Model Railroading > Athearn's SD70ACe - possible truck fix?

I got my UP SD70ACe yesterday -it has most of the flaws previously mentioned. I don't mind minor flaws, but I want to resolve the truck problem if at all possible - just too many intermittent derailments especially crossing frogs. I'm now in the troubleshooting mode and have found similar truck problems as initially reported by Bruce "......both trucks had one wheel up in the air. One side was fine, the other wheel slightly up in the air - Warped trucks?......." That's my conclusion too - warped trucks i.e, they are twisted. The individual wheels seem to "hop" randomly. Here is another comment/possible solution from Chris Toth......"This was also a problem with the earlier Genesis SD70 series models. On all those I had issues with, I found that the copper electrical contact plates were bent and caused the problem. I disassembled the trucks and used a straight edge to bend the plates so that the holes for the axles were all straight and level. I then reassembled the truck and placed it on a piece of glass to make sure the problem was solved before putting it back on the model."

Okay, so lets discuss possible solutions and avoid "bitching about QC" which has already been beat to death (I agree with the complaints). Has anyone disassembled the trucks? Can someone confirm Chris Toth's discovery and solution for the SD70ACe? Has anyone found the exact cause and a solution that a reasonably skilled modeler can apply? I'd like to attempt a fix and not just return the loco for another with possibly the same problem.

Please respond with constructive solutions, not complaints.
Joe

Joe

As you mentioned, it is not worth going into the negativity of disappointment and poor QC as it has been said in many of the same ways.

Being overseas, I have not yet received my Sd70ACe's but I have taken enough trucks apart to understand what Chris mentioned was the problem. I am expecting to have the same problem. The only way to understand or confirm the fix is to jump in there open up the unit and take the trucks apart.

The part described as being the culprit with the SD70/75 will be the copper pickup. Being copper, it should be easy to bend. This should be the only problem with this truck derailment issue. The more I think of possible problems, I expect this will be it. The truck pivot point for all locos has been standard since Noah was a Lad and I doubt this has changed or be a cause of derailments. The truck sideframes on every model ever delivered to market merely hangs off the side of the truck gear box. Being injection molded, it usually is designed to not interfere or hold the axle ends so I do not think it will be deflecting/distorting the axles in any way. I doubt any "over detailing" (if there is such a thing - not in my books) will be causing derailments. I suspect if anything, one may lose detail parts but not have any cause for derailments. Use the Atlas track vacuum to find your lost detail parts.

I will be going in to install my own decoder so will look at the trucks seriously. I also will be looking to get rid of those bulbs and put in a lifetime fix by using LEDs.

At this stage, I have seen an Athearn SD70ACe but it is not mine to take apart and play with. All I can write is based on expectation and speculation but I am optimistic I can fix it.

Rick

I attempted to bend the copper contacts. However,the contacts are made to fit into the truck sideframes, not just fit beside them and the axle tips do extend inside the sideframes as well. Basically, everything we know about older Athearn trucks, can be thrown out the window.

For a short time I thought I had bend just enough to fix the problem, but running the unit showed there was binding in the gear train somewhere. The unit would surge.

Although, not impossible, to repair would be quite a project, considering Athearn will replace them such as they did for the original SD70 truck problems a few years back.

That's all I know.

Bruce
BNSF Chilli Sub

Ok, I did remove the side frames and checked the copper-bar pickups for any sort of bending, or warping. They all looked straight and uniform. So I filed the holes in the copper bar pickups on the chance they had burrs or needed to be made more smooth. I re-assembled the unit and tested my work - some small improvement, but not as much as I had hoped. The trucks seem to swivel side-to-side without obstruction and do not appear to be the source of the problem. Tomorrow I will investigate more.

Such a beautiful loco!
Joe

I had the opportunity to look closer at my friend's SD70ACe this afternoon and soon discovered what ChilliSub has written above on the trucks. The axle ends do go into the sideframes which thereby throws out my speculative comments above. It is interesting to see that people are not finding any twist to the copper plate.

