3.69 vs. 3.08 vs. 2.88 - Page 3 - PeachParts Mercedes-Benz Forum

ConnClark · #31 02-19-2008, 02:09 PM

If you can put a 190D 5 speed in a 300SD could you put the same 5 speed in a 240D?

I wonder if that would be a better solution for you rather than playing with the rear end.

winmutt · #32 02-19-2008, 02:13 PM

You cant put a 190d 5speed on a 617

GREASY_BEAST · #33 02-19-2008, 02:28 PM

Quote:

Originally Posted by lkchris

Personally, I'd doubt it could ever get to the same top speed as before.

It will take the same amount of power to do the same amount of work, but once the transmission shifts to high, it's all up to the engine--which, running at lower rpm won't be producing the same power.

It's 100% all-the-time FOLLY to try to second-guess the engineers that designed the car.

I certainly have not found this to be the case... My 300TD with intercooler, adjusted/altered injector pump, upgraded injectors, non-stock timing, 2.47 vs 3.07 rear end, upgraded front suspension components, among other things, is a far better vehicle in nearly every respect than the original car... It is faster, smoother, quieter, and more efficient, while maintaining the same level of reliability. Just because they are "engineers" doesn't mean they designed a perfect car. They designed vehicles that did well with a 55mph speed limit. For an 80-90mph practical car you need to alter the gearing. Mine does quite nicely at about 90mph.. smooth, quiet, about 3200rpm.

With the 240D you are strapped for power, so going to a taller rear is probably going to hurt your top speed and decimate your acceleration. As stated before, you might realize some microscopic gains by switching to a 3.46 (and maybe even measurable gains with a manual 4 speed or better yet finding a 5spd trans, but not from a 190D), however, if you really want to get good mileage, you should look into modifying the aerodynamics of your car. Thats why you need horsepower. Making less HP = burning less fuel = better fuel economy. If you reduce your need to make HP at speed, you save fuel.

Hatterasguy · #34 02-19-2008, 03:24 PM

If you want more speed out of a 240D your best bet is to buy a turbo charged 300D. Same car, twice the HP.

ConnClark · #35 02-19-2008, 03:32 PM

Quote:

Originally Posted by winmutt

You cant put a 190d 5speed on a 617

I stand corrected. I must have been thinking of some one that had an SDL that did the conversion then.

Any way you should be able to put a 300D euro 5 speed into a 240D then.

#36 02-19-2008, 03:39 PM

I don't really see the point of a 5-speed either. It would be useless on anything other than perfectly level ground and it probably wouldn't increase the top speed anyway. If you are driving on the highways, a 240D isn't the best car to buy.

ConnClark · #37 02-19-2008, 04:10 PM

Originally this thread was about improving mileage of a 240D and not increasing its top speed. A 5 speed might improve mileage.

Mark DiSilvestro · #38 02-19-2008, 04:18 PM

I originally bought the manual-shift 240D as a parts-car, because I was considering converting my nicer-looking automatic 240D to a manual. Also my automatic 240D was experiencing low oil-pressure problems, so I was considering swapping engines as well. However the automatic car's oil-pressure problem seems to have subsided, and the 4-speed car runs so well that I decided to go ahead and repair it's floors and keep it as a second car at my parents home in Virginia Beach.
As for swapping the rear-end, it would be a relatively easy change. I actually have a spare 240D manual tranny, but a conversion would still be a major project, requiring a donor-car to supply flywheel, driveshaft, shifter, clutch hydraulics and pedal assembly, with all the extra labor. And If I decided the 2.46 rear wasn't up to my expectations, it would be relatively easy to change back. Besides, If I get the 300D parts-car for free, there's the potential to upgrade engines and make mine a 240D-3.0, while retaining the manual heat/AC which was one of the things that drew me to the 240D in the first placce.

Happy Motoring, Mark

#39 02-19-2008, 04:22 PM

Quote:

Originally Posted by ConnClark

Originally this thread was about improving mileage of a 240D and not increasing its top speed. A 5 speed might improve mileage.

Maybe, on the occasions when you could actually use 5th gear (downhill?). I seriously doubt there would be a reasonable payback time for the project if you were just looking for a couple of mpg.

winmutt · #40 02-19-2008, 05:32 PM

Quote:

Originally Posted by Craig

I don't really see the point of a 5-speed either. It would be useless on anything other than perfectly level ground and it probably wouldn't increase the top speed anyway.

MB seems to disagree since *most* 5speed cars I have seen are 240D and not 300Ds.

#41 02-19-2008, 05:34 PM

Quote:

Originally Posted by winmutt

MB seems to disagree since *most* 5speed cars I have seen are 240D and not 300Ds.

how much of an overdrive do they put in a 240D?

t walgamuth · #42 02-19-2008, 05:54 PM

I have a german language owners manual that came with my euro 300d that I parted out. It shows the five speed as an option in the 240d. Remember the euro 240s have a little more power and are lighter. I believe the five speed is the same in all 123s in which case it has a 17 or 18% OD ratio. I believe that you would be fine on level ground in a 240 with the od and even probably on a small hill but on a bit more you would have to go to fourth.....no problemo in my mind.

Tom W

winmutt · #43 02-19-2008, 05:57 PM

Ya OD is ~.83 iirc

Still wish I had one in my car

#44 02-19-2008, 06:01 PM

Quote:

Originally Posted by t walgamuth

I have a german language owners manual that came with my euro 300d that I parted out. It shows the five speed as an option in the 240d. Remember the euro 240s have a little more power and are lighter. I believe the five speed is the same in all 123s in which case it has a 17 or 18% OD ratio. I believe that you would be fine on level ground in a 240 with the od and even probably on a small hill but on a bit more you would have to go to fourth.....no problemo in my mind.

Tom W

So, that would be the equivalent of about a 3.15 ratio. That might work on level ground, but it seems like you would only gain about 2-4 mpg when in 5th. I can't imagine the average would be more than 1-2 mpg for most people, it hardly seems worth the trouble/expense (until the cost of diesel hits about $10/gallon).

t walgamuth · #45 02-19-2008, 06:03 PM

Quote:

Originally Posted by Craig

So, that would be the equivalent of about a 3.15 ratio. That might work on level ground, but it seems like you would only gain about 2-4 mpg when in 5th. I can't imagine the average would be more than 1-2 mpg for most people, it hardly seems worth the trouble/expense (until the cost of diesel hits about $10/gallon).

It might be hard to justify in dollars and cents but the lessened wear and noise would be good too. And the value of the car would be increased as well.

Tom W