Atlas Das 8-40b VS. Atlas GP40-2

Discussion in 'FAQs' started by Mrplow123, Aug 7, 2006.

  1. Mrplow123

    Mrplow123 Member

    I was sooo happy with my new Atlas Southern Pacific Dash 8-40b I just had to have another one. So I went down to the LHS today, and ended up with an Atlas GP40-2 in Souther Pacific. He had a great price on it, mainly because it had been in the display case for awhile, but it is new and runs great and is decoder ready. My only problem is, the dash 8 runs just slightly faster then the GP40. It isn't much difference, but it is enough that if I put them on the same track at the same voltage, the dash 8 catches the GP40. This isn't really a problem except I want to run them together back to back, and was wondering if it will be a problem that one is slightly faster? And which one should I put in front, the slower or faster one? Thanks everyone.
  2. TruckLover

    TruckLover Mack CH613 & 53' Trailer

    :wave: Hi Mrplow123,

    I have a ATLAS DASH 8-40B also, but it is a BNSF. Its my frist one of many to come.:) :D

    I think the slower one (GP40-2) should go in front but I am not sure about it. Anyone no for sure??
  3. 70Runner

    70Runner Member

    Unless there is a huge difference in speed it won't really matter too much. After the GP40-2 breaks in it will run closer to the same speed.

    The only time that speed difference is an issue, is when you have an older Atlas with a newer one with the slow motor.
  4. Jim Krause

    Jim Krause Active Member

    and if you go to DCC you can individually adjust the speed. Our club GN Empire Builder has an Athern AB locomotive set up and the B unit runs faster than the A unit at any given voltage on straight DC voltage. Hasn't been a problem.
  5. Russ Bellinis

    Russ Bellinis Active Member

    If you have directional lighting in both locomotives,, they will tend to run faster in reverse because the lights will be off. If their is a light in back, remove the bulb. Run the gp40-2 backwards coupled to the dash8 40b, and it may run close to the same speed because the gp40-2 will be runnig slightly faster in reverse.
  6. Mrplow123

    Mrplow123 Member

    Thanks for all the info guys. After running the GP40 for awhile, it did loosen up a bit, but is still slightly slower. I think I will try the idea of removing the reverse light from the GP40. It makes sense that removing the light will increase the voltage to the motor, therefore making it run a bit faster. Since I don't plan on running the GP40 in reverse by it's self, the light wont be missed.
  7. green_elite_cab

    green_elite_cab Keep It Moving!

    I think its nothing to worry about. none of my locomotives got a the same speed in DC, but i never have any problems. Don't remove the headlight, its not worth your time. If you want, you can get a reed switch, which magnetically turns things on and off. just wire a reed switch in, and attatch it near the top, and wave a magent over the switch to turn the lights on and off.
  8. Triplex

    Triplex Active Member

    It's quite normal for engines to not be speed-matched. I wouldn't be surprised if you were to get another B40-8 and another GP40-2 and find that none of the four ran at the same speed.
  9. Herc Driver

    Herc Driver Active Member

    Sounds like a good reason to go and get more diesels to me...or am I missing something???
  10. Russ Bellinis

    Russ Bellinis Active Member

    Are you suggesting it is easier to wire in a reed switch than to remove a light bulb?
  11. green_elite_cab

    green_elite_cab Keep It Moving!

    then again, common sense just hit me. Aren't the lights plugged into that circuit board? :rolleyes:

    well, i suppose i'd make a good super villain. the reed switch idea was needlessly complicated and unneccisary:D
  12. santafewillie

    santafewillie Member

    In some older Kalmbach model railroading books, the authors always recommended putting the faster unit in front. With DCC you just match them.
  13. KCS

    KCS Member

    We alway's put the fastest locomotive in the rear so the load can hold it back and everything will match up. How ever I think it's the way the Atlas Dash 8-40B was made. I have three of them now and they all run the same speed but I have 2 Atlas MP-15's I bought not to long ago and they run slightly slower. Maybe Atlas was trying to reproduce The Dash 8 speed's sense they were built for high speed reight service rather than switching and local service. One of the guy's in our club does the reed/mercury switch for lights operated simply by waving a magnite over the top of the shell in the center or rear. I think it's neat myself because you can run any given locomotive on the front and only have the lead engens lights on. Works really well for those switching operations when locomotives are moved around and run in both directions a lot. As for Athearn locomotives it's been known to split the axle gears if one is running faster than the other do to, to much wheel slip. I've replaced a few axles thn stopped doing it because I got tired of buying parts. To much pull or push though can put a strain on the motors and add more wear and tear even known to lead o burning motors up. I've had to replace motors in 3 of my AC-4400 units from one running faster than the other. I hadn't realized it but after I installed light kits in 2 of them I realized what the problem was. Lghts were drawing more power causing them to run slower. More on this later after I get some sleep.
  14. Mrplow123

    Mrplow123 Member

    Thanks for all the suggestions guys. I ran the GP-40 by its self for a while and it seems to start running faster. I put the 2 together with the Dash 8 in front and the gp-40 in back, pulled 25 cars without problem. They seem to run at the same speed when together now, ar atleast they don't cause any problems with eachother. It sure does look nice having the 2 engines pulling 25 cars up my 4% grade.

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