135 convertible regrets??

[TheSt|G]

Originally Posted by BrokenVert

Everyone needs to shut the hell up with comments like this. They're stupid, uninformed, and pointless.

You own an automatic convertible that happens to have a bit of power. Nothing about that combo inspires confidence in your ability to feel a car.

Your car weighs 3705 pounds, that is 300lbs more than a base E60 5 series.

Other things that weight ~3700lbs:
Chevrolet Colorado crew cab pickup truck
Current generation Camaro
Jeep Wrangler(a convertible!)

Lets look at some torsional rigidity numbers across brands(which you clearly debunked by pushing on your fender). To paint you a more accurate figure, you would need to use somewhere around 5,900 ft/lbs of force to twist it one degree. If you can do that with your hand, you need to find a job as a pro body builder.

BMW Z4 Coupe, 32,000Nm/degree
BMW Z4 Roadster: 14,500 Nm/deg

Ford Mustang 2003 16,000 Nm/deg
Ford Mustang Convertible (2003) 4,800 Nm/deg

Ford Mustang 2005 21,000 Nm/deg
Ford Mustang Convertible (2005) 9,500 Nm/deg

Porsche 911 Turbo 996: 27,000 Nm/deg
Porsche 911 Turbo 996 Convertible: 11,600 Nm/deg

Aston Martin DB9 Coupe 27,000 Nm/deg
Aston Martin DB9 Convertible 15,500 Nm/deg

These aren't "uniformed" comments, they are just how it actually is. If you can't feel the difference, that's fine and dandy. But don't group the rest of us into your numbness. It doesn't take a track to feel the difference. Most of us can easily tell when we have passengers in the car(less weight than a vert) during normal street driving.

Bonus: You do get the closest to a 50-50 weight distribution of the 1ers, other than the 128i coupe. Nice!

[Section147]

Originally Posted by TheSt|G

You own an automatic convertible that happens to have a bit of power. Nothing about that combo inspires confidence
in your ability to feel a car. If you can't feel the difference, that's fine and dandy. But don't group the rest of us into your
numbness. It doesn't take a track to feel the difference.

Good effort...but, alas:

[TheSt|G]

Originally Posted by Section147

Good effort...but, alas:

Wow, what a well reasoned response. Hard data can be confusing I know.

[ejm3]

Those numbers are nice but tell you nothing of how the convertible handles versus the coupe in real-world every day driving.

Its like saying you have a watch that's accurate to within .00000001 seconds a year and mine is "only" accurate to .0001 seconds a year. Yes yours is statistically many times more accurate than mine but does it really matter?

[BrokenVert]

For one - I can tell that youre simply pushing numbers and that you dont actually understand what they mean in context.

I lifted the car in the air on a rear jack point - a point that is about 8 1/2 feet away from the area of the fender where I pushed down.

I weigh about 220 pounds - put my entire weight on it (I sat on it ) effectively putting a 220 pound force in the z direction- and my father who was with me couldnt see any twisting - we checked if the top was still properly aligned (it was), we checked the doors (it was), and we checked all of the panel gaps - none of them changed meaning that there was no discernible twist in the chassis.


Now me being 220 pounds and 8 1/2 feet away put a moment on the car of about 1900 lb/ft about the z axis about of third of what you say twists the car by a degree.

my same 220 was also putting a moment about the x axis. A moment of about 1000 lb/ft.

If your number is true - than I shouldve noted some type of deflection - but I didnt. It tells me that your numbers are wrong or that you dont know what axis that number is about (a possibility)

Another reason I think that is because I know for a fact that the Z4 roadster is lighter and more rigid than the coupe - it was a big forum thing that went around in 2006/2007. Nobody could believe it, but it was true (thats the power of a car that was designed as a roadster first and a coupe second I guess)

You also got your weight number for the 135 wrong - I checked it in my 2008 sales brochure (which I still have as a keepsake) - its 3660 pounds - 10 pounds more than I thought it was)

But thats not the point.

The point is that without sources your numbers are fallacies - not to say that theyre wrong, but that I dont believe them. So id respectfully ask that you get me your sources.

But if you cant even properly quote me BMW information thats widely available then I dont have high hopes for your bending moment sources.


Also you dont know anything about me, so let me tell you.

I come from a long line of high performance driving blood. Both my father and my uncle were SCCA and Trans-Am drivers in the 60s and the 70s and they taught me how to properly handle and feel an automobile. Ive driven most things on this side of a Murcielago and frankly I prefer open top driving.

Because its more fun.

Im also an engineer with experience designing SAE cars and im trying to get myself into the design house of an actual racing team.

