D-Tech Knowledge Base
Trailing Arm Bolts in Application
The Delorean rear suspension geometry is triangulated with handed left/right trailing arms, also referred to as “radius” arms. The main arm body ties directly to the rear hub carriers, extending forward to meet at the chassis Rear Y to Mid-box zone. At the front, trailing arm mounting point, a pivoting function is achieved via a complex bushing configuration resulting in a high-stress application on the fastener implemented. The trailing arm bolt (TAB) is responsible for maintaining the rear suspension geometry via a stacked shim configuration and structural integrity of the rear suspension system. Maintaining a high level of application awareness is crucial for this safety-critical suspension component.
Factory fasteners have the notable issue of becoming loose within the assembly and or throw shims. Loosening occurs due to the main fastener nut backing off, inadequate torque, or fastener fatigue. The Fastener is also highly susceptible to corrosion, resulting in the fastener seizing in the trailing arm, and a significantly weakened bolt.
Trailing arm bolts should be inspected regularly based on driving conditions exhibited. The recommended interval is 500 miles or six months. The check should include confirming the fastener is properly torqued, corrosion issues are not present and shims are in place. It is recommended to document shim placement to assist with the visual check routine.
The fasteners are accessed from beneath the car by removing the left and right air deflector plates for the nut side of the fastener, and next to the front of the transmission for the bolt head. Removing the deflectors for the first time will likely require the replacement of the deflector retainer strips.
This is a component pioneered and engineered by DeLorean Industries by implementing a one-piece design with PEM insert studs. Removal for future inspection is simplified by this update.
From inside the chassis, the bolt head is accessible readily on manual transmission cars and with an added amount of effort on automatics. Taking tension of the fastener, rotate the bolt head while observing the trailing arm assembly for movement. If the bolt is damaged or failed, an oscillation movement will occur. If the fastener is unable to rotate, the most likely cause is corrosion in the trailing arm. If rotation cannot be achieved, replacement is required.
If the bolts are the factory's original fasteners, they should be replaced to develop a standard maintenance protocol. If the bolt has been over-torqued, the radius arm bushing sleeve is prone to compression and failure.