I'm running code 55 and the rumble of the wheels on the Intermountain AC-12 took about 2 minutes to get to me. I used a combination of IM and FVM wheelsets to replace the pony, trailing, and tender trucks. Taken from Spookshow's recommendations, I replaced the trailing truck with a 33" FVM wheel and the tender trucks with 36" FVM wheels. I didn't have 28" wheels for the pony truck, but I'll be picking some up. I used 33" IM wheels for the meantime. The second fix was to fix the TT problem. The loco uses TT's on the first set of drivers for each engine. The close clearances of the monkey deck and boiler causes the rear TT to lift when it goes over anything less than flat track. I removed the TT from the front driver on the rear engine and moved it to the rear most driver set. To get to the screws, you have to remove the brake hangers, they pop right off. I also removed the spring under the trailing truck, there is no need for it since it just drags along. The last fix, I had to cut one coil off the spring for the pony truck. It was putting to much pressure on the lead truck and lifting the front traction tire. All these and the AC-12 pulls like a champ around my superelevated curves. Here is the TT move for the rear engine. Here is the tender and rear trailing truck with the FVM wheels.
Since "SPsteam" just happened to mention 'Spookshow' etc., here's what 'Spook' posted on his website: http://www.visi.com/~spookshow/loco/imac12.html :tb-cool:
From these above posts and the "Spookshow" site I assumed this problem was very real and well established. I contacted IM about this. This is what I got back from them. "At this point I am reviewing various options, but despite the entries on the internet forums I have only been contacted by a couple of people that state this is an issue. I would guess it is a factor of the variability in the manufacture of the Atlas Code 55 track. I know that our test track here, which is a combination of Atlas Code 55 flex track, Code 55 snap track, Atlas Code 55 switches, and Micro-Engineering Code 55 flex track - everything works fine. If I was to question any of it, the snap track gave me the most review, my final decision was based on an expectation that most folks that buy this high-end locomotive would not be running on snap track. I am very curious about the pending release of the next batch of Atlas Code 55 flex track, knowing that it hasn't been available for several months, it will be worth evaluating. You did not say which Code 55 track you are using but I have had no issues, nor heard any issue with Micro-Engineering Code 55 track" Soooooo, is there a problem or not? I plan to use Atlas code 55 track on my own layout. In the mean time my fellow club members, whose layouts I expect to run on but havn't because I don't have my DCC decoder yet, all have Atlas code 55 track.
Thanks "SPsteam" for the info. Mine would not pull 4 Kato passenger cars up a very mild grade, so I removed the spring under the trailing truck and shortened the one under the front, as you did. Then I needed to file some off the front where it was dragging itself along the track! I wasn't brave enough to swap the driver wheelsets around, so I added "Bullfrog Snot" to both sets of rear wheels and it now works perfectly. I also added a small weight in the tender to guarantee electrical contact, as I was now picking up less from the loco.
Following on from my previous entry, I have swapped the traction tire wheelsets over in the trailing driver set as recommended, to the last set. What a difference! Why weren't they shipped like that? You don't see high powered cars, buses or trucks driving on the front wheels, so why put the traction tires on the front?
They are on the front for better handling in snowy and icy conditions.:mbiggrin: Perhaps it is that way because they thought that was where there would be more weight on the driver. Or it could be that it was supposed to be there all the time but there was a mix-up at the factory.
It looks almost as if whoever designed the placement of the traction tires forgot that this engine usually runs "backwards."
I wonder if Intermountain will take the item back and perform these fixes if the owner requested it ? fatalxsunrider43
So what is the total pulling power after the fixes? I know a guy that pulled 65 MTL & IM 40' reefers on level track no problems before the fix. But I'm still leery on picking one up. I have never had luck with steam. And knowing 3 guys having the pins pop out of the drivers scares me.
Maybe I was just unlucky with mine. It seem some are fine. It will now pull 30 heavy covered hoppers ( as in the video ) or 14 car Daylight set up quite long grades.
A Different Fix All the various fixes to make the AC-12 better are a great help if we encounter similar problems. My fix is entirely different. When I ran my AC-12 for the first time I encountered a track problem on a long grade that I have ignored since building the layout. Up until the AC-12 arrived I got by, but knowing there was a potential problem spot. Well the AC-12 said H__L No! I'm not running through that curve climbing or descending a grade. So I went to work, removed 9' of track. re-aligned and re-worked the surface in spots. Changed scenery and made a big on-going mess for a few days. Now I am ready to re-lay the new track and rebuild the scenery all thanks to the beautiful AC-12.
