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#1
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Regearing a 300SD differential
Things are going along pretty well fixing Guderian, my 1983 300SD. I'm getting close to daily local driving with it.
The next problem I foresee is the top end speed. 75 MPH was about 4000 rpm. Around here, 75 MPG might admit you to the granny lane. Are there any gear swaps that might lower the rear end ratio? Where are the parts available? If only there was an easy way to put in a manual transmission.
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1983 300SD "Guderian" 1987 MR2 2015 Camry 2015 Chevy Spark 2006 Hyundai Tucson |
#2
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With the 3.07 ratio.....75mph should only be about 3200 rpm. 4000 should put you more around 90-95mph
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-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) |
#3
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You can put a 2.88 in there but with that large of a body you will need to make sure its quite spunky off the line.
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http://superturbodiesel.com/images/sig.04.10.jpg 1995 E420 Schwarz 1995 E300 Weiss #1987 300D Sturmmachine #1991 300D Nearly Perfect #1994 E320 Cabriolet #1995 E320 Touring #1985 300D Sedan OBK #42 |
#4
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You can put in a 247 ratio from the v8 eaquipped cars. several have done it. I believe it is a bolt in swap.
Your takeoff from a stop will be a bit sluggish but once rolling you should be fine. YOu will get better mileage too. Tom W
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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC] ..I also have a 427 Cobra replica with an aluminum chassis. |
#5
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If you are looking for a fast car, you made a mistake buying the 300SD. You should have bought a 500SE.
You can drop in the 2.47 from a gasser W126 to lower the engine rpm's at speed, but it will take you longer to get to 75. The 2.88 might be a better way to go. The fuel mileage increase from going to a 2.47 is, in my humblest of opinions, not worth the effort. |
#6
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Sounds to me like you've got a slippage problem, or a p/o put in an incorrect diff replacement.
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1983 300SD Rusty, Loud and Proud |
#7
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I agree with PawoSD & Dieseldoofus, your missing 4th gear. Check your tranny fluid level as these cars are pretty finicky about that. Flat surface, running in Park, and warm fluid..........you probably already know the drill.
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#8
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Check and make sure that the car is really in D and not 3, as it could be a linkage problem.
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1983 300SD Rusty, Loud and Proud |
#9
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correct. if you look at the marks on your speedometer, you will notice the III mark around 75, that is the MAX rpm for 3rd gear. it should be shifting out of third into 4th at this point, unless your foot is on the floor... making the downshift switch preventing shifting out of 3rd. you could also have a bad kick down switch... a bad tranny, a bad shift linkage bushing, etc... fiddle with the shifter while you are around 65mph pop it into N and gently back into D and see what happens.
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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread "as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do! My drivers: 1987 190D 2.5Turbo 1987 190D 2.5Turbo 1987 190D 2.5-5SPEED!!! 1987 300TD 1987 300TD 1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere! |
#10
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Check the bowden cable as well.
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RRGrassi 70's Southern Pacific #5608 Fairmont A-4 MOW car 13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete. 91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K 90 Dodge D250 5.9 Cummins/5 speed. 400K |
#11
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Run 215/75-14 tires. They fit, and will get you a 7% rpm reduction. And you will need new tires sooner or later, so your gear swap will be "free"
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2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss) 1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss) |
#12
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3.07 versus 2.47
Just for fun, the attached graph represents the fuel mileage for each tank of gas I bought for my 1984 300SD before I sold it. Can you guess what date I changed the 3.07 for the 2.47?
P.S. - I did not drive that car in the snow, so that's why the December to March period is drawn out. |
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