116 to 126 Differential swap (with pics) - Page 3 - PeachParts Mercedes-Benz Forum

DeliveryValve · #31 01-19-2009, 07:49 PM

John,

I am sure you know this, but you could swap your Speedo with a 300SD unit geared for 3.07. Or they make a calibration box for to correct your speedo. http://www.yellr.com/index.htm. If you want to keep the original.

Johnhef · #32 01-19-2009, 08:38 PM

about $100 bucks, not bad. I may have to get one of those. I have a 300SD with a 3.07 in it, but the PO kept the cluster, I'll have to see if I can persuade him to let me get it from him... how bout it Joe?

...but weren't 81 SD's an 85mph speedo?

I was going to play around with the cluster a bit anyways. The original speedo is long gone, I have the US 500SEC one in it now. I was thinking about getting an overlay from one of the other members on the site, but with readings in kph, but keeping the miles odometer for my own benefit.

DeliveryValve · #33 01-19-2009, 09:51 PM

Yes the '81 is 85 mph. You'll need a '83 and '84 300SD versions. They are 125 mph speedos.

gsxr · #34 01-19-2009, 10:37 PM

Quote:

Originally Posted by marlinspike

I hope John won't mind the thread drift, but since you're a man who seems to know his rear ends, do you know what it would take to swap the 2.88 w/ABS diff from a 1985 W126 diesel in place of the 2.47 w/ABS diff on a 1985 380SE?

Unfortunately, I know very little about the 126 differentials... but if you're swapping rear ends that are the same chassis, same year, and both ABS... it should be a direct swap, other than re-calibrating the speedo head (easy if it's electronic, not so easy if it's mechanical). But I can't say for sure. Your best bet is to compare all the parts for both models in the EPC, that's all I did to learn this stuff...

gsxr · #35 01-19-2009, 10:43 PM

Quote:

Originally Posted by gsxr

The steels are very likely reusable, there was no visible (or measureable, IIRC) wear on those. That wil save you another $34 list (they are $3.40 each, 10 needed). I'm also assuming you will re-use the ring gear bolts (those are $8.50 list each, x10 !!!) and re-use the main bearings ($97 list each).

Minor correction: The steels are re-usable if they are still the original thickness, and undamaged (not burned, scored, etc). I just measured a couple on my 210mm project, one was 1.00mm, the other was 0.90mm. In theory the worn 0.90 plate could be re-used, but the variable-thickness washer would have to be 0.10 thicker to compensate. Since they are relatively cheap (less than 10% of the total cost of the project), I'd recommend replacing them. Now if you were doing this refresh every X number of months on a race car, then yeah, it would make sense to re-use things as long as possible to reduce costs. When it's once every 5 or 10 years, shoot, I sleep better knowing it's all new stuff in there.

marlinspike · #36 01-19-2009, 11:03 PM

Quote:

Originally Posted by gsxr

Your best bet is to compare all the parts for both models in the EPC, that's all I did to learn this stuff...

The problem is they have changed some of the part numbers many times since these cars were made, to make some of the parts that used to be different the same, but this can mean that you need tons of work to retrofit and there's no real way to tell without trying it.

Johnhef · #37 01-20-2009, 06:41 AM

125? psssh.

DeliveryValve · #38 01-20-2009, 09:15 AM

Thought so!

Johnhef · #39 01-20-2009, 09:05 PM

Quote:

Originally Posted by marlinspike

The problem is they have changed some of the part numbers many times since these cars were made, to make some of the parts that used to be different the same, but this can mean that you need tons of work to retrofit and there's no real way to tell without trying it.

We know a few things will be the same between the gas and diesel models.

Subframe mounting points.
distance between rear hubs

based on that if you have the diff and axles from the donor, it will bolt in and connect to the hubs- what might be different and need to be swapped over from your diff would be the pinion flange. a check of the part number of flex discs for the two models in question would answer this.

marlinspike · #40 01-20-2009, 10:26 PM

It appears the diesels use a different flex disk. What I also wonder is if the diesel rear axles are heavier or less stiff. If I understand the MB diagonal swing axle (and I might not) the rear axles are an important part in the rear suspension.

SirNik84 · #41 06-30-2009, 04:14 PM

OK, I'm dredging up this thread because I'm pretty jealous of Johnhef's rear end!

I have my car up in the air and I'm in the process of installing new rear wheel bearings. with the rear diff 7 bolts from being out I've contemplated taking it out and cleaning it up... that was until I read this thread.

I have a few questions. From what I see here your car came with the flanged axles. I would love to change out my axles for the flange style but never understood what all would have to be changes in order to retrofit. So, my first question, it looks to me that the (Axle + Flange) = Old Axle is this true? Are the axles in your car the same as the axles in a 86+ 126?

I don't need LSD in a diesel... its not exactly a race car, but it would be cool

So my next question is, do I need the LSD diff to convert to the flange style axles? is there a width difference between LSD and non LSD?

gsxr · #42 06-30-2009, 05:43 PM

Quote:

Originally Posted by SirNik84

I don't need LSD in a diesel... its not exactly a race car, but it would be cool

LOL... if you don't need LSD on your diesel, something's wrong with your diesel! I installed LSD on my 1987 300D and it made a huge improvement in driveability. I can accelerate while turning from a stop sign now, without sitting there spinning one tire (particularly on wet or dirty pavement). It cost a small fortune but in the end, it was worth every penny, and it's been one of the few mods I wish I had done years sooner.

Quote:

Originally Posted by SirNik84

So my next question is, do I need the LSD diff to convert to the flange style axles? is there a width difference between LSD and non LSD?

No, the LSD is totally separate from the flanges. The only difference is the carrier, as shown below... note that the pics aare from a 210mm diff in a W124/R129/W140, not a 116/126, however the concept is the same:

SirNik84 · #43 06-30-2009, 06:41 PM

Dang it gsxr! with an endorsement like that I'm going to go broke! LOL

I finally put the SD in the garage for the first time in over a year and I have a laundry list of things to do... but as I go I'm getting more and more ambitious. maybe I'll take this holiday weekend and hit the yards and see what I can find. LSD does sound fun!

Doktor Bert · #44 06-19-2010, 07:56 PM

Very intesresting....

I want to put a 126 diff into my 116.120.....

I am unclear on a few things....

It appears as though the input yoke is smaller on the 116 as opposed to the 126 and the diameter of the axle sealing surfaces are different too.

Would you/could you just use the 126 flex dis and 126 axles in the 116?????

I also found a 2.88:1 from a 123, but would prefer a 2.47:1 axle....Robert

gsxr · #45 06-20-2010, 10:52 AM

Pretty sure the W123 2.88 will be a 185mm diff, using a totally different LSD carrier than shown above (different size, different part numbers). The 2.47 W126 is very common though. I'm not that familiar with the 116/126 fitments so I don't know what you need to do to fit that to a 116 chassis.