Hi all,
I'm fresh to RC. I'm yearning for a project, so when my buddy introduced me to RC (planes) I soon after bought a used HPI Jumpshot MT v2. Fun and well controllable, but it definitely can be a tad quicker to really rip. So I'm going the brushless route. Here is where I'll post updates, and also random information that I come across, that another beginner might find useful too. I use a lot of words and ramble on, but I'll try to remember to post pics as well.
The plan
The goal is mod this truck so that is fun to bash everywhere, from street to forest, with moderate jumps, good run-time and durability to keep playing. The project is as much fun as the driving, and I don't know where it will end.
The trivial answer is to just sell this, and buy the Flux version. But DIY is cheaper (Flux new is €350, I bought this for €130. Going brushless can be done for €70, and upgrading the diff+gear is about.. €100?? So I can save about €50. But most of all I'll learn about this thing and have a project, which is what I'm really after.
(In my introduction post I said I wanted to make huge jumps. What I meant was maybe a meter high at best. Since then I've seen on youtube what "huge jumps" mean, and I'm definitely not going to launch of a skate ramp, to see in how many pieces I can break the thing).
The plan is:
Yes. In 2016 user PraetoR got the MT v1 and put a Castle + Sidewinder ESC in. And promptly stripped his spur gear.
https://www.msuk-forum.co.uk/forums/topic/211549-hpi-jumpshot-mt/?do=findComment&comment=2215991
HPI Jumpshot MT v2 first impression
Positives:
Neutrals:
Negatives
Pics of the release party of these rims:
Phase A: brushless motor and ESC
Motor
As any engineer knows, the first phase is always more power. Then control. And reliability follow later.
(It is actually painful for me to joke about this as I've worked as reliability engineer for years )
With help from Tudordewolf I figured out this first step and left Castle and Hobbywing and looked into Hobbyking and Surpass.
With so many motor types, I had to think of some constraints and settled on:
Why 3900kV?
If I go lower, it'll just make less power. Let's say 3650 / 2300KV, which is also rated at 900W, but only with 22V (22V * 41A = 902W). But as I don't have a 22V battery, so with 3S it will only 'make' 12.6V * 41A = 516W, quite a loss, that you can not get back with gearing.
If I go higher, I lose the ability for 3S. In itself not so bad, but in order to make 900W it's coming from the amps. In general, higher current means higher losses, so that's also less ideal.
ESC
Then for the ESC, there's a 80A that they combo it with. But I wanted one step up to 100A, because then I can fit almost all Surpass motors between 3650 and 3670 (1400W), although that last one will require 4S LiPo's. So that's just a bit of futureproofing. There's no Surpass 100A (goes from 80A to a too large 120A), but there's 100A Rocket that fits As an added bonus, the on/off switch is on a cable, so I can mount it somewhere that doesn't require me to get the body off.
I'm waiting for the parts to arrive.... so let's move on to
Phase B: metal gears, solid.
As mentioned, the gears need to be updated, which I will do with the HPI parts for the Flux. I also need to change the diff because HPI changed it from 4 straight roller gears to 4 45-degree angled gears, and the old diff won't fit the new gearbox. For anyone who wants to do this same thing, this is the list of parts that you need to get:
In the Netherlands, this was about €115 total, shopped at 3 different RC's shops (Toemen, TopRC and Wetronic). Quite a number of these parts are only carried by one of these three, even though they all claim to "have all the parts". And some listed this as being the last parts. So definitely check beforehand if you can actually get all the parts.
I haven't located 160037 Diff Shaft 5x22.7mm (2pcs) yet, but I'm going to ask a shop here to import it, and otherwise I see I can get it from the UK.
I'm also now waiting on these parts to arrive....
They should be here faster than the Motor+ESC from China so I'm going to start on the diff+gearbox first.
As some extra's I ordered some cheapo 2.8" tires with road/street thread, just for the looks, and some Leds. But led placement will have to wait until I figure out what to do with the body. I quite like the idea of running the bare frame, with a rear wing to give it a buggy look. The rear wing should then also act as a sort of roll bar. And some top cover protection for the electronics would be wise. The frame absolutely lends itself for interesting single-seater designs, so I wonder why HPI didn't do anything with it
This is all for now. I kept it short. Updates hopefully soon. Cheers!
Edit: Measurements
Adding measurements here for future reference.
