On March 06/07, I made my “New Member Introduction” and as for “whatever you consider interesting”, I mentioned the installation of a Borg-Warner Overdrive Unit in our 280SL Roadster. Indeed since that time, several members have expressed interest in this novel approach to obtaining such a function. Subsequently I wrote a more detailed article on the subject that was published in the July 2007 issue of our Pagoda World. The text and photos can be found on pages 14 to 16 inclusive.
A number of members that assisted at Blacklick 2007 inspected the installation first hand, and a few, our honourable President Cees Klumper included, went for a test drive to actually experience the results.
As an update, I am pleased to relate the following:
Indeed, fellow Montreal member - Michel Gendron and his wife, in their White 1970 280SL and my wife and I in our “Dark Olive” 1969 280SL made the latest trek to Blacklick, Ohio. This was an excellent opportunity to perform a true potential fuel economy test.
Both vehicles are equipped with the same 2800 cc engine and automatic transmission. However ours has the front drive shaft replaced by the Borg-Warner Overdrive unit. Both vehicles were filled with premium fuel at the same service station prior to leaving Montreal on Thursday morning July 26th. Michel led the way and we followed at a proper distance throughout the whole journey. Both Michel and I drive in the same conservative manner respecting the value and beauty of our machines. We filled our tanks at the same service stations on route, keeping our gas receipts for a final compilation and comparison.
Over the 1600 mile trip, we can report a net 15 % fuel economy resulted from the continuous employment of the Borg-Warner unit in our 280SL. (The Overdrive function kicks in at 28 mph, dropping out upon deceleration at about 22 mph.) One may have hoped for a greater economy, but at todays ever rising fuel costs, this is still significant.
Frankly my specific desire in tackling this project was “to reduce the engine rpm at highway speeds”. By so doing we have definitely improved the comfort level by reducing noise and vibration.
Since our return home at the end of July we have clocked another 1000 miles with continued pleasure. (To me the 2350 rpm at 60 mph is much more satisfying than the original 3450 rpm.) The only issue I have yet to correct is a minor but persistent leak of fluid from the overdrive unit. I keep an eye on the level to assure it does not drop below a critical mark, topping up when necessary. Once our touring season is finished at the end of October, I shall cure the problem for good.
Keep on motoring, and enjoy the good weather whenever possible!
Sincerely;
Tom Forsythe
W.T.Forsythe
