TFX chassis test
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Hi great video yes the TFX are great chassis i got mine when they first came out. just need a slight higher rear tires . chassis drag on track but all other items are great on it. what ohm armatures did you order on yours . there full line of parts are great. do you also race the vintage aurora t/jets yet. i am new to slot forum .
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Welcome to the HO forum, GK58. 
in general a lower ohm armature has thicker wire on it . needs more power to run fast . the higher ohms armatures have thinner wire on the armatures lower ohms run hot and fast. good for drag racing. higher ohms armatures are good for road racing and every day racing. they run cooler.
Hi on the car you are showing are you running gears on the gear plate or is that the new/old belt drive that is back again now. car looks like a good runner /racer. track also looks great to run on. great job on everything you are doing.TFX cars come with silicone tires and those work best on a perfectly clean track. The TFX tires have better grip after they have been scuffed in. I run some of my TFX cars with the stock tires and some with Pro Series Super Tires on CNC machined wheels.
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I don't think that OS3 offers a TFX belt drive option. RT-HO sells the pulleys and belts to convert pancake cars to belt drive. SouthShoreRacing started a thread about the conversion a year ago. I was tempted to evaluate a car with belt drive, but it would not have been legal for formal racing.
For people having track clearance problems with TFX cars several larger diameter front and rear tire sizes are now available. If you were using a body with the screw posts cut for a regular T-Jet type chassis you would need at add a front spacer when you put that body on a TFX chassis. I find that guide pin bases are the right thickness.
Using an armature with a lower ohm rating does not always result in a car with better performance. An armature with a lower ohm rating will pull more amps. The amount of power that the armature will generate will depend on a number of factors, including the ohm rating, the number of windings and the strength of the motor magnets. For a start, if you use thicker wire to lower the ohm value the number of turns would be reduced. Another thing to consider is that while an armature has an ohm value it should not be considered to be a resistor unless the armature is not turning. An armature that is turning becomes a generator and the voltage that it will produce opposes the applied voltage, that back EMF will cancel part of the applied voltage. That is why a motor that is operating properly will draw a nearly constant amount of amps over a wide range of applied voltages. If the motor magnets are stronger the amount of back EMF will be higher. Magnets need to be matched to the armature, if you go to a lower ohm value armature you would be more likely to benefit from using stronger magnets.
Lower ohm armatures do not necessarily run much hotter. I am racing a T-Jet with a 8.4 ohm armature and that does not get hot. A fellow racer has a 2 ohm armature in one of his cars with no heating problems. There are several more reasons that a motor might heat up, you could be using the wrong oil, the gears might need lapping or the motor magnets might be too weak.
For people having track clearance problems with TFX cars several larger diameter front and rear tire sizes are now available. If you were using a body with the screw posts cut for a regular T-Jet type chassis you would need at add a front spacer when you put that body on a TFX chassis. I find that guide pin bases are the right thickness.
Using an armature with a lower ohm rating does not always result in a car with better performance. An armature with a lower ohm rating will pull more amps. The amount of power that the armature will generate will depend on a number of factors, including the ohm rating, the number of windings and the strength of the motor magnets. For a start, if you use thicker wire to lower the ohm value the number of turns would be reduced. Another thing to consider is that while an armature has an ohm value it should not be considered to be a resistor unless the armature is not turning. An armature that is turning becomes a generator and the voltage that it will produce opposes the applied voltage, that back EMF will cancel part of the applied voltage. That is why a motor that is operating properly will draw a nearly constant amount of amps over a wide range of applied voltages. If the motor magnets are stronger the amount of back EMF will be higher. Magnets need to be matched to the armature, if you go to a lower ohm value armature you would be more likely to benefit from using stronger magnets.
Lower ohm armatures do not necessarily run much hotter. I am racing a T-Jet with a 8.4 ohm armature and that does not get hot. A fellow racer has a 2 ohm armature in one of his cars with no heating problems. There are several more reasons that a motor might heat up, you could be using the wrong oil, the gears might need lapping or the motor magnets might be too weak.
