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Post by markfj on Apr 15, 2014 10:44:15 GMT -8
Hello All, This is the first step in my efforts to improve the performance and reliability of an older P2K four axle drive system. I know many modelers opt to simply replace this drive with a Kato chassis rather than try to improve it. However, I own over 12 diesels and upgrading my entire collection to the Kato chassis would be expensive. Also, finding enough Kato chassis would be difficult since they are so scarce (probably because swapping them with the P2K drive is still very popular). Upon disassembling my first drive from a NIB GP-30, it immediately became apparent how many issues there are with these drives. The grease used for the gearboxes was everywhere, there were numerous metal chips, and the soldering was horrible. One lead was attached to the motor contact strip by only one strand of the wire! Also, there was the infamous “cracked gear” problem, which was the first problem I attempted to fix. As we all know, Athearn p/n ATH 60024 is the replacement part for P2K cracked gears. I bought several packs, replaced the gears, and reassembled the gear housing. However, I notice that the wheel/gear assemblies have a tremendous amount of lateral play (about 3/32”). This tolerance seemed excessive to me and could allow a bearing to become lodged between the metal contact plate and the side of the truck housing. To reduce this excessive play, I decided to add metal washers between the bearings and the gear. The photos show all that is involved in trying to correct this problem. This first photo shows a stock housing and axle assemblies. You can see how the excessive tolerance allows the bearing block to move almost off the contact plate and the back side of the wheel is up against the plate. The wheel/gear assembly is not centered. Here are the wheel/gear assemblies: the one on the left has #2 black washers added (available from Mirco Fasteners, P/N FWK02) while the on right is stock. Both axles are in gauge. To allow space for the washers, the Athearn gear must be shortened slightly. I made this simple styrene gage/tool to help keep the ends neat and square while I removed material from them. The stock Athearn gear is approximately .122-.125 from the gear teeth to the end. I only need to remove about .010 to fit the washers, so the modified gear now measures .110-.115. Another issue was the sloppy fit of the bottom housing cover. This is a problem because the cover will not fit over the axle assemblies with the washers in place. This photo shows how the stock cover fits. Here you can see how I carefully thinned the sidewalls of the cover from about .040 to .030. (Stock is to the left, modified is to the right). With the truck assembled, the thinned cover fits neatly and providing sufficient clearance for the washers on the axle assembly. I performed a very simple rolling test with a piece of flextrack elevated about and 1 ½” at one end to determine if the washers (and overall tighter tolerance of the axle assemblies to the housing) added more friction. My conclusion is that the modifications do not appear to add more friction. Actually, I think there is less friction because the back side of the wheels cannot rub against the metal plate as they can on a stock truck assembly. However, I need to do more testing to be sure. Even if friction does increase slightly, the benefits of keeping the bearings from binding should outweigh any loss in the free rolling characteristics of the truck. In addition, this modification should allow for better electrical contact between the side plates and the bearings since the trucks will now stay centered over the axles in turns and tight switching areas. So, the big question is, “what do you all think of this modification?” Do you think it is worth the effort or not? I know these P2K chassis have been running on layouts since the late 90s and they probably performed very well. I’m just trying to get the most out of this design so I can save money and, more importantly, have fun. Thanks, Mark
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Deleted
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Post by Deleted on Apr 15, 2014 11:56:36 GMT -8
Don't get it too tight or it will bind. I speak from experience.
Running up and back on a piece of straight track does nothing. The acid test is running it through a sharp curve. This is where in the factory design there was play to allow things to shift just enough and not bind.
Actually the play isn't a big deal, but the axles and bearings must be equal on both sides of the gear. Too much on one side or the other and the square bearing shifts and falls out of the square opening in the gear box steel stamping. At that point the choo choo stops dead in its tracks.
While doing the gear work, if you want to replace the P2K wheels with NWSL wheel sets that would be a possible worthwhile modification.
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Post by Donnell Wells on Apr 15, 2014 12:04:55 GMT -8
So, the big question is, “what do you all think of this modification?” Do you think it is worth the effort or not? I know these P2K chassis have been running on layouts since the late 90s and they probably performed very well. I’m just trying to get the most out of this design so I can save money and, more importantly, have fun. Thanks, Mark Hi Mark,
IMO it's always worth the effort! If the work you put into tuning up the chassis results in silky smooth operation, then I would suggest this treatment every time!
Back in the the day (early 90s), there was a guy at our club who knew how to tune Athearn chassis so smooth and quiet to the point where people thought they were repowered with an expensive can motors. Wasted effort? Not in the least! Keep at it!
