That and some people with WAY too much time on their hands.

 

Mat, I'd agree with a contribution of weight somewhere in the range of 2-4x the wheel/tire weight, but you are using an artificially small difference by using 17 lbs. and 20 lbs. as examples.

How about a 13 lb/corner difference between 22 lb. 18" JCW wheels (large radius) and 9 lb. 15" SSR Comps? The perceived difference is a lot closer to the .3 sec. to 60 mentioned in the SCC article, than the .1 sec. figure that you prefer.

BTW, the article is quite clear that the .3 sec. figure is accurate, although a good chunk of the difference is in rolling radius.

Also, the difference in adhesion over bumps due to the lower unsprung weight and greater tire compliance is night and day. You don't see WRC cars on 18" wheels unless the stage is on dead-smooth new pavement or a track.

 

0.1 sec difference for 0-60 mph means that its all human driver error in the difference

So much for dropping $1K on lighter wheels

 

I concur with flyboy and the good Dr.

1# off the wheels equivalent to about 1.6-1.8# off the chassis.

The decrease in sprung/unsprung weight definitely improves
handling on rough roads also.

 

Same applies to braking distances. I'd argue that optimal reaction time or stronger brakes, and especially combined, would do far more for shorter braking distances than lighter wheels could ever. With that one could argue that lighter wheels is a variable and the same driver is a constant; therefore the lighter wheels equals consistently shorter braking distances, but stronger brakes should beat lighter wheels. With that though, the money in brakes only gains braking efficiency while lighter wheels creates gains across many performance areas. So lighter wheels may be the better spent money, but the performance gains are so small that these mods are all low bang for the buck, especially when considering the ratio of mod cost to the purchase price of the MINI. Since there's MINImal (couldn't resist) return on the mod investment, I think you have to be careful if you don't plan to keep your car for a long period, provided resale is important to you.

In the end, I can't see spending big dollars on a MINI (wheels, brakes, high-$ suspensions, etc.). It's not and never will be a sports car. Adding thousands to the purchase price gets you too close to the purchase price territory of true entry-level sports cars, like the Boxster or perhaps the upcoming Z4 Coupe. Trying to get a MINI to perform at Boxster level puts you in a high unreliability territory, and would potentially kill resale value, or at least considerably narrow the perspective buyer market.

My appreciation of the MINI is that it's a fun commuter car, even bone stock. My disappointment is that it takes so much effort to drive consistently fast on the autobahn, and at speeds over 100 mph it's incredibly inefficient. Considering all this, I know I've made my last mod.

 

The math says that the difference is limited to a max of 2x IF all the weight is at the tread. 2-4x is just wrong.

If you do a larger weight savings by using 13 lb wheels, you still get that 1.6ish difference, just with a larger weight to multiply.

the only way to get greater than a 2x improvement, is by actually reducing the diameter of the overall wheel/tire combo.... But then you start messing with contact patch, effective gear ratio and the like...

Matt

 

Certainly cannot underestimate reaction time! As I understand it though, as long as your brakes are able to lock up the wheels, they are strong enough. There is no need to go to huge slooted rotors and 8 piston calipers for the street. Assuming you do have ABS, and all other variables being equal, that is you are not tracking the car and you are driving on a dry, paved road, temps are up etc. the ony way you will shorten your braking distance is to increase the stickiness of the tire and keep the tire in better contact with the road, that is more constantly in contact and optimizing the actual contact patch.

Tire/road contact can be improved by decreasing the the tire and wheel weight and improving the suspension geometry. Of course, if you choose to reduce the the tire/wheel weight by going to a smaller size, you will also reduce the tire's contact patch, so you must find the right balance here or risk a self-defeating cycle. I won't get into rotational moments and such because I am not that smart and it makes my head hurt. There are other, smarter people around here who get into that sort of thing.

Tire stickiness, well that is self-explanatory.

The rub comes when you must do repeated stops or modulate your braking (perhaps if you do not have ABS).

