What is your AZL SD70/75 capable of pulling? A few minutes ago, after getting bored, I placed every MTL Gunderson Husky I own on a loop oval test track I have. 48 empty Husky's. I just finished pulling maintenance on my BNSF SD75i. Found where the binding was and corrected it. She runs real good now. No more warming up for this baby! I put it on the track and I had it pulling all 48 Husky's without containers. I then started putting containers in each well car. 24 full and 24 empty. Still pulling, no problem. At about 30 it started slowing down. I had room for one more loco so I placed one of Jeffrey White's UP SD70's to assist mine. All 48 loaded with containers and the consist moved nice and sweet down the tracks, a little slowing as they negotiated the 195mm curves. Next, I pulled Jeffrey's SD70 off. Dead Stop!!!! Slippage with rubber tires! Hmmmmmm!! I often wondered what this SD75i would be capable of if it had the weight of one of AZL's C44-9's. So I placed one of my Dash 9's on top to add weight and away the SD75i went. Hauling 48 fully loaded MTL Gunderson Husky's! Now, I need two more SD75i's, running sweet, alot of Tungsten Powder and 100 more Husky's and I will have one heck of a Train!!!! Hobo Tim p.s. John, let me know what your Dash 9 pulls when you get that traction tire installed!!!!!
I found my SD75 are simply too light for the traction wheel to be really useful. May be some one can suggest a easy way to add weight to this loco.
I also find the SD70 to be too light, so mu it with a GP35. I will get a second SD70 soon, then I will know how well they run without the help of a GP35. I am not seeing the big benefit of traction tires, but I excepect a different result with my C44. The combination of weight and traction tires should make it into a strong puller.
Wow, Tim, that's a big difference! Let us know how the tungsten powder goes. Anyone else tried weighting these yet? Thanks, Randy PS - John, got the article in the maill yesterday. Bottom of page 22 was cut off. can you send me the last couple of lines of text in an email?
Here's a cute one. NO PULLING POWER what-so-ever, but levitation in action. Kind of interresting, and a diversion for the folks looking at the Japaense scales beginning to come on the market. http://www.flixxy.com/magnetic-levitation-model-train.htm ...don
adding weight to an sd70 Hi folks the easiest way to add weight to any loco is thru the fuel tank. So far the only Z scale hood unit loco's to have a metal one are the Dash-9's This adds tremendous pulling power due to the extremly low center of gravity. That's why they pull so well. As far as adding weight to a SD70. Remove the fuel tank. Hollow it out as much as possible. Then it's your choice as far as the metal you want to use/pour. Tungsten, bb's, conrete??? Since I have never removed a fuel tank from a AZL loco. (but I have sure tried by hand). How does one do it and have an intact one. Are they super glued on?
I'm not real pleased with the AZL fuel tank design. The plastic is very soft like styrene, and has buckles and nubs to hold 2 halves together. It was designed to be a 1 time assembly, as when you take them apart, the plastic buckle side breaks off trying to go over the nub. I have shaved the nubs down and glued the buckles back in place to allow it to be asembled one more time, but it's not as nice as a 1 piece snap on design like all the other manufacturers use, and the plastic is, well, for lack of a more descriptive term like you have available with metal castings, "Pot Metal", could similarly be called "Pot Plastic". Best advice is not to mess with it.
Robert, There must be a way to make a tank out of a solid piece of metal, even cold rolled, and then save the air tanks off the plastic tank and super glue the new metal tank with old air tanks onto the bottom of the unit. My Sd75i can pull about 15 of your cars and then thats it, its slipping but the radius of my curves is too tight so that doesn't help either. Bob
The tank would have to be insulated, as this loco is a split frame type. Maybe remove the old tank, use double sticky tape, and stick a new metal tank in its place.
