W124 conversion from manual to automatic
 

Hi,

I got a 1991 300E and at my last research i discovered that the car was a 5shifts manual car converted to automatic before i bought it. I am noticing that the car doesnt go up more than 190km per hour. I am wondering if i have to change the differential or other parts in it to be fully converted to automatic since the manual W124 has a 5shifts and the automatic is just 4 gears. I feel that one gear is missing, the car is running 34 rpm when speeding at 100km which is find pretty much high. And the rpm keep going up faster than the speed which makes the car do 45 rpm for just 130km per hour.
what might be the problem...differential or other parts should be changed?
what about the speedo?

If it's any consolation everyone driving a 300E feels like they are missing a gear, except maybe for the people driving the 5 speed manuals. But you can change rear axle ratios. What axle ratio do you have now?

i have no idea about my rear axle ratios.
If i aint the only one it makes me feel more comfortable but the problem is that my dash is still the manual one so i see the gear transfer at the 1st 2nd and 3rd and then im noticing that my car is blocking with rpm at 7rpm and a speed of 200km which is the max speed on the 4th gear on a manual transmission!

The ratio is stamped on the axle housing - probably something like 2.87, 3.07, 3.27. Where are you? How do you know it was once a stick?

I got it changed recently because i thought it was the problem.
The new one is 3.07 and the car still got the same problem and i even noticed a huge lack of power since the 3.07 is fixed.

I got the car checked by the dealer once...and the mechanics there told me that the numbers that are printed on the top front of the body (in front of the engine) tells that this car is a manual one (i remember him sayin something like 0 means manual and 1 automatic...something like that)
Other than that my dashboard got the 4th gear yellow marker at 200km which doesnt exisit on a normal 300E automatic. The last yellow marker on the real automatic car is at 180 km and its for the 3rd gear.

Run your VIN here - http://old.mbclub.ru/mb/vin/?lng=eng - to find out for sure. You probably should have gone to a taller axle ratio when you changed it - for example a 2.65.

here is what it resulted
VIN WDB1240301B440468
Model 300 E
Chassis 1240301B440468
Engine 103983 10 041321
Transmission 717433 01 776196
Order 0 0 221 07591
Approx. year 1990

the older axle ratio was a 2.65 if i do remember well
Might the speedo be the problem?
I noticed another thing...near the automatic shifter there is the E and S slider button.
well it seems my car doesnt do any difference if it is setted to E which stands for economy or S which stands for standard i think! what about that? how is that supposed to work?

The USA spec 300E cars with a manual used a 3.07 differential. Same as the automatic cars.

Jim

mine is european...it was imported from germany.
i have no idea what is wrong with that car.
i will change the fuel distributor and the injectors to see if it will still have a lack of power! i dont know what to do with the transmission problem

Sure enough - a 717 is a stick. Hard to say what transmission you might have now - would be stamped just above the pan. The E and S are not from that era but it could be just something on the console and unrelated to the transmission. The 2.65 is from later cars, not earlier. Sounds like multiple problems but the feeling of needing another gear would be alleviated by a taller ratio, e.g. 2.65 - unless perhaps you're stuck in next-to-top gear whatever that is.

i will look for a 2.65 one
i will let you know how will that do.
although im convinced that there is still something to do with the car...i mean...changing from manual 5 gangs to automatic 4 gangs would not be as easy as just changing the gear and removing the clutch.

Does any 300E owner might tell me what is his rpm for the speeds of 100km and 140km?

I have a 190E with a 2.6 liter 6 cylinder and a 5 speed manual, and it turns 3000 rpm at 80 mph in 5th gear. I'll let you do the conversions. I'm pretty sure it has the same transmission and differential as yours, with a shorter drive shaft.

From what I heard the auto and manual gear ratios are the same, gear for gear, but the manual and one more.

well mine is doing 34rpm for 62miles! I stpped driving it until i find a solution. If i will go up to 80 miles i think it will do 44rpm.
If both cars must have same rpm at same speeds seems not logic because you got a gear more than me....im pretty sure your car will do 34rpm for 62 miles on the FORTH gear...if thats true...means your car is running great and mine is till missing a gear.

How about this
 

Maybe the conversion was poorly done and the shift selector is not allowing the automatic transmission to get into top gear and he is running along in third or "S" range. That would be verifiable by driving along in what you show as "D" range and then without changing the throttle pull the selector into "S" range. If the engine rpms jump up a thousand, then that is not the problem.