Three-pointed star letter

Sir,

Reading your magazine has become a must for all the staff who look after historic racing cars here at DaimlerChrysler.

We read the Wish I’d Designed article in your January 2002 edition with a great deal of interest. It fills us with pride that a designer as famous as Ted Cutting describes the 300 SLR of 1955 as one of the highlights of automotive history. Nevertheless, please allow us to make a few comments.

In the M196 engine, the engineers tried to eliminate problems of valve spring breakage and poor cam following, resulting in the choice of desmodromic valve gear — a successful assembly in view of the fact that more than 10,000rpm was reached in rig testing of single-cylinder engines.

The valves were removed and checked for cracks after every race — and re-used in most cases. The engines in the GP car and SLR usually clocked up 1500 and 5000 kilometers, respectively.

DaimlerChrysler Classic currently owns several 300 SLR cars which are driven regularly and are serviced and repaired in the Mercedes-Benz Classic Centre workshops. In a recent overhaul of one of these cars, the valve gear was not worn to any extent worth mentioning after 6500 kilometers. We believe, therefore, that the use of desmodromic valve gear was by all means successful in terms of both performance and reliability.

As to the drum brakes, at the time, Daimler-Benz was already engaged in tests with disc brakes. However, since the surface of the disc was much smaller than that of a drum, heat dissipation proved a problem, causing warping of the discs and air bubbles in the brake fluid. For this reason, drum brakes were preferred.

We hope that this information is of interest to you and your readers.

I am, Yours etc, Stefan Röhrig, Gert Straub, DaimlerChrysler