Well, I finally got some track laid this weekend and got to see how well my engines ran through the Atlas code 55 turnouts. I was a little concerned because when trying to slide them through, there was a bit of a catch at the frogs. When I hooked up power, my ER-Models shark ran ok through the turnouts, but it noticeably lifted each truck as it went over the frogs of each turnout. My Bachman 4-8-4 northern on the other hand liked to derail every other time through, and significantly lifted itself up over the frogs.
I thought maybe the problem was the depth of the frogway, but every boxcar I tried ran smoothely through, it was just the locomotives. So I decided I’d check the gauge of the turnouts and it seemed perfect. Then I checked the gauge of the wheels and sure enough, the gauge rocks slightly back and forth rather than settling around each flange. The 4-8-4 was a little worse than the sharks.
So now here it is, what’s the best method of adjusting the gauge of the wheels on these two puppies? The 4-8-4 looks straightfoward enough… just pry the wheels apart a smidge as they look to be press-fit onto the axles. But I can’t see the end of the axles on the sharks to know if they’re adjustable. Does anyone have any tips?
Thanks!
you may be able to move the wheels out or in without removing the trucks. the axle is held together by the drive gear and the wheels can be pryed over a little to put them in gauge. be careful not to move the gear or it may bind up.
Nobody else?
Should I use two screwdrivers to pry the wheels in opposite directions? Will I bend an axle? Would pliers tear up the surface of the wheels? I could really use some insight here from anyone who has done this before (and I know someone has!) 
Thanks
Use a flathead jeweler’s screw to nudge the wheel out. Once you’ve felt you’ve moved something, check it against an NMRA or Micro-Trains gauge.
In some cases, re-gaugung a locomotive wheel can even improve electrical contact.
My Athearn F59PHI kept stalling randomly until by chance I fixed the gauging of the wheels, and it stalled no more!
Well, with the relative lack of advice of what not to do, and confirmation that using a screwdriver to pry would be ok, I dove in this morning…
…and after re-gauging all 16 wheelsets of the loco and tender, my Bachman 4-8-4 Northern now runs perfectly smoothely through my nice pretty atlas code 55 turnouts. Hurray!
And, I didn’t break anything
For anyone that digs up this thread in a future search (like I tried to), I used a dremel vise to hold the loco or trucks still and used two small flat-head screwdrivers to pry the wheels apart. For the pilot trucks and tender, I used one screwdriver to apply gentle pressure to each wheel at the same time to avoid stressing the plastic too much in any one direction. For the larger drive wheels, I used two screwdrivers, one on each side of the axle of one wheel to apply even pressure, prying slightly with one and twisting slightly with the other.
I did remove the front pilot truck and one of the tender’s trucks to adjust them, but the the others I left attached as I got better and more comfortable with it.
** You think your model railroading skill has improved! **
I’m all fired up and ready to lay more track now
Thanks Metro and Retsignalmtr!