norco kid

iTrader: (20)

Alright, so like pretty much everyone, I've accepted that the Savage Flux is probably the baddest, craziest monster truck you can get right now. I was seriously considering buying a 2350, but since I had a nitro savage already, I decided to convert it in an effort to hold off a bit and wait for the next generation before buying one from HPI (crossing fingers for a waterproof flux). Now HPI sells the conversion kit, but at ~180 + ~250 for electronics, you'd prolly be better off buying a factory flux in the first place. No doubt their conversion/electronics are probably 100X better than what I'm gonna do here, but I wanted to see if it was possible to convert a Nitro Savage over to brushless for under $100.

It started with this:



This is an original Savage .21!! The very first model that HPI came out with!! I recently updated it with a rollbar, wheels/tires and 17mm hexes from the latest Savage X. Also bought it a new engine, which in light of this project, seems to have been a total waste.

Not gonna need this crap



The very first part has arrived! HPI #100905 (cost 8.79) will essentially convert my nitro tranny to Flux standards (direct drive single speed) and allow the motor to do the braking so I can ditch the stock brakes & servo.



First thing I noticed was when I removed the brake cam, there was a hole going to the inside of the tranny. I don't know if mine had just worn through or if it's made like that. I prolly could have left it but decided to plug it up with a screw/nut.





Good to go! (the stock 2 speed on the right was rejected)



Then came the good stuff.. My order from Hobbyking!! This stuff will make or break this project. No idea how it will perform, but I'm hoping good.
-KD36-74-09XL 1900kv Motor (31.95) (use my buddy code to get it for 29.60 and save us both a couple bucks!! Only works for the next 2 days!!)
-Hobby King 120A ESC (39.48)
-Motor Mount (7.52) (again, buddy code for 5.73)
-17T Pinion (2.50)



Motor and ESC (Both giant)



Problem #1 - The pinion I bought is the wrong pitch (DOH!) and will not work. I bought a 32p pinion but the Savage uses Mod 1 gears, which are coarser.



The lower holes in motor mount from HK line up perfectly with the stock Savage engine mount screws (suprisingly) and even use the same M4 screws!

Problem #2 - Though the bottom bolts up perfectly, the lower mounts are too far apart for the heatsink cap that secures the motor to bolt on at the top... Sooooo...



I cut it in half! This also allows me to stick on another heatsink (from my parts box so it was free) in the middle to improve cooling. The motor is very secure once all the screws are tight.



Problem #3 - The motor is way too close to the spur gear. I guess the HPI mount somehow positions the motor closer to the side plate and away from the spur. My HK motor mount cannot slide farther away than pictures without interfering with the chassis. I tried with the 52T gear (pictured) and a 47T (smallest plastic spur that HPI makes). I thought about going with the 43T metal spur, which is the smallest available, but I still don't think it would be small enough to give me the right gearing (plus it would break the budget). I needed a smaller spur.



Solution? I picked apart my other rc's and found that I could mate a Jato pressure plate with a 38T Revo Spur (Mod 1) and it pretty much bolts up perfectly and uses the stock savage slipper plate. This gives me a lot more clearance (keep in mind I'll be switching to a Mod 1 pinion which will be larger than the 32P in the picture). I thought about using the Jato 32P spur so I could use my HK pinion, but I was worried about durability. Plus the smallest Jato spur (54t) is still significantly larger than the 38T Revo spur, which would mean a larger pinion to get a decent gear ratio, and I don't think I have the clearance for that.



So I decided to order a 18T Mod 1 pinion (7.99) I wanted to go with a bigger one, but wasn't sure it would clear. The 18T with the 1900KV motor and 4S Lipo should give me ~35MPH.. I might jump up to a 20T later if I depending on clearance and motor temp. So now I just have to wait for the mail man...

