electric overdrive?

[Erik]

Hello,

Fuel prices are getting crazy over here (almost the price of low market wine) so I am looking for possible means to limit the fuel consumption of my 230 SL automatic. A sensefull solution should be to limit the r.p.m. at higher speeds .

Reducing the ratio of the rear axle is the obvious choice but I considered to install an electric overdrive. Constructors like Triumph, Jaguar, Volvo and Scimitar successfully installed such devices and I suppose there must be aftermarket solutions available.  If it can be achieved we should benefit from the rather good acceleration related to the standard high ratio axle combined with lower consumption at highway cruising.

Has anyone achieved in mounting an electric overdrive and, if so, does it actually give the results we hope for?

Thanks for your advice

Erik

[Shvegel]

I have not seen anyone use the Borg Warner Laycock overdrive unit but 2 problems come to mind. The first is that the unit is about 175mm in diameter which may be too wide for the driveshaft area. Also that unit would require some pretty expensive machine work to get working. the output shaft of the transmission would have to be re-made to provide the proper spline pattern as well as an eccentric to drive the hydraulic pump of the OD.  Then there is a problem of adapting the transmission housing as well. There are some that are set up to be mounted independently of the transmission but that might be a hard find.

THese guys have it set up for remote mounting but they are not afraid to charge for it.

http://www.nostalgiacars.co.uk/downloads/overdrive_Brochure_2010.pdf

Much better off with a 5 Speed OD transmission like the Getrag 265. There are threads on the Recearch and Development board.

[Naj ✝︎]

Tom Forsythe from Montreal has done this Borg Warner conversion (280 SL Auto).
He brought the car down to Blacklick in 2007.
There is also a 'PW' article around that time.

http://www.sl113.org/forums/index.php?topic=7276.0

Naj

[Ulf]

Even with fuel prices going crazy, you would need to drive a lot to break even on an investment like that. Furthermore, the overdrive solution (Laycock de Normanville A-type and J-type btw) on the cars you mention were merely a complicated way to get the revs down on motorway cruising before it was normal to have a 5th gear. The fun part of having an overdrive was that you usually had a ration between each gear that you could flick in and out of during "sporty motoring" to always be in the optimal revs. I would go for the Getrag solution too (if I could afford it), but more for the sake of comfort (I still reach out for the non-existing 5th gear occasionally) rather than saving money on fuel :-)

Best regards

Ulf

PS: Never drink wine that are in the same price range as gasoline ;-)

[Erik]

Hello Nay & Ulf,

Thank you for sharing your expertise.
My car is fitted with the automatic and I really would like to keep it that way. It shifts very smoothly and it completes the character of my car.
I was just looking for a solution to fit a kind of a 5th gear to the automatic.  I guess I will have to stick to changing the rear axle and drink quality wines.

Ps: did anyone ever fit an modern 5 of 7 speed MB auto?

Greetings,
Erik

[JamesL]

Is it Stickel in Germany that will stick a 5th cog in an auto box?

Check under Customisation. Not cheap mind (IIRC from a post on here)

http://www.pagoden-center.de/

[Ulf]

I remember reading an article about their 5-speed conversion in a German car magazine some years ago - as far as I remember, the conversion cost somewhere in the area of 10k EUR!!!