TractionRoll RC

  • Xbility Axles – Get Rid Of The Slop

    I’ve really been enjoying my Xbility F1 over the last couple of months. For the most part, the car is great and I’ve had very few issues with it. If there’s one that needs to be fixed though, its the axles and that’s due the the excessive amount of play between them and the wheel bearings.

    A number of people I know have replaced the stock axles with those from Atomic or Reflex but the best solution I’ve found is the new axles from GL with the tiny o-rings on them. With these axles on my car, there is zero play. These are the ones for the LMP2 but GL sells similar axles for the Formula One that should work as well. Best of all, they’re less than $6!

  • Atomic MRX Ultra – Fixed Knuckles and Rear Spring Correction

    When I was building the MRX Ultra, I noticed something was a bit off with the caster on my car. No matter what, the two sides were not the same. After tearing everything down again, I found that this problem was caused by the knuckles. Long story short, the two threaded bits did not line up, causing about a degree of difference in caster.

    Fast forward to today when I received a box of goodies from Atomic that included a new set of knuckles, knuckle ball shims and a set of tuning springs.

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  • Atomic MRX Ultra Tip – Lowering Rear Ride Height

    Like most MRX Ultra owners, I’ve been waiting for Atomic to release springs for their flagship car. While we are getting new springs for the sides, the company said this week that Ultra owners should use the rear springs from the MRX Master.

    The Master springs are longer and wider than the stock spring so I was curious to see how well they would work.

    Right off the bat, I had some issues getting the Ultra’s ride height down to where I had it before, which was around 2mm. The only way I was able to come close was to barely screw on the spring tension nut.

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  • How To Fix Atomic MRX Ultra Wheel Rub

    If you’re like me, you probably built your MRX Ultra, mounted up a set of fresh front tires on your favorite wheels, gave them a spin and was surprised to hear a rubbing noise. The reason for this is that the car was designed to be used with Atomic’s own wheels which have a fairly narrow inner bearing hub.

    Atomic S20 wheel

    With other wheels, like those from Reflex, the hub is a bit wider and may rub on the ball cups. Here’s a picture below of a wheel rubbing on the bottom ball cup.

    Major rubbage!!

    The fix here is pretty easy and that is to take one of the extra silver 0.5mm shims that come with the kit and put it between the knuckle and the bottom ball. You may also need to place a shim above the knuckle if you’re experiencing rub up there. You’ll want to check this with your wheels straight and when turning.

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  • Atomic MRX Ultra Unboxed

    My MRX Ultra was delayed due to Chinese New Year but it finally arrived late last week. Like the MRX Master and MRV, the car comes in a small black box. Inside, you’ll find twelve bags with an assortment of parts. I’ve included pictures of the bags below.

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  • Atomic MRX Ultra Manual Online

    Atomic has posted what appears to be the final version of the manual for the MRX Ultra online. It has some great pictures showing how the new trailing axles and rear damper work.

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  • Atomic Unveils MRX Ultra

    The big news over the weekend was Atomic’s latest pan car, the MRX Ultra. Featuring an extremely low center of gravity, the MRX Ultra comes with an integrated aluminum chassis and one piece motor mount. To further lower the CG, the mid damper has also been moved to the rear of the car and there is an opening on the chassis to allow the servo to sit lower.

    There really isn’t much that carries over from the MRX Master. Even the front end has been updated with new lower arms that mount from the bottom like the BZ Master and knuckles that allow for 2 axle positions.

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  • Atomic BZ Master – Upgraded Diff Pulley

    The new BZ Master pulleys showed up on my doorstep today and I was surprised to see that this wasn’t just the one from the aluminum BZ5 diff in a different color. Atomic has in fact made two major changes:

    1. The new pulley uses 10 balls instead of 8
    2. The new pulley is about 1mm wider
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  • Atomic BZ Master Diff Upgrade Parts

    If you’re looking to build up your BZ Master diffs like I did in my previous post, you’re in luck. Atomic is releasing the upgraded, aluminum parts and dust proof pulley separately. They’re currently shipping from Miracle-Mart. Otherwise hit up your favorite Atomic reseller and pre-order a set!

  • Atomic BZ Master – The Diffs

    It’s been a few weeks since I got the BZ Master and, while I originally intended to provide lots of content, showing me building and tuning the car, I’ve spent the little free time I’ve had driving it. I do want to go back and touch on one thing that I thought was interesting though and that is the ball diffs.

    If you own a BZ3, BZ5 or even an SZ2, the diffs probably look familiar. While Atomic has tweaked things a bit over the years, the basic design hasn’t changed much. Needless to say, I was a bit surprised to see that one of the diff halves was now aluminum. With the SZ2 and BZ5, this piece came with the aluminum diff upgrade. Score!

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