RPM A-arms for the Associated B4, B4.1 & B4.2 were designed to solve several customer-related complaints about the stock A-arms. Foremost is durability. Our B4 front A-arms are designed to withstand some serious abuse! We’ve redesigned the entire front end, replacing the stock front bulkhead with a version that helps spread impact forces over a larger area at the inner hinge pin mounts. RPM front A-arms are wider at the inner hinge pin by nearly 3/16” without altering suspension geometry.
We also focused on the hinge pin retaining system used on the stock A-arms. Using a small screw hole so close to the hinge pin like the stock arms do creates structural weaknesses. We moved the hinge pin retaining screws in-line with the hinge pins, significantly strengthening our A-arms in the process. By eliminating the smaller 2-56 hinge pin retaining screws, we’ve also eliminated the problem of the hinge pins falling out due to varying screw head diameters.
Our final focus was on slop elimination. Our strict quality control allows us to tighten up all of our tolerances without fear of binding the suspension system. The final result: a smooth, free moving suspension system with minimal slop. Our tighter tolerances on our A-arms allows other critical adjustments such as camber and toe angles to be much more consistent, which provides better and more consistent control of the B4.
RPM B4 A-arms come with all necessary mounting hardware and instructions. RPM B4 A-arms are sold in pairs and include the front bulkhead.
Tech Notes: RPM B4 Front A-arms require the use of the bulkhead we supply in the kit. Stock or any other aftermarket bulkheads will not work with RPM A-arms.