Arrma Kraton 4S V2.5

[phm14]

Hey...What's in the box?

This truck deserves a name...ATM, "Green Meanie" is sounding OK. Release the Kraton!

Funny, all 4 of these trucks are sold as 1/10 scale" ... Hoping to take her out for a shake down run, tomorrow, before it starts raining here. First, we'll treat her to a little bench inspection...maybe check that thread compound on the pinion. Drop tested a couple of times, to work the shocks. No oil under this one.

 

[SrC]

The 4s 2.5 or whatever it is, is not true to any scale. Just it got bigger over the years.

 

[phm14]

Ran 4 packs through this yesterday, 3 3s and one 4s. Running on freshly cut grass, with some small jumps. The truck does feel light, and I appreciate the well designed rear dirt guards. Runs fairly quiet, too. Steering felt lazy, especially under acceleration. I may have had a thermal cut, since the 3s lipo showed 30%. Didn't have my temp gun, but both the motor and ESC got pretty hot to the touch. Started letting her cool down, between runs. As I assumed, if I were going to keep this one for a while, I'd up grade all the electronics. It needs a servo, and maybe a servo saver upgrade, just to get it turning at speed. I did add 4mm preload spacers, at all 4 corners, just to level out the lower arms. Maybe if I pulled those off the front, the car wouldn't push as much. The shocks felt good-properly sprung for general use, and good damping. I gave the truck a pretty good thumping, landing short on a mild step up, blasting over some rough, and the car stayed well settled. As far as I can tell, all the fluids are still where they're supposed to be. The wing took some fair abuse, but has nearly straightened out. No issues with the body taking damage, or coming off, after multiple cartwheels and bad landings.
I think the chassis has good potential, but on post run inspection, I noticed that the center support drive shaft bearing is very close to the end of the motor can. Not only that, but the stock 3668 motor only has ~3mm static clearance, from the drive shaft. The two HW XR8 G3 combos I have on hand both have 4268 cans (one 1900kv, the other 2200kv). Has anyone tried to shoe horn a larger 42mm can in this new 4s? Layout is revised, correct? I thought I had seen most reviews on this new 4s, but I don't remember any mention of motor upgrade space issues. I figure a larger pinion may push it out, away from the shaft a bit, but I'd be surprised if there was no contact between the shaft and that 6mm larger diameter can. These HW set ups are pretty powerful, and could be a handful, for the chassis. The areas between the motor, drive shaft, and center spine of the chassis, also have pockets that sucked in lots of grass/debris, that was hard to blow out. The truck is speced to weigh 9.26lbs, but is 10.5lbs on my 60lb digital hook scale.

 

[phm14]

I pre-ordered the Kraton 6s EXB, before getting impatient, and deciding to see what this new 4s was about, while I waited. Well, they shipped the 6s EXBs, and now I have that truck. Since these trucks are not much different in size or weight (~1.75lbs), the plan was to choose one, after running both. I sold the 4s yesterday, to a buyer who was picking up another car. I've seen a Tuber run the 4s truck on 6s, with a ESC upgrade, on the stock motor. I'd say you'll need spare (stock sized) motors, if you go this route. The lack of space for a larger 4268 motor in the 4s chassis set up, was enough for me to sell the truck.

 

[phm14]

I think I'll give this 4s another shot. It seems the Kimbrough 124 servo saver works well enough, and with a servo upgrade, should sort out the steering. I think I can shoe horn a HW XR8 Plus/4268 1900 kV combo in her. Gonna find out...meanwhile, cold bash!:

 

[phm14]

Mmmm, fresh plastic. Zero hour truck is getting an electronics transplant. Hoping I can cram a 6mm larger diameter motor in there...then we'll see how she likes big dunes While I'm in there, I thought I'd top up the center diff fluid. Going to try to mix the 1M and 80K I have, with the 100K K that's in it, to wing up with 400-500K. This will be the 1st time doing a swap like this, on any Arrma, besides a 6s.

 

[phm14]

This is what I was afraid of. Can't jam a piece of paper between the 4268 motor, and the drive shaft, with the stock .8 mod 13T pinion. I could try a 15T, or 18T, but I'm not sure that would push the motor over far enough. Are parts available to convert this to mod 1?

 

[phm14]

Called Amain, on the mod 1 conversion, and came up empty. I have 16T & 17T .8 mod pinions inbound. If you asked me, mod 1 would be the appropriate size for a truck of this weight & power, and it would help alleviate this motor/drive shaft interference issue. For a given tooth count, mod 1 gears are quite a bit larger, both in width, and diameter.