there should be no sensors in the diff, or on it.

and you have choices from 3.5 to 4.11 as far as final drive goes, 4.083 is most common.

like i said, once i get my jack fixed (broken 400 dollar craftsman jack wtf) i'll get under it and see what i think

 

I think what bmorgan trying to point out is that there are sensors in the wheels and in the transmission, and when the computer sees that the wheels are spinning at different rates than it thinks they should be compared to the rpm of the crank shaft, it goes into limp mode.

That would indicate that if you can't fool the computer, the only replacement differential you can use would have to have the exact same gear ratio.

 

you can be off by a few percent, the ecu has to have leeway for tire/wheel size.
and you can fool the computer, they make things for that.

theres no way with an r200 to get down to 3.07, but you can get sorta close.
they make speedo healers for this purpose to manipulate the signal from the wheel speed sensors.

 

I will eagerly awate the outcome of this. It would definetily be sweet if we could put a higher gear in the rear end.

 

Well, if you figure out how to fool the computer, you'll make a lot of people happy. I'm not saying it can't be done, just that no one has yet.

 

For racing operations, you could cross wire the front wheel signals to the back (needs a buffer amplifier ) wheel sensor inputs.

I would not like that and feel that there should be a way to send a signal to the tcu to make it ignore the real wheel speed sensors. Unplugging them would be a simple test to see if that went limp also or not not..

This being said, I race the autocross circuit with my YAW sensor switched OFF and have NO issues. It might be as simple as that, but NO ASK: NO GET.

[ The Legal department has requested that I include the fact that the BAS lamp indicator lights up during the time the YAW sensor is switched off. It requires the steering wheel to be turned lock to lock for a reset when YAW is switched back on ]

WOODY

 

The only thing the ecu should be looking for is that the rear wheels are at or slower than the speed on the front wheels.
as long as you keep it like that, it should be an issue.
I dont think the ecu works rpm vs. wheel speed unless you're below 10mph

 

Actually in this case, it's the TCU rather than the ECU.

 

well, you're automatic. Im not

 

So I was still going through this diff trying to determine if it is definately incorrect since Soward says it was ordered off his VIN.

Well the diff gear counts:
SLK32 - Ring = 46 / Pinion = 15 Ratio 3.066
New one - Ring = 36 / Pinion = 11 Ratio 3.272

Woody: Do you have a step by step to tear the diff down?


(EDIT: Wow, nothing like missing the obvious... There is a stamp on the rear lip of the housing that shows the gear ratio...)

 

diff dis-assembly is simple.

pull the output shafts, keep track of left/right

mark the bearing caps, left and right. i use a punch and mark one with one hit, one with 2 and mark the case to correspond.

remove bearing caps and shims, keep them in order to left right, this is important.

the diff should pop out, removing the final drive is simple. the pinion gear uses a crush flange iirc for pinion gear preload so you'll have to get a new one from mercedes.

download the service manual on here and it should tell you everything you need to know

 

Ok, got them disassembled except for knocking the pinion out. I use a center punch and knock it out correct?

BTW, I had to run by a machine shop to get the retaining clip/shims out. I just didn't have a set of pliers that could compress them enough. What a pain!

The old pinion is toast:

 

The speed sensors are connected to the ABS controller and from there it outputs the front and rear wheel speeds in a summed/2 fashion. The actual speed reference that the transmission uses to compare to the N2 speed sensor is read via CAN. There really isn't a way to make this work and no, speedo healers will NOT work for this application as the only things that don't use the CAN for speed outputs are the radio, amplifier and wipers. As for what waldig suggested, you could tie the front and rears together but the problem there is that the front and rear wheels spin at different speeds so you'd have to hope that the speed difference would be within tolerance but then, the first time you spin the tires, you'd fault the TCM into thinking there is massive slip in the transmission as the N2 does not match the summed wheel speed sensors divided by the final drive ratio or 3.27. There are lots of systems at play here and unless you can account for every single one, you're bound to have a problem sooner than later.

 

Well, I finally am back together... my buddy located a junkyard unit in FL for me. I was going to swap the gear set on the new 3.27, but it was going to be twice the money of a junkyard unit in the end. Someday, I'll build this other unit so I have a spare, but until then, this will have to work.

One note, I sent 3 e-mails to Phantom Grip and called (no answer) and left voice mail , They have yet to return a call or e-mail (been a week)... guess they don't need new customers. I 'was' going to throw one of thier units in while I had it apart...

Install by yourself is not recommended, but not imposible either with the right tools. I borrowed a motorcycle jack from a buddy. Made the job a whole lot easier.

The 2nd pic is the new 3.27 broken down for reference, for those that where curious what's inside... Yup, a plain old open diff...

 

Thanks for the photo"s. Great to hear that u found a replacement unit. Hope that it did not set u back a lot$$. Danny

 

I've been hoping somebody would come up with an "off" brand differential that could be modded to fit our cars ever since I joined this forum, and found out Mercedes wasn't a viable alternative. Stupid me, I bought my car thinking it was a simple matter of purchasing a new ring and pinion over the parts counter.
I would think you might be able to "fool" the SRT's puter by using a 3.50 gear out of Nissan and compensate with a taller tire.
It would be great if you guys finally crack the code and defeat the computer though. I'd love to see what a SRT would do with some 4.11's

 

Oh Hell Yeah If I Could Run A 4 Plus Rearend I Would!!!!!


Went Ta The Local Dealer For The New Challenger ....said Heres The Deal I Will Give You Cash....change The Rear End....said No Way For No Amount Of Money.......i Walked They Been Callin Everyday Since.....can Ya Say Jeep Srt8...............