Here's a comment that should make everybody laugh ..... I had the vintage cars running backwards. I picked them up, rotated them 180 degrees and VOILA  problem solved!!!!! 

Is there any difference in HO scale trains between manufacturers? eg. say Bachmann vs, Tyco or Bachmann vs Athearn. is there a difference in dimensions? I have been building my 4'x8' layout with Bachmann trains and track. I'm quite impressed. Everything is working great.My reason for this post is  I recently aquired a Vintage Tyco HO train that won't run on my track very well.