W126 4-speed auto to W116?

[John S]

I looked up a 1970 USA road test and the 4 speed automatic transmission used in the 280SE 3.5 unfortunately has the fluid coupling gear box as used in all the automatic Mercedes until the 116 series used the 3 speed with torque converter.

 

[Andrew280SEL]

Thanks John S.

That narrows down the choice a fair bit more I reckon

 

[Styria]

Hi JohnS, thanks for that information. Now, I know that a torque converter provides for smoother changes (or so every Road Test would have you believe that) but, really, is it all that bad to have a fluid coupling ? I have owned cars that employed that method and quite honestly, I failed to see what the problem could have been with them.

6.3's for instance have a harsh gearchange and that is reckoned to not only be the norm, but also a desirable feature. I think otherwise. Gearchanges, and harshness thereof, can be adjusted by usung different length of adjustment pins and these are fitted during assembly of the box. I have always liked the positve, but not harsh, changes of the 6.3 and 300 (finny type) boxes. Regards, Styria

 

[John S]

I believe that the 6.3 with the fluid coupling jerked during changes more that the other smaller engined models because of the greater torque applied by the much larger motor. Once the car gets moving at a reasonable rate a fluid coupling almost locks up solid, hence its greater efficiency (lack of slip)

The torque converter allows greater rev differences between the motor and the gearbox to give a torque multiplication of around 2:1, which is equivalent to a variable gear, helping make up for the one less gear used in the 3 speed gearboxes that the 350, 450 and 6.9 models used compared to previous models..

 

[Goldacre]

On the 4 speed note, someone at the Perth W116 get together said a bloke in the Eastern states has done a modern Holden 4 speed to adapt to any W116 motor, bummer is i do not have the name of it. It sounded like a posh name from what little memory i can recall.

GM and Mercedes had a transmission relationship years ago so i've been told, the Holden Trimatic (Trau-matic in the business ) was a Mercedes design, still holds the record for the most internal parts in an auto transmission (>450).

Jules

 

[116Benz]

What, a THM 400? will bolt up to a Benz engine? the tri-matic was in Royces (BenzBoymight be able to shed some light on this too) up until the Silver Spirit?

 

[BAR]

On a technical note or more like a question.

A four speed box may be better than a 3 speed unit, but how and why?

If the 4 speed unit is basically a 3 speed item with 4 gear as overdrive, then it would only benefit in fuel economy and in engine running quieter as higher speeds. The acceleration may not be relatively different, if only for the fact that the lower 3 ratios may be similar to a 3 speed.

On the other hand if the 4 speed has the same final gear ratio and the 3 lower ratios are spread, again it may have better accleration 'in a specific gear'. but may loose out in a 0-100Kph or 0-120Kph race because of the loss of drive during the 'extra' gear change.

It is worthy to identify the actual ratios for the 4 speed unit, be it a donor 126 unit or that from an AMerican engined vehicle [Ford or Chevrolet].

SO if someone has the manuals, please refer to them and supply the details.