W123 limited slip Diff

[OM616]

I originally posted this over in the performance paddock not being sure where the best place to ask. Please do not hesitate to remove this if it doesn’t belong here.


I got a call today from a customer of mine today. He wants me to design and build a limited slip differential for his 82 300D.

I asked him if there was already such a thing he could just buy, and he said that he could not find anything. I have not looked myself, but bet it would be a rare thing if it was available, but rare is still cheaper than a custom made one off.

Any thoughts as to where he should be looking?

I did get a suggestion to look at a 126-107 diff. I then asked if there are limited slip diffs for a 126, would they be a direct swap, or would it require fab work and custom axels. I have heard that some early 126 parts will fit on a 123, but not sure about the axels and such.

I am putting together a quote to design and build a custom carrier that would have an aftermarket locking mechanism. I still need to find out the number of splines that are on the inner CV joint, what the OD of the splined shaft is, and how long it is.

Needles to say it will not be cheep as it will be a one of a kind piece, so if it is practical to find a posi diff out of a different model, I will direct him toward that before I start the clock.

Thanks,

Dave

[winmutt]

You can find 116's with them occasionally. I spend some time under the back of a second gen 126 and a 123 and figured that it would be pretty easy to mount a second gen diff back there with some fab work. Drive shafts may or may not be so easy...

[panZZer]

Anybody looked into a Gleason tru-trac (torensal) into the benz housing?

[MTUpower]

Originally Posted by OM616

[COLOR=black][FONT=Verdana][COLOR=black][FONT=Verdana]I originally posted

Good luck. The Gen I w126 diff will fit with slight modifications but not the LSD ones. They are much too large. If you can fab one you may have more than one customer- me.

[OM616]

Originally Posted by panZZer

Anybody looked into a Gleason tru-trac (torensal) into the benz housing?

I think I read some where that Gleason no longer made it or some such thing, (plus I heard there were some issues with the Gleason version), but Eaton is building one.

I have not had the back cover off of a 123 diff to know for sure, but from the pictures I have seen, the carrier is very small, the odds of finding a tru-track unit that is small enough and can be made to mate to the ring gear is doubtful. The way the tru-track works, it needs its own housing, so there will not be any "conversion" kits that use you stock carrier.

The odds of Eaton making a tru-track for the 123 benz is a long shot, but should be investigated.

I am looking at using the Powertrax "no-slip traction system” or “Lock-right”. Both are meant to replace the stock spider gears in an OEM carrier. The trick will be getting the spline and shaft OD to match, and dealing with the axle clips.

[t walgamuth]

I have a 369 ls I built up from a 16v rear end and a 240d rear end. I would sell it for the right price.

[Hit Man X]

Originally Posted by panZZer

Anybody looked into a Gleason tru-trac (torensal) into the benz housing?

I have a TrueTrac in my F350, works great... and a very similar unit in my Z71 the Torsen diff. Love 'em, nothing to wear like clutch style units.

[OM616]

Originally Posted by t walgamuth

I have a 369 ls I built up from a 16v rear end and a 240d rear end. I would sell it for the right price.

I am not familiar with the 16V model, is it a 123 chassis?

I am assuming that you took the ring and pinion from a 240D and put them into 16V housing, and that it is different from a 123 (240D) housing. My customer wants to eventually put an overdrive automatic trans, (he has a prosthetic left leg), so he wants to keep the 3.08 gears, (i think 3.08), until the trans swap.

If the housing you have built will directly mate to a 123 chassis, will the 3.08 or 2.88 gears fit?

If all that is good, how much do you want for it?

[W124 E300D]

I know of three W123 LSD conversions done in total, I didn't do them myself, it was a good friend, (he did all sorts of weird stuff, lister diesel jaguars, etc) but he's been dead this few years so I can't find all the details of why and wherefore, I do know that all three featured Jag LSD's if that is any use.

I also know that the only equipment he had besides the usual garage tools was a 6" swing lathe, and I *think* the only lathe work he had to do was shorten the axles and make a couple of bolt up to crimp (like hose clamp) sleeves for the merc suspension to attach to... but the axle shortening might have been down to his other signature feature which was really wide rear rubber on gkn wolfrace alloys

[OM616]

Originally Posted by MTUpower

Good luck. The Gen I w126 diff will fit with slight modifications but not the LSD ones. They are much too large. If you can fab one you may have more than one customer- me.

I talked to Eaton today and they actually laughed when I told him the make and model car, well, more like chuckled.

I really need to get a diff and tear it apart to see what I would have to work with. I can't imagine the ring gear is larger than 7 inches and the carrier has got to be very narrow.

Just doing a quick materials cost to machine up a custom carrier and purchase a locking mechanism it is at $1,200.00. P20 is quite expensive so I am hoping that the carrier is much smaller that I am thinking, (less material).

The other option is to design a locking mechanism that will work with the Benz carrier. Until I get one to look at I'm just spinning my wheels thinking of ways to approach the task, if it is a go that is.

Either way, unless it turns out to be a minor massage to fit an off the shelf locking whatever, in the 123 diff, the cost will be at least $1,200.00 to do it.

Still interested?

[OM616]

Originally Posted by W124 E300D

I know of three W123 LSD conversions done in total, I didn't do them myself, it was a good friend, (he did all sorts of weird stuff, lister diesel jaguars, etc) but he's been dead this few years so I can't find all the details of why and wherefore, I do know that all three featured Jag LSD's if that is any use.

I also know that the only equipment he had besides the usual garage tools was a 6" swing lathe, and I *think* the only lathe work he had to do was shorten the axles and make a couple of bolt up to crimp (like hose clamp) sleeves for the merc suspension to attach to... but the axle shortening might have been down to his other signature feature which was really wide rear rubber on gkn wolfrace alloys

Interesting.

I would think that BMW parts would fit before Brit parts, but that’s what I get for thinking!

A big goal is to not to have to alter any peripheral components, (axles, drive shaft, etc), as to maintain serviceability. Its good to know it can be done though.

[W124 E300D]

This may help

http://www.differentials.com/pdfs/43.pdf

[OM616]

This is from my thread in the performance paddock;

samiam44
Registered User

Join Date: Aug 2008
Posts: 409

Well... MB only made 185mm and 210 mm ring gears. Said another way- there is 1.1 liter and 1.3 liter cases.
Figure out which case/gear it is.. then you can get a carrier which is posi depending on the gearing.
The 126, 210 mm is on order with MB right now- with a delievery tenative date of Feb 28th.
107's had posi as options too. W201 uses the small 185mm in the 16 valve engined cars...

I think your probably looking at 10 hrs labor, $771 list for the carrier, plus $200-300 for the side bearings, shims and seals.

Is he up for that?

Michael

Very good information!!

[t walgamuth]

Originally Posted by OM616

I am not familiar with the 16V model, is it a 123 chassis?

I am assuming that you took the ring and pinion from a 240D and put them into 16V housing, and that it is different from a 123 (240D) housing. My customer wants to eventually put an overdrive automatic trans, (he has a prosthetic left leg), so he wants to keep the 3.08 gears, (i think 3.08), until the trans swap.

If the housing you have built will directly mate to a 123 chassis, will the 3.08 or 2.88 gears fit?

If all that is good, how much do you want for it?

We took the 123 housing and installed the LS spider into it and a spacer to use the 369 ring and pinion from the 123. it has new friction discs throughout and will bolt into any 123 chassis. We could retrofit the original gears from the 190e 16v diff which are either 327 or 333 ratio I believe.

Tom Walgamuth

[winmutt]

PS the right price is between 1200-2000 is my guess... Reasons why few get LSD for 123..