Quote:
Originally Posted by Moupe
10/10 F31 journal. I love how thorough and enthusiastic you are about every addition and modification you feel me? Loving the blue threading over black Dakota, oooweee! Would read on the john, would read on the bus, would read at work.
Keep reppin' us F31s mayn! Oh yeah, when you ordered the wagon you should have told your CA to put in for 5DC (folding read headrests). It amazes me how this effective, cheap ($65), and aesthetically pleasing factory option isn't available on US build configurators. In any case, it's something east to add on after the fact.
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Thanks for the kind words! I definitely have much more exploration and things I'm working on that I'm looking forward to sharing here. I wish I had your foresight on the 5DC option when I put my order in. I wasn't even aware of it then! $65 is a whole lot cheaper than what I paid for those salvaged headrests!
K-Mac Camber Adjustable Bushings
One of the things I've been chasing last year was how to get more negative camber, without having to resort camber plates. With all of the rough/unpaved surface driving I do, I was worried about the additional noise from camber plates. Plus extra knocking noises would annoy the heck out of me in daily driving. I started off this journey by seeing how much the stock components could be pushed (-0.6deg), followed by Superpro's camber adjustable bushings (-1.1deg). Powerflex also has a camber adjustable bushings, but the adjustment range is the same as Superpros (+/- 0.5deg). RWD owners are lucky enough to be able to use M3/4 lower control arms/wishbones, but it's a bit interesting since you need to put shims between the bushing and subframe mounts. xDrive owners are out of luck with that method as Kies Motorsports found out.
I read in the 2-series forum that K-Mac had made a camber adjustable bushing, and was able to get a larger adjustment range than Superpro or Powerflex. I got in contact with them last August, and found that they did have a design, but it wasn't very well vetted since Australia doesn't get xDrive cars. Kevin is the owner of K-Mac, and was very responsive via email and phone. We had a couple good chats about testing the product for xDrive. One of the fun facts I learned was that the owner of Superpro used to work for Kevin at K-Mac.
K-Mac's bushing (PN 193616-8H) uses a steel core "main bushing" encapsulated by polyurethane caps and steel washers which go between the subframe mounts. On the opposite side of the subframe mounts go "bite washers," which clamp the bushing in place to hold the camber setting you want. The polyurethane caps are two pieces, so you don't need a press to install this bushing, and you don't need one to remove the original either since K-Mac includes an extraction cup/tool (however I didn't use it and did use a press to remove my old bushings). Adjusting the camber is easier than other solutions too. You just use a regular socket or wrench and turn the head of the included bolt to rotate the bushing/camber setting. No proprietary skinny wrenches required!
All the pieces with "teeth" are meant to bite into the subframe mounts, and the end washers need to be even/on the same plane as the ends of the main bushing so both sets of teeth can bite. There's a washer with tabs to fold and "lock" the nut in place that the main bolt screws into, but I don't recommend using it. Torquing the nut to spec (100Nm / ~74ft-lbs) crushes the washer and you'll need to use a dremel to cut it off. Note that the bolt included isn't a torque to yield bolt, so don't do the extra 90deg after torquing to spec.
I had to go through a couple rounds of revisions with this part before ended up with what I have now. The first revision of the product had the main bushing too long. It, plus the polyurethane caps and end washers wouldn't fit between the subframe mounts. The next revision I received corrected the main bushing length, but I found that the end washers didn't sit centered and flush with the heads of the polyurethane caps. I asked Kevin about this and he confirmed that they should sit flush with each other and that he has made a revision to the polyurethane mold to correct for that. For me, I ended up using my dremel to grind down the caps till they fit the curvature of the washers. Lastly, since the caps I had were for the original longer main bushing, they also had to be shortened. This required more dremel work, but was straightforward. I confirmed with Kevin that he had made the necessary adjustments to the new pieces and he verified he had.
If there's one thing I've realized about K-Mac, is that they're definitely more of a small business where the owner is heavily involved in ground operations and passionate about what he does. This means they're able to iterate very quickly, but also that there aren't the same business practices and protocols of larger organizations. An example of that is the lack of PN revisions. In all the revisions of this part I've been through, the original PN hasn't changed (nor are there revision modifiers). I think K-Mac is able to compensate for this partly with their quick communication.
So after all was said and done, what camber was I able to get? -1.8deg! This is -1.2deg more over stock, and right in the range I was hoping for (-1.5 to -2deg). It made a very significant difference at the track this weekend and my tire wear and corner grip was noticeably improved. In addition to the two track days I had this past weekend I've also put about 1500mi on them in daily/weekend driving. I'm glad xDrive owners finally have a non-camber plate solution that you can get a respectable amount of negative camber with.
*spoiler* I'm also working on testing/iterating a caster adjustable tension strut bushing for xDrive.