1970 280SL Rear differential and Engine Revs

[w113abudhabi]

Taken from a separate thread:

"the non-US 280 SLs started out with a 3.92 ratio (US ratio was 4.08), then at chassis no. 011132 the non-US cars went to 3.69 while the US cars went to 3.92.

With the 3.92 my car shows 70 mph (110 kph) at 4000 rpm."

I am enjoying driving my US spec 1970 280SL with automatic transmission which has a 3.92 ratio diff. I notice that at highway speeds (70-80mph) the engine revs are fairly high and comparable to the quote above. Would I derive any significant improvement by changing the diff for an alternative ratio?

Any comments or suggestions please?

[Rolf-Dieter ✝︎]

Some of what you seek can be looked up here

---> http://www.sl113.org/forums/index.php?action=dlattach;topic=18239.0;attach=20119;image

I am quite happy cruising around 3,200 RPM in my 1969 280sl to change would not make too much of a difference in MHO ... If I like to go faster I'll take my DD besides to change would make my car no longer original.

[w113abudhabi]

Thanks Rolf-Dieter

I was hunting for info yesterday and read a few related threads. It would be good if the graph you linked could be stored in the Technical Manual which I was looking through yesterday prior to posting.

It suggests to me to leave my car as it is as the benefits are relatively little. Where I live currently it is necessary to use the highway regularly although I anticipate that will change in due course and on country roads I may well prefer the existing and original set up.

Best wishes,

Pierre

[Peter van Es]

As a full member, you can add the graph in the Technical Manual yourself...

[w113abudhabi]

Oh really. Then I shall do so. I didn't want to step or drive on any toes...