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  #1  
Old 10-15-2011, 11:08 PM
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has anyone tried.A 3,69 gear in a 83 300D?

I have a rearend out of a 82 240D..of a change the.speedo head also from the 240D.the.odometer and speedo.should be dead.on....right.? I know i will.lose.mpg but i will be pulling a a 5 by 14.tralier at times.
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  #2  
Old 10-16-2011, 12:03 AM
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A 240D Differential will fit into a 300D. you are correct, use the spedo from the 240D in the 300D, they are geared together.

Charlie
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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/automatic transmissions)




Anyone that thinks a 240D is slow drives too fast.

84 300SD 270K
85 300D 360K
82 Datsun Kingcab Diesel 483k
83 Nissan long bed Diesel 134K
80 240D Naturally Exasperated, 370k
78 240D $300
86 Ford 6.9 195K
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  #3  
Old 10-16-2011, 01:02 AM
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Im not sure.how many mpgs.i will lose?
I got 3.07s.Now..alao i got.a.85.300D rearend wit gears with the odometer to go with it to go for most mpgs possible.but.that rearend makes.noise.
I just got.new.axles.last week..since im a.mb tech.it.wont take no time do numerous swaps
di you think.the.3,69 gear will make it get out the hole quicker ? Or.turbo.spool up faster?

Anyone ever done.this.before.

Right now.the.way it.now.with.it.filled.to rim of the.fuel neck i got 22.5.mpg..that was alsl.woth.a.stuck.right.front.brake.calobers.sticking on the.way home backfrom work it.wwas low.on power.then noticed smoke.coming.from the.right.front.wheel.so hoping.i.will.get more now.
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  #4  
Old 10-16-2011, 03:36 AM
pawoSD's Avatar
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It will be quite a bit quicker on acceleration, and have better towing ability, but its going to not be very comfortable much over 65mph.......mega rpms. Like a truck....
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'82 300SD 322k -mine (OC-323,450) -for sale!
'89 420SEL 152k - mine (OC-158,000)
'93 190D 2.2 - 210k - mine (OC-213,000)
'05 C240 4matic Wagon - 136k - wifes (OC-139,500)
'82 300SD 342k -dad's (OC-346,300)
'87 420SEL - 311k - dad's - (OC-314,550) -for sale
'01 E320 - 131k - dad's (OC-133,700)
'02 E320 - 156k - brother's (OC - 157,730)
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  #5  
Old 10-16-2011, 04:01 AM
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Quote:
Originally Posted by pawoSD View Post
It will be quite a bit quicker on acceleration, and have better towing ability, but its going to not be very comfortable much over 65mph.......mega rpms. Like a truck....
My truck.without.the.tralier.on it gets 6.2 mpg.on interstate at.steady 70mph gets only 10.5 mpg..with.408W With.3.27s.
Iam going.to take ins off the.truck..amd have ths.300D for towing lawn stuff.
i burn 4.5 gals in my.truck with trailer thats less than 5mpg.

Im.going.to drive.it tbe.300d with full tank.to the.rim..with.the.307s and see how many mpg i get..round.trip to wprk and back is.28/30miles
i hope i can go 25plus days


My.91.560sel i get 12.5 mpg thays 9.5.days before.filling up.with.266 milea on the trip tick.not.thaT good...hiway i only get 17.5.mpg.
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  #6  
Old 10-16-2011, 06:59 AM
t walgamuth's Avatar
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Quote:
Originally Posted by partsman225 View Post
My truck.without.the.tralier.on it gets 6.2 mpg.on interstate at.steady 70mph gets only 10.5 mpg..with.408W With.3.27s.
Iam going.to take ins off the.truck..amd have ths.300D for towing lawn stuff.
i burn 4.5 gals in my.truck with trailer thats less than 5mpg.

Im.going.to drive.it tbe.300d with full tank.to the.rim..with.the.307s and see how many mpg i get..round.trip to wprk and back is.28/30miles
i hope i can go 25plus days


My.91.560sel i get 12.5 mpg thays 9.5.days before.filling up.with.266 milea on the trip tick.not.thaT good...hiway i only get 17.5.mpg.
Wow, I rarely comment on typing but your post is really distracting. Let me guess, did you send it from a phone?

As for the mileage with a 369 vs a 307 the mileage difference will be very significant. Your engine will turn over about 23% more often at highway speeds so you can count on spending about 23% more on fuel. So if your car gets 23 mpg with the stock rear end you will be lucky to get 18 with the 369 diff.

I have done a lot of experimenting with changing rear ends for improving fuel economy. Before going to the trouble of changing a diff for occasional towing, I would recommend trying it out with the stock diff and seeing how it does. You will probably need a tranny cooler if you plan to take long trips with the trailer.

Frontal area is the biggest factor in drag so if it is a tall enclosed trailer it will impact everything a lot more than a flat utility trailer.
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  #7  
Old 10-16-2011, 07:29 AM
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maybe if you put in the 3.69, and used tall tires, like 225's for economy, then switched to the 195's for towing, it would not be as bad. aspect ratio for tallest, on the road. the problem would be knowing your velocity, as the tires would throw off the speedo's ratio...
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  #8  
Old 10-16-2011, 07:55 AM
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Maybe try the stock diff first. Even if it is a bit noisy, it will let you see what it is like with the load behind. Unless you are working in the hills the standard ratio should be fine.
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1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
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  #9  
Old 10-16-2011, 08:17 AM
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I really do no t think you will see a 23 % decline in fuel mileage. Some yes, but you may get better fuel mileage when towing. Nothing worse then lugging an engine for fuel mileage.My 47dodge had a 3.73 rear. I changed to a 4.10 rear fuel mileage when towing went up about 1, and not towing did not hurt it any. I think the big cam pushed the happy rpm range of the engine up, and running were it is happy makes a lot of differance. Do also remember that it takes "X" amount of power to move the car no matter the gear ratio. So the only losses can from engine losses of spinning it faster.

