History: A Day in Death Valley

Death Valley National Park is the ultimate testing ground for automakers who spare no expense when it comes to vehicle developers. Located on the border of California and Nevada, Death Valley is the hottest place in the world and the driest place in North America, making it perfect for evaluating how motor vehicles perform in the most extreme summer driving conditions. There is no better place for a test like this. To be one of the finest cars in the world, W140 is no exception.

As one of the must-have overseas test locations, Death Valley has the advantage of combining extremely high temperatures and slopes. Therefore, testing is only conducted in the summer, with the highest temperatures usually arriving in July. For W140 prototype, its first Death Valley test was in June 1988, when the highest temperature in Death Valley reached 127 °F (about 52.8 °C). Then in July 1989, the second Death Valley summer for the W140. The parts tested include A/C system, engine mounts, spring, dampers, seats, mounts of front and rear axles, literly everything. The only thing that is not done here is high temperature testing at extremely high speeds, which is done in Nardo, Italy. W140 remained active in Death Valley until at least the summer of 1993.

A few years ago I had the pleasure of interviewing Wolfgang Schöffel, test engineer in the Mercedes-Benz Research and Development department, who experienced the first and last test of W140 and currently works in R&D as director of NVH Integration S-Klasse i.R. Wolfgang shared with me one of his days with W140 in Death Valley.

How did your career at Mercedes-Benz begin? Which S-Klasse have you experienced?

Wolfgang: Starting with Daimler in 1977 in the overall development department for the S-Klasse.That means we got all the parts ( body-seats-interior-engine-axle–exhaust-steering-and so on )– we build the car and made the integration belonging to function – durability- comfort- for integration all parts of a carto a summary. My first project was the integration of the Diesel engine into W116. Than I made or helped to develop the 6-cylinders with the W/V 126 until series-production including MOPF. Than we started with W140. Than I was involved W220-W221-W222 : start in the design of the specification sheet to developing the car to series-Production. And specially responsible for the over whole integration from NVH-problems to solution.

What specific work did you participate in for the W140 that we love?

Wolfgang: Not involved In the specification sheet and not really involved in the in the predevelopment project of W140 . That means to create new axles and first to market a subframe under the body for more comfort. These was made 1986 with W126 including these new parts. Both things were done in the period 1982-1986.We started with W140 in 1986 when our department got all parts with are necessary. After this we started with the first driving tests on our proofing ground in 1987 with these VPT (Vorprototyp), 1989 – 1990 PT (Prototyp) . Some parts as the body out of preseries- tools but assembled in our department as well. 1990-1991 NS (Nullserienfahrzeuge) that means cars from the beginning of the series- production in the factory. Ending in the presentation of the new car 1991 in Cannes France.

How does your day in Death Valley start?

Wolfgang: Beatty Nevada was in these days a small town with 1000 inhabitants , one General store, two gas stations, and perhaps three to four hotels. It was named to Montilius Beatty who owned a ranch in this area as a stopover for travelers from Las Vegas to Goldfield Nevada. In the 1910’s at the near by Ryholite there were a lot gold mines and nearly 10.000 inhabitants. We lived in El Portal Motel and after wake up we went to near by Exchange club for breakfast: ham – eggs and hash browns including two minutes of gambling at the slot machine.

At 08:00 am we started in our workshop in the Beatty High school: we got this location all the years – class rooms were our offices and they have had a workshop we delivered tools and so on for the pupils during the year. So we started with an all over meeting were we get and givet the newest information’s for the day and we make a timetable for the workshop for necessary modifications with our cars. Then perhaps we started our testings at 10 o’clock because earlier it was too cold in the valley in the morning: 33 degrees – afternoon 50 degrees which we looked for. But never forget a lot of drinking water and a cooling box with ice because the high temperatures , the low humidity and there was almost a little bit of wind. Before starting we have to sign a paper when we were leaving the facility – were to go – and when we would be back. The reason was that mobile phones were not so common and our radios sometimes were not able to reach the High school office.

For lunch that means fruits or a sandwich we drove to furnace Greek to the general store. After this we have to do similar tests or we have to return to our base to make some specifications on parts or systems in fact that the temperature measured was to high or something went wrong. We restart at the late afternoon for more tests: same place – same procedure – new results. Sometimes we can see a small tornado– or a coyote or a desert fox. But always the Mesquite sand dunes of stove pipe wells. And always we past historic places as “Devil’s Golf course” (salt desert and very deep point) – Devil’s corn field – Stones on the Racetrack (stones which were moved by the wind) – old borax mines. After ten days of testing we lost this place with al these results for high temperature measuring we need and we will came back next year.

How do you relax when you are in a completely different country and time zone?

