22 June 2023
It's been over a week, and I owe an update. Been putting in long hours on the "2023 Crossfire Tech Refresh Program" (TM), and haven't sat still long enough to give an update. Drivetrain is out, and has been pushed to the side for now while taking car of more chassis/body centric chores that need to be complete before that stuff can go back in. We last talked about the stock rear subframe coming out, to make room for the new and improved subframe that can take several different Mercedes rear ends, including the HAG 215. So, here's where we left off: the new subframe is tacked up and several test fits with the Challenger differential have been completed. Here's what the subframe looked like at that point:

The trick here is that third offset differential mount hole. That mount allows the newer 'dogleg' rear ends. So we're cruising at this point. Perfect time to sit back, take a sip of tea, and decide to scrap it all. Yes, that's right, this subframe was binned. OK, I just moved it to the back of the shop. Everything about it was going to work just fine, but it was just overly complicated. Does this mean we're giving up on the dream of the HAG215? Oh, no, no, no! Now we'll just start cutting up the only other good Crossfire rear subframe left! And that's exactly what happened next. Except this time, the rules would be slightly different. Only the portion of the subframe where the third differential mount is would be cut out this time, and then a lot of measuring, messing up, cleaning up, re-doing and finally that sausage was made!



This was also the proper time to replace the subframe mounting bushings, and so:



I cannot stress enough the importance of having the proper special tools for this job. Doing it without them would be awful. These were purchased off eBay for around $100 per set (there are two sets). These do all of the bushings in the rear subframe, and I believe the front control arms. (Do not replace front control arm bushings - just buy complete SLK320/32 front control arms. You can thank me later)

So now, it was finally time to setup the rearend with the Wavetrac. This went mostly smoothly, with one minor exception. Nowhere does it tell you that the Wavetrac will not fit into the housing as it is. It is physically larger than the stock differential, and you just cannot get all the angles needed to insert it into the housing. I have had similar experiences on other rear ends and transaxles when installing Quaife LSDs in them. The fix is relatively simple, grind a chamfer on the sides of the back side of the housing to allow more angle when inserting the differential. In the future, do a test fit BEFORE the pinion shaft is installed. In this case, everything had to come apart to grind, clean, and then reassemble. Here it is, in place. If you look closely, you can see the chamfers on the rear of the housing:


So now that is done, install it in the frame, right? First the game plan is to use the early style bolt together axle shafts like the SLK, W210 and W208 cars used. Problem is that there are no stub shafts out there for the HAG215, but fortunately an Australian user on MBWorld had made some, so I purchased those.

So now, we need to bolt in the differential, pop in the W210 axles I already had, and go. Yeah, ok


Two big problems. First, the axle is about 1.25" too long. Second, the bolt patterns on the hubs and the axles do not match. *sigh* Back to the drawing board, and about two days' worth of research, looking at junkyard shafts, etc, until a brainwave was had, and we actually went back in time 18 months when the idea of a HAG215 first came to light: A hybrid push-in axle. I had purchased four axles with the idea of coming out with two that worked. Two Crossfire axles and two Dodge Charger Hemi axles. The idea? Take the shaft and outer joint from the Crossfire axle, and the inner joint from the Charger. And this was what had been done, and then the axles were forgotten about when the lure of the ease of maintenance of the bolt in axles and stub shafts from Australia came along. Before putting the axles in, one item needed to be addressed. When the V8 first went into the car, there was an issue with the exhaust. Specifically an SRT-6 exhaust was to be used, but the 2004 limited rear subframe was missing a provision to bolt up an exhaust hanger bracket that the SRT-6 resonator needed. In hast, the bracket was welded to the subframe, and it was a really lousy job. On top of that, the bracket was not in quite the right spot, so the exhaust was a little crooked. Referencing the SRT-6 subframe I had discarded earlier, holes were drilled and nutserts put into the Limited's subframe

SRT-6 subframe with the bolt holes for the exhaust bracket

Out of room for pics in this post, more in the next....