The single biggest tip I can give is to buy a 3mm (M3 x 0.5)tap and use it everywhere that a 3mm screw needs to screw into a plastic part. The only exceptions would be where the droop screws go on the control arms and the screws that hold the battery retainer plate (the one that swings away for loading the battery). For the rest, pre-threading the holes will help the assembly process go much smoother, and you will be able to more accurately tighten the screws. This helps prevent stripping the plastic by accident and rounding out the hexes in the screw heads.
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3 Racing includes some shims for the front and rear lower suspension mounts that are intended to tune the roll center. These can also be used to introduce some anti-squat (or even pro-squat) in the rear, or to add some kick up in the front. The changes would be subtle, but it is nice that they are included in such a basic kit.
The kit comes with both 3 degree and 1 degree rear toe blocks. 3 degrees seems like way to much rear toe in the rear, especially with a chassis that has rear weight bias already. I installed the 1 degree mount to start with. Here you can see the difference.
When taking toe out of the rear, the wheelbase gets extended in the process due to the change in angle of the control arms. You can compensate for this by moving the two included shims to be behind the rear lower suspension arm, which will push it forward by the thickness of the spacer. A little more play gets created in the lower arm from front to rear because of the smaller angle of the mounting shafts. I added a thin spacer to take up the slack but still keep the movement of the arm completely free.
I also moved both of the spacers for the front lower arm forward to help bring the wheelbase back to the standard length.
I am not sure why 3 Racing decided to put so much KPI in the front knuckles, but it creates some really strange geometries at full lock steering. I saw this mod and thought I would share it. You have to carefully mark, drill, and tap new holes into the knuckle to reduce the KPI. It makes the camber adjustment a little harder, but I think I may buy longer turnbuckles to make it a little easier.
Finally, I decided that I didn't need another car with pink anodized parts all over it, so the anodizing was stripped off all the kit parts that were pink. Easy Off oven cleaner was used for the process. There numerous tutorials on the internet that explain how to do this, so I won't cover that in detail. The parts do get a bit of a black coating on them during the process, so they will need to be polished some to give them a bare aluminum finish. It takes a little work, but it is worth it to get a unique look.
This is kinda the first time I hear/read about someone tapping into thermoset plastic parts such as in your D4 chassis kit which for me is kinda strange and can risk removing to much material rendering the part weaker. Why not just leave the self tapping screws that came with the kit and screw them in and unscrew them. This will create the tap needed for future re-assembly if things need to be taken apart.
ReplyDeleteThanks for the reply. Tapping into plastic is nothing new, and is good practice when using machine screws. The tap is designed to cut precise threads that match the screw perfectly and will not remove too much material. The screws that are included in the kit are machine screws and not self tapping screws. Creating the threads with a machine screw and unscrewing it is not very optimal. The threads of the screw don't actually cut the plastic and do not create a thread like a tap will. Instead it simply displaces material inside the hole and creates high stress areas. The threads will be poorly formed by the screw and weaker using that method. Warping and bulges in the plastic parts can also occur. Sure, you can run the screws right into the kit plastic without tapping it, but using a tap to form the threads is better craftsmanship.
DeleteWell then, I didn't know the screws provided weren't self-tapping screws makes sense why you decided to tap the existing injection molded holes, but I personally wouldn't do that as the plastic itself from personal experience is probably Nylon 66 which is engineered to take machine screws without requiring a tap. Craftsmanship has nothing to do with good fastening procedure, the bite a self tapping screw offers into a plastic part is quite strong, while a machine screw fastening to a tapped plastic part might be offer a more smooth entry but wont have the same strength. Now this is my opinion and perhaps the molded parts on the D4 use a different plastic, perhaps even tapping into them and then screwing in machine screws (which in my business is only made for alloys or parts with inserts) is what works for you at the moment. I still think its quite unorthodox.
DeleteWe can keep arguing about it if you want, but you are making assumptions and talking about self-tapping screws when machine screws are what are being used. If you do some research, you will find that tapped or molded in threads with machine screws provide better fastening than a self-tapping screw in a plastic joint, if the joint is designed to be taken apart. Yes, a metal insert is superior to both, but it is very costly, and not very practical when used on parts this small with such small threads. I am an engineer by trade and design machinery, tools, and fixtures for a living. I currently work for a company that primarily makes injection molded plastic parts and assemblies. We do in fact tap holes on some mass produced parts after they have been molded. It is far from unorthodox to tap into plastic for using machine screws. It is the preferred method other than molding the threads (which is expensive and complicated to build into a mold).
DeleteDo you have any more detail about the KPI modification? Were there measurements you used or simply guessed best place based on material available?
ReplyDeleteThanks!
I simply drilled it as far out on the flat portion of the knuckle as I could before it tapers down. Any further out and the drill bit will "walk" down the tapered portion and not drill an accurate hole.
DeleteHow did you get the e-rings on the shock shaft? Cant get a single shock piston mounted after trying for an hour. Also lost an e-ring. Very frusterated.
DeleteHow did you get the e-rings on the shock shaft? Cant get a single shock piston mounted after trying for an hour. Also lost an e-ring. Very frusterated.
DeleteIt can be tricky. I usually put the the one for the bottom of the piston on the shaft first, Then after I install the piston, I carefully use needle-nosed pliers to install them. It takes some patience.
DeleteHello friend i would like to ask you about the wheelbase,i have an hpi silvia s13.i have the shortest wheelbase front and rear and i also trimmed the rear suspension arms but the wheels just doesnt match the bodyshells length.i have 1 degree toe in.i wonder if anyone else has the same problem.thanks
ReplyDelete