Swapping out rear end - PeachParts Mercedes-Benz Forum

cmac2012 · #1 04-14-2005, 11:51 PM

I have an ’81 300 SD and I’m pretty certain my rear end is in need of help, my car’s rear end that is. Mine is serviceable. This is a recent acquisition and I know very little of this rig’s history, but I think it was rode hard and put away wet more than once. But, the body is nice and the engine is sound enough, so…

I found an ’85 380 SE at the local pick ‘n pull and the rear axle looks just like mine and sounds a lot tighter when you rock the wheels back and forth plus the bearings sound better than mine. My question is, is this the same part exactly? Or is the ratio different and other things different as well? I remember the old network style wrecking yards had big reference books spelling that sort of thing out but I haven’t seen that lately. Anybody know?

whunter · #2 04-15-2005, 12:05 AM

Two ways to tell.
#1. Gear ratio stamp, I think the 380SE had a higher gear than the 300SD.
#2. It is a part question, you could call and ask Phil, worst case he says it is a technical support question.

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Brian Carlton · #3 04-15-2005, 12:15 AM

The 300 SD has a 3.07:1 diff.

The 380 SE has a 2.47:1 diff.

There are a couple of threads that tell the story of putting a 2.47 into a 617 powered W126. Generally, the two members that did it were quite satisfied with the end result. The engine runs much slower and quieter on the highway. However, you do give up some acceleration potential in the city with the taller ratio.

pawoSD · #4 04-15-2005, 12:20 AM

I'd like to put a 2.47 diff in mine once my cv boots are toast, I'll have a whole rear end swap done. For now time only tells when those boots will finally give way and tear....they're in pretty bad shape.

veg_burner · #5 04-15-2005, 12:54 AM

hi carl!

ran a search for 2.47
click here:http://www.peachparts.com/shopforum/search.php?searchid=273323
the first post of the first thread is pretty detailed.
told ya these guys are awesome and would point you in the right direction!

see ya!

veg_burner · #6 04-15-2005, 12:59 AM

BTW, i saw an 82 SD at dorris today, fairly fresh....
the 2.47 might be more than you want to bite off considering you have to deal with the speedo etc.

cmac2012 · #7 04-15-2005, 01:29 AM

Yo Jeff!

Yeah thanks. I did a search for that topic also after reading Brian's post and it is an interesting story. I have mixed feelings. I'm kinda tempted to try it but I'd hate to lose off the line power and I feel pretty good about my cruising speed capability as it is. If my engine were a little younger and stronger it would be a better adventure to undertake.

Thanks for the Dorris tip. I was going to going to go down to the Winton Ave. 'Pull yer, pick yer, aw just take yer part' operation and see what they have so I'll drop in on Dorris as well.

Have you ever checked out E & J also way out on Winton? They're quite the old school operation. It's a bit refreshing after dealing with the low budget, low common demominator Pick 'n Pull, but their stuff is not rotated all that much it seems. I did find a great seat there, however.

Carl

veg_burner · #8 04-15-2005, 02:57 AM

up late...
went to pickyerpart today on my alda hunt; nothing to speak of in the way of mbz's. a few older 78-79s. there was a bunch last time i was there.
no, i'll have to check out e&j. have to go back out tomorrow to try & find a good alda. mine's not holding pressure = no fuel enrichment at boost

dieselgeek · #9 04-15-2005, 08:38 AM

Quote:

Originally Posted by Brian Carlton

The 300 SD has a 3.07:1 diff.

The 380 SE has a 2.47:1 diff.

There are a couple of threads that tell the story of putting a 2.47 into a 617 powered W126. Generally, the two members that did it were quite satisfied with the end result. The engine runs much slower and quieter on the highway. However, you do give up some acceleration potential in the city with the taller ratio.

You MIGHT give up a hair of acceleration potential but my butt dyno says its no slower. Sure is a LOT more pleasant to drive. Operating a diesel engine at or near its torque peak will yield better mileage.

Jim

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