500E Ring gear

[David Hendy]

Does anyone know the size of the ring gear in a 500E diff?

[Tobias MB]

David,
The outside diameter at the largest point being the edge of the teeth is 8.223" but this is for a 500SL ring gear which I believe to be the same as it is for a 400E and 500E. I happen to have one out and off the carrier as the carrier is out to be converted into a limited slip. This a 2.65 R&P ratio which also shouldn't make any difference. In comparison of size the ring gear for a Viper and Corvette ZR1, a Dana 44, is 8.25" OD.
Hope this is what you're looking for, if not, email me for the rest of the dimensions.

Tobias MB
190.5.8

[E DREAM]

Toby, drop me a line when U get that limited slip diff back in UR ride

[David Hendy]

The reason for my interest was research for a possible 560 diff swap. The W126 560 was an LSD from the factory, with a 210 MM ring gear (8.26") which is almost exactly what you measured.

The gear ratio is slighlty taller than the stock 500E diff, but that won't make much difference, and 560 are reasonably priced from a bone yard.

[ke6dcj]

David- unless you want to disable/not have ASR, you really shouldn't use a W126 diff (moreover, the ratio is less aggressive than the 500E's (2.82) vs the 560SEL/SEC's 2.47).

You can find a 3.46 or 3.69 from a R129 300SL or W140 320S/SE which did have ASR, and then have the fiber clutches (129.353.11.62) installed (some of the early R129's and early 140's had the LSD, but no ASR).

:-) neil

[David Hendy]

So how about the 3.06 AMG diff that is for sale on the parts page of this website?

[ke6dcj]

Again, no ASR.

:-) neil

[David Hendy]

So I found a 1990 500SL diff. for $300. Does that come with an LSD?

I really want to run without ASR all the time, because I prefer it, but unfortunately when you corner hard she tends to lift the inside rear tire and that just is annoying, and slow!

[ke6dcj]

The only "129"-cased diff with limited-slip is an early R129 300SL with a ratio of 3.46(manual) or 3.69 (automatic). Unfortunately, you can't have BOTH ASR and limited-slip.

While you could swap the innards of a 3.69 or 3.46 limited-slip, you would need a donor ASR diff case, as well as the 4-point propellar-shaft flange AND the bigger 126 axle-output flanges.
The labor for a correct swap, with all the trial and errors to have a quiet and properly shimmed diff, would not make it economically prudent unless you did the work yourself and had $5K plus in specialized tooling, or access to it.

Moreover, 99% of the time, all the clutches of the 3.69 or 3.46 are GONE.

Your best bet is take a R129 ASR diff (3.69, 3.46, 3.06, 2.82, 2.65, or 2.24) and then ADD limited-slip to it, thus giving you 100% new clutches.

I believe ASR versions of 3.69, 3.46, 3.06, and 2.24 all came from 6-cylinder cars, so again you'll need the 4-point propellar-shaft flange, the bigger 126 axle-output flanges, and the rear-cover from your original 500E diff.

:-) neil
1988 360TE AMG
1993 500E

[Tobias MB]

Neil,
After reading your last post makes me feel great about installing the 8.8 Ford differential into my 190. All the ratios are interchangeable, choice of what kind of LSD...clutch, locker or Torsen... and a choice of housing to use. And the best of all .... economical by MB standards!

Have a great Thanksgiving...
Tobias MB
4 MBs

[ke6dcj]

Here's a note from Stu Ritter of the Ritter/Easeley MB list, he's also a veteran MB tech/shopowner and Technical Editor of the MBCA 's "The Star" magazine:

=============
There are two ways to change the differential ratio in our MB's.
First is to swap the entire differential and the second is to swap out just the ring and pinion for the ratio you want. In order to swap the gears, you must have ALL the measuring tools from MB to set up the pinion seating depth, the backlash and the case spread (bearing preload). While you can cob up some of the tooling you cannot cob up the pinion depth setting arrangement. The zero point for the pinion exists in space, inside the case. The only way to arrive at zero and the deviation from zero etched on the back of the pinion is to have the gauges. You could of course attempt to assemble it and blue the gears and read the pattern and take it apart and put it together, but OHMYGAWD, what work.

