Lionel Legacy SD40 "Lash-Up" Problems

Check the traction tires on the trailing unit and make sure they're not dragging the brake shoes (check both units while you're at it). Lionel's "new" traction tires are too thick and cause all sorts of problems.

The lurch and jerk looks like thats what the problem might be. 

Do they run smoothly separately?  If you address them as the same TMCC ID, will they run around the layout at close to the same speed together separately?

John

They are programmed together as a "lash-up" as Lionel calls it. In the video I show how one unit accelerates faster than the other while uncoupled, but still being addressed as a "lash-up"  I would not expect running them together using the same TMCC ID to be a relevant test, since they're supposed to work together using the "lash-up" feature.

My MTH units stay synced perfectly while uncoupled, but running as a "lash-up" as do my non-speed-controlled TMCC Weaver GP38-2s, although not always, after all they're not speed-controlled, but they pull and play nicely together whereas the new SD40's, as you can see, do not.

Just trying to figure out what's going on. Will a Legacy command base fix this?

Well Rich, running them together with the same ID is a very valid test.  The point of the test is to see if with identical configuration, they run at different speeds.  If so, you're going to have a significant issue trying to MU them, and it also verifies that the MU configuration isn't the cause of the speed variation.

We'll have to agree to disagree on that point.

Running a Cab2 setup would not change the situation. The lash-up in both bases are essentially the same.

It seems to me that the rear unit is the one with the problem. It runs fine and then bogs down and continues that cycle. Make sure to check the traction tires as Boilermaker stated. They could be rubbing on something on a truck. It's also possible that the issue could be internal - say something is rubbing against one of the flywheels. I would suggest calling Lionel and sending it in for repair as it is certainly under warranty still. Don't take the shell off yourself or you risk voiding the warranty.

Thanks for the input John & Dave.

I'll give both units a quick look over to see if it's anything obviously mechanical like the tires.

From what I understand, the TMCC signal and the Legacy signal are different somehow and Legacy deals with absolute speed steps and TMCC only has relative speed steps. (is that right?)  I guess I was hoping that this was the cause rather than the brand new, expensive locomotives not working properly straight out of the box. Now I'll have to pay an additional expense to ship them back to Lionel.

Thanks again for the help guys.

Well, when you think about it, at least one has to have some issue.  If you program then identically and run them in the same mode, they should give you the same performance.  If not, something is clearly amiss with at least one of them.  That was the point of my TMCC test.

Have you entered the engine info of both of them into the cab-1?

This past Wednesday, I received my new BN SD40 back from Lionel for a warranty repair.

Customer Complaint/ Problem:  engine running jerky, trailing truck making a grinding noise.

Comments and Corrective actions:  Rear truck would not move until high speed step - last axle on front truck had wide wheel spacing causing gears not to mesh and given inaccurate feed back readings to Odyssey encoder.  Wheel spacing corrected and capacitor added to encoder.  Test run four hours 4 hours.

My views and observations.  In my opinion, the Lionel Customer Service Department is in the same league as LL Bean off Maine - The best of the best.  The only qualms I have about sending repairs to Lionel is exposing anything to any shipper of my choice. Another story in of its self.

Under legacy control and Odyssey on, the engine surges from speed step 1 to 50. Above 50, it starts to smooth out.  Before the repair, the engine would just about stall at speed step 25 and then become excessively jerky.  Which ever truck is the trailing truck,  that truck  stills makes a grinding noise on the 084 fastrack curves.  Running a 7 car consist with the engine and a quite train room, one can hear the train surging as is comes up through the program speed steps.  Seems like every wheel rotation, the engine will slow then speed up.  

I am responding to this post to gain any further insight into this problem/solutions and, most importantly, in hopes of providing useful information for others. Having worked in the auto industry during my younger years, I fully understand that resolving quirky problems often takes more than one attempt.

I will be corresponding with Lionel to ascertain if I should allow for more break in time or if a return trip is in order

Chris

Hi Chris

So even after you sent yours in for warranty repair, it's still has problems?  It sounds like my problems are somewhat similar. I really hope I'm not going to have to play the "send it back & forth" game. That gets expensive quickly.

I'm going to see if I can get mine shipped out to L today. I'll let you know what I find out.

Wow I have the exact same problem as you Chrico. I bought a new sealed SD40 and mine has the surging problem also. It's been frustrating as my first Legacy engine. 

I think I may have found the source of my binding. Check out the difference of spacing between the drive gear and wheel on the two driven axles. One has a gap and one is tight against wheel. This is on the rear truck. The front truck has both gears tight against the wheels on the drive axles. I pressed it back but still have a lurching at speed step 25.