Will a w123 diff fit a w115? - PeachParts Mercedes-Benz Forum

bgk202 · #1 01-04-2010, 02:47 PM

Hello - Ive got a 1975 300d and would like to put a 3.07 diff out of a w123 turbodiesel in for better highway fuel economy. Do you know if this will fit?

diametricalbenz · #2 01-04-2010, 05:03 PM

I am interested to know if and how it fits too.

DeliveryValve · #3 01-04-2010, 05:14 PM

Yes it will fit. You might have to change out the input flange though.

.

79Mercy · #4 01-04-2010, 05:25 PM

Like he said, it will fit but beware the 3.07 will really slow down the acceleration.

diametricalbenz · #5 01-04-2010, 05:34 PM

I wonder how much real world difference it would make since the transmission is a non lockup torque converter. It would in theory allow more top speed. Theoretically 105mph at 4285rpm...

79Mercy · #6 01-04-2010, 05:36 PM

I guess we'll have to wait for BGK202 to do the swap.

0-60 stock is 24 seconds, thats pretty slow, I personally wouldn't want to slow it down much more.

t walgamuth · #7 01-04-2010, 07:05 PM

I am running a 307 in my 83 240/300d. It has a newish euro na engine backed by a five speed od tranny. I could pull another gear with maybe 8% od I believe. It will still accelerate in od without downshifting.

wolf_walker · #8 01-04-2010, 07:49 PM

Quote:

Originally Posted by 79Mercy

0-60 stock is 24 seconds, thats pretty slow,

I thought my old vw diesels were slow, sheesh.

79Mercy · #9 01-04-2010, 07:52 PM

haha, my injection timing is also a bit off, so i'll see if I can improve that.

0-50 is pretty decent, 50-60 takes a while

thebenzbar · #10 01-04-2010, 09:03 PM

Quote:

Originally Posted by 79Mercy

0-60 stock is 24 seconds, thats pretty slow, I personally wouldn't want to slow it down much more.

Quote:

Originally Posted by wolf_walker

I thought my old vw diesels were slow, sheesh.

Quote:

Originally Posted by 79Mercy

haha, my injection timing is also a bit off, so i'll see if I can improve that.
0-50 is pretty decent, 50-60 takes a while

Factory specs designate 0-100 km/hr (which is 0-62 mph) acceleration is 20.6 seconds for your specific model.
Something is definitely wrong there Stewie, maybe it's more than timing... but hopefully not.

wolf_walker · #11 01-04-2010, 09:10 PM

You know, in VW circles, there is 20hp in pump tuning to be had without dramatic losses in MPG. Anyone ever pursued this with these?

79Mercy · #12 01-04-2010, 09:13 PM

I don't think there is much you can do with these US pumps. Although there are mods you can do to the Euro version injection pumps, they're called M-pumps.

diametricalbenz · #13 01-04-2010, 09:37 PM

Quote:

Originally Posted by t walgamuth

I am running a 307 in my 83 240/300d. It has a newish euro na engine backed by a five speed od tranny. I could pull another gear with maybe 8% od I believe. It will still accelerate in od without downshifting.

Is that the Getrag or did you mate up a different transmission?

I presume you mean accelerate without downshifting on a level grade?

bgk202 · #14 01-04-2010, 10:00 PM

Quote:

Originally Posted by DeliveryValve

Yes it will fit. You might have to change out the input flange though.

.

Any differences besides the possible input flange? Do they have the same housings /and or mount up the same way?

bgk202 · #15 01-04-2010, 10:03 PM

Quote:

Originally Posted by 79Mercy

I don't think there is much you can do with these US pumps. Although there are mods you can do to the Euro version injection pumps, they're called M-pumps.

What does a M-pump look like? Did the early non-turbo 617 engines (like the w115 300D) use M-pumps in American models?