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  1. #1
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    Revo 2.5R budget brushless conversion

    So the story begins when I purchased my Revo 2.5R sometime around 2006.
    Changed a few things here and there as they broke and eventually got tired of the constant tuning of the 2.5R.

    I decided on the OS .18TM, which, once broken in I basically tuned it once and it's been running beautifully up until I removed it for this conversion.

    This all came about after driving my friends brushless Stampede. I thought, wow this thing is pretty fast, it makes almost no noise and it's still clean.

    As an experiment and for fun I have tried to convert my Revo to brushless as cheaply as possible, obviously trying to avoid skimping in areas where I felt a slightly more pricey part was required. I also did not want to modify anything to permanently as I may want to change back.
    What I can say is that so far the conversion seems good and I am happy with the parts that I choose.

    Things removed:

    2 steering servos (did single servo conversion at the same time)
    Throttle servo
    Receiver box & battery(receiver moved to where throttle servo was)
    OS .18TM (pullstart) with exhaust and fuel tank
    Brake disc (gearbox locked in 2nd, had FOC kit already as optidrive has issues)

    Things purchased:

    ******* ********* 120A Brushless Short Course Truck ESC
    http://www.*********.com/*********/s...dProduct=22632
    $53

    S3674-2370 Brushless Inrunner (2370kv)
    http://www.*********.com/*********/s...dProduct=15198
    $38

    ******* Heat Sink with Fan
    http://www.*********.com/*********/s...idProduct=9131
    $5

    ******* Metal Gear Servo 60g/15.5kg/.16sec
    http://www.*********.com/*********/s...idProduct=9617
    $11

    ******* 5000mAh 4S1P 14.8v 20C hardcase pack
    http://www.*********.com/*********/s...dProduct=15521
    $22

    Total $129 (including servo)

    Also bought a programming card and some connectors which were quite cheap.

    I decided to make a battery and ESC tray from PVC. It mounted on top of the servo mounts, radio mount and fuel tank mount.
    I had to make small triangular supports in order to use the screw holes currently in the chassis.

    I also made a engine mount from a piece of 50mm angle aluminium. I used 3mm at first with a gusset, however this bent in multiple places after one crash. It looks mostly due to the cutout made for the throttle linkage mount.

    My second attempt used 5mm angle with a 3mm gusset. This time I moved things around a bit such that they are stronger. The throttle linkage mount was also filed flush with the rest of the mount. Seems pretty decent now, had a couple of harsh crashes and nothing moved an inch.
    I also made a small spacer to support the back of the motor. It's also made from PVC, and hopefully it does something useful.

    I used a bit of thermal paste when I put the heatsink on, hopefully this helps a bit with the conductivity.

    I've heard of people breaking many diffs after doing brushless conversions, so I don't tighten my slipper clutch that much. The car won't wheelie from a standstill however at about 30-40 km/h the front wheels often begin to leave the ground. The car is rather fast, I'm slightly scared to drive it other than in a large open space with no trees. If the clutch is tightened the car wheelies on demand.

    ESC and motor seem to stay cool.

    Driving time seems about 30mins +

    One strange thing I've noticed is that my range (radio range) is terrible, I'm not sure if this is due to interference from the ESC? I checked the aerial wire and it is still fine.
    It's still running the old 27MHz AM radio and receiver. It's probably time to move to 2.4GHz?

    Things on the way:

    RPM Carriers (current bearings are shot and pivot balls have pulled out a few times)
    Bearings for diffs
    Spare diff
    Spare driveshaft


    My new body needs painting and the old one is too ugly to show

    Here are a few pics:

    Stripped diffs to inspect them, they still look pretty good.




    First attempt on the motor mount


    Second attempt on the motor mount


    Motor support spacer


    Sorry if some of these are slightly blurry...

    Battery tray, one can see the triangular spacers I was talking about on the left






  2. #2
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    On the move



    A while before the conversion

  3. #3
    RC Turnbuckle Jr. vxlrocket's Avatar
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    Good job! Looks great.
    Associated rc8TE, rc8.2E, B4.2, Ofna LX2E, Slash

  4. #4
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    Thanks. Was a bit easier to do than I expected. The motor mount is the only thing that has given me hassles.
    If this design works well, I will post a drawing here for others to use. If people want it.
    Luckily I found someone to weld it for me for free

  5. #5
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    I'm using a 16T pinion and 38T spur by the way. It's possibly a bit to fast like that.
    I will try get some videos this weekend

  6. #6
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  7. #7
    RC Turnbuckle Jr. 87 GN's Avatar
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    tell the truth, more fun that nitro? lol
    Would you go flip my truck back over??