Now having sais all that, I do agree with others you should try it stock first and see how it does. My 300 has the 2.88 rear and I have towed boats up to about 3000lbs with no issue. I would change to the 3.06 in that car if I was towing a lot with it. So you are were i would have changed to.

Change the rear end oil, and I would use synthetic oil. Must say I have to wonder about towing all the time, it is a car, and not designed for it. A very good car, but still pushing it.Expect to do more maintenance, and do drive it reasonabily This will go a long way to keeping it in one piece. I do tow light loads with my 240, but have a truck for real towing.
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  #10  
Old 10-16-2011, 10:12 AM
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Quote:
Originally Posted by partsman225 View Post
Anyone ever done.this.before.
Yep. I run a 3.69 in my 300TD with a normally aspirated 617 and 722.3
"daily driver".

It makes it much more manageable for around city driving, with better
response "off the line". Much better than the 3.07.

Freeway driving is actually pretty good, although I'm running the engine
at the "top of the pump" at 73mph. Foot to the floor, more or less.
Last year, I went to WI->ME->WI -- almost without lifting my foot.

I wear hearing protection for freeway trips. But I really like how it changes
the torque curve for everyday AND freeway use.

I get 24mpg on the highway, and about the same in the city.

One issue: when running full on, 73mph, the breather tends to get over-pressured and spill oil onto the hot exhaust manifold. I can smell it.
Its a side effect of running ~4Krpms+ for hours.
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.......... ............ ......................

Last edited by franklynb; 10-16-2011 at 10:15 AM. Reason: added "breather" thought.
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  #11  
Old 10-16-2011, 10:20 AM
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Quote:
Originally Posted by franklynb View Post
Yep. I run a 3.69 in my 300TD with a normally aspirated 617 and 722.3
"daily driver".

It makes it much more manageable for around city driving, with better
response "off the line". Much better than the 3.07.

Freeway driving is actually pretty good, although I'm running the engine
at the "top of the pump" at 73mph. Foot to the floor, more or less.
Last year, I went to WI->ME->WI -- almost without lifting my foot.

I wear hearing protection for freeway trips. But I really like how it changes
the torque curve for everyday AND freeway use.

I get 24mpg on the highway, and about the same in the city.

One issue: when running full on, 73mph, the breather tends to get over-pressured and spill oil onto the hot exhaust manifold. I can smell it.
Its a side effect of running ~4Krpms+ for hours.
Its 2011.....hearing protection should not be needed to drive on the highway!
__________________
-diesel is not just a fuel, its a way of life-
'82 300SD 322k -mine (OC-323,450) -for sale!
'89 420SEL 152k - mine (OC-158,000)
'93 190D 2.2 - 210k - mine (OC-213,000)
'05 C240 4matic Wagon - 136k - wifes (OC-139,500)
'82 300SD 342k -dad's (OC-346,300)
'87 420SEL - 311k - dad's - (OC-314,550) -for sale
'01 E320 - 131k - dad's (OC-133,700)
'02 E320 - 156k - brother's (OC - 157,730)
'12 VW Jetta - 14k - Sisters (has begun falling apart)
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  #12  
Old 10-16-2011, 10:35 AM
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Quote:
Originally Posted by franklynb View Post
Its a side effect of running ~4Krpms+ for hours.
The second side affect is your brain turning to jelly...............
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  #13  
Old 10-16-2011, 11:07 AM
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Im going to run the stock 307 on this tank full just to work and back get avg mpg then swap over.to tbe 369. It dont tske me long to do 2hrs max. Will report back with resultand rpms at say 70 mph also..thanis 195/70/14 the right size tire?
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  #14  
Old 10-16-2011, 11:17 AM
t walgamuth's Avatar
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I get 24mpg on the highway, and about the same in the city.

Whenever I see or hear folks making statements like this I always think they don't know how to check their fuel economy accurately.

I have owned over 100 cars. I always check the fuel economy using the proven methods of getting accurate calculations. I have never had a vehicle which got the same fuel economy around town as on the highway, nor have I ever had a tow vehicle which got the same fuel economy towing as driving without the trailer.

I have changed differentials and gear ratios on at least a half dozen vehicles and through the years. Putting in a taller differential has never failed to give better fuel economy. On my diesels it is pretty much equal to the difference in gear ratios, on gas engines it is not as strong a relationship.

People say that it takes the same energy to run the car through the air and down the highway no matter what rpm the engine is turning. That is true but no engine is equally effecient under all rpm and load conditions. One day with our computers and so forth this may become true, but it is not true yet.

In recent years multiple gear ratios in cars have gone through the roof. the newer benzes are running (what is it?) Seven speed automatics now? The additional ratio choices makes it much easier to achieve both good acceleration and good fuel economy.

If it were true that a car uses the same amount of fuel no matter what rpm the engine turns simply because it only takes X amount of energy to go X miles per hour all cars could simply have one gear and the ratio would not matter much.
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  #15  
Old 10-16-2011, 11:36 AM
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Im going to do.a.perf.check with my.vericom perf computer on both ratios also
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Old 10-16-2011, 11:36 AM
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