Hello w116ers.... A mate of mine who should know tells me that there was a 4speed auto on some of the late model 4.5ltr motors? Does anyone know if this is true and what year it was? I thought you guys would have a fair idea , Ive never seen it ???
Only the 6cyl W116 had 4 speed auto, However I believe they fitted a 4 speed in the
450SLC 5 ltr at the end of production. Who knows, there might have been some experimentation in that final year 1980.
Hmmm. I wasn't aware of that about thr 450SLC5.0. That's interesting. I've driven standard 450SLC's and 450SL's, and I always thought the 4 speed would be cool. My dad has a 1982 500SL R107 with the 4 speed. I presume it would be the same unit in the 450SLC5.0.
re the 107, Greg from the NSWMBC site has put together great info on the slc. He mentions the 4spd in later models that are the same as 126 boxes. But does a 4spd w126 box fit w116 motors, ie 350,450. I've heard the question before, but don't know what the answer is. Maybe the 4spd was only fitted to 5.0l and 3.8l. I dunno, but like robertd says, they're could've been some experimentation on the w116 towards the end. We know they used 126 steering wheels on some.
Here's Greg's links.
Topic: New addition to my family (http://www.mbcnsw.org.au/forum/index.php/topic,1486.msg6700.html#msg6700tt)
Topic: The 5-litre SLC Rally Cars (http://www.mbcnsw.org.au/forum/index.php/topic,186.0.html)
I briefly asked my mechanic about swapping a 126 or 107 4-speed for the standard 3-speed and he simply responded by saying there would be little benefit as they both have the same top gearing level. If my transmission ever completely dies I would consider it but then the gearing marks on the speedo would be wrong :P
Okay, this leads to a question:
Why - in your humble opinion - was the w116 fitted with a 3 speed? What do you think are the pros and cons to the 3 speed, that the engineers would have gone with it.
Here's my "guess".
-Firstly, I think 3 speeders were the main technology back then across the board, the same way that 5+spd AT boxes are these days.
-Secondly, the 70's 4spd boxes were designed for small engines with low torque. So the first gear which is non selectable in the early boxes are used just to get the Battleship116 moving without labouring the engine too much. In the end, the final gear ratio is the same as the 3spd.
-Lastly, I'd love an overdrive gear that would cut fuel usage on longer trips. Even in the 350 going 3000rpm whilst coasting at 110km/h or so, there's enough power to cope with a taller gear without overloading the engine. So whilst I think another high gear is possible, I think availability at the time and no pressure early on to design an overdrive has conspired to leave us with relatively high revving engines whilst cruising. Even the manual 4 spd box has the same final gear ratio. So an easier box to modify for overdrive was left wanting.
FWIW, the diesel 116's were also fitted with 4 speeds. :)
Regarding a 3 speed to 4 speed swap...here are my thoughts on the matter. As others have said, simply swapping the tranny won't do any good, just because you'll still have the same top gear ratio (1:1). However, I think that changing transmissions coupled with putting in a taller differential (for instance, a 2.65:1 ratio instead of a 3.07 ratio) would help. This would give you a lower freeway cruising RPM (and, therefore, better economy), and with a lower 1st gear, wouldn't compromise your off-the-line performance.
Just my opinion on the matter...I still want to put a 2.65 or a 2.47 differential under my 300SD for economy purposes. :)
Hmm, this is a bit bizzare, I remember my Mom's Euro 450SEL had notches on the speedo like it was a 4 spd auto. And I seem to remember getting it into the lowest gear in its younger days. Perhaps I'm having a senior moment a month before I turn 24 :P
Warden, if you get serious about a 2.65, I know where one is you could probably bargain for. I'd have to get dad's 6.9 up off of the dirt, but for the right price, I'm sure he'd part with the diff.