Thin Metal on RS Models

[RWebb]

Thin Metal on RS Models

The following parts are thin metal (0.7 or 0.8 mm)* on the first 500 RS and RS Touring:

Front fenders
Front hood
Rear quarters
Door skins - frame from production
Back seat area
Door sills
Trunk floor
Top of dash (under the dashpad)
Instrument panel

French versions had the rear panel in thin metal as well, and English (RHD) cars had the center tunnel in thin metal too


* Stout 2002 claims the thin sheet metal was 0.8 mm thick; others, including Adler (1998, p. 39) claim it was 0.7 mm thick.

First, this gives us an idea of what areas the factory thought were least important in providing structural rigidity (and could thus be weakened with thinner sheet metal to save weight). Naturally, this thinking is circa 1972, but cf. cutaways of the different types of steel used in modern production cars like the 997.

Second, how much wt. did they save?

Sheet metal gauge tables (http://www.engineersedge.com/gauge.htm) show that the weight of sheet metal is not a linear function of gauge or thickness. Nor do the metric thicknesses correspond to exact US gauges. I therefore used linear interpolations within each increment between two gauges to provide closer estimates of the weight savings from the thinner sheet metal used.

0.8 mm » 21+ gauge – from sheet metal gauge tables (http://www.engineersedge.com/gauge.htm), 0.8 mm steel sheet weighs 1.285 lbs/ft2

0.7 mm » 22+ gauge, weighs 1.14 lbs/ft2


The stock steel in the unit body ranged from 1 mm to 1.25 mm thick.

1 mm = 0.0394” » 19+ gauge, weighs 1.61 lbs/ft2

1.25 mm = 0.0492 » 17+ gauge, weighs 2.01 lbs/ft2

Assuming that the parts that used the thinner steel were formerly 1 mm thick (and not the stronger 1.25 mm thickness), this means that changing from 1 mm to 0.7 mm thickness saved 0.47 pounds for every square foot of area.

Some of these areas are complex shapes – but one can easily measure the square footage of the other areas and multiply by the density figures above to get the total wt. savings in kg or lbs.

[RWebb]

oops - the cites:
Adler, Dennis. 1998. PORSCHE 911 ROAD CARS. MBI Publishers.
Adler, Dennis. 2003. Porsche: The Road from Zuffenhausen. Random House. NY, NY.
Excellence # 110: 56-65, May 2002 – Pete Stout compares the 2002 GT2 with the 1973 Carrera RS; first time a new car was “more rewarding” in a comparison test.

[varunan123]

The RS/RSR

Prototype chassis numbers 911 360 0001 and 0002 the only two ST conversions documented have non-metallic front wings with weight of around 850kg.The fiberglass front wings are unigue to the 72 ST/RSR.

Raj

[RWebb]

thx, Raj - do you know the answer to the 0.7 mm vs 0.8 mm debate?

[Wayne 962]

Originally Posted by RWebb

Assuming that the parts that used the thinner steel were formerly 1 mm thick (and not the stronger 1.25 mm thickness), this means that changing from 1 mm to 0.7 mm thickness saved 0.47 pounds for every square foot of area.

[edited - I completely read the post wrong]

I have always thought that the lighter sheet metal use was more of a marketing ploy than an actual weight savings. It would be interesting to see how much actual weight would be saved using the lighter metal. I think you can compare the weight of an RS touring to a 911S to get some semi-accurate approximation...

-Wayne

[RWebb]

that could well be

or maybe they had to get down to a certain level for a particular race class (Group 4?) and that didn't require as much wt. reduction by FG as in the 911R

[RWebb]

Originally Posted by Wayne at Pelican Parts

... some semi-accurate approximation...

the M471 weighed 2,112 lbs. -- 253 lbs. less than the M472 (2,365 lbs.) - but that also included the effects of the Glaverbel glass and accessories

but we do have an upper bound of 250 lbs.