MacKenzie Angeledes
A)Description
This project is intended to aid the Electric Vehicle club in furthering the construction of the vehicle. Construction and assembly of the components will be a group effort shared by the members of the club. The frame will be made using material on hand in the machine lab, or donated/acquired from a metal supermarket. The dampening unit (“coilover”) will be acquired from an automotive parts supplier, in the interest of minimizing cost. Bushings and bolts will be acquired from an automotive parts supplier or hardware store. By minimizing the number of custom-manufactured parts, the suspension will be easier to maintain/repair as time goes on.
The lower beam (the engine mounting surface) will be manufactured in the Central Washington University Machine Lab using sourced materials. Choosing materials that exceed the minimum-strength requirements will ensure that later additions to the vehicle will not cause the system to fail. Once the beams are manufactured, the existing engine mounts can be affixed to the beams and the beams can be affixed to the rear of the vehicle frame. The dampening system will be fixed to the frame using standard bolts and mounts, and can then be fixed to the lower beams with bushings and bolts.
B)Drawing Tree and Drawing Identification
C)Parts List and Labels
2x Lower Control Arm (Motor Mounting Member) ......................... Drawing 001
1x Motor Mount............................................................................ Previously Completed
2x Axle Mount............................................................................... Previously Completed
6x Coilover Bracket (Mounting Provision)....................................... Purchased
2x EMPI Coilover Unit..................................................................... Purchased
D)Manufacturing Issues
Potential manufacturing issues lie in the availability of the square tubing for the lower control arms. 1-in-square tubing may need to be purchased if extra materials from the machine lab are not available. Welding the lower control arm – an angled 45 degree joint – will need to be performed by an experienced welder in order to ensure a correct fit. Any failure in the welds could be a source of danger for an occupant once the vehicle is completed.
The coilover brackets, which were originally designed for larger diameter tubing, had to be modified in order to work with the narrower tubing of the frame. Each bracket was hand notched and fit to the chassis.
Additionally, the chassis tubing was not entirely square – the bars were uneven. In order to compensate for this, the chassis was leveled with the lower rear bar of the frame squared with respect to the ground. A hand level was used, and each bracket was tacked onto the frame , hand leveled and tweaked, and tacked again. To ensure that the upper brackets remained in line with the lower brackets, a plumb bob (or plummet) was used to transfer the location to the lower bar. The leveling procedure was repeated for the lower brackets.
Another manufacturing issues occurred in the form of a delay from the outsource manufacturer of the lower control arms. After a significant delay, the manufacturer did eventually build the pieces necessary. This created some concern, but ultimately worked with the schedule.
The coilover units themselves also had to be modified slightly to accommodate the bolts provided with the brackets. This was performed by hand drilling the bushings at the ends of the coilovers until the inner diameter was large enough to accept the bolt.
The upper bar to which the two upper brackets were welded to was moved 3.5 inches in order to better accommodate the coilovers and allow for a more upright position. This should also allow for the coilovers to handle future weight changes more adequately. The system is currently oversprung, but once additional weight is added by various components, it should be effective.
E)Discussion of Assembly, Sub-Assemblies, Parts, and Drawings
The top level assembly is the rear subframe itself, which connects to the existing vehicle frame. Separating the assembly, the two major components are the dampening member system and the lower control arm/ motor mounting member system. The motor mounting member has provisions for holding the engine, the axle mount, and the necessary mounting hardware for connecting to the dampening member and frame. The dampening member consists of the commercially available EMPI-Coilover shock and mounting provisions for the frame connection and lower control arm connection.