  8. #8
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    I would say they are about the same amount of fun while driving.
    They are 2 different machines to drive but both have their perks.
    The fun sort of stops afterwards when the nitro requires quite a bit more cleaning.

  9. #9
    RC Turnbuckle Jr. 87 GN's Avatar
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    BL... almost plug & play,
    charging now....
    congrats on the conversion...
    Would you go flip my truck back over??

  10. #10
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    Thanks
    So far so good.

  11. #11
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    I like it. I was hoping see video of a budget setup like this. This is more performance than many people would be looking for, especially if their main goal was to eliminate the nitro. For those that can't do the fab work, an SCTE battery tray can be made to fit and an there is a sub 30 dollar mount copy cat of the original Teckno mount available too. So just add about $46 bucks to relflexsa's total.

    How are your temps on the battery after some good hard running? At 100A rating, I'm curious if it's getting hot with that motor. Also, how close does the left rear upper arm come to hitting the motor?
    Last edited by metoo2; 07-31-2012 at 04:00 PM.

  12. #12
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    Quote Originally Posted by 87 GN View Post
    tell the truth, more fun that nitro? lol
    I'll answer that, as I too am a recent convert. It is more capable and less of a hassle. Those things make for more fun, but there's something cool/fun about the sounds and sights of nitro. I like both, but the convenience factor of electric is hard to overlook. I now have acquired 5 electric vehicles in the last 3 months and looking to get a 6th. I sold 2 nitros. I still have 3, but have no desires for another.

  13. #13
    RC Turnbuckle Jr. 87 GN's Avatar
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    Heheheee ^ we are converting you nitro guys one at a time
    give it time they will improve the nitro motors.
    Would you go flip my truck back over??

  14. #14
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    Quote Originally Posted by 87 GN View Post
    Heheheee ^ we are converting you nitro guys one at a time
    give it time they will improve the nitro motors.
    I doubt it. It's my belief that they can't get much faster without getting a lot more expensive. The cool thing about 8 years ago, big block nitros with a lot of power (usually not very high rpm) started to come out at very low prices. I love my $100 STS28...best tuning motor since the OS RG, and its got lots of power. The really nice high power, high revving, quick revving engine used in serious 1/8 buggy races are twice the price of a faster electric setup. Serious 1/8 onroad engines can easily cost over $500 and won't pair well with a monster truck. The physics are too hard to fight.

    I'm not a total convert, but I do like electric now. My 1/5 baja will remain gasoline forever and I may even get a gasoline Savage once they come out and someone sells me their used one. I look at gas like noisy brushless. It's just as convenient, reliable, and has long runtimes.

  15. #15
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    I don't actually have a thermometer, however I was told that this motor runs hot. After driving like a normally do which is some high speed runs and just some driving about the motor is warm to the touch, but definitely won't burn you (motor shaft is quite a bit hotter). So probably about 45C -50C.

    The ESC seems cooler than the motor.
    As for the battery, it is in a plastic case so it's hard to tell. But it does get warm. I should have an infrared thermometer in a week or 2.

    Battery/ESC tray clearance:


    This is with the truck bottomed out, I was considering turn the motor upside down so the wires are at the top but it does not seem necessary.





  16. #16
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    This is a great thread. I spent $350 for the category of items you listed except the servo, including shipping and tax. That's nearly $200 you saved (after the shipping you paid). Albeit mine is ballistic, but again, your's runs awesome and may not require the diffs and rear drive shaft be upgraded. [Keep and eye on warping at the joints of the shaft]. For the average joe, that's about $160 saved as most can't make their own motor mount. I talked my buddy into doing it with your parts list plus the mount and battery tray I mentioned earlier.

    I'm still curious about motor and battery temps. Post'em when you are able to get them. I run a 2200 40 series motor (fan but no heat sink), 25C soft pack 4S battery, and 36/18 gears. The motor temps, according to my telemetry, have hit over 160F, but typically around 145. The battery just gets a bit warm. This is in 90-100F weather.
    Last edited by metoo2; 08-01-2012 at 08:26 AM.

  17. #17
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    Thanks. I guess at the moment it is relatively cool where I am. About 64F, perhaps a bit warmer. I guess it also depends on how you drive and things. I'm usually fairly controlled on the throttle

  18. #18
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    Oh and I think it's only really worth doing if you have a Revo already or if someone gives you one.

