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#1
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rear diff woes
I want to replace the rear diff. in my 1984 300d, it is wining and I like to take this opportunity to change it and lower the ratio for better mpg and alittle less noise at highway speed. I talked to the local mb dealer to see what my options are. They say I currently have 3.06 gears and that I have to order a ring and pinion for a 1985 which would turn out to be 2.88 ratio.
My problem is, my shop manual says I have 3.46 ratio and and it says the same thing for the 1985. Who or what is right. I took these #'s off my rear end this afternoon. can anybody tell which ratio I have with these #'s 115 351 32 08 3826 6N 84 +6f+m any help would be appreciated |
#2
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Hello dieselnut14
The 1985 300SD has 2.88 ratio. ![]() If you can find one. ![]() I looked under a 1985 300SD at a junk yard today, someone put an 1984 or earlier differential in it. ![]()
__________________
ASE Master Mechanic asemastermechanic@juno.com Prototype R&D/testing: Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician. Noise Vibration and Harshness (NVH). Dynamometer. Heat exchanger durability. HV-A/C Climate Control. Vehicle build. Fleet Durability Technical Quality Auditor. Automotive Technical Writer 1985 300SD 1983 300D 1984 190D 2003 Volvo V70 2002 Honda Civic https://www.boldegoist.com/ |
#3
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The diff should have the ratio stamped in the case, to left and below the cover, looking at it from the rear. A '84 300D turbo should have the 3.06, the 3.46 came in the non-turbo versions.
I just pulled a 2.88 from an '85 300D at a local u-pull-it, for $60 including the axle shafts. That is the way to go instead of ordering new parts and having the unit rebuilt, IMHO. Properly maintained, a used unit should last a good long while. How much are you quoted to price new gears and have them installed?
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'83 240D with 617.952 and 2.88 '01 VW Beetle TDI '05 Jeep Liberty CRD '89 Toyota 4x4, needs 2L-T '78 280Z with L28ET - 12.86@110 Oil Burner Kartel #35 http://i16.photobucket.com/albums/b1...oD/bioclip.jpg |
#4
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Rear gear ratio's listed in 123 cars by service manual 1985 are: 3:58, 2:47, 2:24, 3.69, 3:92, 3:46 and 3:07.
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'10 Chrysler T&C Stow-N-Go White. Grandpa's ride. '13 Chrysler 200 Touring Candy Red. Grandma's ride. Age and cunning will always over come youth and vigor. |
#5
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diff replacement
i replaced mine over 2 years ago with a used diff with 132k on it that was pulled out of an '81 300D.still going strong and running like a scalded dog
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1984 300D Turbo - 231k....totalled 11/30/07 RIP |
#6
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I have the 1985 Turbo Diesel brochure from Mercedes and it state a 2.88:1 rear gear ratio for the complete line-up.
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Adam Lumsden (83) 300D Vice-President of the MBCA International Stars Section |
#7
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Quote:
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__________________
'10 Chrysler T&C Stow-N-Go White. Grandpa's ride. '13 Chrysler 200 Touring Candy Red. Grandma's ride. Age and cunning will always over come youth and vigor. |
#8
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rear diff
A new ring and pinion would be $600 from the dealer. my friend that runs a shop said that we would install it together, no charge.
also if I go by the way of a used diff from an 1985, do I also have to swap the speedo drive at the transmission? I would think so since it would keep everything in calibrated as it was before. thanks for your help guys |
#9
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Quote:
Or, you could just have a few speeds checked against a car you trust.
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Tony from West Oz. Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine. Josephine '82 300D 390kkm White/Palamino int. Elizabeth '81 280E, sporting a '79 300D engine. Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior Various parts cars including 280E, 230C & 300D in various states of disassembly. |
#10
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gps?
you could use a dash- mounted GPS to get the most accurate MPH times, then mark off your speedo. Not the best looking result, but at least you have accuracy in your favor.
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Gil 2004 ML350 1984 300CD; Ivory (sold) |
#11
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diff woes
first, the diffs are notoriously noisy according to the mb buyers guide. personally i dont think so. are you sure yours is unusually noisy? these diffs are extremely durable.
if you take the decision to change it note that the 2.88 diffs from 85 and up are matched with an electronic speedo gizmo and wont work in your 84. a 380 gas car comes with a 2.65 i think and they have the mechanical speedo that will work for your car. this will give mileage improvments and less engine noise at road speed but will make your takeoff more doggy. lots of recent posts regarding these subjects.
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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. ![]() ..I also have a 427 Cobra replica with an aluminum chassis. |
#12
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I believe dieselnut was considering swappin a diff into a 300D. 1985 300D speedometers are conventional meaning a diff from an 85 will work all the way down to a 79, further back perhaps.
I have them in my 123's. I love that 2.88 diff! They are NOT noisy! Definitely worth looking for one if you have a turbo engine that is strong. The SD is another story though but I thought the thread was about a 300D?
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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting! |
#13
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Quote:
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
#14
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diffs
first i have been lead to believe that the 85 has the electronic gizmo for the speedo. is this wrong?
second, what 123 body cars have a 2.47 and 2.25 ratio? i would have thought that those were ratios for the s class. with v8's.
__________________
[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. ![]() ..I also have a 427 Cobra replica with an aluminum chassis. |
#15
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Quote:
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Never a dull moment at Berry Hill Farm. |
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