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-   -   Gear ratios for 300D auto? (http://www.peachparts.com/shopforum/showthread.php?t=7137)

zachv 04-14-2000 02:23 PM

Does anyone know the ratios for the automatic trans in an '85 300D? My engine seems to be screeming at 70 mph as it is spinning at 3100rpm's or so. Is it OK for the engine to be spinning so fast? I figured that it had to be as these cars are meant for the autobahn. Thanks for any replies.

LarryBible 04-14-2000 03:08 PM

I believe this would be about right for a 300D. A 240D is geared even lower and is doing about 3,500 rpm (calculated) at 70MPH.

I have the gear ratios in a book at home, I will try to dig it out and do the calculation. This, of course, is if I manage to get my taxes finished with time left over.



------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

zachv 04-14-2000 08:10 PM

Larry, I would appreciate it. Thank You.

fz500sel 04-14-2000 10:55 PM

Hey zach,

I've got an '85 300D and ditto for me. Mine does about 3100rpm at 70mph as well. I think this is normal for our model.

Frank :)


------------------
FrankieZ
84 500SEL EURO 87K
85 300D 267K (and still goin' strong)

LarryBible 04-15-2000 08:33 PM

The book I have indicates a 3.46 rear gear ratio for a 300D. My calculations indicate 3,266 RPM at 70MPH with 185/75 14 tires. You probably have a 195 or 205 which would work out a little slower engine speed. 3.100 seems about right.

The 240D engine really screams, it has a 3.69 gear. I would really like to have a five speed with an overdrive fifth. I can always dream I guess.

Good luck,

------------------
Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

mbdoc 04-16-2000 08:30 AM

The 1985 US version is supposed to have a 2.88/1 rear axle ratio. It's the only one with this ratio. All other diesels with turbos used 3.07/1, so they reved even higher than the 1985.

zachv 04-16-2000 12:36 PM

Would I be correct to assume that third gear in the auto is 1:1 and that fourth is something like .8:1?

LarryBible 04-17-2000 07:39 AM

I would expect top gear to be direct (1:1).

MBDoc shed a little light on gear ratios. I wonder if the book I have is giving Euro ratios. I had a US 240D before my Euro model, it seemed that the Euro had a lower gear ratio (higher numerically). I thought maybe it had an optional mountain ratio. Goodness only knows, if you were driving a 240D in the mountains, you'd need all the help you could get. But maybe, the Euro cars are geared differently.

Larry


mbdoc 04-17-2000 09:27 PM

None of the 1980's automatics had anything but 1:1 top gear.


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