I have a 2012 facelift s204 with p31 but without option 470. I was checking with my mechanic to install a wavetrac lsd.
He was not familiar with the brand/type but after checking on it his general feeling is that this unit is pretty cheap (compared to plate based racing diffs that he usually installs) and that gear driven diffs could pose faster issues than plate diffs (disregarding the fact that the plates wear). Long story short, his advice would be to go with a stock (plate) LSD instead of aftermarket. Now, he is checking if it would be possible to retrofit the stock (open) diff with plates to convert it to an lsd.
This sounds a bit weird to me. Does anyone know that this is possible? Is the stock open diff unit actually the same as the lsd stock unit with only a couple of plates and springs?

 

Your mechanic is an idiot. The wavetrac is very reliable and strong. Clutch type diffs tend to need more maintenance and rebuilding. The clutch type is better for the track but a wavetrac makes a big difference in these cars. Find a new mechanic.

 

wavetrac solid 11 years no issues

 

A quick search will tell you that a Wavetrac is the most popular LSD swap on this forum.

Mine has been fault free for over a decade

 

to answer you question, yes you can retrofit an oem lsd into an open diff housing. My mechanic did it for me about a month ago and everything is sound.

 

You can also check out OS Giken which is tunable. This is what Renntech supplies for the C63 as far as I know. https://renntechmercedes.com/index.p...lsd-204-detail

Either OEM or OS Giken be prepared to pay.

Wavetrac is likely your best option from a street and practical point of view.

 

Thanks for the input all ! Yes, I´ve read may threads and indeed, did not find anything negative on wavetrac. Given these car have been last produced 10y ago and the popularity of wavetrac, it sounded already odd to me that there would be problems with it.
The same goes for quaife whereas both are comparable in the sense that they are gear driven. I don´t think my mechanic is an idiot however, the wavetrac goes for about 1.3k euro which is very cheap for a diff.
I believe these are only sane for a specific category: cars with an open diff that want to retrofit and don´t have intended track use and above all don´t want to spend 3-4k on a diff, not everyone can understand that

For all that have a wavetrac, are there any downsides? I´ve read that gear driven diffs could cause rattling when braking from high speeds etc?

Do you have any details on it? Is it literally inserting missing components like friction plates and springs or was the diff replaced completely?
I´ve searched mb parts everywhere but I could not find the diff itself (the actual part like what you get when ordering a wavetrac or quaife, not the housing)
I did find the housing + diff, but this is everything and goes like 6-7k (funny it nowhere states it is open or lsd however) but not the actual diff part

 

Your mechanic might be on the right track, but it sounds like he doesn't have a lot of experience with this platform. Maybe find a different mechanic that knows the W204 or Mercedes in general a little better, it sounds like he's thinking the old school way with a lunch box locker.

The Wavetrac differential is a helical-type differential that doesn't require special LSD gear oil and provides a much more smooth and progressive but slower responding lockup. Decades ago these helical type differentials (which also includes Torsen and Quaife) had issues handling large amounts of torque and they would grenade. This isn't an issue anymore, plenty of people running 1000hp drag cars with helical type LSDs. They're smooth, quiet, and never need maintenance beyond changing the gear oil. Some types of helical LSDs also cannot transfer torque in a no-torque scenario, such as when you have one wheel lifted in the air; when there's not enough torque applied to an axle it will fail open. Wavetrac addresses this with some mechanical trickery and is able to maintain semi-lockup even in zero torque situations.

I believe the 471 option is a plate type LSD, which uses metal friction plates and clutches to distribute torque and lockup, but the style that Mercedes uses has a very low ramp rate meaning the torque transfer is relatively low. This is because high ramp rate clutch type LSDs will engage even at part throttle and have a reputation for having harsh engagement, which can cause chattering. This is usually addressed with special LSD gear oil that has friction modifiers to control the lockup. The advantage of this type of LSD is the very quick and precise lockup. Clutch type LSDs were (see above paragraph) considered more "bulletproof" than helical type LSDs, but those metal plates do wear down over time and you need to be on top of changing the gear oil to maintain proper operation. Also, clutch type LSDs are able to transfer torque even if one wheel is in the air by design. The ramp cones in the clutch determine the torque split and lockup. Most lockup under acceleration, and are open under deceleration but this can also be modified.

 

For what it's worth the Option Code for the MB OEM - Mechanical Locking Differential is 471 not 470.

 

Don't have too much info besides my mechanic had to match the lash with a digital gauge? I had bought a used oem lsd internals and my mechanic took my open diff internals made it work. Only thing he had to buy new was two axel seals and lsd specific diff oil

 

i've got an extra *brand new in box* OEM Black Series rear diff (with plugs that allow you to equip the B27 optional OEM rear diff cooler) if anyone is looking to go with an OEM+ route, i've ordered it by accident, ended up only needed a rear diff cover for my C63BS instead of the entire unit; thing is quite heavy, not looking to ship, available for pickup here in SoCal.

only looking to cover my cost (receipt available), this is not for the penny-pinchers on a broke budget, DM to inquire from serious buyer only.

 

If the user goes the giken route, I had no luck going the renntech route and just got a os giken lsd ordered through another website. I heard good things about the wavetrac too, but ultimately I just spent the dollars on the giken and saved by installing myself. I did have to do some grinding to get it to fit the housing, this is known. I absolutely love it and would recommend changing the driveshaft too while down there. If OP wants a parts list just dm me, but what the mechanic said seems like a mess to me.

 

Wavetrac recommend a Performance Gear oil and in particular their recommendation is:
75W90 MOTUL Gear 300 (100118 1Litre) or
75W140 MOTUL Gear Competition (1011161 1Litre)

I have MOTUL 75W140 oil in my BMW 135i with a Quaife LSD (same principle as Wavetrac) and it has been absolutely spot on.
I will soon have my recently purchased Wavetrac installed in my 2012 C63 and will use the same spec oil - 75W140.