Tweeking the SD70/75 Chassis I've taken apart my BNSF SD75i twice since I have gotten it for Christmas. The first time was to see the internal workings and then put it back together. Robert definitely hit the nail on the head when he says the fuel tank was a one time assembly/snap in place! The clip is very fragile indeed. I have not broken any, yet, but it is inevitable. No matter how much care you take to un-clip the fuel tank, you will crack at least one side. Recent Understanding; In my disassembly of my SD75i and one of Jeffrey White's SD70's, I have noticed that the fuel tank does indeed perform a vital function to the SD70/75 running and not falling apart. I have found that the fuel tank, which when clipped together, forms a very tight hold on the bottom of the SD chassis'. Upon re-assembling the chassis, I have snapped the geared trucks into the chassis both with and without the fuel tank attached to the chassis. When the fuel tank is NOT attached, the trucks will very easily snap into place. Sometimes to the point that pressure needs to be applied to the sides of the chassis to hold the trucks in place. When the fuel tank is attached, snapping the trucks in place took some effort. After experiencing this I have come to the conclusion that the fuel tank plays a vital role in the SD's working properly and not falling apart. Now, is their a quick fix for the clips breaking off? Well, if you glue the tank halves together, you'll have to break them apart to disassemble the SD chassis in the future. The only thing that comes to mind at present is using a small, thin piece of styrene, preferably nylon and attaching the chassis together, then the fuel tank to the styrene/nylon. Remember, the chassis halves are positively and negatively charged to operate the motor/functions so a strip of brass or metal cannot bridge the halves. I could bore you with the details that are swimming around in my head but I won't. This is but one idea. Even a drill and tapping of the chassis fuel tank area for a nylon bolt to secure the bottom is an idea. Not recommended for anyone without a drill press set up. My Conclusion; The fuel tank on the SD's do play a vital role in the function of the units!!! I know that if one of the clips breaks off, I will definitely have to find a solution that will allow me to dis-assemble the unit in the future!!! My suggestion to those who have not taken their SD's apart! Don't, unless you have to. If you do, take Extreme care when removing the fuel tank. Hobo Tim
A word of caution. Rob told me there are no replacement fuel tanks. If you break it, you will have to find a way to repair it.
I finally found some free time. That means I had time to paint my wheel, Install BLMA detail, fix my engines. Now my F59PHI will pull six passenger cars, and my SD70 finally can pull cars by itself without help. I found out that by regauging the SD70 can make it run smoother and pull more cars. I guess reading all those post do help, because I remember one of Robert's post on how to regauge.
After regauging the SD70 I spend most of my free time testing it. For some reason, it pulls much better going long hood first then short hood. I can pull 22 cars when running long hood forward. When I run it short hood first, there is some serious wheel spin. My only theory is because the traction tires is on the Long hood axle. Tim, do you want to do a experiment to see if the placement of the traction tires makes a difference. I would do it myself, but I dont break the fuel tanks.
