There are two things you can

There are two things you can do to close the gap, they both employ gluing in shims.  1) Glue a  vertical shim to the side of the guard rail so that the shim extends into the frog area to make the gap narrower. 2) Glue a horizontal shim to the bottom of the frog so the wheels don't drop as much when they go through the frog.  

Bouncing up?

If the equipment is bouncing up, have you looked to see if the flanges are bottoming out?  Double check the flangeway depth, and the size of your flanges.  I have some older non-RP-25 equipment which runs on it's flanges on code 70 track, and I used to have problems with solder filling the flangeways on my handlaid track before I started using a brass plate under the rails.

Also check the gauge.

Check and make sure the track spacing is in gauge. I've found some flex track and switches I have were a bit narrow and would cause the cars to "jump up" when going thru that section. Also check the wheels as well to make sure they are in gauge as well.