Double check the wheel gauge on all the wheels on the steamers. Also look for binding with the side rods. Travel through the straight route should not be affected by steamers if the wheels are correctly gauged. It is possible on teh diverging routes the turnout is too sharp for the steamers wheel bases - but that can be worked only on teh steamers chassis modifications or installing larger turnouts.
Place a straight edge on the turnout and check that all is level, aligned and no bow or bend vertically along the rail heads or at the frog.
To make corrections - you have to determine what is causing the 'bump'.
-ed-
_________________
-ed mccamey-
COSLAR RR -
http://www.coslar.us/NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.