nope 45 to 50 in my manual reduces tendency to shimmy, never have had a shimmy but then i don't have a stock tail spring either...Scott 3400 with a Piper Pawnee tail spring... Super heavy duty...

iceman wrote:nope 45 to 50 in my manual reduces tendency to shimmy, never have had a shimmy but then i don't have a stock tail spring either...Scott 3400 with a Piper Pawnee tail spring... Super heavy duty...

That now-famous diagram by Pierce Aero shows that shimmy is mainly a product of a slack castor angle of the tw pivot, and the factor that contributes to it is mainly worn or slack tailwheel leaf spring(s.) Really, really good article by Gilbert Pierce (Steve Pierce's dad) here. Of course he also suggests 45 psi in the tailwheel, but more as an anti-slip/shear precaution.

So, even if your spring is super heavy duty, I think it's still possible for it to shimmy if it creates too slack a castor angle while loaded. In that article, Pierce says he had his main spring re-bent to steepen the castor angle of the tailwheel pivot.

Perhaps this is another topic...

exactly why I got a new tail wheel spring... I could have searched out someone to re do it but I just bit the bullet, which wasn't all that bad , and got a new one... Angle is better than it was but it still isn't where the recommendation says it should be. Like I said I never have experienced tail wheel shimmy for whatever the reasons it's caused...and 45-50 lbs is what Maule recommends although that's for their factory tail wheel I suppose... anyway I go with that for what it's worth.