Changing rotor and caliper size and shape - and the master cylander and brake fluid if necessary - will merely change its ability to absorb and transfer heat - not shorten braking distance (may actually hurt it in some cases - unsprung mass and rotational moments - arg! head hurting again). Very helpful if you are on a track and the brakes have soaked up all the heat possible.

Improving brake feel by switching pads and installing steel brake lines will enable you to better control your braking up to the point of lockup. New, premium fluid can help with as well, particularly if it is old and contaminated. In the dry however, ABS will usually do a better (read shorter and with more control) job at stopping a car than the average driver.

Very true, It is what it is. You can enhance, it and expand its limits but it is no Ferrari 430 or Bentley GT. But of course, those cars aren't Mini's.

 

If the part doesn't rotate, it's multiplier is 1x, like wieght savings from lighter calipers....

And for lighter rotors, you need to do the math. Most of the wight savings usually comes from Al hats that are near the axis of rotation, and the diameter increases..... Getting hit in the R-squared contibution to the moment of inertia.....

But they all do contribute to suspension response, that is only dependant on linear, vertical motions...

Matt

 

The other part of it is this: I have SSR Comps (at 12.9 lbs) like the looks of the SSR GT7 (at 16.8 lbs) and I asked Alex at Tire Rack what the difference in weight would make and he said, "It would be like carrying 60 lbs around in your MINI at all times.

Earl

 

3.9 times 4 is 15.6
15.6 times 1.6 is about 25.....

So he missed by a factor of 2 (about).....

Matt

 

Since taking delivery of my Mini, I have subsisted on a diet of raw carrots and tofu, and run 15 miles each day, followed by long sessions in the sauna. I am now down to 135 lbs., thus saving 30 lbs. of useless driver weight. I do tend to get a bit dizzy and lose focus while driving, but I believe I have shaved perhaps .5 sec.. off my rolling 5mph to 60mph time. I do not allow my fiancee to ride in the Mini with me, thus shaving another 110 lbs. of useless passenger weight - in fact, I have welded the passenger door shut, thrown away the spare tire (that's what AAA is for) and the side view mirrors (I can turn my head for Chrissake). I would welcome further ideas for weight reduction . . .

 

The .3 sec difference was for 1/4 mile. The 0-60 dropped .5 seconds! They said that the rolling diameter changed from 25.2 inch to 24.9 inch.

Dr Obnxs, what change would you have calculated for the conditions in the article?

 

OK, so what? Like you never have to carry anything in the car? stuff from the store? a wife? kids? Dogs? Who cares? (UNLESS your trying to win a TRUE road race or AutoX) for daily driving, what does it matter?

 

And what if I am?!

 

In that case, see Onasleds gutting car. Thats should inspire you to get rid of all that extra weight.

But, far us pedestrian types, it dont mean much of nothing.
Hmm, just think, maybe those German engineers got it right.

 

Not to get OT, but a Boxster is "entry level" hmm. An 06 S comes in at about $60K. The M coupe is being predicted at $55K (to undercut the Boxster S). What happened to the "Corvette" at $43K or Elise at $44K. You can get a "new" 05 Elise today for maybe $40K ... cheaper than a "optioned up" MINI

Do other cars like the Honda 2000S not qualify as a "true sports car"? I'm just wondering because I thought I drove sports cars most all of my life (and know the MINI is not one) but I never considered $60K to be "entry level"? I'm curious ... are our concepts of money that far off?

 

nonononono! more math professors!! less "math? we don't need no stinking math" hyping vendors and 3rd hand anecdotes from my-brother-in-law's-friend-down-at-the-service-station.

 

as there is in ALL CARS!

What's the big deal if someone wants to shed some weight (I know, my wife would love it if I did, she doesn't really care about the car though...)

Every ounce shaved contributes to an improved power to weight ratio. Where is it written that cars come from the factory with the "perfect" number? Where is it written that there is a perfect number?