So you have to understand - I understand how to drive and I know how all of the components work. So if you want to start quoting numbers please - get me sources and get them in context.


Also please stop insulting my choice of car. If you want to run and compare well take it to the track, ive been fabricating myself a rollcage in my spare time - should be fun.

Originally Posted by TheSt|G

You own an automatic convertible that happens to have a bit of power. Nothing about that combo inspires confidence in your ability to feel a car.

Your car weighs 3705 pounds, that is 300lbs more than a base E60 5 series.

Other things that weight ~3700lbs:
Chevrolet Colorado crew cab pickup truck
Current generation Camaro
Jeep Wrangler(a convertible!)

Lets look at some torsional rigidity numbers across brands(which you clearly debunked by pushing on your fender). To paint you a more accurate figure, you would need to use somewhere around 5,900 ft/lbs of force to twist it one degree. If you can do that with your hand, you need to find a job as a pro body builder.

BMW Z4 Coupe, 32,000Nm/degree
BMW Z4 Roadster: 14,500 Nm/deg

Ford Mustang 2003 16,000 Nm/deg
Ford Mustang Convertible (2003) 4,800 Nm/deg

Ford Mustang 2005 21,000 Nm/deg
Ford Mustang Convertible (2005) 9,500 Nm/deg

Porsche 911 Turbo 996: 27,000 Nm/deg
Porsche 911 Turbo 996 Convertible: 11,600 Nm/deg

Aston Martin DB9 Coupe 27,000 Nm/deg
Aston Martin DB9 Convertible 15,500 Nm/deg

These aren't "uniformed" comments, they are just how it actually is. If you can't feel the difference, that's fine and dandy. But don't group the rest of us into your numbness. It doesn't take a track to feel the difference. Most of us can easily tell when we have passengers in the car(less weight than a vert) during normal street driving.

Bonus: You do get the closest to a 50-50 weight distribution of the 1ers, other than the 128i coupe. Nice!

[BrokenVert]

Originally Posted by ejm3

Those numbers are nice but tell you nothing of how the convertible handles versus the coupe in real-world every day driving.

Its like saying you have a watch that's accurate to within .00000001 seconds a year and mine is "only" accurate to .0001 seconds a year. Yes yours is statistically many times more accurate than mine but does it really matter?

Thats a really good way of putting it

[TheSt|G]

Yes, it really matters. The weight of a car and the cornering forces involved determine how much flex is exerted on the chassis. You would notice if you are familiar with torsional rigidity at all(which you clearly are not), that heavier cars like the Veyron tend to have high figures, while featherweights like the Exige or Elise tend not to need it as much. The more weight there is, the stronger the forces. Convertibles find themselves in the worst of both worlds as they add significant weight yet cut the rigidity in half.

[BrokenVert]

Originally Posted by TheSt|G

Yes, it really matters. The weight of a car and the cornering forces involved determine how much flex is exerted on the chassis. You would notice if you are familiar with torsional rigidity at all(which you clearly are not), that heavier cars like the Veyron tend to have high figures, while featherweights like the Exige or Elise tend not to need it as much. The more weight there is, the stronger the forces. Convertibles find themselves in the worst of both worlds as they add significant weight yet cut the rigidity in half.

are you talking to me?

Because I still dont see you quoting sources.


Ohh sorry you arent. It doesnt matter because of street driving. Nobody is saying a vert is better than a coupe on a track and nobody is saying that theyre exactly the same in all out performance.

Every vert owner is saying to you guys yes there is a small difference at the limit but when and why are you even getting close enough to that on a daily basis to actually notice the differences in chassis rigidity in corners?

[TheSt|G]

Originally Posted by BrokenVert

are you talking to me?

Because I still dont see you quoting sources.


Ohh sorry you arent. It doesnt matter because of street driving. Nobody is saying a vert is better than a coupe on a track and nobody is saying that theyre exactly the same in all out performance.

Every vert owner is saying to you guys yes there is a small difference at the limit but when and why are you even getting close enough to that on a daily basis to actually notice the differences in chassis rigidity in corners?

Nope, was talking to ejm3.

For your source, the compiled list from www.**************.com where people submit cited figures that get compiled into the master list.

http://www.**************.com/commun...igidity.12334/

If you think it only plays a role at the limit, that just demonstrates how clueless and out of touch you are. Torsional rigidity is a key component of suspension design. Without a proper amount for the weight of the vehicle, the chassis absorbs the suspension deflection instead of almost solely the strut and spring(as it should be). When that happens tire contact to the road is unsettled and grip is reduced.

Not sure how much more basic I can make it for you. This is a bit like trying to teach a park bench how to play the violin.