Hi RichD yes that is very true . Rt-HO is the one making them. i was just asking if he was running the new belt drive. i did not see any gears on the gear plate .it looked like the belt drive to me. but he did answer me back and said he is running gears. do you remember when they first came out i think it was in the late 1960 the real auto world had them then. did you ever run any back then. do you also still run vintage aurora t/jets yet. what do you think about the new items out they have now.by wizzard dash/motor sports the new auto/world. it is great we are always trying to make them better and faster . aurora t/jet cars/racing is the very best. always the real deal i enjoy all scales of slot car racing .
Hi when i answered him on that about ohms on armatures i was just in general saying lower ohms armatures need a good power source to run them. and do run hotter. a lower ohms armatures do run cooler . but yes any armatures need the right set up. to run there very best. that would be any motor. if i may ask on the 2ohm armatures how long can he run and how many laps before a cool down was needed. 2ohm drag racing only. your 8.4 ohm armature is very road race able. but will need a cool down on a very long race. and yes every build is going to need the right set up to live a long race. that is what is great about slot are racing teaches you a lot on many things.
Hi when i was talking about the armatures before i should had said only new ones or a good one with the right ohm reading on each pole .being checked with a good ohm meter. then you can do the build for that motor. pancake motors run way different than inline armatures. take a 8.4 pancake and a 8.4 inline . the inline will always win. so i am talking about pancake motors when talking about ohms and heat and rewinds and dewinds on them only.
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The 8.4 ohm armature is in a T-Jet, so is the 2 ohm arm that I mentioned. The car with the 2 ohm armature is a handful, it has to be run choked down, so it would see an applied voltage of 15 volts max with the power supply set at 18.5 volts. I do not have to choke back on my car. The armature in my car is a double wind, probably the 2 ohm car is as well. We race with four 3 minute heats with a couple of minutes between the heats. I have measured the amp draw of an inline car with a 6 ohm armature on the track with an 18.5 volt applied voltage. That is 0.5 amps when the car is accelerating and 0.25 amps when it has reached top speed. Someplace I had readings for the same pancake car with a 4.7 ohm single wind armature, that one drew 0.4 to 0.7 amps.
The magnets in my pancake car measure 1100 gauss.
The magnets in my pancake car measure 1100 gauss.
Hi RichD this very true on everything you are saying .i am a older slot car racer my self..i still race all my vintage aurora /tjets . you and i understand what it takes to get these little hot rods going good and be fast . parts for them are crazy now. at one time there were no company left out there parts were very low all discontinue so i started doing my motors my self. . when i build i work in the range of 3ohms to 18.5 ohms. 3 to 5 ohms for drag racing. with 2 transformers per lane. for each car. and the transformers are 20volt each the aurora tan ones. for road racing i stay in the range of 10 to 15.5 ohms . but do up to 18.5 ohms. all track are different in size i like were there is at least one 25ft long straight and a bank turn. on road race layouts. and running one 20v transformer per lane to be fair . there is so much you can do with slot car racing .all of us love to build and race . and its good to share with each other on what we like to do and race. all scales of racing are great. ho 1/32 and 1/24 . new and old.
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Back when I was trying to determine how many amps the cars were using as they were circulating around the track the method that I used was to point a video camera at the power supply digital display and record the changing readings. The two sets of results that I posted earlier were done that way. Now I have a VRP dynamometer connected to a regulated power supply with volt and amp displays that read to three decimal places. I put the car with the 8.4 ohm double wind armature on the dyno and read 0.4 ohms at 18.5 volts. That confirms that the on track readings are good when the car reaches top speed. For cars with a significant amount of magnetic downforce the VRP device can be adjusted to simulate the on track conditions, but that would not apply to the car with the pancake armature because that has no magnetic downforce to speak of.
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