Starting the build off of my Yokomo B-Max2 MR V3 kit. Since there are some products under development at Tekin as well as the stock buggy class being the largest in my area I planned on building up this car for stock racing to begin with. Here are a few things I found during the build parts wise to look out for which can shave some serious weight.
Right out of the gate the car is getting a full titanium screw kit from Protek RC. The kit includes all the screws needed to replace the kit screws. They look great and are much lighter than stock. Make sure you use a good quality driver set like the ones I use from MIP.
Next on the list was the optional aluminum top shaft kit and plastic transmission gears to replace the stock steel top shaft and aluminum idlers that come with the kit. Part # YOKB2-503I for the idler gears and YOKB2-303TA for the aluminum top shaft. These parts alone shave 10.4 grams!
Next up was the light weight skeletonized motor plate part #YOKB2-304LW which drops another 4.7 grams from the kit part. Now don’t get me wrong all of the kit parts are top shelf, but the steel top shaft and aluminum idler gears add a lot of rotating mass, a stock driver’s enemy. Weight savings here can add up to tenths on the track.
Back to the Bmax MR V3 build! I managed to wrap up the ball differential and transmission build. In doing so I was given some lightweight aluminum idler shafts from a fellow Yok driver(Thanks Will S!). You can see the difference in weight, over 3g for the pair. A very quick and easy upgrade indeed. I also build the ball with a B-Fast ceramic thrust assembly and carbide diff balls. In my experience this is the best setup overall for smooth action and reliability.
Also on the agenda were some upgraded spring cups from Avid RC. The new “Avert” spring cups have material removed for weight reduction. They also securely fit onto the shock eyelet and provide a very true surface for the AvidRC springs to sit on top of. They’re a tick lower height than the factory parts but this isn’t an issue to make ride height, etc. They also are lighter than stock which is nice to remove unsprung weight from the car.
While on the subject of shocks and dampers I’d like to point out a few things I noticed about the Yokomo shocks. If you look at the way the cartridge is designed you will see a recess built into the face. This prevents there from being any “suction” effect when the piston face and cartridge face meet during cycling. This phenomenon can cause a car to stick ever so slightly during a full suspension cycle/landing. It doesn’t seem like much, but if you’re not running any limiters and your cartridge/body face is flat and your piston face is also flat, it can be the difference between a nice landing and one that is a little “off” for no reason. I learned this at a chassis/damper school in the 1:1 genre back in the days. Yokomo did a nice job here also including some nice tapered pistons in the kit to complement the chassis setup and other parts. As per normal for me, I build my shocks using Factory RC’s O-Slip shock o-ring wetter. This stuff is pretty amazing, especially if you follow the recommend guidelines and pack the cartridge area voids. Not only do you lube the o-rings, you fill the cartridge fully to prevent any air and of course shock oil from entering the cartridge. This prevents the shock oil from even reaching the o-rings in the first place! Everyone always comments how smooth my shock action is, no matter the car. Give it a go, you’ll be happy you did. Also when assembling your shocks be sure to use a nice set of shock shaft pliers like the ones I use from Protek RC. A nice feature is the shock eye installer tool. Funny most people don’t realize what that little press bolt is for! Now you know!
Stock racers are adamant about having a super free spinning drivetrain. Having been on the Avid RC race team for a little over 5 years now, I’ve never been let down by a bearing failure in a race, ever. So without hesitation I installed fresh Avid bearings, removing one shield and cleaning out the factory grease. I’m building this as a stock car so I’m willing to give up some maintenance to use the Avid RC “Slip” bearing oil. Removing the stock grease is as simple as allowing the bearings to rest in some motor spray and or carb/brake cleaner in a can(don’t use plastic) for 30 minutes and blow out the rest of it with the spray cleaner and straw. Once done dry the bearings and lube them with the Avid RC “Slip”oil, done.
Now that the build is pretty much sorted mechanically. I’ve begun to install my electronics. One quick tip is to drill a small hole in the chassis side plate to allow your receiver wire to run through directly to the antenna boss. I used a 1.5mm drill bit. I also chose to upgrade the stock plastic servo horn with one of Ko Propo’s carbon fiber and aluminum servo horn kit. The 16.5mm kit fit perfectly and dropped right into place. I can’t tell you how cool this little piece is! They have multiple sizes sure to fit any car.
