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Tekno ET48 Build - TP 4070

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Tekno ET48 Build - TP 4070

Old 01-04-2015, 03:37 PM
  #46  
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Originally Posted by 0verkill
What kind of gearing do you think is appropriate with no fan? I only have a 23T pinion at the moment.

Diff Ratio - 4.44
Spur - 44T
Motor KV - 1440 (or it could be closer to 1740 based on your findings)
Tire Diameter - 5.85"
Battery - 6S
Alright, so assuming 1440kv (did you check it yet with your ESC?), your gearing gets you, coincidentally, exactly the same no-load wheel speed as xmods 22T pinion set-up: 66 mph. There are a couple of differences, wheel weight being the most important one I think (yours are heavier, so higher load during acceleration), but his tires were ballooning and yours won't, meaning, assuming all things equal, actual top-speed load on yours will be smaller. Xmod ran that set-up fine without a fan, so if your motor does not turn out to be a much higher kv, you should be good with no fan.

Personally, I would throw on a fan though, just gives you some more breathing room. It's cool to see how the Tekno mount seems to accomodate much bigger pinions. Your 23T pinion seems only little over half of the available "sliding space". With fan, I unknowingly (thought kv was lower, you know the story) ran 79 mph gearing on ballooning Badlands without heat issues. Was a bit hard to get it to full throttle without taking-off though . I'm working on trying some higher gearing for some on-road fun now, but when I get my GT2 up and running I'll probably gear the 8T back to ~70mph for off-road use with fishlined Badlands and call it a day. My skills seem to be lacking to go much faster off-road .

Finally I thought I'd throw in a pic for the "ballooning is good for handling" discussion... This is what ballooning Badlands look like on a fun truggy (yes, those exist ) at 76 mph no-load gearing, center diff is no light 10k cSt racer diff with massive front unloading, but filled with 2.000.000 cSt fluid, so rears look very similar, if not identical...



Personally, I'm not a fan of taping either; for one I suck at gluing tires and in addition I don't like the weight it adds. I'd probably also do such a poor job it would add massive imbalance, which would take even more weight to get rid of. That's why I fishlined mine, works for me and keeps the tire nicely in shape so it actually can keep some surface contact area, and thus traction:

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Old 01-04-2015, 04:55 PM
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Ah, almost forgot, you happen to have one of those low voltage alarms you plug into your battery balance leads? I'm very curious if your Nano-techs can also be made to trigger those with clumsy throttling, like with my regular and HD Turnigies. Still haven't figured out what that's all about, as my data logs do not show sags to below 3.3V/cell. Then again, data logs are total voltage and the lipo alarm reads individual cells...

Very interested in your first 6S impressions!
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Old 01-04-2015, 06:04 PM
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Just saw this very nice. Will follow the thread now.
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Old 01-04-2015, 08:44 PM
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Originally Posted by Dr_T
Alright, so assuming 1440kv (did you check it yet with your ESC?), your gearing gets you, coincidentally, exactly the same no-load wheel speed as xmods 22T pinion set-up: 66 mph. There are a couple of differences, wheel weight being the most important one I think (yours are heavier, so higher load during acceleration), but his tires were ballooning and yours won't, meaning, assuming all things equal, actual top-speed load on yours will be smaller. Xmod ran that set-up fine without a fan, so if your motor does not turn out to be a much higher kv, you should be good with no fan.

Personally, I would throw on a fan though, just gives you some more breathing room. It's cool to see how the Tekno mount seems to accomodate much bigger pinions. Your 23T pinion seems only little over half of the available "sliding space". With fan, I unknowingly (thought kv was lower, you know the story) ran 79 mph gearing on ballooning Badlands without heat issues. Was a bit hard to get it to full throttle without taking-off though . I'm working on trying some higher gearing for some on-road fun now, but when I get my GT2 up and running I'll probably gear the 8T back to ~70mph for off-road use with fishlined Badlands and call it a day. My skills seem to be lacking to go much faster off-road .