Weights and Sizes
I'm fresh to RC. I'm yearning for a project, so when my buddy introduced me to RC (planes) I soon after bought a used HPI Jumpshot MT v2. Fun and well controllable, but it definitely can be a tad quicker to really rip. So I'm going the brushless route. Here is where I'll post updates, and also random information that I come across, that another beginner might find useful too. I use a lot of words and ramble on, but I'll try to remember to post pics as well.
The plan
The goal is mod this truck so that is fun to bash everywhere, from street to forest, with moderate jumps, good run-time and durability to keep playing. The project is as much fun as the driving, and I don't know where it will end.
The trivial answer is to just sell this, and buy the Flux version. But DIY is cheaper (Flux new is €350, I bought this for €130. Going brushless can be done for €70, and upgrading the diff+gear is about.. €100?? So I can save about €50. But most of all I'll learn about this thing and have a project, which is what I'm really after.
(In my introduction post I said I wanted to make huge jumps. What I meant was maybe a meter high at best. Since then I've seen on youtube what "huge jumps" mean, and I'm definitely not going to launch of a skate ramp, to see in how many pieces I can break the thing).
The plan is:
- Brushless Motor and ESC (size / power tbd)
- Upgrade gearbox from milk chocolate to at least pure chocolate
- Get a 3S battery to see if I can break the space-time fabric (I now have two HPI Fuzion 2S 5300mAh's 40C.)
- Install some LEDs for visibily
- Get nicer rims and tires. Looking at the belted Protires. (Grip is important but mostly I find the stock plastic chrome atrocious)
- Perhaps get a different body.
Yes. In 2016 user PraetoR got the MT v1 and put a Castle + Sidewinder ESC in. And promptly stripped his spur gear.
https://www.msuk-forum.co.uk/forums/topic/211549-hpi-jumpshot-mt/?do=findComment&comment=2215991
HPI Jumpshot MT v2 first impression
Positives:
- Now this truck is somewhat of a good base for more power, as proven by the brushless Fuzion (discontinued) and Flux versions.
- The frame seems sturdy and has a (imo) nice symmetrical layout.
- Seems to handle well on youtube vids compared, or at least it rolls over less on asphalt than it's Traxxas and Arrma counterparts.
- In my first run it was easy to get the hang of it, and it modulates nicely on the throttle.
- While driving head first into a wall (oops), one steering arm popped loose, but that was it.
- The frame itself looks amazing. So good infact that most people comment I should ride it like that (and I agree if not for the fact that as soon as I did that, I flipped it, and it chafed off a whole lot of the body mounting pins.
- Integy and other companies make aluminum/aluminium parts, including a metal spur, which might be needed.
Neutrals:
- The gearbox is mostly plastic, but the Fuzion and Flux models have an improved metal diff and a full gears. (The housing and spur gear are plastic). So that should be an easy swap.
- The body looks okay. Red and blue with white stars and strips is an obvious US flag, and the stars are actually little HPI logos. Looks good. But then the Square black/orange HPI logos slapped on the side don't match them at all and stand out sorely.
Negatives
- Pretty weakly powered. It'll go on asphalt, but on short grass, it's already not that fast, and overpowering the rear for a power slide is impossible.
- There's quite a bit of slack in all the wheel knuckles, giving the wheels a free toe-in-out movement of about 5 degrees. On the rear wheels it's the connection between hub assembly and the A-arm that has a lot of slack. On the fronts it's on the wheel-size steering knuckles. And also in the upper suspension struts, but that only rotates the wheel in its natural rolling direction so that doesn't impact steering (much).
- The stock 'rims' atrocious, but then I've always hated chromed plastic. It just looks like fancy disposable plates.
- The gearbox housing is the rear skid "guard". And since it sticks out like a weber-carbureted engine out of a beetle, it'll hit the ground a lot.
Pics of the release party of these rims:
Phase A: brushless motor and ESC
Motor
As any engineer knows, the first phase is always more power. Then control. And reliability follow later.
(It is actually painful for me to joke about this as I've worked as reliability engineer for years )
With help from Tudordewolf I figured out this first step and left Castle and Hobbywing and looked into Hobbyking and Surpass.
With so many motor types, I had to think of some constraints and settled on:
- No higher battery cell count than 3S, because those are easy to get.
- No larger motor than 3650 for now, 900W seems plenty and it'll keep it lightweight.
- Crawling or excellent low speed operation isn't important to me. I play Snowrunner for that
Why 3900kV?