  19. #19
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    Oh with my standard 27MHz radio I seem to be having range issues. Not sure if it is interference from the ESC. I have ordered myself a 2.4GHz system so hopefully that will solve it.

    Just did a speed run and got 54.4km/h. Not to bad but I think it had a bit more in it and due to range issues I was getting a bit scared. 16T pinion 38T spur.

  20. #20
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    Quote Originally Posted by reflexsa View Post
    Just did a speed run and got 54.4km/h. Not to bad but I think it had a bit more in it and due to range issues I was getting a bit scared. 16T pinion 38T spur.
    What form of speed detection did you use? That sounds WAY slow. That's 34mph to us Americans. From the looks of it in the video, it's capable of a lot more. 2350kv on 4S?...more in it for sure. If your temps are good, try 36/18. That's what I use. Your motor is smaller than mine, but you also have smaller tires, so that motor shouldn't have an issue. Before you do any of that, make sure your slipper is set just below hard wheelie action. I tried setting mine to control breakage and aparently set it a bitt too loose and ended up melting a spur gear instead.
    Last edited by metoo2; 08-01-2012 at 01:18 PM.

  21. #21
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    That was done using a GPS, it did seem a bit slower for some reason. I shall investigate further, although that was plenty fast for me.
    My car won't wheelie off the line, but it seems to want to at probably around 40km/h. When I get a new radio I will check the speed again, will be able to use more road then...

    Here is my new body. It sustained damage while I was trying to mould it, so I did not put too much effort in :-/

  22. #22
    RC Turnbuckle Jr. MITCH316's Avatar
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    Looking good...welcome to the dark side of plug and play.
    Rock n Rolla !

  23. #23
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    I just bought everything for my buddy's truck: your motor, your battery (2 of them), your servo, your heat sink with fan, some 270mm velcro straps, SCTE battery tray, XT60 connctors, that motor mount I mentioned, FOC, and pinion for a grand total of $265. About $55 of that was shipping. At least it will all be here in 5-10 days.

  24. #24
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    Good luck! I'm sure it will work great. I'm going to find myself a large empty parking lot this weekend and try the speed thing again.

    I locked the gearbox in 2nd by the way. Found a nice guide by googling that.

  25. #25
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    Quote Originally Posted by reflexsa View Post
    I locked the gearbox in 2nd by the way. Found a nice guide by googling that.

    I used this method,....


    .....but after shearing a pin on the main shaft inside the tranny, I got to take a look at the mod after a bit of run'n. The notches I made had widened and the screws were at a bit of an angle. I don't believe I clocked the clutch correctly before doing the dremel work.

    I wish someone would pickup were Oomp left off who made this little beauty. That person may be me, but I prefer it wasn't.


    As for that sheared pin, I replaced it with a thicker one.
    Last edited by metoo2; 08-02-2012 at 12:34 AM.

  26. #26
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    I think I'm going to rather do another speed run when I get my new radio.
    Better safe than sorry, I current probably only have about 100meters to work with...

    I was looking at other methods to lock second as I dislike the screw method, but that is the one I landed up using...

  27. #27
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    Just out of interest where do people normally measure the motor temp? On the case?
    Did a bit of a bashing after work today, about 30mins and it doesn't look like I broke anything

  28. #28
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    Have some bad news guys. It would seem my super cheap motor has died.
    Not sure if it got to hot from driving on grass or if it's faulty. I'm starting to think the thermal conductivity from rotor to case was extremely bad as the case was always warm but not hot.
    However just before it died it was at about 65C.

    Anyway long story short the rotor seems to have mostly lost its magnetism.
    This motor is decent otherwise, but perhaps there are some flaws in the design (could have been the grass...).

    I shall be ordering a Castle Creations 2200kV motor and attempt to use it with this ESC.
    Pity it takes 3 weeks for the parts to get to me...

  29. #29
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    So I've ordered the Castle 2200kV motor. Will see how it does with my current ESC.

  30. #30
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    There goes the budget, but it is a high quality engine. 38/16 gears will have you on the lid everytime you touch the trigger with that motor. I'd try 36/18. It will be a bullet and reduce the stress on you rear axles. You should be fine with your ESC on 4S...at least by spec.
    Last edited by metoo2; 08-10-2012 at 08:42 AM.

