Mercedes 300 e 3.0
 

Hello,
I am a bit new at this. I bought a 1991 300 e sedan with a 3.0 engine. The transmission was bad. I had a rebuilt trans installed. The car shifts great in all four gears. My question is there an overdrive? When I am at 60 mph the tach is reading 2500 rpm. I have a 1994 Chevy Camaro and at 60 mph it is about 1700 rpm. Just making sure this is correct.
The next question is that the cruise control will not hold. I have it on and push up on the set lever and it engages for about a minute then shuts off.
If some one can answer these questions it would be deeply appreciated.
Thanks

I have the 2.6 190e which is functionally the same as a 3.0. It's a drop in swap. 722.409 transmission. At 60 mph I'm around 2500 rpm. At 70 it's closer to 3500k. At 80mph it's getting up to around 4500. Screaming. Our max speed limit on a toll road is 85mph but I don't think I've hit it yet.

The auto transmissions were geared for a 55mph speed limit.

But it sure does have a lot of umph left at the higher speeds due to the lower gearing. Feels like it would hit 100 easily.

does the camaro have a 6 speed? not fair to compare because those have 2 overdrives.

4th is an overdrive but the 2 cars are geared differently, regardless of the camaro's trans, especially if the camaro is a v8. good luck, chuck.

Cruise Control
 

PM forum member James Dean. He repairs cruise controls for PP members.

https://sites.google.com/site/mbcruisecontrolrepair/

Correction:

Fourth gear in the MB transmission is direct drive, 1:1, not an overdrive.

It's not uncommon for vintage Mercedes to run at a higher rpm than you might be familiar with if your frame of reference is a lazy American V-8.

Different philosophy, MB engines can run all day at or near redline. Torque and power curves are based toward the upper range for this reason.

Later, for example the last W124s, had a low numeric differential, which essentially shifted all the ratios up one gear. By dropping the rear diff ratio (lower), you bias the final ratio lower. So, once you combine the diff ratio with the intermediate gear ratios of the transmission, you can see the "real" ratio.

Did you also notice your transmission starts in second, not first, unless you floor it or manually move the shifter into low position.

So, bottom line, the car sounds like it's doing just what it should....
So let her rev. Doesn't hurt a thing, and the cost of modifying the car for a lower ratio far exceeds and return on investment.

Jim

I've noticed gas mileage is better when you go screaming down the highway at 4k+ rpm than when you go the same distance in stop and go traffic.

my bad. i alway thought the 722.4s were a slightly od version. like 0.95/1 instead of a real od like 0.8 or more. thanks, chuck.

Thank you for your help.

Hello Chuck,
I was not comparing the two just trying to make sure the trans was performing correctly. You are very correct the two cars are very different. Thanks for the help!

Hello Jim,
Thanks for the help!! I understand now that there is quite a difference. there was definitely two trains of thought between the to vehicles.

Thanks for the info. So what kind of gas mileage do you get?

Thanks for the info.

I have both an auto and 5 speed manual M103 powered W124 and the difference in RPM between the two is very dramatic. The 300TE with the auto cruises around 3300 RPM at 70 MPH while the 300E with the 5 speed is around 2300 at 70 MPH. I can also get 27 MPG fairly regularly in the 5 speed.

My 190e w/ m103 gets 18 mpg mixed. Around 23 mpg highway only. Very close to EPA estimates.