Is there a final say - w123 with limited slip? - Page 3 - PeachParts Mercedes-Benz Forum

t walgamuth · #31 04-10-2007, 09:12 PM

so if a car came with the optinal 15" wheels, what did they look like?

and if you ordered them did you get taller springs too for more ground clearance?

tom w

POS · #32 04-10-2007, 09:39 PM

Quote:

Originally Posted by A. Rosich

Hope this helps to clarify the issue.

Absolutely it does. Thanks for the answer.

A. Rosich · #33 04-10-2007, 11:43 PM

Quote:

Originally Posted by t walgamuth

so if a car came with the optinal 15" wheels, what did they look like?

and if you ordered them did you get taller springs too for more ground clearance?

tom w

The 15" wheels fitted to the models with optional rear differentials were exactly the same as the 14"s.

The light alloy design was the same and the regular wheel with hubcap were also the same design. Although, visually, you could easily tell the models at the dealer garage with 15"s because the tires looked bigger and the cars looked much taller.

I will asume the springs were also different for the cars fitted with 15" wheels. I have been told by the shop manager that each class could have up to 12 to 14 different types of springs (depending of country of origin, original and optional equipment fitted, and factory tires). Just one example: cars fitted with A/C have completely different springs from cars without A/C.

As most equipment is standard in the U.S., I will asumme spring variences are limited, unlike in the rest of the world.

POS · #34 04-11-2007, 12:11 AM

Do they put part numbers on springs, and if so, where?

t walgamuth · #35 12-06-2007, 01:25 PM

Quote:

Originally Posted by A. Rosich

According to my trusted Diplomatic and Tourist Worldwide Sales Prices/Specifications/Options brochures (ref. years 1979/82/84/85) there was a Limited-slip Differential, M-B option code No. 256, but it was available ONLY for W126s and SLs. The option had to be ordered in conjuntion with code 601 (Special oil for rear axle with differential).

There was no limited differential available for W123s.

The only rear axle option codes available for W123s were:

Code No. 230: Rear Axle ratio 1:3.69, which by the way was mandated to be combined with option Code 646 (Tyres 15" tubeless). This extra cost option was only available for the 300D/230E and 280E models -sedans, wagons and coupes-

Code No. 212: Rear Axle Ratio 1:3.92. Code 646 had also to be ordered and this option was available only for models 240D/200 -sedans, wagons and coupes-.

I have a seen few W123s here with either of those options, they used to easily recognizable because of the 15" tires instead of the 14". But, as far as I know, I have never seen a W123 with a limited-slip differential fitted from the factory.

The limited-slip differential was a popular post-factory option. I have seen it installed on a Holland imported W123 (300TD) and a French 280CE. Several brands were available (as I remember seen several ads on european car magazines at the time).

Hope this helps to clarify the issue.

so would the diff be marked #256? if it is a lsd?

tom W

t walgamuth · #36 12-24-2007, 07:05 PM

and installed it in the 123 housing with the 3.69 ring and pinion. Just a test fit, but preliminary measurements suggest it will fit just fine. After taking it all apart we were looking at how the carrier is shimmed in the housing to get perfect meshing on the pinion bearing and my favorite machinist said Viola' or words to that effect and measured the rather large circlips the hold the bearings in the housing and said "these circlips are used to center it....they are different thicknesses." ....and so we measured the ones from the 123 rear and they were 54 and 62 (thousands?) and the ones from the 190 diff were 56 and 60....so both pairs added up to 106. He said ......"they must have pairs of these and pick them in varying thicknesses to center the carrier."

So after christmas he will disassemble the clutches and measure them so I will know what clutches to order. We feel the bearings and races will be fine and so I will be ordering seals and shims (clutches) and that is it.

He was just chortling at the end. He has never had a benz rear apart before but he was duly impressed with the robust nature of its construction.

Hooooohaaaaaa!

Tom W

tilac1 · #37 12-25-2007, 03:01 PM

I think they all should have limited slip. In snow, one-wheel-drive is a cruel joke. Useless.

t walgamuth · #38 01-20-2008, 05:16 PM

for wear. Actually my favorite machinist did and I watched and held onto things while he hit them with large hammers and similar important tasks!

We measured everything and I will be ordering end clutch rings that are 3.2, 3.4 and 3.6 to make up for the wear in them and in the thin double faced friction discs.

He likes to tease me about how the benz hardware is strange and all but he is truly impressed with the quality of the construction. He said the spider gear shaft on any american made diff you can push out the shaft with your fingers after removing the split hollow shaft locking it in, and pointd out that on the benz you have to press it in and out.

So depending on how long it takes to get the parts I should have a working benz limited slip in my autocrosser with a 369 ratio in a couple of weeks!

Thanks to all who have made helpful comments to keep this moving along.

