So for the bump steer... it seems like the goal is to raise the rack and make the tie rod ends lower?
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When I order the new subframe could I buy a few steering rack shims too?
We want the rack as high as we can while still clearing everything well (generally I think that 1/8 to 3/16" clear is a reasonable). I want to be a little careful about referring to "raising the rack." All possible Ronin rack positions are lower than stock, we add shims to minimize how much rack lowering is required. However, we felt this was where the engine needed to be. The only alternative is to be like Sikky and drive the engine higher and even further aft, but then we force folks to do a great deal of clearancing. In retrospect, I have to give to Sikky props for clever marketing, but at the end of the day, it's doesn't fit right, and weren't going to go there. I had to laugh when I realized that Sikky oil pan isn't appreciably thinner than the F-body--at least at the point we care about--but of course either pan still has to clear the crank.
Anyways... all bump steer correction needed results from lowering the tie rods pivot position. We want it lower to adjust for the factory bump steer. Side note, I do wonder if Mazda's wheel fitment on 16s was part of why factory bump steer exists. We need to lower the ball joints further yet to compensate for the rack being lower and it's not a 1:1 move (which is where we think Samberg went wrong). You'll want to dial it in via test but it's closer to 1.5:1 with the ball joints needing to move ~3/16" for every 1/8" rack move.
The Speedway motors nut is a jam height nyloc so that should help a bit vs. Samberg's castle nut. That said, you may want to consider jumping into 18s next time you need tires. I seem to recall RPF1s having a pretty small barrel for a 17 as well.
Shims... These are dirt simple, so I'd suggest you make your own to be cost effective. Flat bar with a couple sloppy holes would work fine. Hell, you could get away with a couple washers under Samberg's aluminum block. If you need them we can talk, but for tiny add-ons like this I always feel like we have to charge more than they're worth given the cost of time and handholding to make custom requests happen. We will likely offer some subsets of the steering kit as well, but probably not broken down the level of individual shims.
-Joel
