[W126 Coupe] Help! : diff ratio's

[Steve Nervig]

Alex, first off, let me say that I am not an MB diff expert, so  
verifying what I say would be a good thing.

My understanding is that MB has generally had two sizes of  
differential housings and gears. There is a smaller size (1.0 or 1.1  
liter oil capacity, 185 mm dia ring (crown) gear) and a larger size  
(1.3 liter oil capacity, 210 mm dia ring gear). There also appears to  
be some changes within these two categories. See Job 35-500 for some  
visual clues on differences.

My belief is that the two sizes are not interchangable as a unit in a  
particular chassis because of mounting configurations and that the  
gears are not interchangeable between housing sizes.

I've heard that the smaller size generally came on cars with less  
than 200 HP and the larger size on cars over 200 HP.

I've also been told that changing or installing a gear set in a  
housing requires a special tool jig set and can't be done properly  
without it. In the past, I've set up rear ends (non-MB) with shims  
and machinist blue, but apparently this isn't how an MB rear end is  
set up. Something about crush washers on the pinions seals. How an  
improper set up would manifest itself, I do not know. Maybe you could  
get by with it for limited racing, and the only problem would be a  
leaky pinion seal. Maybe not.

So apparently, the trick is to find a suitable donor car that has the  
same configuration housing and replacing the whole thing, without  
opening up/changing the gears.

I'm sure there is someone who can either confirm or poke holes in the  
above statements.

Regards,
Steve Nervig


On Apr 29, 2007, at 3:54 AM, Divov wrote:


> This website is just great!  Without it I would be floundering  

> around in the dark.

> Thanks to the various inputs, I have located a 3:46 diff from a 80  

> 350SE saloon and the best of it is that it is available free,  

> gratis & for nothing!!

> Now, what I am scheming is the following:

> This 3:46 diff is not LS so what if I take the 2:47 LS diff  

> available from the friendly scrap yard and strip the crown wheel &  

> pinion from the non LS 3:46 diff and fit that into the LS unit. Is  

> this do-able? Does anyone have experience of whether the crown  

> wheel & pinions are interchangeable?

> Thanks guys.

> Alec D

> ----- Original Message -----

> From: Barry Corno

> To: Mercedes Coupes Mailing Lists

> Sent: Saturday, April 28, 2007 5:45 PM

> Subject: Re: [W126 Coupe] Help! : diff ratio's

>

> From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes- 

> bounces at mbcoupes.com] On Behalf Of Divov

> Sent: Saturday, April 28, 2007 8:21 AM

> To: Mercedes Coupes Mailing Lists

> Subject: Re: [W126 Coupe] Help! : diff ratio's

>

>

>

> Thanks for that tip Barry.

>

> I take it that it is also the diff with the big square rubber  

> mounting situated aft?

>

> Its good to know that such a ratio exists but down South, SL spares  

> are pretty thin on the ground.

>

> Would the 450SL have this type of diff or is it only from the 500SL?

>

> The 450SL is an absolute dog but a friend had a late 500SL (same  

> shape as the 450) and though it was years ago,

>

> I recall the acceleration was reasonably impressive from the  

> passenger seat.

>

> Do you know if your 3.07 diff is an LS diff?

>

> AD

>

>

>

> Alex,

>

>      My 3.07 is out of a 450SEL “78”. I believe it is not LS, but  

> someone on this site would know

>

> For sure. 450 SL’s have the 3.07’s.You need to know that you will  

> be turning around 3,000 RPM’s

>

> Around 65 MPR and your speedometer will need to be re-calibrated.

>

> Gary Dempsey has put 3.07’s in his 560. What a difference in that  

> car also.

>

>

>

> B.C.

>

> ----- Original Message -----

>

> From: Barry Corno

>

> To: Mercedes Coupes Mailing Lists

>

> Sent: Saturday, April 28, 2007 4:52 PM

>

> Subject: Re: [W126 Coupe] Help! : diff ratio's

>

>

>

> From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes- 

> bounces at mbcoupes.com] On Behalf Of Steve Nervig

> Sent: Saturday, April 28, 2007 6:46 AM

> To: Mercedes Coupes Mailing Lists

> Subject: Re: [W126 Coupe] Help! : diff ratio's

>

>

>

>

>

> On Apr 28, 2007, at 5:46 AM, Divov wrote:

>

>

>

> Dawid,

>

> The 500 is really a bit of a slouch off the line. The 560 is a  

> rocket in comparison.

>

> My 500 (at highveld altitude) does about 230 kph in 3rd (at  

> 6000rpm) but max'es out at only 240 in top. At 240 it is only  

> revving around 4200...

>

> The 500 mill is free revving and goes to red line willingly (except  

> in 4th!)

>

> That 2.24 diff ratio on the 500 really really makes it an old mans  

> car. 160 kph @ 2900! - its hardly working up a sweat.

>

> Your 560 does about 7 sec  0 - 100 kph & is way, way faster. I  

> think partly from more beans & partly from

>

> better ratios.

>

> Clearly the 560 was aimed at being more sporty - and certainly is.

>

> I have only 170KW vs your 220KW. That's a serious difference... 170  

> KW moving 1600kg aint no ball of fire.

>

> Alec

>

>

>

>

>

> Alec, it seems like you would benefit from an even lower rear end  

> (higher numerically). You mentioned that you were going to try to  

> find a 2.65, I believe, to replace your 2.24? Isn't there a 3.07  

> available and wouldn't that be even better?

>

>

>

> I know Barry Corno's 380SEC really improved in acceleration with  

> the change to the 3.07.

>

>

>

> Steve

>

>

>

>

>

> April 28 2007

>

>     Steve is right on the improvement. I did loose 1 ½ mile per  

> gallon, but have picked it back up

>

> With cats removed.  It is a cheep fix for a 380 PIG. On the pre  

> 86’s it is a bolt right in Diff from

>

> Any pre 80 SL or SEL.

>

>

>

> B.C. 380 SEC AMG  514K

>

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.

>

>

>

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.

> The MB Coupes Website!

> W126 SEC Mailing List

> Postings remain property of MB Coupes, L.L.C.


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.pairlist.net/pipermail/mbcoupes/attachments/20070429/f4642efc/attachment.html>