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getting back in RC, converting a 3.5 earthquake

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Old 11-24-2018, 07:19 AM
  #1  
napkinthief
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Default getting back in RC, converting a 3.5 earthquake

hi i just joined on here looking for advice/tips

i have a variety of rc cars, drones, helis, and getting back into the hobby now.

my rc in question here is redcat earthquake 3.5. the nitro engine has been very good to me, but this year, not so much. broke the pull start, ordered a roto start, broke the wand, reordered a wand, broke the one way, replaced one way, now cant get it to start. i gave up on this.

i ordered a tksy 120a esc and a few brushless motors and spur/pinions (2800kv 3300kv 5900kv motors) these were all off of amazon, under 25$ each. anyway, i blew up the first tksy esc, by simply running the 2800kv motor on a 3s. the motor only is supposed to handle 10v. mistake is on my part. it ran OK on a 2s. reordered the same tksy esc, and run the 3300kv motor on 2s and 3s successfully. it was really choppy, almost like the esc was cutting the power out. after 2 back and forth runs maybe 50 ft long, i tried to reverse and the esc caught up in smoke and wouldnt drive the motor anymore. at this point i gave up on tksy and bought a hobbyking 120a (8w?) esc. now i have to say, comparing to the tsky, the hobbywing esc is massive, water proof, feels heavy duty. i wired it up to the 3300kv and it runs pretty good (no smoke yet)

1st question, my issue is with the chassis. it has a disc brake, that the old throttle servo used to clamp down on when throttle closed and hit reverse. im using the 2nd channel now to drive the esc, instead of the throttle servo. if i hit reverse now the motor spins backwards but the spur just spins and doesnt brake or drive the wheels reverse. i think earthquake had a 2 speed trans,dont rememebr if it has reverse... any ideas here? id like reverse, but at minimum i need some type of braking lol

2nd question is on gearing. i havent run it enough or fast enough (since no braking) to test motor temps. im running the upgraded redcat steel spur gear (43t?) and a 14t pinion. its my first shot at gearing, and i have 12 to 18t pinions to play with at the moment, and more variety in a different pitch.



greatly appreciate any advice
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Old 11-24-2018, 10:31 AM
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tcharger
 
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It does have a 2 speed, you can't drive the spur in reverse. The way to get your brakes back is to run a splitter from ch. 2 to the esc and the brake servo so it will operate the brakes. As far as the gearing question, I believe the stock clutch bell was a 16t. So you should have no issues running a 14t pinion.
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Old 11-28-2018, 02:03 PM
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napkinthief
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Originally Posted by tcharger View Post
It does have a 2 speed, you can't drive the spur in reverse. The way to get your brakes back is to run a splitter from ch. 2 to the esc and the brake servo so it will operate the brakes. As far as the gearing question, I believe the stock clutch bell was a 16t. So you should have no issues running a 14t pinion.

thank you kind sir... i split the channel 2 and it does work the brakes and esc now. i have some major adjustments to make since its hitting the brakes at mid to full throttle, but it does work.


also my motor mounting method needs revision... the gears are too tight and adjustment is maxed. back to the drawing board
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