Donnell
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Post by nebrzephyr on Apr 15, 2014 12:47:16 GMT -8
I would second Jim's comments. Too tight and you'll have issues on the curves. The other issue is making sure the gear in centered and both axles match. A few years ago I had a Athearn RTR SD40 that would consistently derail on curves, always the same truck. Dis-assembled the truck and found the gears on the two axles did not line up when you placed the wheel sets back to back. Re-adjusted the one axle gear to match the other one and never had another derailment.
Bob
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Post by bnsf971 on Apr 15, 2014 15:17:58 GMT -8
If and when you get to that point, I think it's a very worthwhile project to remove the old Proto resistor/light board things. Depending on the version, there can be either a lot, some, or none of them wired in to the motor circuit. The original Athearn-type motor is usually pretty good, but you can get a Kato HM5 motor for $20 or so, which may be worth the effort.
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Post by tdspeedracer on Apr 15, 2014 19:46:22 GMT -8
I believe this came out of an old RMJ article on tuning Athearn bb, but I can't remember for certain. Anyway, you can bend the metal piece that the bearings set in inward a little bit. By putting that at an angle, it in effect makes it wider and harder for it to fall into the crack. I drew some lines on the op's photo that show roughly where it was bent per the article. Trevor Attachments:
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Post by Brakie on Apr 16, 2014 2:00:09 GMT -8
So, the big question is, “what do you all think of this modification?” Do you think it is worth the effort or not? I know these P2K chassis have been running on layouts since the late 90s and they probably performed very well. I’m just trying to get the most out of this design so I can save money and, more importantly, have fun.
Thanks, Mark ----------------------------------- Mark,Here's is my thought.Are you happy with the results of this modification? If so you have accomplish your goal and that is the main thing.
However.
My policy is "If it ain't broke don't mock with it".
I suspect there is a reason for that side to side play since most locomotives have it and IMHO that reason is its probably needed for 18" curves,snap switches,sloppy track work and mach 5 speeds that is very common among home layouts.
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Post by drolsen on Apr 16, 2014 5:13:00 GMT -8
One option that a few guys recommended to me a while back is to completely replace the trucks with Atlas GP40 (or 38/40-2) trucks. They're not exactly cheap, but not as expensive as finding Kato parts or a chassis. I ordered a few pairs of trucks but haven't gotten around to that project yet (seems to be the story of my life with two little kids now). This was specifically for a CSX GP30 slug project, to ensure compatibility with the Atlas GP40-2 "mother" unit, but also to address the cracked gears and other issues with one quick fix.
Dave
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Post by riogrande on Apr 16, 2014 5:50:52 GMT -8
I've got a bunch of P2K GP30's (11 of them) but am inclined to not re-invent the wheel if they work ok - assuming I will need to replace some/all of the gears as I've read about the cracked gear issue for a long time. I suppose now that they will be getting out for testing I should bite the bullet and order some gears - should've gotten them for free under warranty but suppose it's long too late for that.
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Post by Spikre on Apr 16, 2014 13:50:43 GMT -8
if the Kato Motor is used the Stewart mount for the Kato motor makes replacement rather easy. bigger problem may be finding those mounts as parts. or maybe in some older locos,that would also supply trucks if needed. Spikre
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Post by antoniofp45 on Apr 20, 2014 18:57:50 GMT -8
Thanks for the helpful tips guys.
I have a pair of the early run P2K SCL GP9s that I plan on tweaking. I plan to clean out the excess grease, replace the wheels, axles, and (hopefully) convert them to DCC/sound with LED lighting.
Re: electrical pickup. I understand that for better performance, it's better to remove the wire from the contact strip. What spot is best recommended for the wire to be soldered on to?
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Post by Judge Doom on Apr 20, 2014 19:32:38 GMT -8
Thanks for the helpful tips guys. I have a pair of the early run P2K SCL GP9s that I plan on tweaking. I plan to clean out the excess grease, replace the wheels, axles, and (hopefully) convert them to DCC/sound with LED lighting. Re: electrical pickup. I understand that for better performance, it's better to remove the wire from the contact strip. What spot is best recommended for the wire to be soldered on to? Having it go to the contact strip is no big deal, just make sure there's a bit of extra wire so the wire can flex when the truck turns, and not the wire-to-solder joint area (which will eventually cause a failure and the wire to come loose). It's best to actually run another set of wires to the sideframes in order to bypass the "hot frame" pickup through the bolster (that can accumulate grease and oil that can interfere with electrical conduct). I run extra wires, soldered to that side of the trucks on one of the rivets holding the plates on, and run the wire either behind or in front of the gearbox, up through the frame, and to the rest of the wiring. Be sure to run the wire somewhere through the frame cutouts where it won't interfere with truck swing.
