality though.

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Masterbeatty

Or get these by HRE. $2.5k-4.5k a wheel but carbon fiber and magnesium. The 20's weigh only 21lbs

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totopo

Unsprung weight is SUPER important.

Basically, bumps apply an acceleration to the unsprung weight, not a force. So lighter unsprung weight means less acceleration, and less perturbation of the chassis on the other end.

The major way of measuring the end effect of springs on a suspension is the wheel frequency. Basically, you have 2 weights separated by a spring, so the wheel frequency is dependent on the weight of both, but more so on the lighter weight (the unsprung weight). The wheel frequency is almost linearly proportional to the minor unsprung weight. So a decrease of weight of 10% iirc is basically like having a 10% stiffer spring. This is where you get where people say xx lbs unsprung weight = xx lbs sprung weight. like shaving 15 or 20 lbs or whatever off a corner weight has the same effects on wheel frequency that shaving 1lb off unsprung weight will have.

but it isn't like exactly true, since shaving off unsprung or sprung weight has the same effect on the normal force on the tire and the lateral force needed to turn the car.

Other benefits of lessening unsprung weight is you usually decrease rotational mass as you do it, since most of the unsprung weight is wheels and rapidly rotating components. decreasing rotational mass effectively improves your braking and acceleration.

spacers are kind of interesting from a vehicle dynamics standpoint. They increase the wheelbase, which is super great for decreasing weight shift, but it changes your scrub angles in the front, and changes your overall suspension geometry (and i think kills bushings). I think the motoiq people actually like running modest spacers for cheap wheelbase increases for more lightly modded projects.

jz321

F = M * A

The acceleration of a mass is a force.

totopo

what I meant was that if you vary the mass (unsprung weight), it's the acceleration that stays more constant and the force that varies. so less unsprung weight means less force for same acceleration, and less momentum and less energy, and less perturbation of chassis.

cofo11

Except A = F/M. It's not really that the lighter wheels provide a lower force, the decrease in mass allows for an increase in acceleration (the same reason the car brakes and accelerates better). You will actually notice a rougher ride as the wheels' reactions to bumps will happen much faster. What also happens is a a reduction in momentum which, potentially, doesn't cause the wheel to travel quite as far initially or on the rebound stroke.