2.47 diff in 300SD - Page 2 - PeachParts Mercedes-Benz Forum

thorsen · #16 02-17-2006, 07:54 AM

Quote:

Originally Posted by bravohotel

It is from an '86 SEC...

I don't have my list in front of me, but I'm not sure that will work. You'll be ok as long as it has the 4 mounting studs. If it has the goofy round mounting lugs I don't think it will work.

thorsen · #17 02-26-2006, 03:57 PM

I took the car out for a brief spin today, and got it up to 80mph - the engine was turning less than 3000 rpm.

thorsen · #18 04-04-2006, 09:07 PM

I have put just shy of 1,000 miles on the 2.47 diff. I've gone through two fillups since I have completed the swap, and my mileage has increased by 2 mpg over the mileage I averaged in 12,000 miles on the 3.07.

The 2.47 diff does not put you in Jetta TDI territory, but it makes the car much quieter on the highway. I used to limit my speeds to 65-70mph (about 3k rpm), but now I'm doing that around 2.5k rpm. Below 45 mph, I leave it in 3 to keep the engine from straining.

imdavid28 · #19 04-04-2006, 09:22 PM

Wow, so you have to replace the entire differential to do this? You can't do it by simply replacing the ring and pinion like a Chevy, Ford, etc...?

This only for the 126's? Can you do the same to a 123?

Hit Man X · #20 04-04-2006, 10:12 PM

It's easier to just swap the entire diff, no gears to setup.

pawoSD · #21 04-04-2006, 10:19 PM

My boots are quite cracked on my CV axels, and I was thinking of having them rebooted since they seem to be in great shape (no sounds, clunks, or anything whatsoever, even with the car weighed to the ground with stuff)

When having it rebooted etc, I would want to have a 2.47 diff put in at the same time, plus a flex disc...etc....anyways, I found this 2.47 on ebay from a 1989 420SEL, it appears to have the 4 stud mounting style needed for a 300SD, and being from an 89, I bet it has reasonably low miles on it. Even has the mount still attached to it.

This one would fit my 1982 300SD wouldn't it? I am quite confident that it would....

Hit Man X · #22 04-04-2006, 10:22 PM

What's the deal with the mounting lugs?

Brian Carlton · #23 04-04-2006, 10:22 PM

Quote:

Originally Posted by pawoSD

I found this 2.47 on ebay from a 1989 420SEL, it appears to have the 4 stud mounting style needed for a 300SD, and being from an 89, I bet it has reasonably low miles on it. Even has the mount still attached to it.

This one would fit my 1982 300SD wouldn't it? I am quite confident that it would....

The 1989 diff will not fit the earlier W126 vehicles. The diff has a completely different mounting configuraton. You must stay with vehicles that are 1985 or earlier.

pawoSD · #24 04-04-2006, 10:30 PM

Will this one work then? Its from a 1979 450SL, did they have a 2.47 also? It also has the 4 lug mounting system with bolted rear mount...just like that 1989 one does....

I found it fishy that the 1989 diff did not have the "weird" mounting configuration on the back like some of them seem to have.....maybe this was for the limited slip ones only? It really does look like it'd fit....

But if this one from the '79 would....I'd try and buy it.

Brian Carlton · #25 04-04-2006, 10:35 PM

Quote:

Originally Posted by pawoSD

Will this one work then? Its from a 1979 450SL, did they have a 2.47 also? It also has the 4 lug mounting system with bolted rear mount...just like that 1989 one does....

I found it fishy that the 1989 diff did not have the "weird" mounting configuration on the back like some of them seem to have.....maybe this was for the limited slip ones only? It really does look like it'd fit....

But if this one from the '79 would....I'd try and buy it.

The '79 is from the W116 so I can't say for certain. But, it does have the four mounting bolts in the proper position and it does have the rear mounting bolts which are identical you the earlier W126.

Don't know the ratio.

Hit Man X · #26 04-04-2006, 10:39 PM

So you have to stick with the 1st or 2nd gen W126 for the axle?

Such as my SD would need a 500SEL diff and the SDL would need one from a 420SEL?

Brian Carlton · #27 04-04-2006, 10:42 PM

Quote:

Originally Posted by Hit Man X

So you have to stick with the 1st or 2nd gen W126 for the axle?

Such as my SD would need a 500SEL diff and the SDL would need one from a 420SEL?

Yes, the mounting configurations are completely different.

The earlier W126 has the diff bolted to the differential mount and uses four nuts on the studs.

The later W126 has the subframe bolted to the differential mount and the diff has a more complicated mounting using rubber bushings on several points and some real strange hardware that you can't easily remove.

pawoSD · #28 04-04-2006, 10:46 PM

So the one from the '79 SL I showed there should work? Anyone know what ratio it is? It has the 4 studs and proper mount-bolting features....so why wouldn't it work......

t walgamuth · #29 04-04-2006, 10:54 PM

to my mercedes buyers guide the 79 450sl has a 3.07, same as your sd. and i doubt very many had positraction.

the 80 450sl shows a 2.65 ratio, which would be pretty good for you i think.

the later 380 sl has the 2.47 which is prob a lot easier to find cause lots of them were built. and 300sds and 380se and 500se and sels as well. all ran the 247 except the euros which in the sedans were 224s.

happy hunting

tom w

Hit Man X · #30 04-04-2006, 10:57 PM

Quote:

Originally Posted by Brian Carlton

Yes, the mounting configurations are completely different.

The earlier W126 has the diff bolted to the differential mount and uses four nuts on the studs.

The later W126 has the subframe bolted to the differential mount and the diff has a more complicated mounting using rubber bushings on several points and some real strange hardware that you can't easily remove.

Weird. Looks like both will be money well spent to have removed, I think I can get them between $75-100 pulled for me at the yard I spend some green at.

They do have an '86 560SEL diff in the trunk out there, I suppose that'd work for my SDL.