Wolfgang: When we finshed the day with testing between 7-8 pm , sometimes we find the time to go to Zabriskie point or Dante View with magnificent views to death Valley. In the meantime one of our colleagues was preparing our own daily barbeque in the Motel garden. Large steaks from general store , potatoes preparing to be backed, salads and some drinks were always the best end of the day. But after this we went to to Sourdough Saloon an old fashioned bar as meeting point of all kind’s of testing people around the world to play billiard, dart or to have some beers.

What kind of special equipment was there in the prototype to record the data you need?

Wolfgang: The picture shows the data logger – floppy disk drive and printer. This was necessary for the measuring for temperature profiles of 200 to 300 measuring points. In the middle of the dashboard you can see two of them for the blow-out-temperature. This equipment was installed instead of front passenger seat – on which later the test engineer sits monitoring speed – and a lot of temperatures points and the test time. Each measuring point (as well as fluid’s – air condition – exhaust – engine mounts – steering – body -… and the driving speed and engine speed) was installed in our workshop at Stuttgart factory. Each one get a number for example for outside temperature was Nr.1 and so on. We have had for every part a temperature max pemisible that everything is doing well with the car. All these cables were layed into the trunk to our transducer in a package of ten. After this the data logger was programmed to these numbers and all the data’s were continually saved on the floppy.

Is W140 the first S-Klasse that data logger were being used in the testing?

Wolfgang: W116: we have had a thermal printer with continuously paper feed for only 6 measuring points. Later we took a manual switch so we can measure 12 points. Than we have to evaluate the print with a ruler. W126: the first data logger if you can say so: temperature signals from approx 100 points were registered on a magnetic tape. Every minute you can print a temperature listing like a receipt from your checkout. 30 to 40 or more of these receipts were one measurement.

As an NVH expert, what did you see from the W140 in your testing?

Wolfgang: Main thing is that NVH-Problems exists earlier than 1990 but they were called: Vibrations or acoustics. The development of those problems were not in one hand – and they were handled as god as possible with less computer simulation and less measuring systems. But as usual we could see that a solution can be good for one problem and bad for another. Therefore worldwide NVH was born as one solution tool. I will figure out three points:

Side windows:

• W126: Windows as ESG (Toughened safety glass) or VSG (Laminated safety glass).
• W140: VSG with double sided windows for less acoustics from (includes an air gap) : surrounding noise – other driving cars – wind – tires roll off acoustics.The front windows were glued in with a hard glue to get an higher body stiffness.

Engine mounts:

• W126: Engine mounts complete out of rubber – with a little hydraulic damper aside. This system was effective, but we saw, that small level vibrations were not reduced as well as some acoustic frequency’s.
• W140: Hydraulic engine mounts were developed. So it was possible to put the damping maximum to a special frequency . The decoupling of vibrations and acoustics was improved. The whole system was easier to assemble in the car. Less parts . The rear engine mount was an new mount without empty way (free way of 2mm) against vibration. This was softer and more effective in interaction with the new disconnected front axle carrier.

Accelerator system :

• W126: Mechanical linkage between accelerator pedal and throttle. Difficult to find a place in the engine compartment – heavy –and the transmission behavior was difficult to design in fact of a curve track.
• W140: electrical linkage: electronic accelerator pedal – all in one (incl. cruise control ) control unit. More options to create a better transmission between driver and engine/car. Easier assembly – less weight.

What was the most memorable story that happened to you?

Wolfgang: One story of the coupe development happened in Death Valley perhaps 1991. We tested the whole car to high temperatures – that means outside 120°F or 49 °C. We drove from Stove Pipewells elev 10 ft. to Daylight Pass Elev 4317 ft. (20 mi – mountain road). Everything was fine ,but after half of the route smoke was coming out of the engine compartment. We stopped – we have had a look to the engine – the engine oil hose was leaky and oil dropped on the exhaust manifold. In fact that there was no more wind the oil inflamed. Quickly we put off our personal belongings and some drinking water and made a call to the Beatty (Nevada) fire department – 13 miles away. After 20 minutes the firefighters were at the car – but in this time the car was totally burned . So we drove with the firefighters back to town. As an souvenir of this accident we took the rest of the melted alloy-radiator back to our office in Germany.

At the end, what did you feel after this work experience?

Wolfgang: The W140 was for me a S-Klasse which a lot of parts were going hand in hand to perfect solution in this time. And it was always exciting to work with this car. When we started our testings we can drive a car but no more. That means for example a lot of things didn’t work – but this is normal for the first period. So you have problems in this development period and you have to improvise the solutions that you can do your job. The conclusion is that every testing all over was a very busy time and you was far from home and only sometimes it was possible to have a phone call at home. But the work with the car was always very interesting and you can learn a lot of the car. And we were able to visit places we would never go for holidays and we met intresting people and different cultures.

All history are based on limited information, please email me if you have doubts about the veracity of this article. If you want to quote the content of this article, please contact me in advance, please do not use my text for any commercial purposes.