3.69 differential trade anyone? - PeachParts Mercedes-Benz Forum

rudolfgreen · #1 10-01-2006, 10:34 AM

have the 3.69 in the back of the 4spd 240d, and would like to swap in a 3.07 from a turbo slushbox for better highway driving.
looking for someone with a *good* well maintained 3.07 to trade pumpkins, that wants to smoke the tires around town with their 617.
would consider a slightly higher ratio swap (ie. non-turbo automatics), but prefer the 3.07. thanks.

Brian Carlton · #2 10-01-2006, 10:40 AM

I've got a 3.07 with a touch of pinion whine.

But, you won't beat the price.

And, if you meet me in CT, you can save the shipping as well.

Alastair · #3 10-01-2006, 10:49 AM

Anyone know of a list of the different ratio diffs that the W123 range used?

t walgamuth · #4 10-01-2006, 11:52 AM

i would advise strongly against a 307 in a 240. i would recommend if you want to swap the rear, to stick to the next higher ratio, which i think will be either a 354 or a 346.

the 346 was used in na 300ds.

i happen to have one that i can spare. actually i think i have one of each. the 354 being from a 280e. and i can spare that as well. if you have interest in either of them please pm me.

tom w

#5 10-01-2006, 02:13 PM

A 3.07 would be painfully slow in a 240D and you will wear out the clutch alot sooner from having to slip more at takeoff.

dieseldiehard · #6 10-01-2006, 02:31 PM

Now if it was the 240D that my friend owned with a 300D NA engine installed, the 3.07 would be perfect. I donated the diff from my '83 300D when I went to a 2.82 and my friend put it in his modified 240D (stick shift). It's like what the factory should have supplied to MBNA. It went like a dream on the road at 65 MPH it didn't sound like the engine was about to come apart and there was still a little headroom to pass (with the wind to your tail).
I agree that a 3.07 is not the right diff for a 240D.

engatwork · #7 10-01-2006, 02:45 PM

I've got a spare 307 that I think ya'll have about convinced me to put in my na '81 300D auto. It is currently running the 346. I just want to drop the rpm's a little on the interstate.

rudolfgreen · #8 10-01-2006, 08:21 PM

makes good sense bretheren.
you have talked me out of the 3.07; was wondering if that might be too steep.
definitely the 3.46 then, been astounded with how the 2.47 has changed the 300DT.
tom you have a pm coming. thanks guys.

t walgamuth · #9 10-01-2006, 10:59 PM

i did a 307 in my 83 240 with the euro 300d na. it was a bit too high really. if it was only me driving it it would have been fine, but my kids did too. once rolling it was just fine but we have hills here and taking off going uphill was a bit dicey. the factory 346 is what i would recommend for anyone doing a 300d turbo or na in a 240 if using a stick. with an automatic you can get away with a lot more as long as you dont mind a leisurely start from dead stop.

tom w

LUVMBDiesels · #10 10-03-2006, 08:29 AM

I have a line on a 2.45 differential from a 420SEL. I want to install it in the 300SD as I do mostly high speed highway driving and I would love to drop the RPMs at 75MPH. If I do this, would it completely kill my acceleration?

Also for you guys who have done this, what mods did you make to the electric speedometer to make it work with the new rear end?

Thanks for the help!

t walgamuth · #11 10-03-2006, 08:42 AM

it wont kill it completely but you will feel the difference. i would suggest it would be like the difference in driving alone and with four adults in the car.

the differnece on the highway will be very noticable too. fuel economy will be enhanced and engine life as well.

tom w

#12 10-03-2006, 08:47 AM

Quote:

Originally Posted by LUVMBDiesels

I have a line on a 2.45 differential from a 420SEL. I want to install it in the 300SD as I do mostly high speed highway driving and I would love to drop the RPMs at 75MPH. If I do this, would it completely kill my acceleration?

I hope you are only planning on driving on level ground. I would consider putting a 2.88 in, but I don't think I would go much taller than that.

OMEGAMAN · #13 10-03-2006, 09:32 AM

Quote:

Originally Posted by Craig

I hope you are only planning on driving on level ground. I would consider putting a 2.88 in, but I don't think I would go much taller than that.

I think he'll be just fine. Breckman did that diff swap in his SD and he lives in the mountains. Says he likes it just fine. I just drove over the divide in my car with 3.07 gears and all the way I was thinking about the 2.45 gears.

ytr1903 · #14 10-03-2006, 09:52 AM

LUVMBdiesels,

I changed out my 3.07 to a 2.47 almost two years and 25,000 miles ago. I would never go back to the 3.07. Yes, there is a slight decrease in acceleration off the line, but not so noticeable to be irritating. A very slight increase in MPG, maybe 1-2 on highway driving, but the big advantage is in the comfort level on the highway. There is a very obvious decrease in the noise level of the engine and consequently one's ability to sit behind the wheel is increased due to an enhanced comfort level. Your rpm's will decrease by around 700. Mountain areas have been no problem for the car since the change, either. One round trip through the Eisenhower Tunnel outside of Denver, three trips through the Ozarks and one through the Smokies has proven this to me.

Good luck,
Tom

#15 10-03-2006, 10:15 AM

I've thought about going to 2.88 gears, but I still like the 3.07 in this car. It runs right around 3500 rpm at 80 mph, which is perfect for cruising. The 80 to 90 mph acceleration is decent for passing because the engine is within the 3500 - 4000 range. I just don't think I would be willing to take the performance loss associated with higher gears.

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