hello just a small question for all u railroad gurus
i was just reading the athearn tune up at the nmra page, and i’ve notyiced something all my athearns have the cast iron wheels, and due to the fact that i’m going to tune up my gp7s,gp9s, f7s and sw’7s all are bb’s which wheel sets should i use size wise since there are conduction issues for the electricity (Mainly rust spots) so I looked up the north west short line site and found:
new as in inside frames or old in ouside frames in nickel-sliver, and i see that there are different sizes in wheel diameter from 36", 42" and 45" in both types which ones do i get? or does size really matter?
yes it matters very much, as it will affect fit and coupler height. Most Athearn are 40" wheelsets. Also make sure you don’t have an older wide body with metal trucks, if you do you will need the wheels that have axels that go through and conduct to the motor thorugh there.
you have a choie of Jay Bee, NWSL, and a few others I can’t remeber but also Proto 2000 will fit (be careful fitting the axel to the gear it may be too tight) and modern Athearn wheels too.
Athearn BB kit Locos come with a sintered iron wheel, which when measured with a dial caliper, scales out to 41 inches. It has been mentioned on other threads here, and confirmed by Athearn that the wheel size is actually considered 42 inches, NOT the 40 inches mentioned previously in this thread.
Prototype Locos generally use 40, but some use 42, so Athearn split the difference to be able to reduce production cost by using a “one size fits all” wheel set. As mentioned above, 40 inchers can be used, but you must correct coupler height, and check anti-climber/plow clearance, BUT the actual replacement is the 42 inch wheel sets.
Another consideration when swapping to NS wheels is that you will lose traction, and should add weight to the loco. The sintered iron wheels are slightly porous, giving them some grip, where as the Nickle Silver wheels are very smooth, and will spin/slip much easier.
If you do a search at the bottom of this page for “athearn wheels”, or “dummy wheels” you’ll fined a lot more information.
It took about a weeks worth of research to find out the previous info.
I recently acquired a pair of Athearn SD40-2’s (power/dummy) from the mid 80’s(??), very slightly used, details not applied and still in sealed envelopes, and in quite nice condition overall, that I’ve decided to make my first “super detail” projects.
I’m still debating on NWSL or Jay-Bee wheel sets, and I was going to put an Ernst reduction gear set in the powered unit. A-line also makes an additional weight that goes under the motor called a Cradle Weight, that may help get some of my tractive effort back.
Today I went out to the LHS and picked up a Digitrax decoder and harness, a couple sets of Kadee couples and some decals for the number boards. I think I ought to test run it to get a “base line” to compare my upgrades to.
A little long-winded, but that’s what got me to researching the Athearn wheel sizes, cause when I measured them I came up with 41 scale inches, which seemed a little odd to me, until I found the previous mentioned explainations.
The 2 different truck frames you are talking about are different in all aspects. The first one is the older meteal truck frame with a pressed in bronze bearing that is on the inside of the truck, these used a wheel that has an end that sticks out about 3/16 to an 1/8 inch. These ride on the inside of the centered bearing on the truck and pick up electricity. These worked really well after they broke in, but it took forever breaking them in. And if you over oiled them, they would not run very good.
The newer style trucks on the BB Athearns used a small drop in box bearing that has the axle slipped though the box bearing then the gear, these are 95% the same as the ones they used on the Proto 2000 line, better detailed trucks though but the gears, bearings were the same.
Another thing you can do is to polish the factory wheels using a dremel and a brass wire wheel on the dremel. Putting the NWSL 42" wheels on is a good thing to do though.
If you’re talking old Athearn BB engines with iron wheels, they are all 42" - regardless of what the prototype used. Athearn believed in the 'one-size-fits-all theory = (benefits of lower cost).
Better replace them with 42’s. or you’ll have coupler match up problems.
Jay Bee I believe is out of busines, but NWSL still machines brass & nickel-silver wheels to NMRA. Check to see if your axles are the older ‘stub’ or newer ‘flush’. Your engines will thank you.
Next upgrade is the motor and machined flyweights. The guy selling parts for upgrade is: