2.47:1 or 2.88:1 Axle for 116.120: - Page 14 - PeachParts Mercedes-Benz Forum

Squiggle Dog · #**196** 06-06-2013, 07:37 PM

Thanks for the information. I think all of my questions are answered, short of if a W123 or R107 would have a 210mm axle.

Doktor Bert · #**197** 06-06-2013, 07:43 PM

Yes, the R-107's did have the 210mm axle and I am told there is some interchangeability between the R107 and W126.

The interchange manual lists the following:

Mercedes Models - Differential 3.47:1 ratio - 210mm:

MERCE SL (R107) 300 SL (107.041) 09.1985 -08.1989
MERCE SL (R107) 300 SL (107.041) 09.1985 -08.1989
MERCE S-CLASS (W126) 260 SE (126.020) 09.1985 -06.1991
MERCE S-CLASS (W126) 260 SE (126.020) 09.1985 -06.1991
MERCE S-CLASS (W126) 300 SE,SEL (126.024, 126.025) 01.1986 -06.1991
MERCE S-CLASS (W126) 300 SE,SEL (126.024, 126.025) 09.1985 -12.1989

Ratio choices in the R107 1st generation are limited....

R107
1st Generation mounting
1972-1980, 350 SL/SLC, M116, 3.46, 1.1 Liter, 185mm
1973-1980, 450 SL/SLC, M117, 2.65 / 3.06, 1.3 Liter, 210mm
1981-1985, 380 SL, M116, 2.47, 1.3 Liter, 210mm
1981-1982, 380SLC, M116, 2.47, 1.3 Liter , 210mm

Squiggle Dog · #**198** 06-06-2013, 07:48 PM

Quote:

Originally Posted by Doktor Bert

FYI, I am told by many that 2.65:1 or 2.88:1 is preferable in a W116 diesel and I would have to agree....

So, it looks like if I went with a 2.88:1 differential, I would be forced to use homokinetic axles since they all seem to be 185mm. Finding a limited slip 2.88:1 might be difficult, if they were even made--though I could probably add the LSD components if I was willing to reset the preload.

I had not heard of the 2.65:1 before. Hmmm... I better do some research to make sure I get the ideal gear ratios.

I don't want my 300SD to lose any acceleration, though I do plan to advance the camshaft and injection pump timing, and increase the turbo boost. I already have the ALDA screw backed off all the way and have the 05 camshaft, so hopefully I'll have plenty of power.

dieseldiehard · #**199** 06-06-2013, 07:49 PM

Quote:

Originally Posted by Squiggle Dog

Cool. I will be looking for an '81-'85 W126 with a 2.47:1 gear ratio and LS (good luck, I know). Apparently the LSDs should have a "spezial" tag on them and rotating one wheel should make the other rotate in the same direction. I will also have to figure out how to make my W116 speedometer work with the new rear differential. I'll use my old W116 yoke.

I wonder if maybe W123 or R107 differentials will fit, though I saw a 1984 or 85 W123 at the wrecking yard that had homokinetic axles and didn't have the bolt-on seal cover plates on the side. I will also have to find out if LSD parts from a different gear ratio will fit a non-LSD differential to make it LSD.

I would check out the 450SEL W116 differential, some were LS. And should fit your chassis no problem. I do not know the ratio however.
Search for the topic 6.9 differential

Doktor Bert · #**200** 06-06-2013, 07:51 PM

Quote:

Originally Posted by Squiggle Dog

I don't want my 300SD to lose any acceleration, though I do plan to advance the camshaft and injection pump timing, and increase the turbo boost. I already have the ALDA screw backed off all the way and have the 05 camshaft, so hopefully I'll have plenty of power.

I'm running 10 psi at part-throttle and 14.7 psi on the wastegate with pump and cam advance. I did lose some takeoff power with the 2.47:1 axle, but for me, driving 1,200 miles a week, I feel it was worth it.

My 1978 300SD got 30 mpg if I drove 55-60 religiously. Now, with the 2.47:1 axle, I get 30 mpg driving 75-80 mph, so it was a good swap....but you won't beat any Smart cars off the line.

Doktor Bert · #**201** 06-06-2013, 07:53 PM

Quote:

Originally Posted by dieseldiehard

I would check out the 450SEL W116 differential, some were LS. And should fit your chassis no problem. I do not know the ratio however. Search for the topic 6.9 differential

Behold, he who searcheth!!!!

