640i Test Drive

[Barks]

For what reason?

I'm no engineer but it's a fairly intuitive assumption. A metal folding roof is going to pose more problems for structural integrity than a canvas roof. For example the roof of a 3 series cab is detached into several different parts.

If I'm wrong then why is the Porsche Boxster - a car designed from the ground up to be a roadster - still sporting a soft-top?

Who knows perhaps I'm completely wrong, like I said I'm not an engineer!

 

[ZG002]

For what reason?

Weight and where that weight sits at different times with roof up and roof down.

Roof down on folding hard top you have a lot of weight now at the back of the car and centre of mavity has moved a fair bit I'd imagine.

With the soft top you really ain't moving half as much weight about.


Having said that, I really couldn't care a less and would like a roadster (folding hard top) MX-5 over the soft top.

 

[Django x2]

One of the fundamental reasons the 6 is and will remain a soft top cabrio is because it's a GT style car, therefore, it needs to realistically be able to carry luggage. A folding metal roof takes up far too much boot estate whilst the cleverly engineered soft top takes up very little. Not a 5 series size boot though no, but I would be interested to see the load capacitys

 

[Fett]

I'm no engineer but it's a fairly intuitive assumption. A metal folding roof is going to pose more problems for structural integrity than a canvas roof. For example the roof of a 3 series cab is detached into several different parts.

If I'm wrong then why is the Porsche Boxster - a car designed from the ground up to be a roadster - still sporting a soft-top?

Who knows perhaps I'm completely wrong, like I said I'm not an engineer!

Why would a metal roof pose more problems for structural integrity? If anything, it's the opposite, removing the number one "issue" in a convertible, scuttle shake.

The Boxster eschews the benefit in favour of weight reduction and not have to deal with a rear-weight bias with the roof down. And cost. A good hard top is mechanically more complicated and far more expensive than a soft top to implement and maintain.

One of the fundamental reasons the 6 is and will remain a soft top cabrio is because it's a GT style car, therefore, it needs to realistically be able to carry luggage.

I think the SL is right up there with what a pure GT is all about. It manages.

 

[[TW]Fox]

I'm no engineer but it's a fairly intuitive assumption. A metal folding roof is going to pose more problems for structural integrity than a canvas roof.

Oh great, here we go again with you

Folding metal hard tops have better structural integrity - with the roof closed there is a huge slab of metal forming the roof!

The problem with folding hard tops is not structural integrity at all - its weight.

 

[Barks]

Why would a metal roof pose more problems for structural integrity? If anything, it's the opposite, removing the number one "issue" in a convertible, scuttle shake.

A metal folding roof made up of several parts is still no substitute for a fixed roof.

Oh great, here we go again with you

Folding metal hard tops have better structural integrity - with the roof closed there is a huge slab of metal forming the roof!

The problem with folding hard tops is not structural integrity at all - its weight.

How you doing?

Like I said I'm no engineer and weight distribution didn't cross my mind although I can appreciate it is a more important factor.
I'm sure I read somewhere that the 335d was not available in convertible form because the structural integrity was not great enough to handle the torque or something of that ilk.

 

[[TW]Fox]

A metal folding roof made up of several parts is still no substitute for a fixed roof.

And TommyB moves the goalposts - correct, a metal folding roof is not as stiff as a solid roof.

But it's more stiff than a canvas roof, which should be fairly obvious!

Why are you even mentioning fixed roofs - a car with a fixed roof isn't a convertible.

 

[Barks]

We're venturing off topic here. The fact is that a metal folding roof is a far more complicated piece of engineering than a canvas roof. I didn't appreciate that it was the weight distribution which posed the main problems.

 

[Fett]

A metal folding roof made up of several parts is still no substitute for a fixed roof.

I did not say that, nor imply that.

You said: metal folding = more structural integrity problems than a soft folding roof.

I said: you are wrong.