VTA tuning Q&A
#181
Tech Fanatic
iTrader: (21)
got a question. I am running 21.5 lipo with an lrp tc spec. geared at 4.21 my car comes of the track at 92*. Do I really need the heatsink and fan on the esc can I do away with one or both? I have not temped the esc since I have thought about doing this. just wondering if anyone else does it.
#182
Tech Elite
iTrader: (26)
got a question. I am running 21.5 lipo with an lrp tc spec. geared at 4.21 my car comes of the track at 92*. Do I really need the heatsink and fan on the esc can I do away with one or both? I have not temped the esc since I have thought about doing this. just wondering if anyone else does it.
#183
Tech Apprentice
Try a couple friends temp gun. It sounds like yours is miscalibrated.
#186
Tech Elite
iTrader: (9)
I'm not suggesting you touch any motor after racing, but is it warm to the touch? If it is truly reading 94, then that is cooler than the average person's mouth. I wouldn't suggest putting your finger into your mouth at the track either unless you like the taste of traction compound.
I don't doubt that the motor is coming off reasonably cool. If the ambient temperature of your track is low, that could explain some of this. However, I've yet to see a car geared at 4.2 that came off the track I race at temp that low. Granted, I race at a tight indoor track that requires you to be on/off throttle for the entire run. A large flowing track will usually result in cooler motor temps than a tight technical track or an asphalt parking lot track during the summer time.
This leads to the question of proper calibration of a temperature sensor. Most IR sensors have to be calibrated to the type of surface they are reading. I'm not going to claim to understand this, but this is called emissivity. Here is an section from the Duratrax Flashpoint Infrared Temperature Gauge (http://manuals.hobbico.com/dtx/dtxp3...ual-v1_1.pdf):
I don't doubt that the motor is coming off reasonably cool. If the ambient temperature of your track is low, that could explain some of this. However, I've yet to see a car geared at 4.2 that came off the track I race at temp that low. Granted, I race at a tight indoor track that requires you to be on/off throttle for the entire run. A large flowing track will usually result in cooler motor temps than a tight technical track or an asphalt parking lot track during the summer time.
This leads to the question of proper calibration of a temperature sensor. Most IR sensors have to be calibrated to the type of surface they are reading. I'm not going to claim to understand this, but this is called emissivity. Here is an section from the Duratrax Flashpoint Infrared Temperature Gauge (http://manuals.hobbico.com/dtx/dtxp3...ual-v1_1.pdf):
Emissivity is the way that any object emits heat
energy into the air. Emissivity is always rated by a
numerical value. Different types of materials have
different emissivity values. An object's emissivity is
dependent on its surface condition, material type,
temperature and wavelength of temperature
measurement. Adjusting the infrared temperature
gauge to compensate for the emissivity values of
different objects is the key in getting the most
accurate temperature readings.
energy into the air. Emissivity is always rated by a
numerical value. Different types of materials have
different emissivity values. An object's emissivity is
dependent on its surface condition, material type,
temperature and wavelength of temperature
measurement. Adjusting the infrared temperature
gauge to compensate for the emissivity values of
different objects is the key in getting the most
accurate temperature readings.
Last edited by IndyRC_Racer; 01-23-2009 at 12:33 PM.
#187
Tech Addict
iTrader: (13)
I'm not suggesting you touch any motor after racing, but is it warm to the touch? If it is truly reading 94, then that is cooler than the average person's mouth. I wouldn't suggest putting your finger into your mouth at the track either unless you like the taste of traction compound.
#188
Tech Champion
iTrader: (261)
If you're running a pre-T2 Xray chassis in VTA I've just listed up a like-new one-way diff at http://www.rctech.net/forum/r-c-item...ml#post5338228 if you've been wanting to give one a try. I bought this for the only Xray I ever owned, a 1/12 sedan, that I ended up selling before I ever ran it.
#189
I am running a TC4 with a 21.5 brushless and am wondering what other people are using for gears to reach the 4.2 FDR. Are you using 64 pitch or 48 pitch and which ones (i.e. 81/48 64p, 69/41 48p)?
Thanks
Thanks
#190
Tech Regular
iTrader: (1)
I have both the 72t and 69t spurs and currently a 40t and 38t pinion. I wanted the 39t also but it was out of stock. I prefer the 48 pitch as it's less susceptible to damage IMO.