Tom W

gsxr · #39 01-20-2008, 08:33 PM

Wow, there is a lot of speculation in this thread.

Pretty much everything MB Doc has said is absolutely correct. No W123 was available anywhere in the world with limited-slip from the factory, but yes some may have come from AMG with limited-slip. (And probably a G-T LSD, if it was from AMG.) Or someone may have installed an aftermarket conversion. If it's factory LSD, the VIN will show option code 256 in the datacard, and no, that is not stamped anywhere on the diff. There will be a little metal tag under one of the diff cover bolts, with German text specifying special diff fluid. That's it.

For the record, the only models I'm aware of that came to the USA with true LSD are the 116 6.9, the 190E-16, and all 560SEC/SEL models. The end. A handful of 124 and 140 diesels, and also a 202, had optional ASD, which is an LSD plus some hydraulics to allow 100% lock under 19mph when wheelspin is detected. ASD was more common in Europe than in the USA. The vast majority of US cars with any kind of traction control used ASR, which was an electronic simulation of LSD, but ASR cars have open diffs. ASR will reduce throttle and/or apply the brake to the spinning wheel to mimic the effect of LSD, without pesky diff clutches to wear out.

Tom, about your project: Yes, the large circlips are of various thicknesses, and yes they are used to adjust the backlash. However, they are ALSO used to adjust the bearing preload! You need to measure & set both backlash & preload. Now, I know you're dead set on using the 3.27 LSD carrier with your 3.69 gears, but if it were that easy, Mercedes woudn't have created a different part number for a 3.69 LSD carrier. I will almost guarantee that you won't have enough adjustment with the circlips to correct the backlash with that setup. If you're lucky you might be able to have a spacer machined, but it will be a full custom job. Let's hope I'm wrong though.

Finally, about the friction discs. Ordering 3.2, 3.4, 3.6 is too wide of a spread. If you studied the photo below, you'll see that with the rest of the clutch pack replaced, the tolerances on the end discs were in hundredths of a mm, not tenths. I tried going up +0.2 from the old ones, for the same reason you did... "to make up for wear"... but they wouldn't fit AT ALL. Even +0.10 was too much - it would assemble, but refused not rotate; it would bind up. If your worn disc(s) are 3.2 (or less!), then +0.40 is way too big. The good news is that you can machine the back side to make them thinner as needed. I had to shave off a couple of hundredths at a time until it worked properly, which ended up at +0.05 (+0.07 was still too much). Also, remember that the thicknesses may be different left to right... if so, you must retain the delta between sides! Othewise you'll end up with one side too loose, and the other too tight. Note that mine were 0.10 different left to right. I don't know how to measure that if you lose the factory baseline, so I hope yours are the same, or your tech wrote down the number as he took it apart.

gsxr · #40 01-20-2008, 08:35 PM

Quote:

Originally Posted by POS

Do they put part numbers on springs, and if so, where?

Coil springs have the part number stamped into the last few inches of the bottom coil. Sometimes you can read the number with the spring in the car, sometimes it has to be removed. IF there is an corrosion on that area of the spring, the part number may be difficult or impossible to read. I've seen springs where you'd almost swear the part number was never there, but it's just corrosion that made it vanish...

t walgamuth · #41 01-20-2008, 10:26 PM

Quote:

Originally Posted by gsxr

Wow, there is a lot of speculation in this thread.

Pretty much everything MB Doc has said is absolutely correct. No W123 was available anywhere in the world with limited-slip from the factory, but yes some may have come from AMG with limited-slip. (And probably a G-T LSD, if it was from AMG.) Or someone may have installed an aftermarket conversion. If it's factory LSD, the VIN will show option code 256 in the datacard, and no, that is not stamped anywhere on the diff. There will be a little metal tag under one of the diff cover bolts, with German text specifying special diff fluid. That's it.

For the record, the only models I'm aware of that came to the USA with true LSD are the 116 6.9, the 190E-16, and all 560SEC/SEL models. The end. A handful of 124 and 140 diesels, and also a 202, had optional ASD, which is an LSD plus some hydraulics to allow 100% lock under 19mph when wheelspin is detected. ASD was more common in Europe than in the USA. The vast majority of US cars with any kind of traction control used ASR, which was an electronic simulation of LSD, but ASR cars have open diffs. ASR will reduce throttle and/or apply the brake to the spinning wheel to mimic the effect of LSD, without pesky diff clutches to wear out.

Tom, about your project: Yes, the large circlips are of various thicknesses, and yes they are used to adjust the backlash. However, they are ALSO used to adjust the bearing preload! You need to measure & set both backlash & preload. Now, I know you're dead set on using the 3.27 LSD carrier with your 3.69 gears, but if it were that easy, Mercedes woudn't have created a different part number for a 3.69 LSD carrier. I will almost guarantee that you won't have enough adjustment with the circlips to correct the backlash with that setup. If you're lucky you might be able to have a spacer machined, but it will be a full custom job. Let's hope I'm wrong though.