Unfortunately, this particular SD70ACe also has a truck problem in that the middle and inboard wheels on the trailing truck engineer's side are off the ground/glass. I did the "slide the paper under" trick to find this out. The good news is that his unit went through various bits of dodgey trackwork and turnouts (there is alot of it on our club layout) without any derailments. ... Lottery winner!!!!

I can say it is a lovely model for sure.

The next question should be wondering if anyone has communicated with Athearn on this subject to find out what their official stance is on correcting the truck. Will there be warranty replacements if we cannot fine tune the twisted truck ????

Rick



Edited 2 time(s). Last edit at 11/28/10 03:52 by rschonfelder.

Guys thanks for your constructive comments and encouragement. I just did the "paper under the wheels test" again after truck disassembling, checking and filing the copper-bar pickups and reassembly. Looks like only small improvement in operation. My trackwork (600 linear feet with 100+ switches) is well-laid. I have about 100+ locos of all manufactures and they all run well. My other Genesis locos (SD75,FP45(2),F45) negotiate the trackage without issues). My Athearn RTR locos run great! So today I'm gonna look at the trucks on my older Genesis units to discover why they run better that the SD70ACe. I'm wondering if the older Genesis trucks have more "vertical play" for each axle set which gives the individual wheels some flexibility to maintain rail contact while traversing small track imperfections. For comparison I performed the paper test on a RTR SD40-2 and all wheels were level.

[NEW] For comparison I just did a "paper test" on my other Genesis locos (SD75,FP45(2),F45) that I mentioned above - only the SD75 has a tiny space between one wheel and rail. Then I ran them for comparison -all run "solid" across my switches, but the SD70ACe trucks continue to hop or twitch and intermittently derail. I measured the weight of the locos: the two FP45s are 27oz, F45 24oz, SD75 17oz and the SD70ACe is 17oz. I measured a smooth running RTR SD40-2 and it is 17oz.

If I can't find and resolve the problem, my intention is to ask Athearn for replacement trucks. As I said before, returning the loco for a replacement may provide a loco with the same issue.



Edited 1 time(s). Last edit at 11/28/10 09:16 by jsnoy.

I worked with another friend this weekend on fixing some warped trucks on his BNSF SD70ACE. It took a long time to remove the trucks. You have to remove the shell, remove wires from trucks with that stupid tab system, pop the gear case covers, then remove the worm and drive shafts. Trucks will then drop out.

Then we had to disassemble the trucks. We worked with the copper strips and tried to make them true. Then a full reassemble process. Took about 90 minutes. When completed, we found the problem was even worse.

The only hope is too ask for new trucks or return to Athearn or return outright. When the same truck problem existed with the original run of the SD70's, I emailed Athearn and they sent me new trucks. The replacement trucks were more warped then the ones I had. I just ebayed the engines.

Bruce

I had a weird thought last night and I will trow it out to see what the group thinks. What would happen if you removed the center axle so the truck rest on the out board axles.

Andre

Andre Wrote:
-------------------------------------------------------
> I had a weird thought last night and I will trow
> it out to see what the group thinks. What would
> happen if you removed the center axle so the truck
> rest on the out board axles.
>
> Andre

I had a similar thought. File the center copper-bar axle opening larger so that the center axle set moves up and down (vertically) more freely, thus allowing the truck to rest on the outboard axles. I don't think you could completely remove the center wheel set because the gears on the axle are necessary to turn the gears on the outboard wheelsets.
Joe

Sorry, I know this thread is old, but I just read it this week.enlarging the middle axle hole sounded intriguing, so I tried it. Amazing, my Athearn SD70ACe tracks and picks up like a charm now!

I posted the question about these trucks to Athearn's FB wall a few weeks ago and didn't get an answer. I decided to try again over the weekend, and this time I got a response.

Athearn: Yes. That is why the second run is a bit delayed - we are retooling several things that we discovered needed improvement once these models were produced.
56 minutes ago · LikeUnlike.

Athearn: And, if you have models from the first run with the defective trucks, drop our repair team a line at help@athearn.com.

So now we have a better idea of why the delay on the next batch of SD70ACe/M-2's came about.

Glad to see they're working the issue.