I can accept you saying "These kind of differences don't matter to me" but I think it's a bit off base to assume that all of the enthusiasts have your same perpective.

If I'd known (when I bought the car) that the S-lites were anything but light, I wouldn't have gotten them. Also, when you factor in that unsprung wieght advantages can have good effect on handling and braking as well, I can see that there are lots of people that would matter to.

And just because someone wants to get some of the benefit of reduced mass, there's no reason to postulate that they have to go "all the way" to gutting the car of all accessories, sound insulation etc. Heck, I like my lighter wheels, and I like my cup holder too! What's so wrong with that?

As many posters have pointed out, there's nothing wrong with making your car the way you like it, and there's no law saying that "way" should be the same one anyone else wants or even cares about.

Matt

 

More like $40K for the standard Boxster w/o options or even less for the not-so-popular anymore TT, which with 3.2L/DSG and Quattro was/is a great car that can blitz through corners. Considering I can buy BMW products at more or less cost (including MINIs), my price is far under $60K for a M Coupe. I estimate about $47K out the door loaded. My price for the Z4 M Roadster is $46K w/o options out the door. About $48K w/popular options.

Sorry for all the OT banter...

All I can say is I'm glad for MINI2 so that when I ordered my MCS I at least knew I didn't want to keep the S-lites. Luckily here in Germany they'll take your stock wheels on trade so I got R99s for only an additional $300 at the time of delivery. Yeah, I only shaved 3 pounds per wheel but I know the wheels are a lot higher quality than the S-lites. Look a little better too. Can I feel the performance gain? No way. I really wanted to buy a set of BBS or OZ wheels, which I could have done through the dealer, but spending another $800 or $1000 to shave off a few more unnoticable pounds just didn't make a lot of sense to me. Now that I've decided to sell the MINI in a year, I'm glad I made the decisions I did. I'm hoping the Koni FSDs add a little to the MINI in resale. They'll undoubtedly help resale.

 

No biggie at all. That wasnt what I was trying to say. for a small fraction of a sec in times, I just can't see spending thousands to achieve that. However, for someone else ...
"To each their own" Their money ...

I was calling myself "pedestrian"

 

Maybe in Germany but list here on the base Boxster is $45K. Unless you can order one that why, more realistic prices of cars in dealers inventories are low 50s. Add sales tax and yout talking maybe $55K. Don't know if they will sell under MSRP.

 

Cool article on just this topic from SCC

Alex

 

The author there found that a pound on a tire tread is like 2 lbs of car weight, and a pound on the rim of the wheel is about 1.5 lbs.

The interesting stuff about the flywheel can also be applied to the lighter crank pullies as well, although the formula doesn't quite translate perfectly... (this is because a flywheel is basically a uniform disc of metal, and the crank pully isn't). But what it comes down to is that the lighter flywheel will kick *** over a lighter crank pully (more mass reduced, and a greater radius of the item). Too bad is such a pian to change the flywheel.....

He did get a bit sloppy in one of his sentances though, but it contained so much well explained stuff, that I'll forgive him for that one!

Matt

thanks for pointing this out Alex.....

 

...Dave writes some intersting articles...

So my 19lb Michellins and 16lb BBS wheels fair much better when compared with the stock runflat fair. I remember reading about this 'stuff' in Road and Track years ago. I've since installed Wilwoods 12.2 brake kit on my car. The floating rotors help to dissipate heat and the entire kit is about 11 pounds lighter than stock. However, that huuuge rotor - not including the hub - is quite a bit heavier than the stock garden variety rotor. I've taken one step back and three steps forward.

 

the rotor has a radius of just over 6 inches, and the tire 12. A pound off the tread is like 4 lbs at the edge of the rotor. And the rotor is an annular disk, so the rotational mass is distributed over a disk with a max radius of 6"....

So you won on unsprung weight, and won big on rotational mass.

Matt