Budget so far:

What I spent:
HPI #100905 - 8.79
Motor - 31.95
ESC - 39.48
Motor Mount - 7.52
17T Pinion - 2.50
18T Mod 1 Pinion - 7.99
Total - 98.23

Strictly Speaking:
HPI #100905 - 8.79
Motor - 31.95
ESC - 39.48
Motor Mount - 7.52
18T Mod 1 Pinion - 7.99
Jato Slipper - 8.99
Extra heatsink - 2.18
Revo 38T Spur - 3.00

Total - 109.90

Now I gotta figure out how to mount the batteries... Any suggestions? I was gonna just zip tie them to the TVP's...

-Adam

RCaddict0

iTrader: (85)

You could buy the Flux battery trzys. They screw right to the chassie plates.
Good Work man!

mavrick0

iTrader: (17)

They will only bolt up with the flux chassis tvp's. The nitro and flux tvp's are very different.

Good job on the budget Flux. The tough thing will be figuring out battery location. If you're interested I have a set of my stock flux tvp's you could have for the price of shipping.

Cummins Driver

iTrader: (19)

Looks good so far man. The worst thing you are going to run into is that if you havent upgraded the differentials and dogbones in that savage you will probably be doing it soon. The old style stuff wont hold brushless long. I have that same ESC in the 150a and like it pretty well. Its in a converted monster GT. I did have one go out on me, but it never runs hot and i had good luck out of it till then, so i bought another to see how it does. Working perfect so far. Didnt even know they had a 120a version. Motor mount looks good too.

junkman12

iTrader: (73)

Off to a good start, I've been wanting to build me a budget savage myself. Everything looks good except for the motor, that thing is absolute garbage. I have given a couple a try, 2 have burnt up, and another was bad out of the box, and it took out the esc in the process, 1st pack. There are much more powerful options with similar price. With all the heatsink action you have there, maybe yours will fair a little better. I have had decent results out of their trackstar motor, other than trying to keep the temps reasonable, it is a powerhouse. I just got one of the 120a esc's in as well. Have had nothing but good luck with the 150's so was happy to see them get the 120's at that price.

norco kid

iTrader: (20)

Thanks for the offer mavrick! I'm bidding on some parts on ebay but if I end up needing them ill let you know!

I know the driveline may be a problem.. I think the rear diff has 4 spider gears but is otherwise stock. And I think the 120A ESC is new I just noticed it as I placed my order! As for the motor, it seemed to have had good reviews.. Also I'll only be running it on 4S.. We'll see... *crossing fingers*

Cummins Driver

iTrader: (19)

The only real bad things i have heard about that motor is that they run a little warm( which isnt a huge deal as cheap as they are), and that the end's of them sometimes seperate from the can if they get jarred hard. However. since you are clamping yours in and not using the bolt holes you should be good there...

norco kid

iTrader: (20)

Yeah I read that too about the loose front plate.. Apparently they fixed it on the new batches but I don't care either way since I'm clamping it. I'm wondering if I should go with a fan on the center heatsink like this:

http://www.hobbyking.com/hobbyking/s...dProduct=18349

If the motor ends up failing it won't be the end of the world, but I'd be bummed if it takes the ESC out with it.. Still hoping everything works fine when I get my pinion!

n2trouble

iTrader: (27)

Thanks for sharing your progress, and good write up. I just finished converting my Savage 25 over to brushless, it wasnt excatly a budget build but cheaper then a Flux. here's what I got so far:

Kershaw brushless conversion kit (motor mount and battery trays)
Castle MMP
Tacon 2200kv Motor
Flux Transmission gears w/ ti shafts
16T Robison Pinion
45T HPI Hardened Spur
BP Diff Gears (already installed by previous owner)
Hitec 5645mg servo

Future Upgrades:
XL TVPS, dog bones and cups. Not sure yet if they will all work with the 25 parts and conversion kit. 17mm wheels/tires/

Only problems I am having are the battery trays are all the way torwards the rear of the TVPs which makes the truck wheely too easily. And my left side reverse thread wheel nuts keep backing off. Still need to do more testing and runs at the track to dial everything in.

If that motor mount doesnt work out for you I have a nice 540 can motor mount setup that will put it on top of the spur. i also have an extra set of Integy shocks if interested.

norco kid

iTrader: (20)

Well, I have some more progress! The 18t mod 1 pinion came today so I mounted up the motor/tranny. It meshed fine, but there really isn't too much room to go bigger.