W116
1973–1980, 280S, M110, 3.69, 1.1 Liter, 185mm
1973–1980, 280SE, M110, 3.69, 1.1 Liter, 185mm
1974–1980, 280SEL, M110, 3.69, 1.1 Liter, 185mm
1973–1980, 350SE, M116, 3.46, 1.1 Liter, 185mm
1973–1980, 350SEL, M116, 3.46, 1.1 Liter, 185mm
1973–1980, 450SE, M117, 3.06 / 3.07, 1.3 Liter, 210mm
1973–1980, 450SEL, M117, 2.65 / 3.06 / 3.07, 1.3 Liter, 210mm
1975–1980, 450SEL 6.9, M100, 2.65 LSD, 1.3 Liter, 210mm
1978–1980, 300SD, OM617.950, 3.07, 1.1 Liter, 185mm

2.88's are a one-year ONLY item in the W126 IIRC....some W123's had 2.88's.

W123

1985, 300TD, OM617.952, 2.88, 1.1 Liter, 185mm
1985, 300D, OM617.952, 2.88, 1.1 Liter, 185mm
1985, 300CD, OM617.952, 2.88, 1.1 Liter, 185mm

Squiggle Dog · #**202** 06-06-2013, 07:59 PM

Wow! So... a 450SE/SEL/6.9 has a 210mm differential and could possibly have a 2.65 ratio. A 6.9 would most likely have limited slip. Darn, there were a couple of 6.9s in the wrecking yard back in Washington. I guess I should check the 450SEL in the local yard to see what it has. I'll need to remember to get the speedometer as well.

LOL@3.06 and 3.07 ratios... not much difference between the two, is there? Hmm... I should see if the 300D at the wrecking yard has a 2.88:1... I think it may be a 1985... it has the Cali-spec air cleaner, and trap oxidizer, anyway.

dieseldiehard · #**203** 06-06-2013, 10:19 PM

Quote:

Originally Posted by Squiggle Dog

Wow! So... a 450SE/SEL/6.9 has a 210mm differential and could possibly have a 2.65 ratio. A 6.9 would most likely have limited slip. Darn, there were a couple of 6.9s in the wrecking yard back in Washington. I guess I should check the 450SEL in the local yard to see what it has. I'll need to remember to get the speedometer as well.

LOL@3.06 and 3.07 ratios... not much difference between the two, is there? Hmm... I should see if the 300D at the wrecking yard has a 2.88:1... I think it may be a 1985... it has the Cali-spec air cleaner, and trap oxidizer, anyway.

My '83 300D was changed to a 2.88 pumpkin obtained from a 1985 300D.
That was the absoloute best thing I ever did to the car. It ran faster, I was worried about less offline acceleration but that didn't occur. Fuel economy improved measurably and it was smoother running on the road.

If you find a 6.9 with the LS differential in it then do whatever you can to grab it, thats a rare one! and two would be an even greater find.

Doktor Bert · #**204** 06-10-2013, 12:33 PM

6.9 anything is scarce....

Stretch · #**205** 06-10-2013, 12:43 PM

As you're talking about LSD - perhaps this is something for you?

Fancy some LSD for your diesel?

Squiggle Dog · #**206** 06-10-2013, 12:51 PM

It would be a good joke to paint an LSD housing in several different colors.

Doktor Bert · #**207** 06-10-2013, 01:15 PM

My suspected 2.65 R107 odometer reads 78 miles on a known 98 mile trip.

I wonder if a ratio adapter can be installed at the transmission to keep from continuously removing the cluster????

Squiggle Dog · #**208** 06-10-2013, 04:14 PM

Quote:

Originally Posted by Doktor Bert

I wonder if a ratio adapter can be installed at the transmission to keep from continuously removing the cluster????

If you decide to use a ratio adapter and can only find the type with two male ends, you can also use an early W116 (I don't know the cutoff year) speedometer cable, because it is two pieces with the Ford cruise control adapter in the center. You could remove the cruise control adapter and put a ratio adapter in its place.

Doktor Bert · #**209** 06-10-2013, 04:47 PM

Quote:

Originally Posted by Squiggle Dog

If you decide to use a ratio adapter and can only find the type with two male ends, you can also use an early W116 (I don't know the cutoff year) speedometer cable, because it is two pieces with the Ford cruise control adapter in the center. You could remove the cruise control adapter and put a ratio adapter in its place.

Good idea...

My 1978 W116 has a long, one-piece cable with a Bosch cruise servo.

Here are my GPS readings:

INDICATED 30 MPH – ACTUAL 33.5 MPH

INDICATED 40 MPH – ACTUAL 46.5 MPH