yooker

I am very confused at the car right now, I don't know if it's an open diff or a limited slip diff. The car did not have the performance package so it should be an open diff, but today when I was take a corner with a bit too much throttle, I noticed that instead of 1 line of tiremarks, i got 2 lines instead. Also ESP was fully off when I was taking the corner; so does this mean the normal car has a limited slip differential?

hhughes1

An open differential provides equal power to both rear wheels regardless of circumstances. A limited slip allows a pre- determined amount of power to be shifted to the side with better traction or a shorter radius around a tight curve.

yooker

I thought an open diff will apply the power to the wheel with least amount of resistance

boborola

The standard C63 does not have a LSD, but it can also be ordered without the PP.

manilamerc

Certain markets can order the LSD as a stand alone option. I had the same problem as you a while back. Not knowing if my car had LSD or not. I finally begged the official MB importer in country for the data sheet of my car and it showed it had the LSD as a stand alone option.

pshek

If you have the car up on a lift or if you completely raise the back end with a jack and put the car in neutral, you should be able to turn the rear wheels. If both of them spin at the same time in the same direction, then you have a limited slip differential. The other way to check is to have the dealer check your datasheet from the VIN.

GMW

I don't have the LSD option but I once peeled out of parking lot and left 2 lines of rubber. I'm guessing if both rear tires have about equal weight on the ground both wheels will spin.

yooker

But an open diff will always transfer the power to the wheell with least resistance, so for any corner the inside wheel will be spinning like crazy while the outside wheel will get no power. So why did the car leave 2 lines of rubber when i was drifting around the corner instead of having only the inside wheel spinning and leaving one mark? The marks are pretty long to so the open diff should have had a chance to work and divert the power to the wheel with least resistance. I'll try to get a picture of the tire marks for you guys to examine.

PC Valkyrie

That's because your C63 (like the C55) also has a "pseudo" electronic system that tries to mimic a LSD when you press ESP Off.

If the inside wheel is losing traction and spinning in excess compared to the outside wheel, the system will automatically apply some brake pressure to the inside wheel to minimize the excess spinning, which automatically transfers more power through the open differential to the outside wheel which presumably has more grip. In this ESP Off mode, there is NO CUTTING of engine power, just some brake action to limit the inside wheel spinning to mimic the effects of a LSD. Obviously, it isn't as good as a mechanical LSD, but it definitely helps.

yooker

If what you say is true, then wouldn't the install of an aftermarket LSD also cause the electronic system to engage because it wasn't programmed to have a mechanical LSD in mind? Also that's got to be terrible for the rear brake pads.

PC Valkyrie

I'm 100% certain what I posted is true (it's in the C55 and C63 press releases from MB when the cars were released).

With the optional or aftermarket LSD, the inside wheel (wheel with less traction) will NOT spin excessively. Therefore, the electronic system doesn't even have to intervene. So there should be no problems.

Yes, with sustained track use, the constant application of the rear brakes to the wheel which is spinning excessively can result in brake overheating or wearing of the rear pads. I've tracked the C55 many times and it hasn't been a problem.

We know it works, though, as laptimes for the C55 are faster than the C32 (which doesn't have such a system).

You have no choice in the matter. The electronic "pseudo" LSD system cannot be deactivated in any of the ESP modes on your car. This is basically the exact same system found on the 135i, which people more commonly call the "E-diff".

yooker

Well since you are able to put the power down with "both" wheels on the C55 as opposed to the C32, it should be faster.

Thanks for the info, it helped a lot, i'll still try to get the pictures to you guys.

PatSC23

so why is it that you only have a differential service scheduled if you have the LSD and not the stock differential?

yooker

A LSD uses actual gears to slow the action of the spinning wheel so it's a wear item so to speak. It needs the service because all those rough edges are smoothed out during the first service period. An open diff does not slow down the wheels so there is no need.

shaker

Agter your post on the thread "Hey guys, please help with my mods gone wrong..... " I don't believe anything else you post from now on .... LOL

yooker

Learn to differentiate between jokes and fact.

shaker

that is very good.... you do the same then!...... there was "LOL" quoted ....