Drag on curves - knuckle versus hook and loop couplers

[rperego]

I'm trying to determine why I'm experiencing a fair amount of drag with one train on a layout with 5' diameter curves.  It appears the bachmann couplers are so stiff they torque the wheels against rails.  Another train with the same number of cars but with hook and loop couplers draws considerable less current on the same curves.   The cars having the problem are plastic wheels whereas the ones with the hook and loop are metal.

Is there a suggested modification to make the knuckle couplers move sideways better rather than twisting the truck or is hook and loop the better solution?  I've also noticed fewer problems backing up around tight S curves with hook and loop.

Thanks, Bob

[rperego]

Forget this post - the problem is the ID of the track in some places is less than the minimum required.  Also, the wheels on some of the cars with the knuckle couplers don't spin true which is compounding the track width problem.

[hobo]

I run my Bachmann cars on 4' and 5' diameter LGB track without any noticeable drag.  However I don't have any cars with plastic wheels.

If the metal wheels on your 'working' cars are the same width as your plastic ones try switching them and see if that makes a difference.  Plastic wheels are notorius for causing problems.  And Metal wheels generally roll smoother then plastic.

I'm not the biggest fan of Bachmann couplers but they do work. 

If you are not concerned with being prototypical, then the hook and loop couplers will work better for running trains/cars on small diameter curves.  I find that they are easier to couple and uncouple and they stay connected better.