Let's work on the Reflex Racing RX28K roller we got here. Please see my previous video for my initial impression of the chassis. It's already got a nice servo on the chassis, and now we need to add a motor, ESC, receiver, and transponder. My current plan is to install a 3500kv system and a hard body. Eventually it will have a lexan body.
Because this car was run by the previous owner, first, we should service the ball differential. The diff looks pretty clean here. I give the carbide balls an alcohol bath and clean the pressure plates. Then I apply some ball diff grease.
As usual, use thread lock when screwing into metal parts. There is quite a bit of metal in the RX28 chassis.
This first gen non-SE chassis doesn't leave a ton of room for the ESC. My go-to sensorless GL ESC doesn't fit here. I will use this GL sensored ESC instead, paired with a GL 3500kv motor. I haven't developed a good driving feel with this ESC. Ideally, I would prefer to orient the ESC such that the motor wires point towards the rear. But it doesn't quite fit, unfortunately, so it will need to be sideway. This disturbs the left vs right weight balance. The Hobbywing Mini28 ESC would fit quite well here.
The receiver is a Dasmikro AFHDS3 for NB4, with the antenna tucked away in the little tower. This fits very nicely behind the servo.
It's time to test the electronics. I was expecting to need to update the NB4 receiver firmware, but it bound on first try. Nice. The servo, ESC, and motor all function perfectly. I used the AGFRC programmer to fine tune the servo.
Other than the transponder, everything is in place. It's a good looking chassis! It's got metal in components that benefit from from the extra strength. The rear suspension pivots easily. I attached the orange transponder to the left of the servo, in the hope to balance the weight distribution better. But I'm not sure if it's going to get line of sight from that position. I will need to find out later.
With the RX28, electronics can be placed in a single layer to achieve the lowest center of gravity. FYI the KISS frontend is quite wide. It's 2mm wider on each side compared to the standard Mini-Z wide front. What this means is that I will likely to stick with 0 offset front wheels when running on a track. RX28 doesn't have a servo saver, so having a proper front bumper is also essential.
After I put the diff back together and onto the motor pod, I'm noticing quite a bit of play on the diff. There's enough play here to make gear mesh next to impossible. I measured the shaft at the low side of 2.9mm rather than closer to 3.0mm. I heard there was a production batch with this issue. I'm planning to buy a GLR steel diff shaft to replace the aluminum in the stock RX28 diff, and for now I'm running the GLR diff. I also replaced the bearings with ones with tighter tolerance. As a result, the diff shaft is almost free of play.
The final piece of the puzzle is a body. Because RX28 uses a different side mounting position, I'm going to build a new body. Yeah, a red Jomurema GT-01 body. Again, this is not a good looking body by any standard, but it's a solid track body. One inconvenience of the RX28 as mentioned before is the non-standard side mounting position. This is the standard side clip position. For RX28, the clip needs to be moved forward by one notch. I also needed to trim the side clip down by 2.4mm or so to fit the forward position. The new length is 18.3mm. In terms of body height setting, Jomurema needs the side clips to sit about 1mm lower in order for the rear wheels to clear. The body mounts very securely over the chassis. With a few decal stickers, the build is done.
Let's do a quick sanity check at home. This doesn't recreate conditions close to being on a track. The chassis seems to behave pretty neutrally, similar to a well-sorted GLR or GLR-GT. The throttle curve and drag brake of the GL sensored ESC do feel different from the OG sensorless ESC. I probably should play around with ESC programming to experiment with different parameters. It's ready for the track!
This is Sammy and thanks for watching!
Music: "Instructions for Living a Life", Savfk ( • Instructions for Livin... )