W163 ring and pinion choices?

[gsfent]

Does anyone know what other ring and pinion would be compatible with the W163? I have an 01 ML500 and would like to change the ring and pinion, (ideally, the entire pumpkin) but can't find any cross references. Earlier ones had 3.46, mine has 3.70.

Similar vintage S/CL class with same motor? The 5.0L and 5 sp auto tranny is used throughout the product range, so I am guessing that MB wouldn't spec something special just for the w163 diff.

Regards,
Jerry

[lkchris]

Look it up in the parts system. It's free.

http://epc.startekinfo.com

[mbdoc]

Of course if you change 1 differential(ratio) you must change them BOTH.

[gsfent]

Originally Posted by lkchris

Look it up in the parts system. It's free.

http://epc.startekinfo.com

Thanks, great piece of info. Unfortunately, I am having trouble loading after signing up, apparently it is using an older Java application.... We are trying to work around it here...
Regards,
Jerry

[gsfent]

Originally Posted by M.B.DOC

Of course if you change 1 differential(ratio) you must change them BOTH.

Right, but both (must) have the same ratios, so I am pretty safe in assuming the same internal ring and pinion front and rear!
Regards,
Jerry

[mbdoc]

Ring & pinions aren't even available...only the complete differential.

[gsfent]

Originally Posted by M.B.DOC

Ring & pinions aren't even available...only the complete differential.

Thanks Doc.
What I want to do is change the ring and pinion to something else, hence the title of the thread. I would guess a similar year S class using the same motor and tranny would have an R&P compatible, or perhaps even an AMG version with the same motor/tranny combo. There would be lots of different rear end ratios available.

If I can find out, I will buy the entire pumpkin from that car (x2) and do the R&P swap, unless I am lucky enough to find that the entire diff from another MB product just bolts right up. That would be sweet. But if not, I am prepared to buy a couple of used diffs and take out the R&P's and swap out with my current.

Do you know which other R&P's would be the same size for the diffs, or which other diffs might actually bolt up so I can swap out??

Regards,
Jerry

[mbdoc]

No MB car differential will fit the W163 ML's, completely different design than ANY other Benz!

Designed by ZF & built in Canada.

[gsfent]

Originally Posted by M.B.DOC

No MB car differential will fit the W163 ML's, completely different design than ANY other Benz!

Designed by ZF & built in Canada.

OK, so that means no other R&P will fit, correct? Any other diffs built by ZF I could source?
Regards,
Jerry

[lkchris]

I believe you can count on the fingers of one hand the number of people in the USA that have actually rebuilt an MB differential, let alone changed the gearing (that number will be zero).

You are quite unlikely to find the procedures in writing anywhere, meaning for one thing something that contains the list of special tools required.

[gsfent]

Originally Posted by lkchris

I believe you can count on the fingers of one hand the number of people in the USA that have actually rebuilt an MB differential, let alone changed the gearing (that number will be zero).

You are quite unlikely to find the procedures in writing anywhere, meaning for one thing something that contains the list of special tools required.

You are right about the rarity. I suspect someone like Hartmut at Renntech could do it, but then it would just be probably be cheaper to just buy a new W164!
Regards,
Jerry

[gsfent]

Originally Posted by mbdoc

No MB car differential will fit the W163 ML's, completely different design than ANY other Benz!

Designed by ZF & built in Canada.

Thought I would update this thread.

ZF makes the diffs for all the MB ML series as you noted. So that got me to thinking of other W163 versions, including those that are NOT sold here.

So after doing a ton of research, I discovered a non U.S. version that would theoretically work for me.

On a hunch that even MB wouldn't have different specs other than ring and pinion, I picked up a pair of diffs from Germany. It turned out install was pretty straight forward mechanically. But the difference in gearing was outside the computer's parameters and threw the computer off which put the tranny into limp mode.

Although driving the ML in 3rd geas wasn't that bad for short hauls, that obviously wouldn't work. Luckily, I am near Renntech, MB gurus. So off to the see the wizard!!

Hartmut and his wizards were pretty nonplussed. They didn't think it would be a big deal. They were right. REnntech was able to do the reprogramming for me. These guys really know their stuff. After doing the computer magic, and clearing all the old codes, it worked like a charm. Computer was now happy, so no limp mode any more.

So I have a pretty much one off geared ML! I don't know it will approach CDI efficiencies, but it should do a lot better in a world of $4/gallon and up gasoline!

Regards,
Jerry

[itb76]

Originally Posted by gsfent

...Earlier ones had 3.46, mine has 3.70...

Originally Posted by gsfent

...How about the W163? Early ones came with 3.46 R&P; post '01 came with 3.70...

I have a 1998 model ML320, build date of 8/97. I have two labels stating that the front axle ratio is 3.70. Maybe only the V8's got the 3.46?

I know this is an old post, but maybe this may help someone who's shopping for a used front diff because the bearings got all noisy.

How is the acceleration off the line with the new gears? Did the fuel mileage improve appreciably?

[gsfent]

Originally Posted by itb76

I have a 1998 model ML320, build date of 8/97. I have two labels stating that the front axle ratio is 3.70. Maybe only the V8's got the 3.46?

I know this is an old post, but maybe this may help someone who's shopping for a used front diff because the bearings got all noisy.

How is the acceleration off the line with the new gears? Did the fuel mileage improve appreciably?

All the literature I have read showed 3.46 for 98-01 vehicles shipped to the U.S. and 3.70 for 02 and later. Doing what you suggest, 3.70 for 6 cyl and 3.46 for 8 cyl would have made good sense for MB.

So, either your diffs were replaced (unlikely if you are the original owner, possible if you are not, but then there would have had to have been an adjustment for the speedo), you got an early production model where MB "forgot" what the specs were for U.S. vehicles (possible if they used 3.70 in other countries, we know the did use the 3.09 in the V8 CDI, I think they used 3.46 in the V6 CDI), the literature available is incomplete (possible), or the diffs are mislabeled (unlikely).

With the new diffs, I notice no loss of power. I find it easier to accelerate from a stop because it is actually easier to modulate the throttle with taller gearing. I can count on one hand the number of times I have had to do full throttle launches, so I have no evidence of loss of acceleration from a dead stop. No empirical data, but mid gear acceleration feels about the same as before. Depending where on the speed chart the car is, I might actually be in a lower gear than stock, so accelration in gears will depend partly on speeds. Top of 2nd gear in my car will be faster than someone who has already shifted into 3rd with stock gearing. Adding headers along the way didn't hurt either!

In town mileage is up slightly, probably as a result of spending a little more time in top gear or being in a taller gear at a given speed at light throttle. Highway is up between 2-3 mpg, very noticeable. RPMs at cruise reduced about 400-500.

Regards,
Jerry

[itb76]

That's interesting, because the dismantler that is selling me a differential said that he has a 3.70 in stock and a 2000 model that he hasn't dismantled yet, but his book or whatever is telling him that it should be a 3.70. Don't know if he's using Hollander or what. I can't find anything in the WIS or owner's manual stating what the axle ratios should be.

Throttle modulation is overrated, I just floor it all the time. After it's warmed up of course. My other car is a BMW 545, and it's just barely fast enough. The ML is a kid hauler/tow vehicle.

The comment about headers is interesting. I did have to replace a stock exhaust manifold once. It looks just like a stainless steel header, with a second layer of stainless around it to reduce noise and corrosion. It's a really nice piece.