I just got 83 300SD and I love it. My only dissapointment is on the highway, it was suppose to be such a highway machine but I see 3000RPM's @ 62 (that's correct speed from GPS)

Is this normal or something's wrong?

Sounds normal to me. Keep in mind this model was built for the American market and the country had a national 55-mph speed limit at the time.

__________________
2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Sounds about right. I'm reading slightly less but this could be needle placement.

Engine noise and vibration starts becoming annoying with no radio as I approach 80 mph.

Since the US speed limit was 55 mph when it was sold it very well could have been a highway machine for back then. Right now the ride is much smoother staying at 70 mph or less.

my 300SD shows about 2600 @ 60 and 3000 @ 70...it may have higher gears because i notice the shift points on it are higher than they were on my 84 300D

__________________

• 1993 Mercedes-Benz 400E *146,000 Miles*
• 1985 Mercedes-Benz 300SD Turbo Diesel Biodiesel *SOLD @ 346,000 Miles*
• 1984 Mercedes-Benz 300D Turbo Diesel Biodiesel *SOLD @ 284,000 Miles*

My 83 shows 2400 at 65 2900 at 75 mph.Mine speedo is correct,and tach too,I run larger rear tires 215 70 14s.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran

The '85 model has a different final gear ratio that makes for more pleasant highway motoring.

oldsinner, you must not have the original differential.

__________________
2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

The 2.88 diff is the perfect compromise for the SD. It'll spin at 2900 at 68 mph and run very quietly at this speed.

Hills can usually be managed in fourth gear without dropping below 65 mph.

The stock 3.07 gears found on all the vehicles older than '85 does tend to limit the highway speed if you don't want to listen to the engine.

The sound of the engine almost defeats the purpose of having a radio in the car, I love listening to the engine

__________________
RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

____________________________
FACEBOOK: PANZER450

It doesn't bother me too much, I usually go around 70-75 or so. Just turn up the radio!

Now the 300E on the other hand.....its like dead silence in comparison, going 75! Heck....its quiet even at 100!

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

The W124 has more aerodynamic, most of the sound probably comes from our undercarriage, the W124 has covers for the undercarriage, the front is slightly tilted unlike its previous W123 with the ] straight front... Also my 70 mph is around 3300 rpm and 67 is at 3000 rpm i have a youtube video on my car doing around 70-75 for a short period, i had previous SD that is pre 85 and the rpm @ 70 is 3K not higher not lower i wonder why...

__________________
Current Garage
2008 Mercedes GL320 CDI 188k mi Repair/Work in progress
1994 S350 160k mi Garage Queen & prepping for repairs
2005 E320 CDI 203k mi Healthy & Daily Driver
1994 S350 357k mi Retried as parts car
1984 300TD 214k mi Blown OM617 Poss OM603 Swap??

Sold
1987 300SDL 200K+
1994 S320 181K mi
2008 E320 Bluetec 127k mi
1999 S420 130K mi
1980 240D 360k mi
15+ Others that has come, stay and gone

GONE, BUT NOT FORGOTTEN
1995 E320 SE 220k mi
1984 300SD 350k mi

Thanks guys,

So how big of a job is it to change gears to 2.88?

The bigger part of the task may be locating, purchasing, and getting it home.

If you do, take the cluster or at least the speedometer with you since your speedometer will not be correct anymore if you change the diff.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

I was hoping for just ring and pinion replacement, maybe even from someone here or the junk yard.

I wouldn't worry about speed readings, mine are off anyway as I run 17" (bad wheels BTW), I will put some 18" soon and use GPS

Yes I figured someone put a 85 rear end,and trans in my car.The trans looks new.

__________________
1999 w140, quit voting to old, and to old to fight, a god damned veteran

It's a long afternoon of work. With the SD you can purchase a speedometer recalibration unit that will give you exactly the speed of the vehicle. The unit is in series with the pickup wire to the speedometer. You calibrate it to precisely the vehicle speed...........even if the tires are larger, you get perfect speed. It's about $80. and well worth the expense.