Finally I thought I'd throw in a pic for the "ballooning is good for handling" discussion... This is what ballooning Badlands look like on a fun truggy (yes, those exist ) at 76 mph no-load gearing, center diff is no light 10k cSt racer diff with massive front unloading, but filled with 2.000.000 cSt fluid, so rears look very similar, if not identical...

Personally, I'm not a fan of taping either; for one I suck at gluing tires and in addition I don't like the weight it adds. I'd probably also do such a poor job it would add massive imbalance, which would take even more weight to get rid of. That's why I fishlined mine, works for me and keeps the tire nicely in shape so it actually can keep some surface contact area, and thus traction:
I haven't done the motor kv test. I ran it today for the first time and the motor temperature didn't go over 135*F with 30+ minutes of running on grass. The gearing is actually closer to the end of the mount because there's another screw on the bottom of the motor mount and it's almost maxed out, although you could probably open the slot some more. I had no ballooning at all, which I'm very happy about. And that's actually with 10/15/7 diff oil, it drove really nice.

Originally Posted by Dr_T
Ah, almost forgot, you happen to have one of those low voltage alarms you plug into your battery balance leads? I'm very curious if your Nano-techs can also be made to trigger those with clumsy throttling, like with my regular and HD Turnigies. Still haven't figured out what that's all about, as my data logs do not show sags to below 3.3V/cell. Then again, data logs are total voltage and the lipo alarm reads individual cells...

Very interested in your first 6S impressions!
Don't have one.
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Old 01-04-2015, 08:58 PM
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First test run, 90% of this is part throttle. Full throttle for any longer than a second needs more space to effectively use the available power. This truggy is very fun to drive.

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.

Last edited by 0verkill; 01-04-2015 at 09:13 PM.
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Old 01-04-2015, 11:32 PM
  #51  
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poor grass !
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Old 01-04-2015, 11:36 PM
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Drooooool.
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Old 01-07-2015, 07:27 PM
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Apparently I didn't have enough loctite on the motor mount screws and they backed out, which led to a stripped spur. The threads were too clean when I removed the screws.



Topped off the center diff oil with 30k.



On top of adding more loctite, I found these Nord-Lock wedge locking washers at Grainger for even more protection against loosening screws.


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Old 01-07-2015, 08:07 PM
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maybe you could fill the space with the right piece of aluminium next to the screw so that it can't slide further.
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Old 01-10-2015, 03:28 PM
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Originally Posted by werner sline
maybe you could fill the space with the right piece of aluminium next to the screw so that it can't slide further.
It didn't move that way, just backed straight out. Anyways, I had no problems with screws backing out today.
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Old 01-10-2015, 03:53 PM
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Hit 56 mph in the grass today.

On board with GPS Telemetry

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.


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Old 01-11-2015, 03:48 AM
  #57  
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so how many packs have you been through ?

dif box are the same as the EB48 ? I think that the 10z diffgear bearings are quite small (5x11x4 ): do they hold well the tork ?
How do the tekno steel wear ?
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Old 01-11-2015, 10:33 AM
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Originally Posted by werner sline
so how many packs have you been through ?

dif box are the same as the EB48 ? I think that the 10z diffgear bearings are quite small (5x11x4 ): do they hold well the tork ?
How do the tekno steel wear ?
About 5. The original EB48 has an older style gearbox and the ET48 & EB48.2 has the new style with larger 5x13x4mm pinion support bearings. The differential bearings are 8x16x5mm. The ring gear is hardened steel, I haven't looked at them yet. The car is running good.
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Old 01-18-2015, 01:52 PM
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Dog chase

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ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
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Old 01-18-2015, 02:50 PM
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I m not sure that it is a good thing to run such a powerful rc between people

ok there seems to be enough room and you drive slowly between the people but you never know what could happen...
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