Aston Martin - Owners who have bought more than one car.

[Stark999]

Well I bought two in 1 week. A 2020 V8 Vantage - then it had to go and have its alloys refurbished and a couple of minor things and they gave me a brand new 23 plate demo Vantage and I loved it. So that later week I bought a V8 Vantage Roadster on a 22 plate with 4000 miles and every extra I could ever need!!

[Import]

Thant a big week…hope you love them both…

[bridggar1]

V8 Roadsters seem to be softening quite nicely at the moment - seasonal I guess, but also seeing significant stagnation with coupe advertised. I'm in 2 minds to go £80-85k coupe or £110k roadster - that said, not yet driven a roadster and don't want anything too wobbly. (like my M4 cab)

[Jon39]

bridggar1 said:

... - that said, not yet driven a roadster and don't want anything too wobbly. (like my M4 cab)

I have never driven a Roadster, but with the 2005 version, it was strongly emphasised by AML, that the chassis of the Roadster was originally designed, then used for both the Coupe and Roadster. IE. no extra stiffening when the soft top version was introduced.

Whether that was fact or marketing tosh, I don't know.

[LTP]

Jon39 said:

I have never driven a Roadster, but with the 2005 version, it was strongly emphasised by AML, that the chassis of the Roadster was originally designed, then used for both the Coupe and Roadster. IE. no extra stiffening when the soft top version was introduced.

Whether that was fact or marketing tosh, I don't know.

I can't comment on the original 2005 designs, but this is certainly not true of the current ones.

For a comparison, if you look at the launch cycles, Jaguar launched the F-Type as a soft-top and then followed up with the coupe later. The understructure of the car was not re-engineered in between and the coupe program was a relatively minor one, just basically putting a tin-top and liftgate onto the convertible's structure (that's an oversimplification, but I hope you get my drift). So, if only by pure physics, the F-Type coupe is way stiffer than the convertible, but it could be argued it's carrying unnecessary structural weight and cost.

Aston, however, launch their cars as coupes first and follow up with the convertible, the coupe structure being optimised for a balance of cost and (believe it or not) weight, while meeting or exceeding the stiffness targets for the program to give the chassis engineers the platform they need to work their ride and handling magic. So when time for the Roadster or Volante comes along, there's a considerable reworking of the lower tub structure around the sills and undersheets required to replace as much of the stiffness lost by cutting off the roof as possible, the logic being that you wouldn't want the extra weight (and cost) running around in every coupe. You also have to engineer in the detailed structure and packaging for the actual convertible roof and its mechanism which, for various arcane supply chain reasons, you can't easily do on the coupe if it's the lead program. It's a relatively trivial act to take it all out if you want a coupe off a convertible, though.

Personally I'm not convinced by the Aston engineering route, especially for their tiny volumes, as you still have significant extra engineering and tooling investment required for every convertible variant that has to be recovered. For the likes of Porsche or Mercedes, volumes, yes; but for Aston's? However if you want to launch a coupe first, engineering a convertible first gives different program, supplier and cost issues as you have to swap the programs over at some point..

[Calinours]

Jon39 said:

bridggar1 said:

... - that said, not yet driven a roadster and don't want anything too wobbly. (like my M4 cab)

I have never driven a Roadster, but with the 2005 version, it was strongly emphasised by AML, that the chassis of the Roadster was originally designed, then used for both the Coupe and Roadster. IE. no extra stiffening when the soft top version was introduced.

Whether that was fact or marketing tosh, I don't know.

As ever, it was tosh Jon, but as ever, based on a modicum of truth. The DB9 Volante uses essentially the same structure/architecture as other VH cars, and it is a complete blamange compared to the DB9 Coupe.

The Vantage Roadster had one key additional structural component over the DB9, a crossmember running laterally between the A-pillars. This made the Vantage Roadsters more torsionally rigid than the DB9 Volantes to suit their more sporting character. The cross member is also present in the Vantage coupe, but wasn’t really needed as it didn’t add much torsional rigidity when a roof is there. It’s why the DB9 coupe is almost as torsionally rigid as the Vantage Coupe.