And all of that being said, I reach the limit of corning adhesion with my car every single day. I bought this car to drive it, not cruise around with the top down. Not that there is anything wrong with that, but I certainly don't confuse the two.

[Section147]

Originally Posted by TheSt|G

...I reach the limit of corning adhesion with my car every single day.

Sure you do...

[BrokenVert]

Originally Posted by TheSt|G

Nope, was talking to ejm3.

For your source, the compiled list from www.**************.com where people submit cited figures that get compiled into the master list.

http://www.**************.com/commun...igidity.12334/

If you think it only plays a role at the limit, that just demonstrates how clueless and out of touch you are. Torsional rigidity is a key component of suspension design. Without a proper amount for the weight of the vehicle, the chassis absorbs the suspension deflection instead of almost solely the strut and spring(as it should be). When that happens tire contact to the road is unsettled and grip is reduced.

Not sure how much more basic I can make it for you. This is a bit like trying to teach a park bench how to play the violin.

And all of that being said, I reach the limit of corning adhesion with my car every single day. I bought this car to drive it, not cruise around with the top down. Not that there is anything wrong with that, but I certainly don't confuse the two.

Yes im clueless - the only guy in this thread thats actually designed an automobile suspension.

and lol if you think all I do is cruise - I even invited you out to the track




Ohh and Jericho - this is the insult. A coupe guy - with no experience or contructive thing to say - comes into a thread solely for vert owners and starts talking about how we all only bought our cars for cruising, and not fun driving.

Its a problem on this forum that really bugs me. My car handles well and its pretty quick - so who are you to say that I didnt buy it for fun? So please stop insulting me by saying that I didnt.




And thanks for the source. Ill read through it when I have more time.

[BrokenVert]

I found more time because I was curious.

I dont see with E82 or E88 published on that list - so whered you get that number from?

Also I dont see any sources - but im a bit inclined to trust it more than you blurting out random numbers.
Those guys understand double integrals and diff eqs...so they obviously arent stupid. But its still unsubstantiated without these numbers actually being quoted in company literature.

[TheSt|G]

Excellent responses gentleman, back to the sand I see.

Oh, and forgot to address your weight concerns. 2008 135i coupe weighs 3420 as per C&D from BMW specs. 2012 135i coupe weighs 3373 as per BMWs website. Both of these figures are for the manual version, and the weight difference is likely due from the swap to the N55 single turbo from the N54 twin turbo.

As per BMW's website, the 2012 135i vert with DCT weighs 3704lbs. I bumped it 3705 because the weight difference between the 128i vert with manual and the 128i vert with steptronic(what you have) is one pound more. In all likelihood yours is a bit more than that as it has a more reinforced automatic and the twin turbos of the N54.

Do you appreciate the inline citations?

[TheSt|G]

Originally Posted by BrokenVert

I dont see with E82 or E88 published on that list - so whered you get that number from?

I never posted a figure for the E82/88. Since there is a clear trend across brands from cars ranging to $20,000 to $200,000, I took the liberty of assuming the 1er wasn't an absurd outlier like a Zonda Roadster. If you want to assume that is how your car was constructed, be my guest.

I also have a bridge for sale.

[BrokenVert]

Head in the sand?

Im asking for your sources. Thats me generally interested in what you have to say. So wheres you twisting moment data from on the 135? Because it wasnt in that thread you posted.

My car doesnt have DCT and you specifically said your car ill scan the brochure tonight when I get home if you want. But it clearly says 3660 man/3670 vert - and you arent going to notice 10 pounds in the transmission tunnel on a street car.

Also no - I dont have a 128 with a step.

And yes I appreciate in line citations - but C&D is hardly the most accurate source for weights and figures.

Originally Posted by TheSt|G

Excellent responses gentleman, back to the sand I see.

Oh, and forgot to address your weight concerns. 2008 135i coupe weighs 3420 as per C&D from BMW specs. 2012 135i coupe weighs 3373 as per BMWs website. Both of these figures are for the manual version, and the weight difference is likely due from the swap to the N55 single turbo from the N54 twin turbo.

As per BMW's website, the 2012 135i vert with DCT weighs 3704lbs. I bumped it 3705 because the weight difference between the 128i vert with manual and the 128i vert with steptronic(what you have) is one pound more. In all likelihood yours is a bit more than that as it has a more reinforced automatic and the twin turbos of the N54.

Do you appreciate the inline citations?

[BrokenVert]

Originally Posted by TheSt|G

I never posted a figure for the E82/88. Since there is a clear trend across brands from cars ranging to $20,000 to $200,000, I took the liberty of assuming the 1er wasn't an absurd outlier like a Zonda Roadster. If you want to assume that is how your car was constructed, be my guest.

