Grinding Tech U springs for softer vertical release

[skis_the_trees]

I thought I would start this thread as a reference for people wanting or needing to grind their U springs for softer vertical release. There is some limited info on the web for this, notably the Wildsnow post here: https://www.wildsnow.com/19750/modif...t-superlite-2/ (however, the comments are closed, so that makes it impossible to update or add info there).

My Dynafit SSL 2.0 (now known as the Superlite 175) bindings had the standard ridiculous vertical release they shipped with. People have thought the vertical release was 12-14 with the stock springs. In addition to the danger of this, it makes stepping in on soft snow or off camber slopes very difficult.
The Wildsnow post shows Lou grinding the inside of the spring for softer release, he says he "ground the inside of the arc down to 4 millimeters and the step-in feels right, lever test feels like about release value 7, perhaps 8." I normally ski my alpine bindings 8 or 9 and typically tech bindings around 8 without prereleases.

Note that other Dynafit U springs, notably the TLT Speed and new Superlite 150 U springs are ground flat on the outside and not the inside like Lou's mod. This is easier to do on a bench grinder rather than use a Dremel and was my preferred method. I'm actually not sure what the claimed RV on these TLT Speed springs was but they are notably thinner in the arms AND measured 0.125" at the narrowest section of the U. (They look identical to Superlite 150 Z6 based on web photos)

I first ground my SSL 2.0 springs first to 0.155 on the outside of the U but a carpet test still felt too hard to step into. (Of note, part of a hard step in is related to being a U spring and not allowing the arms to rotate like a Speed Radical or Kreuzspitze GT). I then reground them to 0.145 and it feels about right. This was done on a bench grinder followed by some 1200 grit sand paper to remove the grinding marks. I recognize this is very subjective, not measurable with the tools I have available, and therefore not science. YMMV. But I can at least step into my bindings now.

Luckily, if you make your springs too soft you can purchase new ones from Dynafit (including now in 2 different vertical release values). But rather than spend the $ on new ones it seemed worth it to grind mine first.

[Spyderjon]

I ground some SSL 2.0 u-bows for mates and a couple of customers (who'd signed a disclaimer) as the factory ones, especially on the 6-12 version, were ludicrously stiff. Luckily I've got a torque testing machine so I could use that to calibrate them. I Dremeled them with the bindings mounted and the skis in my torque tester (suitably masked out to keep out the grinding dust) to make the testing easier. And I ground the outside like you. Don't think I went lower than 8 din but I didn't keep any thickness measurements. And they're all still going strong. I know a guy that works in the Dynafit Design Dept and he then got me a bag of softer springs so used them thereafter until the different Superlite 175 options came out.

[John_B]

I just got a set of Superlite 2.0s and had initially been a bit concerned that they were the lighter version. Hearing that the higher RV was coming in at 10+ makes me feel better about the softer spring!