Two months prior to the release of these rear A-arms for the HPI Baja 5B & 5T, we released our version of the front A-arms. In that short amount of time, the durability of our Baja A-arms displayed their unbeatable nature! That kind of performance can now be matched out back with our rear A-arms for the 5SC, 5B & 5T.
RPM Baja rear A-arms start with the basic geometry of the stock arms so they are direct replacement parts – no additional parts will be needed. However, we’ve made a number of modifications to the arms to improve performance and durability. Key durability features are as follows:
- The shock mount on the lower A-arm has been moved forward by a full 1/4” to help reduce the severe rubbing issue of the wheel at the shock mount that would cause stock arms to break.
- By moving the shock mount forward, we were able to increase the material around the shock mount to protect the lower shock rod end, preventing it from being the lowest hanging component of the A-arm assembly.
- We’ve incorporated a third inner hinge pin boss at the inside hinge pin of the lower A-arm and tied in structural ribs that help disperse impact energy and rotational forces from engine torque over all three hinge pin bosses.
- Similar corner webs to those found on our front A-arms have been designed into the rear upper and lower A-arms to help improve strength and durability.
In the performance department, we moved the rear hub carrier forward by 1/8” over stock geometry. While this does little to change the overall wheelbase of the vehicle, what it does do is alter the angle of the drive shaft as it exits the differential. This reduces the tendency of the Baja to squat under acceleration. By sliding the rear hub carrier forward, we use the torque of the motor to effectively “push” the rear wheels into the ground, using both the weight of the Baja and the torque of the motor to improve acceleration performance. Up top, RPM rear upper A-arms have had a shape change for added lateral stability – the stock “Y” shape tends to allow the upper pivot ball to move forward and backward while the RPM “D” shape holds the upper pivot ball in place more solidly, providing a more consistent feel to the performance of the Baja.