tim, when reading your post I HAD to try it myself. I had made a big service on all my sd75's: take apart and take the inner 2 of the 4 black plastic parts, which hold the worms and spirals in place, out; regauging and fix middle axle height. they run now as smooth as my best running Geep (and as fast)! one sd75i is able to pull 51 mtl cars, with light wheel slipping. adding just the metal weight of a full throttle cylindrical hopper caused the wheel slipping to disappear. there was no wheel slipping when running the unit long hood forward (without additional weight). running it long hood forward shows up better pulling characteristics, because of traction physics: what happens if you accelerate too much with a motorcycle? it stands up (hm, ain't this called a "wheelie"?). same thing with locos: when accelerating, forces would cause the truck to stand up like a motorcycle. locomotive chassis and weight prevent from this, but it cannot make this effect disappear completly. so, the front axle of a truck has a worse adhesion than the back wheel (about 1/8 of overall pulling power!). locomotives of the company I work for as locomotive engineer/conductor have an electropneumatic system to improve adhesion/traction by distributing more motor power to the back axles than to the front axles. so, for an sd75i in zscale, the same rules can be applied: when running the loco the way the traction tire is on the back-axle of the truck (long hood forward), it's a real power puller. when running it the way the tire is on the front axle of the truck (short hood forward), the improved traction of the tire may not come into effect. to add weight to the sd75i I'd propose tho run it with pilot/snow plow instead of using the truckside coupler. so between truck, pilot and stairs, also between snow plow and pilot there is space to add some grams/ounzes of lead. I'd not touch the fuel tank, as these clip-ons break off too easily and the fuel tank DOES play a vital role for holding the truck in the frame (just as tim mentioned). daniel
Loren, Loren, Loren. But it would take the "fun" of fixing your engine. Now you know every part of your SD70. Does that mean that you are one with your engine. LOL
Adding Weight Knowledge! This thread is being filled with Knowledge and some Experience! This is great!!! When it comes to tweeking the inner workings of AZL's SD70/75's I would say do not attempt it unless you absolutely know what you are doing. Not only is the fuel tank delicate, so are the two upper chassis clips that hold the top of the chassis together. When/If you dis-assemble the chassis, make sure you re-assemble it with the Traction Wheels on the rear of the chassis. If you prefer to run a consist with one or more SD70/75's with the cab facing backwards, change the traction trucks to the front of the loco. Remember which loco's you re-work in order to have the max power in your consist. I have placed the Snow Plow on the front of my SD75i. In order to do this you have to remove the coupler from the truck. Now only the rear truck, with traction wheels, is easily identifiable. No mistaking it. ---------------------- Now, this is how I propose to add weight to my AZL SD loco's. I own a small desktop Unimat lathe/milling machine. I will use some of my small Micro-End Mills and carefully remove equal amounts of white metal from both chassis. I will purchase some of the Tungsten powder from the local PGA Superstore and mix it with some strong glue and fill in all machined areas. I hope to be able to add half to twice as much as what the AZL SD weighs already! We will see!! ----------------------- Loren, I agree with you about locos should work perfectly right out of the box. Well, I can imagine how fast these chassis are thrown together. If you take your time, you might be able to completely assemble one (1) chassis in 5 minutes. Well, the South Koreans probably assemble one in 1-2 minutes flat. It's a speed vs $$$ thing. In order to get these SD's at the price we get them something has got to give. ----------------------- Now, AZL C44-9, John, Spotlight is on you!!!! We want to hear about your C44-9 w/Traction Wheels!!!!! Hobo Tim
Tim, the German customs finally relesed my engine to Oliver, and he will work on it this week. I am hopeful that I will get back this month. I prefer that not to go with body mounted coupler in the long hood, because I usually run shor hood forward. Running it with body mounted truck, will limit it from running on part of my radius. I am also looking to add BLMA details to the SD70. I probably add the mirrors , mu hoses, and cut levers. I also want to weather it a bit. It looks to clean to be UP.
Jeff, yes, and I'm doing big service on the locos now after thousands of kilometres running :shade: I wish a day had more than 24 hours, so I would be able to do some more work on my modules... Loren: I agree absolutely with you, this should not be. well, I must confess, I was badly disappointed when putting my new SD out of the box onto the track and running it. So I had no choice than to fix it. But to do this, I had to open that unhappy construction of the fuel tank what really dosen't make things easier! I appreciate the MTL locos with that snap on shell and fuel tank!! But neither can we expect to run a brand-new loco as smooth as it has been running for dozens of hours, because a proper run-in session should be made, also with a new car or motorcycle.... To run in is the only thing a customer should have to do on its own, to get a new loco running properly, and is able to, without further knowledge of the loco, I think. Tim: I have additionally ordered several spare parts from Z-track (as pilot, snow-plows, etc...) and mounted on each side of my SD's a snow plow. no problem with pulling forces even with double or triple heading (in spite of the warning in the manual of the SD70). only problem are curves, because the locos are pulling cars with truck mounted couplers out of the track. but with radius like the original, also this works. Looks great! greetings, daniel