In addition to the cross member, the Vantage Roadster also used different under trays, either more/thicker or more mounting points (can’t quite remember exactly which). It all resulted in an impressive torsional rigidity increase over the earlier DB9 Volante. Torsional rigidity or resistance to twisting is defined as the amount of force required to bend the chassis by 1 degree. ~ 10kN is roundly the force a mass of 1 metric tonne or 1000kg will exert on the earth when subjected to the earths gravity, or in simple terms it’s roughly a ton weight.

DB9 Volante was 15.5kN per degree
Vantage Roadster was 22kN per degree

But the DB9 Coupe was 27kN, and the Vantage Coupe a tad more, IIRC about 27.3kN. Impressive numbers even today.

For reference, the DB11 Coupe is 34kN and the DB11 Volante is 22KN. Yes, the DB11 Volante got the crossmember, or the ‘garden gate’ as referred to in the factory.

With more of the usual marketing chutzpah, the DB12’s minor chassis bracing tweaks ups the coupe’s rigidity by 1.5kN to ~ 35.5kN, and the Volante version of the new car is increased by a similarly massive 0.8kN to 22.8kN

All numbers are ‘claimed’, but it’s easy enough for anyone to see where the real jump was….

There is no way to completely recover all the loss of structural rigidity that comes from completely removing the roof as a structural element. The cars that come the closest are probably the McLarens with their ultra deep sill carbon tubs.

Edited by Calinours on Tuesday 31st October 12:17

[Jon39]

Calinours said:

As ever, it was tosh Jon, but as ever, based on a modicum of truth. The DB9 Volante uses essentially the same structure/architecture as other VH cars, and it is a complete blamange compared to the DB9 Coupe.

The Vantage Roadster had one key additional structural component over the DB9, a crossmember running laterally between the A-pillars. This made the Vantage Roadsters more torsionally rigid than the DB9 Volantes to suit their more sporting character. The cross member is also present in the Vantage coupe, but wasn’t really needed as it didn’t add much torsional rigidity when a roof is there. It’s why the DB9 coupe is almost as torsionally rigid as the Vantage Coupe.

In addition to the cross member, the Vantage Roadster also used different under trays, either more/thicker or more mounting points (can’t quite remember exactly which). ...

Thank you Calinours.

I seemed to recall reading on here about different undertrays on the Roadsters, so therefore not all catered for as one at the outset. I suppose if the Coupe did not need more torsional stiffness, then no point in carrying extra weight for no benefit.

[LTP]

Calinours said:

<snip>

The Vantage Roadster had one key additional structural component over the DB9, a crossmember running laterally between the A-pillars. This made the Vantage Roadsters more torsionally rigid than the DB9 Volantes to suit their more sporting character. The cross member is also present in the Vantage coupe, but wasn’t really needed as it didn’t add much torsional rigidity when a roof is there. It’s why the DB9 coupe is almost as torsionally rigid as the Vantage Coupe.

Unless you're thinking about a different structural member, Calinours, then the Cross-Car Beam (CCB) running across between the A-pillars in on all VH vehicles (and all modern cars as far as I know), as it's the main support for the dash and is used as a fixture to assemble all of the dash components to. It supports the steering column and reacts the airbag loads, especially passenger airbag. On the VH models the beam is a steel fabricated tube with various brackets and fixings welded on; on the current generation it's a large die-casting, I believe of magnesium. And, as you say, it adds both lateral and torsional rigidity.

In fact, assuming the Aston Store parts catalogue is correct, both CCBs for Vantage and DB9 appear to be the same, which makes sense as the dashboard is basically identical

Calinours said:

In addition to the cross member, the Vantage Roadster also used different under trays, either more/thicker or more mounting points (can’t quite remember exactly which).

The VH undersheets were composite for the Coupes and sheet aluminium for the Roadster/Volante. Not sure about the number/size of fixings.