Now I needed an ESC mount.. I know I could have gone with the HPI one, and it would have saved me a lot of time and probably looked nicer, but I decided to make one. Plus my ESC is HUGE and I'm mounting it to a non-Flux chassis (for now) so I could tailor it to my needs by making it myself. I used some 1/8 aluminum to make 2 'L' brackets that mount up to where the gas tank supports used to be. Prolly could have gone thinner, but this is what I had lying around in the shop, plus the thickness allowed me to tap the screw holes so I don't have to use nuts on the other side. I notched out the rear post to clear the bulkhead screw, and also filed it down a bit to clear the shock at full droop.



Made a top plate out of the same stuff, countersunk the screw holes and notched out the rear corner to clear the shock.



Perfect!!



Now I don't have battery trays yet, but I couldn't resist zip-tying my packs (Turnigy 5000mah hard case) to the TVPs to get a couple test runs in and see if my HK brushless system was a POS or not.. I used some foam from the ESC packaging to cushion the batteries and stand them off the frame a bit.



And...

I like it! I only ran it for 10ish minutes in front of my house, but the truck has plenty of power to lift the wheels with ease. Top speed is good, but a tiny bit on the slow side if I'm honest. I hadn't realized that the Flux's BP diffs are actually geared higher than my original .21 diffs. I've ordered a 20t pinion, but I'm really not sure if there's room for it. The motor was warm, but nowhere near hot, although as I said, only ran it for ~10 mins. Even got my dad to shoot a couple short vids...

<iframe width="640" height="390" src="http://www.youtube.com/embed/2oB0QCRL-ss" frameborder="0" allowfullscreen></iframe>

<iframe width="640" height="390" src="http://www.youtube.com/embed/Oyu4Pqln_ts" frameborder="0" allowfullscreen></iframe>

Not sure about the standing backflips, but I did flip it pretty bad from a standstill and shaved down my rear body posts while sliding upside down for 20ft. Scuffed my ESC wires up a bit too Currently contemplating battery boxes, though that would mean new batteries since my Turnigy packs have the wires exiting out the top, and that ain't gonna fly with the stock HPI setup...

Cummins Driver

iTrader: (19)

Looks great and sounds really smooth The power looks to be a little less than my HK150a and 3674 EZrun motor on 4s, but it doesent look slow by any means. I usually turn my throttle EPA down to help keep the wheelies under control. Plus it keeps me from driving too fast and wrecking it Looks to be geared pretty darn good to me though. Your conversion came out real clean and i really like the ESC mount.

Have you looked at kershaw designs battery trays? He has about 3 different kinds. I have some that were $7 a piece. They have 2 velcro straps that hold the batteries in and they fit my turnigy 5200's or my Hobbypartz "blue" 4000mah 30c lipos great. They should bolt to the TVP's with a little ingenuity, but looks like you have that part covered. So are you pretty happy with the conversion?

Cummins Driver

iTrader: (19)

You still running this savage? How are the electronics holding out?

norco kid

iTrader: (20)

Electronics were fine... I bought the flux tvps, motor mount and battery boxes and I had to make an adapter plate for my 36mm HK motor mount to fit on the flux motor plate (flux motor mount is 40mm). I upped the gearing a bit to 20/38 but I never got to run it because I got a great deal on a real flux HP so I converted this one back to nitro. I knew I was pushing my luck with the diffs/driveline anyways.

turbo scorpion

do you have a part number for that motor mount? i cant find it on their site.

Dadic 78

iTrader: (11)

Gotta say man, this build is stellar! You've done a great job using minimal cash, and a lot of creativity, and customization. Great work! I don't own a savage, but one of my co-workers does, and I told him to read up on this thread. You've done a great job here.

Just want to add that your rig isn't slow by any means. I mean, it's not a rocket, but hell, it's a savage, what do you want from it? My XXL is similar in speed, and it's more than enough for bashing, racing, whatever. Most important, it's a blast to drive! Nice work man!