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  1. #1
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    Best gearing options

    e-maxx 3908L truck

    bashing, jumping and hill climbing

    what would be the best and safest gearing with the setup below. I am almost done building this and the spur is currently 68T and the only pinion I have to fit motor is 17T

    ESC : Hobbywing EZRUN SC8 (120a)

    http://www.falconsekido.com/products/ezrun-esc-wp-sc8

    Motor : Hobbywing EZRUN Brushless 3656 (4700kv) or EZRUN 4065 (2700kv)

    http://www.falconsekido.com/products/ezm3656sl

    http://www.aliexpress.com/item/free-...492181616.html

    Battery : Gens ace 5000mAh 11.1V 40C 3S

    http://www.gensace.com/epages/genspo...1P-HardCase-15
    Last edited by razbus; 03-19-2013 at 11:29 PM.

  2. #2
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    well i have the esc my self and it has a max of 4s only. the motor now the 3656 i can tell you right now dont get it, i wouldnt even get the 4065 too high of KV and the motor is not large enough for the emaxx. You need a 1/8 scale motor like XeRun 4274. hobbypartz.com has it i think for 81-88 worth it and it will match up to your esc prefect as i have that exact combo.
    if you already have the motor 4065 then stick with 17/68 and go from there keep checking temps then go up if you can to like 17/65 or 21/68 only if temps allow if they dont then you may need to go down if they are high.
    DEU 8:18 ESV

  3. #3
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    Thanks for help, what is the safe temp range for this esc?

    I do have the motors, but I can always turn around and sell them to my buddy joe, because he has said that he wants them.

    I did want to get that motor but specs show 4-6s and my lipos are 3s. If I get the XeRun 4278 what gearing should I do since my lipos are only 3s?
    Last edited by razbus; 03-20-2013 at 10:17 AM.

  4. #4
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    Safe range will be 140 you'll want to stay at or under. The cooling fan is always on so it stays cool. I use 2s on mine just fine for crawling sometimes and does a great job too. Try 21/65 first then if everything is cool then up to 21/62 since spur gears are cheaper than pinions best to change that out.
    DEU 8:18 ESV

  5. #5
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    check out valuehobbies.com the ezrun pro 150amp esc is about 90.00 and the gforce brushless motors 4074 size for 60.00. i have the esc but use a tacon 2150kv on 5s geared 19/65 good for all condition my temps are around 120-130
    slash hot rod
    tacon 2150kv 3s
    mod 1 20/36

  6. #6
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    tell me if I am correct

    high kv = speed (4000)
    low kv = torque (2000)

    big pinion/small spur = more speed (21/62)
    small spur/big pinion = more torque (17/68)

    because I want to be able to do steep hill climbing and ramp jumping.....I know it can destroy my differentials but I would like to do a standing backflip every now and then to show off

    So while watching temps start off with 17/68 and work up till I find my sweet spot. I know I will need torque for climbing and flips but I do not want to destroy my gears, should I switch from plastic gears to metal?

  7. #7
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    the KV part i am not too familiar with so i wont comment on.
    your right about the pinion/spur stuff you just messed up on the second one should be small pinion/larger spur=more torque

    You can hill climb with either combo of gearing you posted. i know with my 21/65 i can back flip still if i turned punch control to 9 on my esc but its at 5 right now and still wheelies all the time and just the right spot for my liking both road, offroad, i dont jump so not sure how it would work but should be ok.

    I highly dont recommend going with steel gears or metal gears are plastic like the spur gear so you know something is wrong in the tranny, drive train and such. stick with plastic gears
    DEU 8:18 ESV

  8. #8
    RC Turnbuckle Jr.
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    That would be correct although on a heavy truck stick with the 2200
    I would go with a 65 spur and around 18 pinion to start. Plastic spur is fine. Weak spot will be the diffs. In the long run it would save you money to do the flm hybrid bulkheads and 1/8 scale diffs. Can't beat the strength and peace of mind

  9. #9
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    oooops ... sorry about the typo.

    thanks for the help, I know have an idea on what to do.

    few more parts and it will be done.

    Finished:

    RPM front A-arms
    RPM Rear Tru-trac
    RPM bulk head braces

    Need to finish:

    Shocks
    RPM Shock Towers
    Skid Plates/with RPM protectors
    way to mount down the lipos (these are thick)

    Should I do anything in aluminum? I was thinking the bulkheads and shock towers, but I do not know

  10. #10
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    cut some holes for velcro straps for your lipos.
    here's a picture of what i am talking about
    DEU 8:18 ESV

  11. #11
    RC Turnbuckle Jr.
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    Flm shock towers are nice!