  31. #31
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    Yeah was just about to say that I need to rename this thread...
    The motor came in stock today and I took that as a sign. I only have 38T and 40T spurs and 16 and 13 pinions.
    I will see if I can find a larger pinion at the local store. As it is now 16T 38T it should go about 40mph which I think is okay? Just don't want to overgear...

  32. #32
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    Quote Originally Posted by reflexsa View Post
    As it is now 16T 38T it should go about 40mph which I think is okay? Just don't want to overgear...
    The issue hear is, that on 4S with that gearing and that motor on a chassis that short with the stock arms, you will have to be very easy on the throttle to go more the 2 inches before the front tires are in the air, especially with a sensorless ESC. It simply won't be any fun if you have to be that careful just to keep the wheels on the ground. Don't let the kv fool ya. This motor is a monster compared to the one you had.

    Since you spent this much, you may as well spend another $15 for a 3.3 chassis from ebay, $6 for a Center half shaft for the front (#5456 I believe), and $15 for the adjustable arms (Traxxas #5328 and #5327). Of course that also means a longer body too, unless you don't mind it looking goofy.

  33. #33
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    Haha I don't mind looking goofy but I will definitely keep a lookout for a chassis. It seems like sound advice :-)

    I bought a Rustler VXL which is yet to arrive, so I may play with that for a while before putting more work into the Revo.

    Going to have to learn some good throttle control in the meantime :-)

  34. #34
    RC Turnbuckle Jr. humayrayakongkinaon's Avatar
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    Quote Originally Posted by reflexsa View Post
    I will definitely keep a lookout for a chassis.
    i always think that this is a decent price, at least you get spare body mounts.
    http://www.ebay.com/itm/traxxas-revo...item3a77246d22
    or if you just want the chassis, you can get this,
    http://www.ebay.com/itm/NEW-5907-Tra...item58953f4343
    http://www.ebay.com/itm/NEW-REVO-3-3...item48467eba78
    and if you still flip it over with the extended chassis, you can buy summit rear a-arms
    http://www.ebay.com/itm/Traxxas-Summ...item3f1a09601e
    Last edited by humayrayakongkinaon; 08-10-2012 at 01:23 PM.
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  35. #35
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    Thanks guys. Those chassis look like a real bargain! And I could do with some new body posts haha.

  36. #36
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    I'm also curious how your diff will hold up to the Castle. We are getting into the old habbit like those guys that buy 5.0 supercharged 650 horsepower engines for their Mustang that just had a 4.6L 300 hp engine. Had he just added some bolt-ons and reprogrammed it for 400hp, all would have been good, but now he's popping axles and tranny gears and can't enter traffic without spinning out. The moral is, you can't buy the horsepower without the supporting mods without some issues showing up. 36mm engine = stock everything fine (maybe), 40mm motor = needs stronger axles, different gearing, longer wheelbase, and probably stronger diffs.

  37. #37
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    Yeah I was trying to avoid breaking diffs. Perhaps if I pop one or two I will sell the motor...
    I do like to keep the slipper not to tight, maybe that will give them some longevity

  38. #38
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    Quote Originally Posted by reflexsa View Post
    Yeah I was trying to avoid breaking diffs. Perhaps if I pop one or two I will sell the motor...
    I do like to keep the slipper not to tight, maybe that will give them some longevity
    It should as long as you don't use it as your only form of torque control. I guess I set mine too loose. It melted the spur gear.

    Don't sell the motor, just buy the other things required to support it. That shouldn't cost much more than the loss you would take on the engine. I paid about $50 for 2 new e-revo diffs on ebay. If you're lucky, you can get them cheaper. Some guys are even popping those and going with LST diffs, which take a good amount of modding to use. I'm hoping it will not come to that for me.

  39. #39
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    I did search around for some diffs and they aren't to bad. Will be interesting to see how the originals hold up :-)

  40. #40
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    So my Castle motor finally arrived. Budget = blown
    It fitted quite well with my current motor mount, which was nice. Took it for a quick drive and it appears to be quite a monster.
    In comparison to the ********* motor when turning the motor shaft by hand it is harder to turn and has more notches(more poles maybe).
    Anyway I'm quite sure my drivetrain is relatively frictionless, but now with the motor in it is quite hard to push the car by hand. I'm thinking it is the magnetism in the motor. Any ideas? My mesh is relatively slack, there is a tiny bit of play between the teeth.

    Here are some pics, I apologise for the lack of focus




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