i dont understand the correlation. can someone be nice enough to break it down for me? Thanks.

rotor i can understand as making someone slower, but from a caliper, it is not a rotational mass, so i just dont see the correlation.




[Modified by Soup ****, 3:46 AM 11/29/2002]

 

take out your calipers, go faster

 

unsprung weight = any weight not supported by the spring


the lighter it is.. the better response and handling. i am sure people can elaborate a lot more than me. don't want to give away any false information now.

my guess.. lighter unsprung weight = easier for the suspension components to move up and down = better handling

i did a massive search on the internet, but didn't come up with any good solid information.


[Modified by disordeR, 1:16 AM 11/29/2002]

 

actually fellas, there was pretty good discussion on this i think on one of josh's(itrsport.com) spoon caliper thread. if not, i remember it being on a post about the spoons a while back....try the archives

 

search is down.

 

Don't tell sackdz that or else...........

 

Right.
That's it in a nutshell. Less unsprung weight gives better handling, but there's no difference in acceleration between sprung and unsprung weight.

Soup ****, that answer your question or do you want a more technical explanation?

 

Except when it's turning, like wheels, rotor etc....

 

exactly. losing static weight: good, losing sprung weigh: better, losing rotational weight: best

 

Terminology clarification:

Sprung weight is that which moves with the body (what you're referring to as "static").

Unsprung weight is that which moves with the wheel and tire.

 

oh ok, my bad.....i was under the impression that **** that doesnt move with the suspension was 'unsprung' and stuff that did was 'sprung'

 

 

Yes, but now you can divide the unsprung weight into 2 categories: rotating (wheel/rotor) and non-rotating(caliper/sus. arms).

Reducing non-rotating unsprung weight is good for handling on bumps and very little effect on acceleration.
But reducing rotating unsprung weight is good for handling on bumps and BIG effect on acceleration...

 

 

Common sense, your CALIPERS aren't moving therefore lightening them up really doesn't help at all.

 

false.

 

How much do calipers weigh? stock vs. spoon vs. whatever. I realize the weights must have been covered in a discussion somewhere.

When I put on my Hawk Blue Racing pads, I was surprised at the weight of the brake pads. So, if I save 1 pound on the calipers with such heavy brake pads, does it really make a difference? I would probably only upgrade the calipers if they made the car stop better, not necessarily for weight.

 

I don't know the exact numbers of the stock calipers, but the Spoon calipers weight less than 6 lbs each..I'm betting that is way more than a 1lb. saving per wheel...

 

stocks weigh ~12lbs i believe, so the spoon units are a definate drop in weight.


calipers definately move btw

 

In an article that I read before, the author thought that the most dramatic difference to lowering the unsprung weight was in bumps. On a perfectly smooth course I don't think it will make as much difference.

When the wheel experiences a bump, the unsprung weight is being thrown upwards. The higher the unsprung weight, the higher it will go, and less ground contact you will have.

This is why racers go as far as installing inverted shocks, since they are partially unsprung.

I will try to find the site. I think it was an M3 page.

 

Smooth or not, when the suspension pitches and rolls it will be "quicker".

 

By reducing the weight of the calipers it affects a several things. Most of them have been mentioned and i think i can add a bit more. By reducing unsprung weight it will affect low-speed and high-speed compression and rebound (i think the latter will be more affected in this case). It should allow the spring and damper components to reflect a more real/true spring rate and damping ratio which should translate to better initial turn-in and taking bumps and potholes shouldnt upset the car as much (it should also benefit other areas but thats all i can tink of). I say so since compression and rebound stroke rates will be more controlled due to less compression and rebound motion/velocity to dampen.
By reducing unsprung weight (static or rotational), it will also benefit a better F/R weight ration wouldnt it? It may not be much of a change but why not get a better front to rear weight ratio on our already front-heavy cars.
By reducing unsprung or any weight from the front will also affect the cars PMI [(polar moment of inertia)the distance of the mass from the centre of the cars rotational axis]. An easy way to understand this is by thinking of a pendulum swing. The more weight is attached on the ends, the more it takes to control the swinging motion.
As a note, this will also apply to wheel weights, flywheel weights, and rotor weights too. And a bit OT but say a spun 15*7 wheel weighs 10lbs...where is the most of that weight located? Another 15*7 spun wheel is 10lbs also but more of the weight is located in the center. Which would u choose?

 

Just to add. It will also help just as much in braking.