Team Associated CR12 Monster Truck Build

[Nikko85 2850]

Good news the funtek gears slot right in and seem to work! The gear was slightly thinner in profile but seems to he a direct swap with perfect mesh and quiet when running.

So now all I need is another of these and the spur and step metal gear set and all gears will be metal. I've only heard of the shafts warping with big brushless so I should be fine on a 390.

Pretty chuffed I found those, lots of people looking but not heard anyone else making the link as the GPM ones are long sold out! 

 

 

[Nikko85 2850]

2 hours ago, Mad Ax said:

That looks fabulous!  It's got a sort of MTX-1 vibe going on, great stuff  

Thanks! That's what I was aiming for. Really happy with how it turned out.

[87lc2 2401]

That's great, glad you found some gears that work in there.  I was excited when I found these axles a few years back since I needed something as narrow as possible for a scale build but was disappointed with the internals.  Now that I know these are available I'll keep them in mind for future use.  Nice work.

[Nikko85 2850]

On 6/26/2023 at 10:16 PM, 87lc2 said:

That's great, glad you found some gears that work in there.  I was excited when I found these axles a few years back since I needed something as narrow as possible for a scale build but was disappointed with the internals.  Now that I know these are available I'll keep them in mind for future use.  Nice work.

Now the STX gears are sold out, but I have a plan! Either the full diff or something that looks very similar from another maker. 

Here it is with a few other 1/12 scales. The Chevy is probably too small and the Jeep too large, but close enough.

The diff gears will come back in stock soon, I plan to get three of them - one more of the current build, and then set for any future builds. I am also planning to get a higher capacity lithium ion battery (around 5000 mAh) to give some better run times either a 2S2P 18650 or some larger 21700 batteries.

[Nikko85 2850]

The metal pinion and step gear arrived from the not-so-slow boat from China. I am awaiting stock for the second meal diff gear.

Whilst I wait, has anyone got any recommendations for a 390 motor please? I can't see much data on them like I can with 540s and most don't give turn counts.

 

[Nikko85 2850]

The pinion I ordered turned up, the Blackzon slyder pinion. Its 0.6M with a 2.3 mm shaft and quite long so it works a charm.

Here it is on left next to the stock on right. Much longer which helps reach the spur gear.

It is also a much nicer part with better tolerances. The car has an all metal drive train now apart from the prop shafts which seem to be fine from all reviews.

I will charge up a battery and test soon. If no speed increase I could try a 20T 390 I also picked up.

[Nikko85 2850]

Well the 390 motors were a bit of a let down. It's really hard to find specs on these things, but although it had much more torque than stock, it was if anything slower - not helped by a reduction in pinion size. Torque is fun, but getting to top speed in 3m loses appeal quickly. 

So, I did the only thing that made sense, I put a brushless motor in there. My usual small brushless go-to is the Ezrun 2030 - but these have a 2 mm shaft, so I picked up one of these 4 pole motors.

https://www.amazon.co.uk/5400KV-Brushless-Sensorless-Windings-Removable/dp/B08H1T7R3

Now the shaft is a little short, so the pinion now only touches around half the spur gear - which is not ideal, but both are stainless steel, so hopefully won't just degrade despite the smaller contact area. I've turned the brake and punch right down to try and keep the gears and plastic drive shafts safe. I also don't want something uncontrollable either. Wheelies are down, but top speed is right up.

This is where I drive a lot, a large, dusty gravel pitch, so having a good top speed makes things fun.

And fun it was. I kept the EPA to 75% and it worked like a charm. Donuts if needed, but nice slides off power and a great top speed.

I'm not quite sure how the plastic drive shafts or the spur/pinion gear will cope, but I hope having all the settings on low will keep it safe for a while. Certainly it's now much faster than stock, I would probably be happy at 60% power. Perhaps I should just buy the lower KV motor, or I could drop the timing right down for less power and more efficiency.

Out of interest, is there any real practical difference between running a 5800KV motor at 60% vs a 3000KV at 100%? 

 

 

 

[87lc2 2401]

That looks like an absolutely fantastic spot to run the trucks.  The higher kv motor will have less torque so I'd probably run that backed off a bit.  The lower kv motor with more torque will most likely put more stress on the driveline.  I'm no expert, but that's generally how I approach these things (with much larger motors in general) and its served me well.  Let that 5800 turn higher rpm and get more speed with less low end and it should be better on the drivetrain. 

[Nikko85 2850]

17 hours ago, 87lc2 said:

That looks like an absolutely fantastic spot to run the trucks.  The higher kv motor will have less torque so I'd probably run that backed off a bit.  The lower kv motor with more torque will most likely put more stress on the driveline.  I'm no expert, but that's generally how I approach these things (with much larger motors in general) and its served me well.  Let that 5800 turn higher rpm and get more speed with less low end and it should be better on the drivetrain. 

Yes, it's a lovely place to drive, and its almost always deserted. They run festivals in the park, so a few times a year it turns into  car park but usually empty. I've yet to bring jumps with me, but it's large and mainly flat with a nice coating of gravel so you don't get many roll overs and can power slide. Lots of dust and small pieces of rock to get stuck in a car however, fine in the dry and a nightmare to clean off if the car gets wet. 

That's good news with the KV motor and seems to back up what I've experienced. At the moment the top speed is great, but it is not wheely-ing all over the place.

I've seen a video with the truck with a larger lower KV motor and it didn't look fun, and they shredded things quick. Low punch, low timing, low breaks and 75% D/R should keep it alive and more fun to drive. When I went to 100% D/R it just spun out on the gravel and would roll over on concrete. 

Certainly a match for the others in my fleet now. I just need a better on off switch as right now it's two wires I hot wire together to turn on! 

 

[Nikko85 2850]

I took this to the BMX track and it was great - at 75% it's a handful, but it's not extreme - keeps the nose down fine. What's interesting is that this is a much larger motor than those little EZrun 2030 motors I've got for my QD, but I swear they have less power. 

Although the pinion/spur overlap isn't great it sounded pretty quiet - so hopefully it's all fine there.

They've just finished repaving the BMX track, so it's looking great. Always full with BMX at the weekend, but can take a quick trip on a WFH Monday.

As well as tacking the BMX track it was pretty good at the slopes between the tracks, covering quite steep ground easily, which you would expect from a crawler derived chassis.

[OldSchoolRC1 882]

That looks like a very fun place to run! 

[Mad Ax 7878]

That track looks superb!  The tarmac must be quite punishing on bodies and chassis if you crash, but I'll bet you can have a load of fun there with the right rig.  I'd love to try the LMT on that!

[wolfdogstinkus 1634]

20 hours ago, Nikko85 said:

What's interesting is that this is a much larger motor than those little EZrun 2030 motors I've got for my QD, but I swear they have less power. 

I'm with you on this, I thought I upgraded my brushless QD with a 8200kv motor 2435 size can instead of the 2030 size 7800kv hobbywing ezrun. The EZRUN won hands down.  Bigger motor was topping out at 30mph whereas the EZRUN pushed it past 40 easily and had loads left... hobbywing for the win.