Reducing Unsprung Weight

[colby7]

How much would be gained in 0-60 and 1/4 times by taking 75-80 lbs of unsprung weight off of the car? I suppose this question is mainly for the folks who are already running LW wheels, rotors, etc. But if any one out there has good info, I'd be glad to hear it.

[neverfastenough]

80lbs in this car.... basically nothing. You'd see more advantages playing with tire pressure.

[Mike@PureMS]

80lbs in this car.... basically nothing. You'd see more advantages playing with tire pressure.

Unsprung weight is different. The difference will be very noticeable.

[grovlet]

Well - this is sort of complicated question as unsprung vs sprung weight isn't the only variable here - Basically weight is one part in the equation - and it's really just weight.....

But the OP is also referring to going with the option of that weight specifically in Brakes/Tires/Rims (rotational weight) - but that's the key - it's really not merely the weight - but the effect on the suspension - that may help traction more than the actual weight difference itself.

So the car will have less weight to move - albeit 80 lbs which may not be much on the already heavy S4 (ie minimal) - but the traction difference may be the real key to increases in time - so the car may actually be faster with 80lbs of unsprung weight (vs 80 lbs of sprung weight like seats/jack etc)

Now what is that effect - we have some very good experts that like to track their cars on here - and I bet they can tell you their results....

[neverfastenough]

Sorry missed the unsprung part. It will 100% have an affect on how the car feels in regards to handling and cornering. However cutting 60's and dropping ET's is going to be minimal IMO with that small of a weight reduction, unsprung or not. Obviously the more weight that can be shaved off of these heavy cars the better though.

You'd appreciate a lighter wheel, brake setup in a road course setting a lot more than 1/4 mile.

Again, every bit of weight helps no matter where it's coming from, but don't expect much.

[jran76]

I think it's been pretty well proven that LW wheels and braking components can make a significant difference in terms of acceleration or 1/4 mile times. Cars with LW wheels and brakes (rotors minimum) are consistently .1 to .2 seconds faster to 60', and it's one of the main reasons the cars at the top of the 1/4 mile list are consistently .2 to .4 seconds faster than cars without those components. Everyone's definition of minimal vs. significant is different, but there is no doubt that LW parts is what separates the guys at the top of the 1/4 mile list.


*The stock 19" wheels (peelers) and tires are around 55-57 lbs. depending on the tire. A lightweight 19" wheel (say a 21 lb. Renn Motorsport wheel and 24 lb. Michelin PSS) would be around 45 lbs. So there you have saved around 44 lbs. If you go down to an 18" wheel like the Enkei's RPF-1 some people are running, you can easily shave another 5 lbs. off per corner.
*The JHM front rotors save around 14.5 lbs. The JHM rear rotors save another 11 lbs.

[waxxonMTL]

I plan on doing the same next summer and shall see the result. althought i only driven on the 19 peeler for like a month.

I plan on going with a flow formed wheels 18' . scaled at 19-20lbs. + direzza z2 star spec. Along with 2 piece up front. ( y rear brake are literraly brand new, so i will stay oem in the back for at least another season lol)

Should see better response due to quicker acceleration and sticker compound.

[neverfastenough]

Everyone's definition of minimal vs. significant is different, but there is no doubt that LW parts is what separates the guys at the top of the 1/4 mile list.s.

Exactly! It all depends on what your goals are. My point is .2 is not a lot to most (I get it is for those pushing this platform) but it isn't to me, hence my post. However it does make an amazing different in handling and cornering. The benefit you get from how the car feels on the street/road course by dropping unsprung weight is where the real benefit is.

I guess my point is, would I do it for .2 second quicker ET... No. Would I do it because I know how much better it handles on the street or a Road course... yes.

[S4tranquility]

Even your butt dyno will notice that much. Check out this Car and Driver article:

http://www.caranddriver.com/features...d-tires-tested

[db12]

Even your butt dyno will notice that much. Check out this Car and Driver article:

http://www.caranddriver.com/features...d-tires-tested

0.3 second increase based on the car above (not bad at dropping only 56 lbs). However seeing as that car is almost 1,000 lbs lighter than the S4 the improvement wont be as drastic on the S4. But Im with most posters above. Every lb you can shave of these cars the better.

[neverfastenough]

/\ and most aren't going from 19's all the way down to 15's. However upgrading brakes will add to the weight reduction.

[jimrobbington]

LWFW should help straight line acceleration in lower gears too, no? I know this isn't an option for you dsg folks, but shouldn't be disregarded.

[ECS Tuning-Audi]

Reducing upsprung weight can definitely help with acceleration and getting the vehicle moving. It's mostly noticeable at lower speeds/lower gears.

If I remember correctly every 100lbs removed of sprug weight is equal to about 1/10th of a second in the 1/4 mile. So if your vehicle runs 12.0 in the 1/4 and you remove 100lbs you could potentially go 11.9 given the same scenario.

Jason

[mrmomo313]

I think it's been pretty well proven that LW wheels and braking components can make a significant difference in terms of acceleration or 1/4 mile times. Cars with LW wheels and brakes (rotors minimum) are consistently .1 to .2 seconds faster to 60', and it's one of the main reasons the cars at the top of the 1/4 mile list are consistently .2 to .4 seconds faster than cars without those components. Everyone's definition of minimal vs. significant is different, but there is no doubt that LW parts is what separates the guys at the top of the 1/4 mile list.


*The stock 19" wheels (peelers) and tires are around 55-57 lbs. depending on the tire. A lightweight 19" wheel (say a 21 lb. Renn Motorsport wheel and 24 lb. Michelin PSS) would be around 45 lbs. So there you have saved around 44 lbs. If you go down to an 18" wheel like the Enkei's RPF-1 some people are running, you can easily shave another 5 lbs. off per corner.
*The JHM front rotors save around 14.5 lbs. The JHM rear rotors save another 11 lbs.

Look no further. Great explanation.

My car's 60 certainly improved after adding lw wheels + jhm rotors (went from 1.7x-1.8x 60s down to consistently in the 1.6x- 1.70 range when I get good traction. Gets better as I adjust for conditions...

[mrmomo313]

Reducing upsprung weight can definitely help with acceleration and getting the vehicle moving. It's mostly noticeable at lower speeds/lower gears.

If I remember correctly every 100lbs removed of sprug weight is equal to about 1/10th of a second in the 1/4 mile. So if your vehicle runs 12.0 in the 1/4 and you remove 100lbs you could potentially go 11.9 given the same scenario.

Jason

Yes you typically pick up a tenth and 1 mph on the trap for every 100lbs

[Frinkferta]

Taking this route can be costly! But yeah, you can drop close to 100lbs with rotors and wheels.

[Brother Owl]

Don't forget that removing mass from parts that store kinetic energy/rotational inertia will also increase mpg's