I also have a bridge for sale.

You stated in no uncertain terms that the 1er vert's figure was
5900 lbs/degree.
How did you come to that number if you didnt have an E82 to base it off of?

You could assume that it was similar to the E90 if you want to go with the vert is half of the coupe assumption - which im still not entirely sure is correct but lets go with it.

I say E90 because the E9x and E8x are basically the same car mechanically.

So lets go with that. The E90's figure on that site is - 22500 nm or 16600 lbft.
That would make the vert 11250 nm or 8300 lbft.

So ill ask again where did you get 5900 from? And why did you try to toss it out as fact?



Let alone the fallacy of assuming from a trend where half the data is skewed by older designs/super cars.

[KingOfJericho]

Originally Posted by BrokenVert

Ohh and Jericho - this is the insult. A coupe guy - with no experience or contructive thing to say - comes into a thread solely for vert owners and starts talking about how we all only bought our cars for cruising, and not fun driving.

First of all, this is an open forum and there is not a single thread in here that is "solely for vert owners". I must have missed the velvet rope I may way in... You are proving my point more and more while trying to fight it. You sacrificed *SOME* performance for "fun driving". Again, as Pangloss put it earlier, most vert owners are consciously putting the open-air enjoyment above the overall performance aspect. I'm not saying it doesn't perform extremely well, I'm simply saying that the coupe performs slightly better. I know you and the other vert guys will now come back with "No, you are sooo wrong, it's only a little bit heavier and a little bit slower" which is, again, the exact same thing I am saying but because it's coming from my mouth-errrr keyboard - and not yours, you deem it an insult.

Additionally, I estimate that, since you're still in school, I've got probably a decade of additional driving experience in comparison to you. I've also owned about a dozen cars. Experience isn't told to you by your father or uncle, nor is it found in a text book. Ask Paulina Gretzky how her slap shot is...

Originally Posted by BrokenVert

Its a problem on this forum that really bugs me. My car handles well and its pretty quick - so who are you to say that I didnt buy it for fun? So please stop insulting me by saying that I didnt.

This is the most delusional thing you've written thus far. Not one person has said you did not buy your car for fun.

[Obioban]

You're insane if you think there isn't a significant and noticeable difference between the vert and coupe, on the street or on the track.

The vert has worse acceleration, worse braking, worse handling, worse chassis stiffness, worse back seat space, worse visibility, worse noise at speed, and worse trunk space.

And all of them are easily noticeable. The difference in weight is greater than that of a passenger, and everything about my car feels worse with a passenger than without-- an my car doesn't even have the structural compromises of the vert.

Or, here's some fun stats. 0-60 times for various e46s per BMW:
e46 M3 CSL: 4.8 seconds
e46 M3 coupe: 4.8 seconds
e46 M3 vert: 5.3 seconds
e46 330i sport manual: 5.8 seconds
e46 330i automatic: 6.4 seconds

The e46 M3 had no automatic (SMG had the same trans as the manual, just with hydraulics), so every one of those is just a factor of power and weight. That's not even a stat that's effected by the chassis stiffness! The M3 vert is closer in speed to the 330i than it is to the M3 coupe. Lame.

Lower power cars are only hurt more by extra weight.

Every vert I've driven has felt dramatically worse than it's coupe counterpart-- including 128 coupes I've had as loaners.

[Section147]

Originally Posted by KingOfJericho

I know you and the other vert guys will now come back with "No, you are sooo wrong, it's only a little bit heavier and a little bit slower"...

You're missing the point, J. That being that in the REAL WORLD (i.e. - NOT ON THE TRACK), the negligible differences in "performance" are
insignificant enough so as to mean nothing.

[Section147]

Originally Posted by Obioban

The vert has worse acceleration, worse braking, worse handling, worse chassis stiffness, worse back seat space, worse visibility, worse noise at speed, and worse trunk space.

So you're saying it's....."worse"?

[BrokenVert]

Originally Posted by Section147

So you're saying it's....."worse"?

I never wouldve guessed that my heavier car would be slightly out performed by a coupe.


But I forget - everyone on this board is Aryton Senna. Despite the fact that ive spanked 135 coupes at autox in my lowly and shite vert.

[KingOfJericho]

The weight of a single passenger alone is noticeable before I leave my street. No track needed. The weight difference between the two is closer to having two average sized adults in the car with you. I'm sorry you're apparently so disconnected from your vehicle that you can't detect that in every day driving. BTW, I can hear my exhaust with my windows rolled up so don't come back with "hearing the sounds of the car" as bringing you more in tune with your car.