Hello Everyone, I have an Athearn SD40T2 that has trouble on 18" curves. It has RP25 wheelsets. I was going to try using the oversized "pizza cutter" wheelsets. I was wondering if Athearn ever made engines with the "pizza cutter" wheelsets that I could just drop in to the SD40T2? I was also thinking of grinding down the flanges on one set of wheels per truck. I don't know if it should be the middle wheels or the rearmost wheels (closest to the fuel tank). Has anyone ever tried either of these approaches? Which one(s) worked for you? I have limited layout space so going to larger curves is not an option. And I do love those Tunnel Motors! Thanks a lot for any information / opinions.
As far as i know, there are no over scale after market wheels available, I cant imagine there would be much call for them and they would probably foul on the frame. If you are sure that there is no issue with the track work (I used to have an old blue box SD40T-2 that went round 18"), I would check the cross level. If I was going to remove flanges I would do the middle axle, can you just pop the wheels off and see if it runs round the curve before you do any grinding?
Im not so sure that having blind drivers will help you at all. You might take a close look at all the wheel flanges, I have seen parts of the flanges missing, broken, not there. There is enough lateral play that without flanges the wheels could slip down on either side of the rail giving you more problems. Before you do that I would try making sure your wheel gauges are correct. You could simply remove axles 2 and 5 (middle axle each truck) make a 4 axle SD and see if that helps you as well. The loco will operate just fine without these axles and will not hurt the tractive effort all that much either. Your rail joints in the curves will need to be flat and without kinks to work though. I have had to trim the flash from truck sideframes that interfered with the frame too. Another thing you might need to look at is, sometimes these trucks dont sit square on the wheels, meaning if you take the trucks off and sit them on a flat surface, they should sit solid, any rocking means you need to tweak the truck to get to sit flat, also seen where the bearing slips off the inside bearing mounts, and lets the axles float instead of being where they should be. This can happen if the plastic axle is slide to one side leaving the other with too much play. There is more you can do but this is a start.
Athearn SD40T-2 is a very long locomotive for 18-inch curves. While many 6-axles diesels in HO will handle 18-inch curves, the longer they are the harder time they have - and even if they can stay on the track, they may derail freight cars coupled to it due to the overhang and difference in length, especially if coupled to short freight cars. I strongly recommend shorter diesels on 18-inch curves and for longer HO diesels a 22 inch curve is much better, such as tunnel motors or modern wide cab's etc. My personal preference for longer rolling stock is to use 28-inch minimum radius curves for smooth reliable operation. SD40-2 or SD45 is shorter than a SD40T-2 so those would manage better on 18 inch curves, although I consider 18-inch curves to be very sharp in HO, and due to this, it is really best to run 4-axle diesels on on them and limit freight cars to 60 feet long and less. Freight cars such as 89' autoracks and flat cars, even 85' passenger cars are best limited to 24-inches or higher curves, but I find even on 28-inch curves, long cars look like they are really hanging off, but they will operate smoothly. Anyway, food for thought.
