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Why a 3 speed automatic?

Started by bbnlv, 30 July 2012, 05:39 PM

pompy

My '82 280 E and my aunt's '86 380 SE always started off in 1st gear - and I was always under the impression that's the way it was intended, untill recently. Neither cars had been tampered with.
My 500 SE has a 1st gear good for 80km/h and 2nd is good for 140km/h - that's way too long for my taste. But a punch of the accelerator half way to the floor board ensures a 1st gear start. But it feels laborious, so I'd prefer 1st gear start as 1st gear is long.

TJ 450

I saw a speedometer in Nathan's collection with the 2nd maxing out at 140 (or something like that). That is crazy... Is third maxing out at 240 or thereabouts on yours, pompy? BTW do you have the tri-Ys on your 500?

One has to ask the question then, what on Earth is the top speed? It would have to be well over 260km/h.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

s class

I'm working on a nice 1982 280SL (107) at the moment.  Its a 4-speed auto, and always pulls off in 1st, but its a proper useable 1st gear, not the super low ratio I have on my W116 280SE. 

BTW, this 280SL is a seriously quick car. 


[color=blue]'76 6.9 Euro[/color], [color=red]'78 6.9 AMG[/color], '80 280SE, [color=brown]'74 350SE[/color], [color=black]'82 500SEL euro full hydro, '83 500SEL euro full hydro [/color], '81 500SL

motec6.9

Hi Tim About 252Km/h when ignition cut out comes in to protect from over rev. Having NOS helps you find out these things. :) in a controled environment of course.
Euro 6.9 255.6hp at the wheels. Watch this space.

pompy

Tim,

3rd is good for 220km/h. Its quite a rush to select 3rd manually at 140km/h, floor it, and accelerate to 180km/h. 220km/h comes up at 4000rpm in top gear.
CAR Magazine tested this model back in 1990 and top speed was 233km/h. 0 -100km/h in 8,3 secs. 195kw/405nm.
I prefer it to the 560 SEL I had as it is much lighter and an excellent long distance cruiser. AND it feels more powerful!
Hell, my Hilux 3.0 D4D feels more responsive than the 560 did...
I'm not sure if the 500 has tri-y's - will check...

pompy

Correction: 2nd is good for 145km/h  :D

TJ 450

I've only ever seen one 500SE locally, it was an early one though.

195kW is quite close to the 560, 9.0:1 non-cat at 200kW, but as you say the SE would be a little lighter. I suspect it may have a different diff ratio though.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

pompy

Yup, it has the longer diff ratio.

entresz

I think the 3 speed auto is a really nice transmission in my 450SE. Despite it only being a 3 speed, it takes off like a rocket when I want it to. At 100 km/h it does about 2750 rpm and overtaking is easy ... the other car I drive (a 1999 Ford Falcon) does about 1800 rpm at 100 km/h, but  to overtake, and get up even slight hills it needs to kick back to third. Overall I think Mercedes Benz got it just right when they made that particular gearbox  ;)
1975 Mercedes-Benz 280SE
1981 Mercedes-Benz 300D
Previous cars:
1979 Mercedes-Benz 450SE
1982 Mercedes-Benz 280E

oversize

Except for the 6.9 stator spline....
1979 6.9 #5541 (Red Bull)
1978 6.9 #4248 (Skye)
1979 6.9 #3686 (Moby Dick)
1978 6.9 #1776 (Dora)
1977 450SEL #7010 white -P
1975 450SEL #8414 gold -P

TJ 450

#25
I have seen that the stator spline is actually a weak point on all the transmissions of this vintage, it seems people think that it is more likely to fail on the 6.9, and that has been the case in reality. However, I noted that the teeth on the stator shaft were a different profile to that of the stator spline in the torque converter. I installed a stator shaft with a V tooth profile that was a good match for the T/C spline. I have never seen this on any of the transmissions I have pulled off these cars, thus there has always been considerable lash leading to wear on the spline.

This is what I have observed anyhow.

Later transmissions have a much better fit, and wear is next to nothing.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500