Join Date: Mar 2018
Vehicle: 2002 SLk 320. 2002 SLK32 and others that don't relate to this group.
Other Toys: 1971 Porsche 911, 1981 BMW R80gs, 1969 BMW R60/2, 2013 Smart Electric, various Mercedes.
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Before modifying the SLK32 it was powerful enough to trip the traction control regularity. After I installed a Eurocharged tune and 65mm supercharger pulley, isolated the intercooler circuit, reprogrammed the transmission and built a dual cold air intake pushing the HP to 420 +/- it became nearly undrivable.
With the traction control on it tripped constantly and with it off I just spun one rear wheel constantly.
I ordered the Wavetracl Torson LSD. The installation was pretty straightforward although you do need to have the output flanges of the diff machined. I happened to have a SLK320 diff in my shop and checking the part numbers found that they were the same, so I pulled the back cover off, removed the C clips from the inside of the axle shaft planetary gears and removed the axle flanges and took them to the machine shop. They needed to have the slot in the end deepened a bit and widened. This is because the new carrier comes with spring clips as the torson carrier does not allow you inside to put the clips in place and the modified axles will be popped in place with a rubber mallet.
When the axle shafts were done I painted them and drained then removed my diff. This is straightforward and can be done without removing the exhaust if you are creative. Unbolt both axles from the diff and wire tie them up, unbolt the drive line flange (Photograph it first so you put the bolts in the right way around later) and support the diff. Now remove the long bolt going through the node of the diff and be careful not to lose the washers between the diff and the mount, they should be held in with a dowel which the bolt passes through. Remove the two rear mounts, one from under the car and one from inside the spare wheel compartment in the trunk that is too small to hold a spare wheel... Now carefully lower the back of the diff, you may need a small prybar to get the diff vent past the rear cross member support. As you lower the diff you can slide the nose of the diff off the drive line being careful not to chip the locating shaft on the end of the drive shaft. When it is free remove it and put it on a bench. Collect the two washers on the nose bolt, these set the alignment of the diff when installed. Clean the outside of the diff as well as you can. I sprayed mine with brake cleaner, hit it with a wire brush, blew it off, then sprayed it with etching primer and several coats of graphite gray engine paint and returned the following day to continue.
Remove the bolts around the back plate of the diff and tap a gasket scraper into the glued joint carefully, the back plate is glued in place with sealer and no gasket. Once you have the backing plate off you can rotate the axle flanges while looking inside the carrier until the little round protrusion on the C clip is in view, hook it with a hose hook, place a rag over the hook and the clip and pull it rearward. If the clip comes out the rag will keep it from firing across the shop where it will find the nest of 10 and 13mm sockets which have somehow vanished never to be seen again. Once the clips are removed the axle flanges pull right out revealing the splined shaft which locks it to the planetary gear.
Now remove the seals from the flange holes in the sides of the diff and you will see a large circlip on each side. Remove this from one side with huge circlip pliers. and you can carefully remove the outer bearing race from the differential housing. The bearing itself is pressed onto the differential carrier. Repeat on the other side by putting tags into the are where you removed the bearing race on the first siide and laying the diff on that side. Place each race and circlip in order so you know which was left and which was right. With both outer bearing races removed from the case rotate it so it sits in its natural position. Now the carrier can be slid a bit out of the drivers side of the casing allowing you to pivot the passenger side of the carrier out the back and remove the entire carrier from the casing.
Clean the casing as well as you can, you won't be in here again for a long time if all goes well. Put the case to the side. Set the carrier carefully in the vice (With copper jay liners or rags as not to mar it, and heat the bearing evenly with propane until the oil on it is smoking a bit, use a puller to pull it from the carrier. Set the bearing with the race and circlip you set to the side remembering which is left and which is right. Repeat for the other bearing. Now remove the bolts holding the ring gear to the carrier using air and clean the gear with solvent and air.
Take the new Torsen carrier from the package, it comes with foam you can use on the bench to hold it upright. See if the ring gear will drop onto the carrier, mine was too tight to drop on. I heated the ring gear with propane until it was hot enough for the oil on it to be smoking and it dropped right onto the new carrier, quickly rotate it to align the bolt holes and put tow bolts in by hand to locate it. Put lock-tite on the remaining bolts and install them, now remove the first two bolts and lock-tite them and put them back in and torque everything up. Mine was 75 ft lbs so I had to take it back to the vice.
Back on the bench I heated each bearing with propane to smoke point and dropped it onto the carrier carefully seating it completely. Once cooled the will not slip off. I suppose you could cool it with air, i just waited 15 minutes as I did not want to unevenly cool the bearing.
The rest of the installation is the reverse of removal, when both bearing races are in and held in with the circlips, and new flange seals are installed, you will install the modified axle flanges and seat them with a rubber mallet. Check lash. It should be about .003" I actually just held the axle flange still and rotated the drive shaft flange and compared it to a new Mercedes diff I had on the shelf. Refill the diff with Mercedes oil and carefully reinstall in the car. I mark the nose bolt with yellow paint pen so I can check that it has not moved when I have the car on the lift later.
The difference is day and night. With traction control off I used to be able to swap ends with even light throttle application in a corner, and on launch the car would swing to one side and violently snap back when I let off of the throttle. Now it just smokes both rear tires and locks up again when I back off. Corners are cleaner with less likelihood of swapping ends. The $1,300 seemed like a bit of change but nothing compared to the predictability it provides and nothing compared to the cost of sliding sideways into an obstacle or curb and having to repair the damage… Best $1300 I have spent outside of tires.