In response to a question about hard turning REVs, our friend Harvey Edson provided the following (informative) insight;
â€œI have read your response in the Jan/Feb issue of the subject 600 HO Rev from a Bob Graham. I have a 2003 MXZ HO 800 that I put USI (PX 301) skis on as I didn’t like the Ski Doo “Precision Skis” The steering effort was so high that I re-tore a rotator cuff that had been previously repaired. I had considered all the suggestions in your article, and tried a few, all very valid suggestions. However, I didn’t wish to significantly change the existing responsiveness, and under/over steer characteristics of the sled. Of course most your suggestions do influence those parameters.
Suddenly, I happened to notice that the mounting saddles on the USI skis had three mounting holes. (I was mounted in the normal middle hole) I simply moved the skis forward one hole (now being mounted in the rear hole) and the effort was dramatically improved, similar to what I was used to on previously owned Polaris’s etc. For me, the problem was solved. (SLP also has something similar on their ski saddle mounts as well.)
Moving the ski forward reduces the steering restoring forces (steering effort in a turn). This is because the fore and aft distance is reduced measured between where the steering spindle would intersect the ground, and the center of the ski at the ground where the lateral force is generated (in a turn). In summary, the moment arm trying to straighten the ski is reduced.
In automotive terms, suspension engineers call what I am describing as “Caster Lag”. It affects: 1) On center handling (wandering), 2) Return-ability to “straight ahead” from a turn, and significantly 3) steering effort in a turn.
On manual steering vehicles, we intentionally reduce the caster (lag) to minimize steering effort. Believe me, it is very influential to steering effort on a sled, and by moving the ski fore and aft, one vastly changes the steering effort in turns.â€