Barry,
I ran my Bach K yesterday and thought I’d ask for an update on the new gearing.
jb
John,
Dave is still running the test model. But Dave and I are troubled with the first and third axle lock (these axles have no sideplay). Normally, in prototypes the first and fourth would be fixed and the secon and third would have sideplay (if any). Realize, prototypes usually don’t have sideplay, but modelers do due to the tight curves we run.
We have discussed moving the motor/gearbox to the fourth axle, but have to evaluate the amount of work to do this and any attendant problems.
Thanks for asking John, if we come to an answer I will try to let you know.
Barry - BBT
Barry,
Would you enlighten some of less experienced in these modification/improvement processes what is troubling about the current methodology? Other than the slight relocation of the apparent pivot point (which in it’s current configuration gives greater movement to the rear of the engine) I don’t quite see the issue.
Bob C.
Bob,
The issue is that the current gear ratio is14.5 to 1. Which is like driving your stick shift in high gear, even from the start.
I believe there could be so much more flexibility with a gear ratio closer to 30:1.
Barry - BBT
Bob,
With the factory gear ratio, it flies down the grades and practically stalls on the up grades. It also slows down considerably on curves.
A PITA to operate using batt/RC. The gear ratio is so high, you can literally push it down the track by hand and the gears and side rods all turn almost like it’s a dummy engine.
Barry, John,
I think you both misinterpreted my question. I am aware of the gearing issue with the K, and am very interested in possibly upgrading mine with a BBT drive when it is complete. My question was regarding the first and third vs first and fourth drivers being fixed with no side play.
Bob C.
Oh, OK.
I don’t know much about that. That’s Dave’s and Barry’s thing.
John,
Yep, that is why I posted the question. As for the gearing thing, Dave and I had a spirited exchange of posts here on LSC back a year or so ago (at least I think it was here). Opinions vary about gearing and I will leave it at that. I am sure whatever Dave and Barry arrive at will be far better than what B’mann supplied from the factory.
I just picked up a Spectrum Connie off eBay and was shocked at the over clocked speed it runs at. It seems to be even higher than the K-27. Go figure… Only tested on a piece of track on the dining room table, no cars or grades, and almost had to catch it off the end of the table. Caught me entirely off guard.
Thanks for your reply, and great build on the PNG car.
Bob C.
Bob,
The issue stems from the K-27 as delivered, none of the axles are locked. Dave tells me that it can exit a curve unpredictably, with the nose pointing out or in and the rear of the loco either in or out not depending upon what the nose does. Dave locked the first axle and the fourth axle with the stock drive and the attitude out of the corners was normal. When we exchanged the stock gear box with the BBT gearbox, I couldn’t keep the sideplay in the third axle. So Dave locked the first axle and left the lock in the third axle and unlocked the fourth axle. Now this works, but it just isn’t right. So we are looking at the possibility of moving the BBT drive to the fourth axle position; how much cutting; where and what to cut; is there enough room; etc.
We’ll let you know what we find/determine.
Barry - BBT
Barry
When Dave introduced the concept of locking the 1st and 4th axles I did some experimenting. I found that locking the 2nd and 4th led to much better results then 1 and 4. The first axle is best left unlocked in which case it then becomes more like a prototypical pilot guiding the locomotive through complex trackwork.
You might consider moving the drive from the 3rd to 2nd axle, might be easier to accomplish and might maintain the balance easier.
Stan
ya know they could’a just built it right from the get go…Barry looking forward to your results!
C. Nelson said:That would have ruined Barry's business. We can't have that! :P
ya know they could'a just built it right from the get go...Barry looking forward to your results!
Barry,
Thanks for the reply. Now I have a better understanding of that part of the fuss. Looking forward to your and Dave’s results.
Bob C.
Yeh Barry!!! It is all your fault. 
Ha!!! Ya’ see not everything is my fault!!!
I wasn’t looking for a project, when we found the catch with the K-27.
Originally, I got three “problem” locos from Bachmann. Had to get special permission to get them.
I examined them to see what could be retained and up grade the locos so they wouldn’t die so quickly. Basically, I came to the conclusion that nothing mechanical could/should be retained.
Last week I started on a new project. In that initial evaluation (above), the biggest problem was the motor mount was not doing it’s job (Plus version, gen 3). Bachmann was running a string of hot glue to hold the motor in place. So in this project, I built a motor mount in aluminum, simple install and replaced the pickups with some of my own. Installed SS siderods and am looking at the rest of the valve gear to replace. But runs out pretty good, still using the original Mabuchi motor, so not a lot of power, but it should last.
This kind of product has an application with the owner who doesn’t run much, like around the Christmas tree. We’ll see.
Barry - BBT
Barry Olsen said:Whoa, that's a pretty hard core verdict.
Basically, I came to the conclusion that nothing mechanical could/should be retained.
Barry,
What do you define as ‘not much’? I have run my K-27 at our club shows (indoor and outdoor) with as many as 30 mixed Bachmann and LGB cars in tow (the visitors don’t care about scale, they just like long trains). At the home club layout this is usually on loop 2 with about a 50 foot long 1 1/2% grade up and down. Run times have been typically from 2 to 8 hours continuous running, all seasons, usually in the sun.
So far (knock on wood ), I have had no drive issues. The only modification from bone stock is the addition of a Phoenix sound card installed by RLD Hobbies (great job BTW). I am in my third year of ownership with hopefully many more. Aside from the gearing and what I am learning from threads like this one, it has been a sound performer so long as I keep the voltage (aka speed) low enough.
Bob C.
Has anyone dropped an Airwire G-2 board with “cruise control” into one of these yet? I’ve so far been impressed with how it works on some other locos on my railroad in terms of keeping speeds constant through high-drag areas like curves and some mild grades, but I’ve not put one in my K. (It doesn’t see regular service on my railroad as it’s borderline too big, so I bring it to shows–zero grades and broad curves=no troubles.)
Later,
K
Kevin,
Is that the one that is supposed to be ‘plugnplay’ with the Bmann socket? If so, I am considering one. Most of the people in my club are Aristo Revolution, but I have always been somewhat of a rebel.
Bob C.