Finally, about the friction discs. Ordering 3.2, 3.4, 3.6 is too wide of a spread. If you studied the photo below, you'll see that with the rest of the clutch pack replaced, the tolerances on the end discs were in hundredths of a mm, not tenths. I tried going up +0.2 from the old ones, for the same reason you did... "to make up for wear"... but they wouldn't fit AT ALL. Even +0.10 was too much - it would assemble, but refused not rotate; it would bind up. If your worn disc(s) are 3.2 (or less!), then +0.40 is way too big. The good news is that you can machine the back side to make them thinner as needed. I had to shave off a couple of hundredths at a time until it worked properly, which ended up at +0.05 (+0.07 was still too much). Also, remember that the thicknesses may be different left to right... if so, you must retain the delta between sides! Othewise you'll end up with one side too loose, and the other too tight. Note that mine were 0.10 different left to right. I don't know how to measure that if you lose the factory baseline, so I hope yours are the same, or your tech wrote down the number as he took it apart.

I will go talk all this over with my favorite machinist.

We were not planning to get new two sided friction discs as you did, so that is making our extra thickness in the one sided disc more in comparison to your situation. Does that sound like an ok decision to you?

We also measured the wear on the non friction discs. That dimension was IIRC .0001". Just putting in all new friction discs including the one sided one would nearly put you back to the original setup with the exception that you would have the wear on the plain discs as extra clearance. So with the pretty small wear on the plain discs as the only thing not restored by replacement, you would indeed have a very slight increase in the one sided friction plate. I think I am seeing this correctly, am I missing anything?

We measured the distances from the mounting position of the ring gear for the 327 ratio and the 369 ratio and they appear to be the same. How thick was the spacer that you needed?

Tom W

gsxr · #42 01-21-2008, 12:15 PM

Quote:

Originally Posted by t walgamuth

We were not planning to get new two sided friction discs as you did, so that is making our extra thickness in the one sided disc more in comparison to your situation. Does that sound like an ok decision to you?

We also measured the wear on the non friction discs. That dimension was IIRC .0001". Just putting in all new friction discs including the one sided one would nearly put you back to the original setup with the exception that you would have the wear on the plain discs as extra clearance. So with the pretty small wear on the plain discs as the only thing not restored by replacement, you would indeed have a very slight increase in the one sided friction plate. I think I am seeing this correctly, am I missing anything?

We measured the distances from the mounting position of the ring gear for the 327 ratio and the 369 ratio and they appear to be the same. How thick was the spacer that you needed?

Hi Tom,

1) I would not leave the old, 2-sided discs in place. The only thing creating friction are those discs (and the end disc), for a total of 9 friction surfaces. Replacing one, and leaving in 8 old friction surfaces, seems like a recipe for having more slip than limited (i.e., well under 35% lock).

If the plain metal plates look OK, those can probably be re-used, but I would definitely replace all discs with friction material on them.

2) With all new friction discs, yes, there should only be a very small increase needed in the thickness of the end plate, possibly less than +0.10 (each side) like mine, and almost definitely less than +0.20... although I'm very interested to find out what your final selection is. When you talk to your machinist, see if he can tell you what the old discs measured, and post that info here if possible. I'd like to compare your numbers to mine.

3) About the position of the ring gear. I can't explain it, but there is something different between the carriers for different ratios that is not obvious. I went through this same thing while helping someone else with a 210mm LSD buildup. He got a carrier from a 2.47 diff, and it didn't work right with his 2.82 gears - couldn't get backlash anywhere near spec. I said yeah, there's a different carrier for 2.82's. So he bought one of those, compared them side by side, and couldn't find any difference in the mounting position. Said they appeared identical. I encouraged him to try the new/2.82 carrier anyway, even though it looked the same as the 2.47 carrier. Sure 'nuff, the 2.82 carrier cured the backlash problem, easily set to specs along with preload, and he's now happily frying both tyres. When comparing carriers, make sure you are measuring from the bearing seat to the ring gear flange; not the end of the casting.

4) I did not need any spacers for my setup... I used the correct 2.65 carrier for my 2.65 gearset, and had zero problems.

t walgamuth · #43 01-21-2008, 01:22 PM

He felt that the wear was negligable on the two sided friction surfaces and did not warrent replacement.

I will go back and talk with him again, probably today.

Thanks again for sharing your experiences and expertise with me.

Tom W

gsxr · #44 02-04-2008, 05:42 PM

Any news on the LSD project?

t walgamuth · #45 02-04-2008, 06:35 PM

I got the parts in last week. He will be installing them soon I hope. He had planned to work on it Saturday but did not have a chance to do a whole lot.

I will post more later.

Tom W