The factory sets up each ring and pinion in a test jig. This test jig allows the operator to move the pinion in and out of engagement with the ring gear. The purpose is to determine the point of quietest operation. When the gears are at their quietest they also are at the point of maximum mesh and longest wear with most contact. This is the ideal point you are looking
for if you blue and pattern a set of gears. The operator of the test jig moves the pinion in and out with microphones pointed at the ring/pinion set. Watching dB meters, the operator finds the quietest point. The test jig is set up so that the deviation from the zero point is noted in hundredths of a millimeter. Your job when setting pinion depth is to match that same point. You can't do it without the MB tools.

The measuring tools cost me $3,600 in 1986. I have no idea of what they cost today. As far as I know, RennTech and another shop in Florida along with my olde shop own the measuring tools. There is no other way to change the gears by themselves. Also, when you buy new gears, or take them from a junker, you must also take the ring gear carrier because each ratio uses
a different thickness carrier. Keeps the engagement spot the same.

So much for the limited appeal of changing ring and pinion.

In my car I obtained a 3.07 from a 1973 450SL. Let me explain.
There are several sizes of differentials used by MB and they care
categorized by the oil capacity of the differential, or in other words the size of the case.

There are 1, 1.1, 1.3 and 1.4 liter cases. The gears are not interchangeable between cases. You must use 1.3 gears in a 1.3 case. The case on the V-8 124 chassis is the 1.3 liter case, used since the first V-8's in 1972.

The jump from the 1 liter case to the 1.3 liter case occurs at 200 horsepower. Everything with over 200 horsepower has the larger gears in the 1.3 liter case. The 103 engined 124 chassis has the 1 liter case. The introduction of the 104 engine in the 300CE brought the 1.3 liter case to the 124 chassis. Every 104 and 119 engined 124 has the 1.3 liter case along with a much beefier rear subframe assembly to hold that 1.3 liter diff.

Any gear that fits in a 1.3 case can be used in any E class car that
came with the 1.3 liter case, provided you own the tools to make the change.

If you don't own the tools, then things become a bit different.
You must have the same case to fit the rear subframe to make it work. In other words, you can't go to the junk yard and get a 73 450SL diff and install it. Won't fit and besides, there is no ABS sensor hole in the case. I took the 3.07 pinion to my cam/crank grinder and we ground down the pinion to accept the 3.07 stator for the ABS system. Just had him copy a pinion from another ABS equipped car. No sweat. $50 for the grinding. The 3.07 stator just slipped right on as it was supposed to. All 124 and 140 cars use the same diff case so any ratio in the 1.3 liter case will work.

So, to sum it all up.

If you want to swap cases, it has to be a 1.3 liter case from a 124, 129 or a 140 chassis. The later 126 (86 and later) won't fit. Different design. Those are the limits of your choices.

Yes, the speedo gets modified. It is done at the speedo head and is an $85 proposition in Denver. No big deal. You just tell them which ratio you went to. My speedo is accurate to about 1 mph after the change from 2.24 to 3.07. I show 3,500 rpm at 84 mph. I knocked 2.2 seconds off my 0 - 60 time in Denver. Went from 9.3 to 7.1. I would imagine I am sub 6 seconds at sea level if I could stop the tires from spinning. The acceleration when passing from 50 - 100 is really strong.

Stu

[gsxr]

This is good info. Interestingly, the S350 diesel also moved up to the larger case, despite only being 135hp... the Intro manual says it was due to the torque (went up to 230lb-ft from the older/smaller engine's 200 lb-ft). So the deciding factor may be torque, not HP.

I'm trying to find out if swapping gears for non-ASR cars will mess up the ABS computer. The 'stator' on the pinion shaft has different number of teeth for each different gear ratio.

David - did you ever get LSD in your 500? No 129's or 140's came with LSD, they're actually ASD setups (hydraulic locking diffs). The last true LSD's that I know of were in the 190E-16 and some late W126's, like the 560SEC. The late SEC internal LSD parts are identical to the interal ASD items, but the flanges, side carriers, and other items are different. To answer your original quesiton, the 500E has a 210mm ring gear in the "1.3L" case. The smaller (1.0 or 1.1L?) diffs have a 185mm ring gear. I started a new thread on LSD conversion over here, with lots more info:

http://500ecstasy.com/forums/showthread.php?goto=newpost&t=1353

(note that the ABS issue does NOT apply to cars with ASR.)