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Post by orangeC on Apr 21, 2014 8:56:46 GMT -8
Lots of good ideas here. for the wire on the contact strip, I drilled holes in the contact strip, inserted and resoldered the wire allowing for plenty of play to the circuit board. After it cooled, applied a little bit of liquid electrical tape. Of course in addition to replacing the cracked gears, applying lube, keeping the wheels clean. A friend and I have done this to several P2K GP7, GP9, GP20, and GP30 models. Trouble free operation for over a decade. When they were converted to DCC, another friend played with the CV values and they ran very well with Atlas GP40s, RS3s, P2K U28Bs, U30Bs, SD45s, Stewart U25Bs, F7s, and Kato GP35s.
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Post by Mark R. on Apr 21, 2014 9:44:47 GMT -8
I have a couple Proto RS11's that I replaced the trucks with Atlas ones and they are hands down the smoothest, quietest engines on my roster ! I know this sounds odd, but the Proto trucks always sounded lke they rode "hard" - you could hear the hardness as they negotiated through turnouts. After installing the Atlas trucks, it was almost like they had rubber tires in comparison ! They would glide over the same track with absolutely no noise at all.
Possibly it is because the Proto trucks with those bronze bushings riding in a metal slot contributed to the harshness.
The only modification required was to remove the king-pin on the chassis (as the Atlas trucks have the king pin) and drill a hole in the chassis to match the Atlas' truck king pin. Using Atlas worm gear, female coupling and drive shaft, it mated perfectly to the flywheel coupling with no modification.
Mark.
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Post by calzephyr on Apr 22, 2014 8:05:40 GMT -8
I have a couple Proto RS11's that I replaced the trucks with Atlas ones and they are hands down the smoothest, quietest engines on my roster ! I know this sounds odd, but the Proto trucks always sounded lke they rode "hard" - you could hear the hardness as they negotiated through turnouts. After installing the Atlas trucks, it was almost like they had rubber tires in comparison ! They would glide over the same track with absolutely no noise at all. Possibly it is because the Proto trucks with those bronze bushings riding in a metal slot contributed to the harshness. The only modification required was to remove the king-pin on the chassis (as the Atlas trucks have the king pin) and drill a hole in the chassis to match the Atlas' truck king pin. Using Atlas worm gear, female coupling and drive shaft, it mated perfectly to the flywheel coupling with no modification. Mark. Mark Fine-tuning models to run better is always a good exercise and it gives each of us satisfaction when you get good results. I was hoping for a feed back on the trucks to see if they operated well on turnouts and tight curves after the modifications. Any problems with the operation on tight curves? I have a bunch of older P2K B trucked models that probably have broken gears and this article reminded me to take a look at those models. Thanks for the article of tuning the trucks. Larry
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Post by Mark R. on Apr 22, 2014 9:06:25 GMT -8
I agree. It's this kind of thing that our hobby was based on .... modeling. I've spent MANY enjoyable hours at the bench tweaking and adjusting older engines to get them to work just a bit better. I have a couple old Athearn blue box GP38-2s that many people swear I put Atlas drives in. It's a real sense of satisfaction when you do something like that .... and even more so when somebody calls you on it and you show them what you did !
Mark.
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Post by antoniofp45 on Apr 23, 2014 6:42:22 GMT -8
Good topic, guys!
I've been asked before why I don't just go ahead and purchase the Athearn Genesis version of the SCL GP9, as they show up on ebay. The detailing is more accurate and the mechanism is a good performer.
Fair enough. However, I obtained both of my P2K GP9s back in the mid 2000s, new in the box. One was a Christmas gift and the other I purchased. Having been a "blue box" guy, to me, they're very sweet looking units and I like the challenge of detailing them to a more accurate appearance.
As I pointed out on other forums one of my favorite features (to the disdain of prototype modelers) is the operable doors. In the Tampa Bay area, back in the mid 1970s (before the FRA tightened its octopus grip on engine crew safety) Seaboard Coast Line locomotive crews on local runs tended to leave their cab doors open during moves. It was funny seeing the front door on the fireman's side flapping slowly back and forth as the unit (SW or Geep) cruised along at about 20mph. Likely high humidity and heat was quite a motivator. Anyway, these old run P2K Geeps will enable me to duplicate that aspect of southeastern railroading.
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Post by orangeC on Apr 23, 2014 7:00:32 GMT -8
I like the open doors on the geeps. Seems to me to be a requirement for modeling Penn Central. My projects for next winter include PC GP9s and GP40s with open cab doors and a few open on the long hood where hoslters and mechanical forces hastily started and added water to put em out on the line of road. Maybe the doors flop around while moving about at speed.