If I go lower, it'll just make less power. Let's say 3650 / 2300KV, which is also rated at 900W, but only with 22V (22V * 41A = 902W). But as I don't have a 22V battery, so with 3S it will only 'make' 12.6V * 41A = 516W, quite a loss, that you can not get back with gearing.
If I go higher, I lose the ability for 3S. In itself not so bad, but in order to make 900W it's coming from the amps. In general, higher current means higher losses, so that's also less ideal.
ESC
Then for the ESC, there's a 80A that they combo it with. But I wanted one step up to 100A, because then I can fit almost all Surpass motors between 3650 and 3670 (1400W), although that last one will require 4S LiPo's. So that's just a bit of futureproofing. There's no Surpass 100A (goes from 80A to a too large 120A), but there's 100A Rocket that fits As an added bonus, the on/off switch is on a cable, so I can mount it somewhere that doesn't require me to get the body off.
I'm waiting for the parts to arrive.... so let's move on to
Phase B: metal gears, solid.
As mentioned, the gears need to be updated, which I will do with the HPI parts for the Flux. I also need to change the diff because HPI changed it from 4 straight roller gears to 4 45-degree angled gears, and the old diff won't fit the new gearbox. For anyone who wants to do this same thing, this is the list of parts that you need to get:
- 160045 - GEAR BOX SET V2101298 - DIFF GEAR SET
- 101301 - DIFF SHAFT SET
- 160038 - DIFF CASE 5x30x16mm
- 160040 - HD DIFF GEAR 60T
- 160041 - TOP SHAFT GEAR SET V2 (22T)
- 160042 - HD IDLER GEAR V2 (27T)
- 160046 - WASHER 12x15x0.3mm (10pcs)
- 160065 Spacer 5x8x6.5mm
- 101221 Diff case gasket (3pcs)
- Z263 Pin 2x8mm (12pcs)
- Z663 Lock Nut M3 (6pcs) [1 needed]
- 6921 Pinion Gear 21 tooth
- A020 O-Ring P-5 (4pcs) [2 needed]
- Z181 1000CPS diff oil
- Z478 TP. Flat head Screw M2.6x12mm (12pcs) [2 needed]
- 160037 Diff Shaft 5x22.7mm (2pcs)
- 160064 Lock washer 3x6mm (10 pcs) [2 needed]
- Others:
- Grease (I got Traxxas TRSX-1647)
- Z159 Threadlock
In the Netherlands, this was about €115 total, shopped at 3 different RC's shops (Toemen, TopRC and Wetronic). Quite a number of these parts are only carried by one of these three, even though they all claim to "have all the parts". And some listed this as being the last parts. So definitely check beforehand if you can actually get all the parts.
I haven't located 160037 Diff Shaft 5x22.7mm (2pcs) yet, but I'm going to ask a shop here to import it, and otherwise I see I can get it from the UK.
I'm also now waiting on these parts to arrive....
They should be here faster than the Motor+ESC from China so I'm going to start on the diff+gearbox first.
As some extra's I ordered some cheapo 2.8" tires with road/street thread, just for the looks, and some Leds. But led placement will have to wait until I figure out what to do with the body. I quite like the idea of running the bare frame, with a rear wing to give it a buggy look. The rear wing should then also act as a sort of roll bar. And some top cover protection for the electronics would be wise. The frame absolutely lends itself for interesting single-seater designs, so I wonder why HPI didn't do anything with it
This is all for now. I kept it short. Updates hopefully soon. Cheers!
Edit: Measurements
Adding measurements here for future reference.
Weights and Sizes
weight in grams (ounces) | size 1 in mm (inch) | size 2 in mm (inch) | |
HPI Jumpshot MT v2 total (no battery) | 1906 (67.23) | ||
HPI Fuzion 2C 5300mAh 40c-80c (my battery) | 277 (9.77) | ||
HPI Jumpshot MT v2 total (with battery) | 2183 (77.00) | ||
parts | |||
Stock wheel (115324 6-shot MT wheel with 115315 Jump T2.8 tire ) | 154 (5.43) | diameter: 117 (4.61) | width: 66 (2.6) |
Front shock (115288) | 15 (0.53) | length eye-to-eye: 102 (4.016) | travel: 30,0 (1.181) |
Rear shock (115289) | 17 (0.60) | length eye-to-eye: 119 (4.685) | travel: 30,0 (1.181) |
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