Arrma Kraton EXB by HeavyBag

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RustyUs

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RC Driving Style
  1. Bashing
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It's been a long time coming. The Kraton EXB...my first Arrma RC. It took me awhile to get onboard with buying an Arrma as I normally seek out kits for my kicks. The EXB roller option from Arrma is probably as close to a kit as I'm gonna get from the brand.

The EXB was, honestly, an after thought. I originally wanted to go with a Tekno RC ET48 2.0 truggy to go along with my EB48 2.0 buggy, but Tekno said the truggy is a ways off before we see available pre-ordering. Last year I made a pretty good prediction for the EB48 2.0 being available for Motorama, and I got my buggy the week of the February event. This year I would have made the same prediction for the 2.0 truggy, but Motorama has been cancelled.

During the wait for some sort of notification from Tekno about the release date of the new truggy, Arrma released the Kraton EXB roller. ???:banana:

Since the EXB roller is, what looked to be, what I wanted to do to a Tekno truggy anyhow...on to the shopping cart it went.
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I thought for sure I had made a wrong move with choosing this monster truggy. I wanted another truggy to build up, but with delays and the things that go along with a global pandemic, the 2.0 will have to wait. I sure am glad to have waited for the second batch of the EXBs to come out... all the horror stories over the quality control tolerances being off just a bit to cause rear diff issues.
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Took apart the diffs and found everything to be better than expected. Fluid level was fine. I don't know what people are talking about. When you pop off the sun gear, there is a lot of fluid clinging to it and makes the diff case look emptier then should be. I added a few drops of fluid and buttoned things back up. ?‍♂️
 
One thing that I did get annoyed about was the fact that I came so close to stripping the motor mount out. I really don't know what to say. The motor mount screws were already installed, and I had a heck of a time getting the one screw out in order to get the mount off.

Look at the threads on the right screw. They are definitely...off. "What have I got my self into?", is all I could keep repeating through my mind.
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I tapped the motor mount; got some "extra" material out of there, and things went together smoothly.
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Been wanting to try one of Surpass Hobby's Rocket Taurus 1700Kv motors for awhile now. The 4274 Taurus motor had been on standby... waiting for a truggy to show up. The Kraton just so happens to be that truggy to get the Surpass Hobby treatment. As bonus, matching color scheme.
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I use their 4068 1900KV 4P Sensorless Motor in my buggy with pretty good results. I have to run a smaller pinion gear than I would like in my buggy, but on a tight track, the 4068 1900kv motor is fine.
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All soldered up...
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We'll soon see if this motor can get the Kraton up to speed and hold it.

I am new to this whole "monster truggy" scene. I figured Arrma throws a 4074 in their RTR Kratons so that's where I'm gonna start with my EXB. I do know, a Hobbywing Max6/4985 SL-1650KV combo will be on order shortly whether, or not the Taurus motor pans out.

The EXB "EXtreme Bash" Kraton will not likely see too much "extreme" stuff from me. I just wanted something overbuilt that will handle 6' jumps and give me speeds between 35~40 MPH. At least that is my plans to start with.
 
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Okay, it's time for my roast. ??

Will a 120A speed control be enough to handle my motor of choice and 4S? Yes, that's not a typo. 4S is where I plan to start with the Kraton. I believe the Taurus 1700kv motor is spec'ed on paper at 95 amps maximum. Not only will I be using a 120A ESC, the ESC is sensorless. So, I'll be running the sensored capable motor without a sensor wire.
 
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The size of the Kraton's wheels, and Copperhead2 MT tires had me a bit concerned with the stock droop settings. I mainly didn't want the arms to yankin' on the shocks. After taking the front and rear shocks off, I found the stock droop settings to be off by about 4mm more than I had liked to see (both front and rear).

While having the shocks off, it made the swapping out of the new droop screws so much easier. The stock Kraton droop screws are only adjustable from the button head side. A lot of other 1/8 scale platforms out there use specialty droop screws that have hexes in both the button head part of the screw, and the shaft also including a hex as well. This allows for adjustments to be made to droop screws from above, and below.
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Itchin' to run this thing. Just waiting for the weather to break and the temps to get close to something on the warmer side of things.

My poor beaten down Hobbywing WP-SC8 was just sitting around...into the EXB it went. The ESC has it's onboard caps blown from trying to move a rotor with blown bearings. I'm surprised the damn thing still works (external cap pack is used now).
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I've used other JX servo, in the past, with good results. The CLS5830HV-V2 is said to be the OEM for the EcoPower servo... for more money of course. Anyways, I'm not sure what is included with a RTR Kraton V5, but I chose the JX CLS5830HV-V2 mainly because it's speed specs fall into my comfort zone, and spare gear sets are available.


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I run a max6 in my outcast with the older arrma blx2050kv (pre-spektrum stuff) and it does well.

For the first year, I ran it on 4S only with the stock ESC which was 150A (BLX185). I had it geared for low-mid 40's with 3.8" trenchers on it then. It ran warm and would thermal on me if I pushed it too hard in the grass.

Now I have it geared for mid-upper 50's with backflips on it running 6S with a new blx2050 4074 and the max6. My motor fan died on me and I cooked the original motor. It lasted 2 years... I do run hybrid ceramic bearings in them though.
 
The front camber, on these Kratons, seems to be about -4° on each side. :oops: I'm more of a -0.5° to -1° type of guy for my ride's front camber setting. First, I pushed the top of the steering block/pillowball out a millimeter. Then, I went ahead and ground off about 1.2mm of material from the suspension arm end caps. I did this, because I feared the CV bones would pop out of the outdrive cups when suspension is at full compression if I adjusted the top pillow ball out too far. I still have to smooth out the end caps to clean them up a bit, but I'm happy with how my wheels/tires sit now.
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While having the shocks off, it made the swapping out of the new droop screws so much easier. The stock Kraton droop screws are only adjustable from the button head side. A lot of other 1/8 scale platforms out there use specialty droop screws that have hexes in both the button head part of the screw, and the shaft also including a hex as well. This allows for adjustments to be made to droop screws from above, and below.
That is surprising. My V1 and V3 Arrma 6s trucks can be adjusted from the top. I wonder if Arrma actually made this change, or if this was a parts-swap on the factory side that QA didn't catch?
 
All soldered up...
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We'll soon see if this motor can get the Kraton up to speed and hold it.

I am new to this whole "monster truggy" scene. I figured Arrma throws a 4074 in their RTR Kratons so that's where I'm gonna start with my EXB. I do know, a Hobbywing Max6/4985 SL-1650KV combo will be on order shortly whether, or not the Taurus motor pans out.

The EXB "EXtreme Bash" Kraton will not likely see too much "extreme" stuff from me. I just wanted something overbuilt that will handle 6' jumps and give me speeds between 35~40 MPH. At least that is my plans to start with.
Great job soldering. I’m 💩 at it, should probably practice more. Maybe because I only have two old radio shack soldering irons that only get hot in certain spots 🤷‍♂️
 
I love the JX servo...
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I just don't love it in a monster truggy 😉 😁. After a year of abuse, the gears inside did wear down. I could feel the slop building, and a tooth or two let loose.
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