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  1. #1
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    3800kv motor in Rally question

    Anyone ever try it on 4s?
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  2. #2
    RC Turnbuckle Jr. humayrayakongkinaon's Avatar
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    i think 3s is pushing it already, i dont know if thats good for the motor though.
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  3. #3
    RC Turnbuckle Jr. thedreadedend's Avatar
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    You will find it maxing out in 3s, heat and turns........ but its as fast as heck on 3s! Quicker than a 2400 on 3s geared the some, for what its worth.
    the 3800 is an sediment combo through 2s bit 3s will shoe its limitations ........the 2400 will gear higher and eventually go faster because it's a bit cooler with room for more voltage and gearing.
    I run a 3800 in 2 trucks and a 2400 in the rest of my trucks.... I like theme 3800 in my rally best.
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  4. #4
    RC Turnbuckle Jr. DiggerPede's Avatar
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    I wouldnt do it unless you want to fry the motor. A couple guys on here, dread & pave are running the 3800 in their Rally's and love it. I'd suggest moving up the the 2400kv, which is perfect for 3S-4S setups. It's a beast in the Rally all I can say.
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  5. #5
    RC Turnbuckle Jr. pavmentsurfer's Avatar
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    I ran a 3800 on 4S in a 2X4 rustler a while back. It cogged so bad it would barely move from a stop, then when the wheels did finally start to turn, they just did a huge burn out. It was completely uncontrollable. Heat was bad in that truck after only ONE short pass... imagine how much worse it would be in a 4X4.

    3S with that motor in this car is probably possible with really low gearing and only for very short speed runs with cool down periods in between. But 2S is really where this motor is happiest. Like Dreaded said, if you want to run 3 and 4S, get the 2400 combo. It can handle it.
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  6. #6
    RC Turnbuckle Jr. humayrayakongkinaon's Avatar
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    i have the equivalent MMP/2400kv on my rally GT8 with a 2800kv motor and running it on 4s, temp stays cool at 130-35 motor and 137-40 esc.
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  7. #7
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    Sorry to hijack, but I was wondering what the best one for the rally would be.

    the 2400kv one here

    or the 2650kv here

    I only intend to run 4S does it require new motor mounts or anything else reason I ask is I live in Australia and dont want to wait weeks for it and then realise I need more parts.


    Cheers guys.

  8. #8
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    either of those motor's will require rear aftermarket driveshaft's. MIP, Tekno or the new Traxxas one's. They will chew up stock shaft's quick. The 2400 is a great setup, I run my slash4 with that system and only 4s, it is crazy fast. You could run the 2650 as well with little to no heat issue's. But I think the 2400 is the best choice for the Rally.

    You will want to replace the motor mount and slipper bearing adapter as well. KingHeadz is the only company out with a new aluminium mount system. The bearing adapter I would say is more important than the mount though. The plastic is known to get hot and melt during long runtime's and the bearing can seize in the stock mount as well causing complete carnage. Make sure you get lipo's with at least a 40c rating.
    Last edited by I EAT DIRT; 01-27-2013 at 05:30 AM.
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  9. #9
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    What is the Part number please for the KingHeadz motor mount and slipper bearing adapter

  10. #10
    RC Turnbuckle Jr. DiggerPede's Avatar
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    Quote Originally Posted by mariosol View Post
    What is the Part number please for the KingHeadz motor mount and slipper bearing adapter
    << KHZ-TRX-7460 King Headz Motor Mount>>

    << KHZ-TRX-6893 KH Bearing Adapter>> or << TRA6893X Traxxas Bearing Adapter>>
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  11. #11
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    I have a MMP/3800 in my rustler, geared 31/83, and run it on 3S a lot with no issues. I have ran it on 4S, but it heats up very quick and doesn't give that much of a performance gain.

    I'd say the 3800 should run a rally just fine on 3S, much better than the Velineon 3500 would. When geared the same, you should have to worry much about temperatures.

  12. #12
    RC Turnbuckle Jr. thedreadedend's Avatar
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    Quote Originally Posted by Jws1982 View Post
    I have a MMP/3800 in my rustler, geared 31/83, and run it on 3S a lot with no issues. I have ran it on 4S, but it heats up very quick and doesn't give that much of a performance gain.

    I'd say the 3800 should run a rally just fine on 3S, much better than the Velineon 3500 would. When geared the same, you should have to worry much about temperatures.
    The 4wd drivetrain and weight difference between a rusty and a Rally is significant. You wont see a rally running on 3s geared higher than 15t/54t. I've also run the 3800 in a rusty, sl2sh, sl4sh, p2de, p4de. Its best suited for 2s in a 4wd. The only reason I can pull off a 3800 combo in my rally and sl4sh on 3s is because I run a RCE chassis with tons of airflow and a big fat magnesium block for a motor mount. I had heat issues with my p4de when attempting 3s geared around 11t-13/54 so this tells me a great deal abolition its limits!
    If your looking for fast 3s action out of a rally on all terrain, your best choise is to go with a bigger motor. If your only hitting the streets, less than wide open and not jamming the brake, it could work fine for you but, you have a limited rally at that point...........no one wants to be limited!
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  13. #13
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    Even on 2's with a 3800kv in a 4wd application I usually get up to about 170 in temp after 1 pack. If you want 3's and 4's go with a 2400kv or 2650kv. The 3800kv is a great motor in a 2wd on 3's
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  14. #14
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    I also have a slash 4x4 that I've run that 3800 in a lot. Geared around the same as stock, it'll run 3S easily. The velineon would get too hot, but the 3800 does fine. I agree that 2S is best for it, but I've ran it on 3S a lot without overheating.

    My main combo for the slash is a MMP/2800kv, which does handle 4S just fine. 4S is just too much for the 3800 to handle.
    Last edited by Jws1982; 01-27-2013 at 02:06 PM.

  15. #15
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    Thanks DiggerPede

  16. #16
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    Quote Originally Posted by I EAT DIRT View Post
    either of those motor's will require rear aftermarket driveshaft's. MIP, Tekno or the new Traxxas one's. They will chew up stock shaft's quick. The 2400 is a great setup, I run my slash4 with that system and only 4s, it is crazy fast. You could run the 2650 as well with little to no heat issue's. But I think the 2400 is the best choice for the Rally.

    You will want to replace the motor mount and slipper bearing adapter as well. KingHeadz is the only company out with a new aluminium mount system. The bearing adapter I would say is more important than the mount though. The plastic is known to get hot and melt during long runtime's and the bearing can seize in the stock mount as well causing complete carnage. Make sure you get lipo's with at least a 40c rating.
    Thanks for reply are these the new traxxas ones you are refering to?

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