I hate Kato Sprung Truck Frames

[primavw]

I have about 6 SD70Ace's waiting for Decoder installs, so today I installed a TCS K1D4-NC into one of my BRAND NEW Ace's, and boy what a headache. At first the board wouldn't slide into the front frame notch. So I had to pull the plastic shim piece and file the little nub down. No big deal, but as I gently split the frame a bit, big surprise, the trucks fell out. One of the trucks came apart, spilling its worm gear guts. Not a big deal, just re-assembled. As I tried to re-install the truck, the other one fell out. Again, I re-installed it. I finished placing the TCS board into the frame, having created enough room by filing the plastic shim a bit. I installed the copper tabs on both sides of the decoder using tweezers.

I happily placed the loco on my programming track... and wouldn't you know it, no response from the decoder. So after fiddling with it a bit, and trying it in Ops mode without any success... I replaced the DC board onto the frame. Now with the DC board installed the frame stalls and stops and doesn't run well... and to boot, it doesn't respond at all with the shell on.

I have a Digitrax Zephyr and got responses from my other Kato DCC locos... so that's not the problem... what the hell? I'm re-living my nightmare with dealing with an SD70M "drop-in" sound decoder install all over again. I guess I am just used to the old-school non-sprung chassis that will work in the filthiest of conditions? 

[Chris1274]

Yep, an ill-advised attempt to improve what didn't need improving, with the all-too-predictable outcome.

[peteski]

I have to agree. These are superbly running models (if they are treated with baby gloves), but I think they are way over-engineered.  There was really no need for Kato to improve their already-superbly designed mechanisms.  Well, the only thing that Kato should change (in all of their locos) is to install a slower motor (or higher gearing).  For some reason Kato is still making models that at 12V run at 250 scale MPH!  Not sure what their reason is for doing that. To keep them compatible (speed matching) with their older models?  It doesn't make sense to me.

[jmlaboda - RIP]

Well, the only thing that Kato should change (in all of their locos) is to install a slower motor (or higher gearing).  For some reason Kato is still making models that at 12V run at 250 scale MPH!

I have yet to figure out why others have to have use of a full 12V to run their models when something less is suitable.  Is it a matter of not being able to control the speed or get it to move below 12V?  I know I am playing Devil's Advocate here but I am also trying to understand why using less voltage just isn't suitable.

[Chris1274]

I have yet to figure out why others have to have use of a full 12V to run their models when something less is suitable.  Is it a matter of not being able to control the speed or get it to move below 12V?  I know I am playing Devil's Advocate here but I am also trying to understand why using less voltage just isn't suitable.

Slow-speed motors allow for more fine-grained speed increments. If your top speed is 250 scale mph, then each notch of the throttle is +/- 9 mph, but if your top speed is 100 mph, then you get +/- 3 mph per notch.

[ryan_wilkerson]

I've been frustrated with the Kato SD70ACe also. Just last night my youngest son asked if I had fixed his DRGW heritage 1989. "Not yet" was my answer because the last time I installed the TCS K1D4, it wasn't recognized either. I told him that it might be better to leave it as a DC model to run around their room's ceiling.

[ednadolski]

the only thing that Kato should change (in all of their locos) is to install a slower motor (or higher gearing).

So are there any aftermarket motors/gearsets available?

Ed

[peteski]

I have yet to figure out why others have to have use of a full 12V to run their models when something less is suitable.  Is it a matter of not being able to control the speed or get it to move below 12V?  I know I am playing Devil's Advocate here but I am also trying to understand why using less voltage just isn't suitable.

Well, for example, an exotic sports car with 600hp engine has a multi-speed transmission which allows for a fine control of the power delivered to the wheels.

But a fast Kato loco has no transmission. I can't shift the loco into low gear (while applying full power to the motor).  This means that in DC, the usable speed range is on the lower third of the throttle range. That results in rather jumpy control of the model (compared to the models which have much slower top speed).

In DCC you can compensate by setting come CVs or using speed tables, but it is still extra pain to have to do that.  There really isn't any good reason why the model should be designed to travel that fast on full throttle.

[primavw]

Can anyone suggest a way to improve this loco's performance? Or why the heck the shell being on is not allowing response for the loco? Or why I am having stall issues all of the sudden?????

[jereising]

I have had my share of issues with the sprung chassis also, to the point that I have decided that when Fox Valley brings out their SD70ACes I will be replacing most of my Katos.

I use Digitrax.  I have had some issues with the PCB and the chassis, but I've always managed to get them to work consistently.  You've just gotta play with it - and don't replace the shell until you think it's bulletproof.  Then put the shell on and play some more.  Good luck.

[primavw]

Well, thanks for the advice all. I definitely fiddled with this decoder install way longer than reasonable or prudent. I did manage to successfully program and run the Loco after a small revelation. This big stumbling block for this chassis seemed to be the copper strips that need to be transferred from the DC Light Board to the Decoder. It seems no matter how much bending and tweaking I did they just would not contact the motor strips enough for a smooth ride.

My solution:

Solder.

I guess for the ACE's a decoder that is "drop-in" is a term that is used loosely. All grumbling aside, the solder held the strips firmly in place. I bent them inward toward each other under the decoder, to the point where I had to spread them a bit to slip the decoder over the frame. It squeezes the motor strips just enough to get a good contact.

On the up side the Loco demonstrated to me that I need to add a few more feeders and wire my turnouts, because it its finding the dead spots. After 8 hours... she works like a charm.

[nsbob]

I appreciate everyone's input on this discussion for those of us contemplating purchasing modern units.  The only Kato I have is an older GP38-2 and I am very happy with it.  Kato was on my list for a future purchase of a modern NS unit.  With the problems everyone is having, I will also wait for Fox Valley ACEs.

[Chris1274]

I appreciate everyone's input on this discussion for those of us contemplating purchasing modern units.  The only Kato I have is an older GP38-2 and I am very happy with it.  Kato was on my list for a future purchase of a modern NS unit.  With the problems everyone is having, I will also wait for Fox Valley ACEs.

Not all modern Katos have this issue, only the ones with the sprung trucks. The GEVO, AC4400, SD70MAC, and SD80MAC use the previous design and run flawlessly. Converting them to dcc is a snap too using TCS drop-in decoders.

[u18b]

I agree the new design on the SD70ACes is troubling.

1.  Trucks fall out pretty easily.

2.  The motor tabs are indeed very very thin and delicate.  Soldering (go easy! doesn't take much) is one solution.

3.  kato TOTALLY redesigned how the light board interfaces with the chassis.

The old way, the frame "pinched" the insertion tabs.

But possibly because of DCC and some many manufacturer's boards are NOT identical thickness, Kato went to a new design.

The flex and touch method.

The frame no longer pinches the board.  The board has a slight flex to it and there is slight upward pressure.
This upward pressure pushed the tabs into contact with the frame..... well it's SUPPOSED to do that.

When TCS first released their decoder for the SD70ACe, I pointed out this and MORE problems.  Their first run of boards were too wide by about 1 mm.  They would FIT but the sides brushed the inside of the frame and were hindered from the upward flexing they needed.  I filed mine down just a little to free them up.

I suggested forcing some heavy foam from the box as little wedges under the board.  This solution works.

Kato finally saw that there was a design flaw and ADDED that little bump under the board in later runs.  The purpose of that bump is to REALLY force that board to flex and press into the frame.

Note the very first runs do not have that bump.

So when you trimmed that bump, you were possibly hurting yourself.

Hope some of this helps.

[GaryHinshaw]

Here is why I hate the Kato sprung trucks:

https://www.therailwire.net/forum/index.php?topic=31149.msg343980#msg343980