Indeed. See my calculations.

-mike

 

My calculations would appear to be correct. Here's another site:

http://www.reade.com/Particle_Briefings/spec_gra2.html

I calculated from the area values on the previous site as 157.44 pounds per cubic foot, and the previous site also said 490 pounds per cubic foot for steel. The site above also says 490 pounds per cubic foot of steel, and 161 pounds per cubic foot for glass. My calculation was almost perfect.

It couldn't be more clear - in fact it's as clear as my light sunroof.

-mike

 

so you are telling me that the thickness of the steel is the same as the glass? let's get the micrometer out....

 

You're still assuming that the glass is the same thickness as the steel. You can also add in the weight of the motor and other related gear like the tracks, switches, etc.

Couple the weight penalty with the loss in structural stability that comes from having huge holes cut out of the roof and you'll find that the sunroof detracts from the performance of the car. The degree of which is certainly debatable though.

 

I already made this point... You should read the whole thing before commenting.

And to spell it out for you even further, the glass of the sunroof would have to be more than 3 times thicker than the steel of the roof with no sunroof before the glass started to weigh more. And please, be my guest, I would love for someone to measure the difference in thickness, then we could begin to put this matter to rest. There would also be some weight added to the sunroof option by the mechanisms required to make it open, but my guess is that these would also be marginal compared to the entire weight we're talking about.

-mike

 

let me guess... you have a sunroof?

 

As I just stated above, I am not assuming that. I said specifically that that is an issue in my previous post.

What is it with you people? There's no proof of this. Yes, it's a definite possibility. And yes, having holes in the roof gives up some structural stability (although the glass probably provides some stability, although I agree, not as much as the steel), but if in fact the sunroof with glass weighs less than the roof with steel, then you're talking about a sunroof-car being a lighter car with a lower center of gravity, which will add performance in other ways. So talking about 'detracting from performance' is no longer relevant because there are multiple different elements of performance at play.

Finally, the fact that this sort of minutia even has to be discussed in such detail makes clear the real point - the difference isn't going to be much, and thus even if a sunroof does detract from performance, it will likely be to a very small degree. And yes, as you say, this is debatable.

-mike

 

I already said that above, yes. And let me guess, you do not. The point is not to justify my purchase of a sunroof, my car will see few track/autocross days and the sunroof adds a lot to the car for me, but this has nothing to do with the point at hand. My desire was to respond to all the boneheads going around spreading internet hearsay as if it were god's given truth, with absolutely no basis, and furthermore, with the ability to take 5 minutes to think it through and realize that might not be right.

-mike

 

Is it true that the sunroof makes the car less stiff? Could there be extra reinforcement in the roof to counter that and therefore add weight? Is it a fact that getting the sunroof option nets you stiffer springs?

 

Greg,

You make a good point, and that is that it's unclear for sure whether the car suffers a loss of structural integrity due to the sunroof. My guess is it probably does somewhat, but then again, unless it's been confirmed by MINI, or tested scientifically and shown to be so, it's all a bunch of hearsay.

And as for stiffer springs, I've never heard of that...?

-mike

 

man, you are taking this much too serious, enjoy your car

 

True words from a man who realizes he's been outdone.

-mike

 

you trying to start a flaming war?


grow up buddy

 

Not at all man, just pointing out that there's nothing left you can say on the matter, which is the true reason you are distancing yourself from the conversation.

In any event, I think the point's been made, don't mean to step on any firm-believer toes.

-mike

 

why argue until I find out the answer... you seem to want to confuse weight of steel with glass when you don't even know the thicknesses involved... instead of looking like and sounding like an @ss about the matter I intend to find out... peace and have a great day .... something tells me you won't

 

I agree that you have nothing useful to provide at this time. I do welcome any facts if/when you can provide them. Until then, it seems my goal has been accomplished of getting people like you to keep quiet until they know any actual facts. All I did here was present some more data to get people realizing that they don't know any of this stuff for certain. And it seems it worked.

-mike

 

man... you have issues... goodnight

 

Hehe, why exactly? Because I'm responding to your flames? Because last time I checked you were responding to me as much as I'm responding to you.

-mike

 

The weight comes not just from the extra weight of the glass, but the motor, mechanism, tracks, sliders, sunshades, drain tubes, seals and other goodies that make up the entire sunroof assembly. And a 2x4 foot piece of 1/4" glass does weigh more than the same size piece of 20 gage steel.

 

Here's an ancient thread that says a sunroof adds 61 pounds:
http://www.mini2.com/forum/showthread.php?t=6493

 

Greatbear,

I think the glass does weigh more than steel that is in the car but not by much. As stated in the above threads, the same size steel weighs more than the same size glass. The atomic weight of steel (typical steel) is about twice the atomic weight of glass (typical glass), of course these are rough numbers, because each glass manufacturer and steel manufacturer uses slightly different materials in their alloys and glass mixture. But I don't think the numbers are so far off. Again, I am guessing the glass sunroof at best only adds about 20lbs to the car, which is a lot less than the claims made by many people on this board and others. The main argument for this thread was to look at real numbers instead of these "Mini urban myths" that come out. I think the Xenon issue has been proof of this, especially when some people claim 50lbs or more for these lights and how they affect handling.

As far as stiffness. Again, I don't think it makes much difference. If it was flexing so much more, than we should see glass breakage, or a lot more creaking up there. I have driven a sunroof version of the MCS (which I have) and my father-in-laws stock MCS with no options extensively, and I cannot tell a difference in stiffness. They both feel the same to me, no matter how hard I push them. I think if there was flexing I would have felt it, especially since I was trying to sense it. Maybe with some type of digital laser, we might record some form of flexing, but I would be hard pressed to believe anyone who said that it made a difference in there track times.

Greg,

If you read a little farther up, there is another link that shows that someone removed the roof and they weighed it and it was 53lbs. Which I don't argue. I am arguing that the steel for the roof has weight to it as well.

 

Peter from M7 took his out and I believed it weighed that much.

 

The steel used in a MINI roof is very thin. I work in a fab. shop you are talking about very little wt.

 

Oh add in the wt. for the mechcanism for opening and closing the roof (motor, gearing, wiring, seals, and drain tubes).

 

FACT: The sunroof adds 55 pounds to the very top of the car. So sayeth BMW.

Car is now 55 pounds in the realm of top-heavy.

It's probably not going to flip over like an SUV, but weight is weight.