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Post by bnsf971 on Apr 23, 2014 8:20:24 GMT -8
I like the open doors on the geeps. Seems to me to be a requirement for modeling Penn Central. My projects for next winter include PC GP9s and GP40s with open cab doors and a few open on the long hood where hoslters and mechanical forces hastily started and added water to put em out on the line of road. Maybe the doors flop around while moving about at speed. That would be an interesting thing to model, if at all possible. A door would have to swing pretty freely in order to "swing in the breeze" with the engine rolling down the tracks.
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Post by theengineshed on Apr 23, 2014 17:21:15 GMT -8
An etch maybe? Would make a neat product. Put EMD, Alco, GE, a door or two of each on the etch. Each door would consist of a couple of parts, framing on the inside, sheet metal shell, and hinges. You'd want some mass, either a thick shell or lots of solder. Maybe a touch of rubber cement at the joints to suppress swing and dampen unrealistic oscillations? Somebody has to have already done this in the past, just not as a commercial product...
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Post by gmpullman on Apr 24, 2014 1:44:25 GMT -8
I like the open doors on the geeps. Seems to me to be a requirement for modeling Penn Central. My projects for next winter include PC GP9s and GP40s with open cab doors and a few open on the long hood where hoslters and mechanical forces hastily started and added water to put em out on the line of road. Maybe the doors flop around while moving about at speed. I remember seeing quite a few Geeps in the Penn-Central era with the door propped open with a switch broom stuck through the door handle and jammed in the hand rail. A swinging, floppy door would not do... it would keep the head brakeman awake, no-no, NO! Around here (Cleveland) it seems the E-L crews frequently ran their F's (and later E-8s geared for freight) with the nose doors open during warm weather, too.
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wsor
Full Member
The Route of the Ruptured Duck
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Post by wsor on Apr 24, 2014 3:12:29 GMT -8
Crew members have also been known to stash a bungee cord or two in their grips to hold doors open as well... Most of the ex-IC engines I've been on have some sort of bracket to hold the cab doors open. Usually a rod on top to the door frame, and a tab welded onto the door. Also common is a small tab on the bottom of the door, and a small keeper located to hold the door open.
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Post by orangeC on Apr 24, 2014 8:36:29 GMT -8
I put a lot of thought into it, my favourite idea was put forth by a friend who models ships. He suggeted a pair of tiny functioning hinges. I do believe that would require a microscope. Inspiration came from watching the Emery Gulash PC videos.
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Post by markfj on Apr 24, 2014 10:01:42 GMT -8
Thanks to all for your comments and suggestions in this thread. This project had to wait for some parts to arrive so I wasn't able to move forward or post any updates. Now that I have the parts, I plan to post more photos shortly. If anything, this is turning out to be a fun learning experience.
Thanks again, Mark
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Post by antoniofp45 on Apr 25, 2014 1:58:57 GMT -8
Mark, What will you be using for lubricating the gears? Several years back a friend of mine recommended that I use Labelle 106 after servicing Athearn trucks. When applied properly, it works well and doesn't instantly ooze of the truck assemblies like some of the less viscous lubricants that are on the market. Thanks to all for your comments and suggestions in this thread. This project had to wait for some parts to arrive so I wasn't able to move forward or post any updates. Now that I have the parts, I plan to post more photos shortly. If anything, this is turning out to be a fun learning experience. Thanks again, Mark
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Post by markfj on Apr 25, 2014 4:45:39 GMT -8
Yes, I intend to use Labelle 106 for the gears. My inspiration for this project (and most of the tune-up ideas) came from this well written article on the Athearn chassis. Athearn TuneupMark
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leikec
Junior Member
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Post by leikec on May 31, 2014 22:29:16 GMT -8
I just replaced the gears on a pair of Annie FA-2 locos. Very happy with the result!
Jeff C
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Post by markfj on Jun 1, 2014 3:14:17 GMT -8
Hello Group:
I haven’t forgotten about this project, but have been busy with many other models and life “issues”. The plan is to return to this topic sometime in June.
Mark
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Post by Brakie on Jun 1, 2014 4:30:20 GMT -8
I like the open doors on the geeps. Seems to me to be a requirement for modeling Penn Central. My projects for next winter include PC GP9s and GP40s with open cab doors and a few open on the long hood where hoslters and mechanical forces hastily started and added water to put em out on the line of road. Maybe the doors flop around while moving about at speed. And the boys in the cab would be in deep kimchee..When I worked on the PRR/PC and later the Chessie cab doors had to be closed while moving at track speed..Railroads also frown on cab doors being open on trailing units since the door could be damage. Now yard crews with end cab switchers could switch cars with the cab door open..
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