I didn't see a 41t pinion for sale at SpeedTech RC but maybe you've seen a different source?
From what other's are saying it doesn't seem like you need to go all the way to 4.2 anyway.
#191
I believe A-Main has a 41 tooth 48p pinion. Thanks for the info. Did you have any fitment issues with the pinion. I have 69 48p spur so I may try that.
#193
Tech Elite
iTrader: (9)
I realize this answer is not for 48 pitch gears, but as long as I've paid attention when setting my mesh on my TC3, I've never had any issues with gear mesh using 64 pitch gears.
The simplest (and probably cheapest) way to reach the 4.2 FDR for a TC3/TC4 is to use an 84 tooth spur and a 50 tooth pinion in 64 pitch. This is exactly 4.2. If you plan on only running 4.2 you would only need to buy 1 spur and 1 pinion.
84/50 * 2.5 = 4.2
If you use a tub chassis TC3 you will have to remove some of the webbing or chassis support that will be underneath the pinion gear. I just setup a TC3 for VTA and used a grinding stone/wheel on my dremel and it only took me a few minutes to remove the material so the pinion would not rub the chassis.
The smallest 48 pitch spur that I'm aware of is a 60 that is made by Robinson Racing. It is available on Tower Hobbies (http://www3.towerhobbies.com/cgi-bin...?&I=LXEY18&P=7). The "fastest" you can go with that gear is:
60/35 * 2.5 = 4.286
The simplest (and probably cheapest) way to reach the 4.2 FDR for a TC3/TC4 is to use an 84 tooth spur and a 50 tooth pinion in 64 pitch. This is exactly 4.2. If you plan on only running 4.2 you would only need to buy 1 spur and 1 pinion.
84/50 * 2.5 = 4.2
If you use a tub chassis TC3 you will have to remove some of the webbing or chassis support that will be underneath the pinion gear. I just setup a TC3 for VTA and used a grinding stone/wheel on my dremel and it only took me a few minutes to remove the material so the pinion would not rub the chassis.
The smallest 48 pitch spur that I'm aware of is a 60 that is made by Robinson Racing. It is available on Tower Hobbies (http://www3.towerhobbies.com/cgi-bin...?&I=LXEY18&P=7). The "fastest" you can go with that gear is:
60/35 * 2.5 = 4.286
Last edited by IndyRC_Racer; 01-26-2009 at 08:20 AM.
#194
I realize this answer is not for 48 pitch gears, but as long as I've paid attention when setting my mesh on my TC3, I've never had any issues with gear mesh using 64 pitch gears.
The simplest (and probably cheapest) way to reach the 4.2 FDR for a TC3/TC4 is to use an 84 tooth spur and a 50 tooth pinion in 64 pitch. This is exactly 4.2. If you plan on only running 4.2 you would only need to buy 1 spur and 1 pinion.
84/50 * 2.5 = 4.2
If you use a tub chassis TC3 you will have to remove some of the webbing or chassis support that will be underneath the pinion gear. I just setup a TC3 for VTA and used a grinding stone/wheel on my dremel and it only took me a few minutes to remove the material so the pinion would not rub the chassis.
The smallest 48 pitch spur that I'm aware of is a 60 that is made by Robinson Racing. It is available on Tower Hobbies (http://www3.towerhobbies.com/cgi-bin...?&I=LXEY18&P=7). The "fastest" you can go with that gear is:
60/35 * 2.5 = 4.286
The simplest (and probably cheapest) way to reach the 4.2 FDR for a TC3/TC4 is to use an 84 tooth spur and a 50 tooth pinion in 64 pitch. This is exactly 4.2. If you plan on only running 4.2 you would only need to buy 1 spur and 1 pinion.
84/50 * 2.5 = 4.2
If you use a tub chassis TC3 you will have to remove some of the webbing or chassis support that will be underneath the pinion gear. I just setup a TC3 for VTA and used a grinding stone/wheel on my dremel and it only took me a few minutes to remove the material so the pinion would not rub the chassis.
The smallest 48 pitch spur that I'm aware of is a 60 that is made by Robinson Racing. It is available on Tower Hobbies (http://www3.towerhobbies.com/cgi-bin...?&I=LXEY18&P=7). The "fastest" you can go with that gear is:
60/35 * 2.5 = 4.286
thanks for trhe 60/35 info! I have had problems w/ 64p & rocks outdoors and will go back to 48p for the outdoor/summer season.