  12. #12
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    cool ideas

    Quote Originally Posted by 50togo View Post
    That would be correct although on a heavy truck stick with the 2200
    I would go with a 65 spur and around 18 pinion to start. Plastic spur is fine. Weak spot will be the diffs. In the long run it would save you money to do the flm hybrid bulkheads and 1/8 scale diffs. Can't beat the strength and peace of mind
    Is this what you are talking about

    Front:
    http://www.fastlanemachine.net/prodd...LM17750&cat=15

    Rear:
    http://www.fastlanemachine.net/prodd...LM18750&cat=15

    I was going to be using a Fly sky FS-GT3C Radio system, it is 3 channels. Since the emaxx uses 2 servos for steering

    should I:

    A) Purchase a Y cable and connect them together into channel 1

    or

    B) Purchase a Traxxas 6518 receiver but, will it work with my Fly sky transmitter

    I hope to do option B because I would like to put lights in the emaxx, figure I would use the left over channels, They should power the lights - I think
    Last edited by cooleocool; 03-23-2013 at 09:28 AM. Reason: merge

  13. #13
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    i would say purchase a y cable since it doesnt have the same setup as the traxxas rx's and plug into chan.1
    You can still plug a set up of lights on the 3rd channel it might power the lights if you have a strong BEC i think it is called or you can simply power it your self with a 9v battery i have seen and you put a switch on it. I have a AA box setup for mine which i might not use due to size but i do have a wire for lights with a 9v plug to it. The one to ask if you can run the lights on that tx/rx is jimmie neutron he fiddles with those alot and would be able to tell you if it will power for sure. Reference lol.
    DEU 8:18 ESV

  14. #14
    RC Turnbuckle Jr.
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    yes those are they bulkheads i was talking about. or you can get the hybrid bulkheads and put some other diffs in. i ran ofna hyper 7 in mine

  15. #15
    RC Turnbuckle Jr. MITCH316's Avatar
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    What gearing you settle on mate?
    Rock n Rolla !

  16. #16
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    I only have 17/68 at present time, need to buy the others to try out. still in the building phase. need to save up $$$$

  17. #17
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    ok FedEx just delivered my Xerun 4274.

    ECS: Hobbywing EZRUN SC8 (120a)
    Motor : Hobbywing XERUN 4274 2000kv
    Lipo: Gens ace 5000mAh 11.1V 40C 3S

    So, I should set the gearing at 21/65 to start?

  18. #18
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    Quote Originally Posted by razbus View Post
    ok FedEx just delivered my Xerun 4274.

    ECS: Hobbywing EZRUN SC8 (120a)
    Motor : Hobbywing XERUN 4274 2000kv
    Lipo: Gens ace 5000mAh 11.1V 40C 3S

    So, I should set the gearing at 21/65 to start?
    Yes 21/65 its what I have geared right now and temps are below normal to me of 111 ESC+126 motor max temps I have seen recorded offroading for about 25 mins non stop. Try that gearing out with your set up and see how you like it and post back with results but think its perfect in between of speed/accel .
    Ooh wait its 3s as in only 3s or 2 3s lipos
    DEU 8:18 ESV

  19. #19
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    qty of 2 Lipos

  20. #20
    RC Turnbuckle Jr.
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    I would of started with two 2cell batteries. 3s is pretty wild especially for a new combo

  21. #21
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    They are the only lipos I have

  22. #22
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    Quote Originally Posted by razbus View Post
    qty of 2 Lipos
    the hobbywing sc8 120a esc is only rated for 4s max! it wont turn on even with 6s total. the motor is fine for 6s though. I have to agree 6s is going to be very hard on the driveline so watch out
    DEU 8:18 ESV

  23. #23
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    I just ordered (2) 5000m 2S Lipos. Glad yunz said that, I was not even thinking....Thanks

  24. #24
    RC Turnbuckle Jr. mike-susieq1's Avatar
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    no problem glad you posted that you were planning to use 2-3s lipos the esc wouldnt even turn on with that much voltage but then again it can but shouldnt. 5000mah will last a while with that esc i have lower and runs for a long time with LVC set at 3.4v
    DEU 8:18 ESV

  25. #25
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    Or if you don't want to do AS MUCH dremel work...you could do something like this
    It's just a Velcro piece with a screw through it and bolted to the chassis

    And this is just a computer wire Velcro piece stuck threw a small slit I dremeled
    You ain't bashin unless your crashin!!

  26. #26
    RC Turnbuckle Jr.
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    I would feel better with two straps like this kershaw box on mine

  27. #27
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    Ya 50 yours is probably much better ...I don't know how well my rig will hold up haven't done much testing but it works great so far
    You ain't bashin unless your crashin!!

  28. #28
    RC Turnbuckle Jr.
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    much easier then the stock setup!

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