Charles C. Roberts, Ph.D., P.E.


Defects in automotive equipment can be the basis for subrogation actions against parties allegedly causing a loss. However, not all defects found in automotive equipment pose a high probability of a successful recovery.  Four automotive related defect case studies are presented with analyses of potential subrogation. Also included are several references that can act as a data base for reviewing subrogation potential for future cases. 


Figure 1 is a view of two brake fluid reservoir caps from a late model automobile.  The cap on the left was taken from the insured’s vehicle that was involved in an accident. The insured indicated that the brake pads had recently been replaced and that the brakes failed, causing the accident. Inspection and testing of the brake system found that, in fact, they did not operate properly, i.e., very poor stopping performance.  The red arrow in Figure 1 points to a swollen polymer seal on the cap as compared to an exemplar cap and seal, as indicated by the green arrow.


Figure 1

Figure 2 shows a brake caliber from the insured’s vehicle with the red arrow pointing to a swollen caliber piston seal. All polymer components showed a similar condition.  This happens rather quickly when power steering fluid or other incompatible fluids are added to the brake fluid reservoir. Since the brakes had recently been serviced where fluid had to be added to the brake system, the evidence implicates the brake shop where the repairs had been made. It is likely that brake shop personnel accidentally filled the brake fluid reservoir with an incompatible fluid, causing the brake system damage and failure.   Subrogation potential is high in this case study.

Figure 2

Figure 3

Figure 3 shows an automobile involved in an accident with a tractor semi-trailer unit. According to the insured, the left rear wheel locked up, causing the vehicle to swerve into the oncoming lane. Inspection of the left rear spindle bearing yielded the photo in Figure 4. The bearing had failed and welded itself to the spindle, causing the wheel hub to lock. The red arrow points toward metal debris generated in the grinding process before the bearing failed. Additional investigation found the vehicle mileage in excess of 120,000 miles and that the insured heard the grinding noise prior to bearing failure, but failed to have the condition corrected.  The high mileage on the vehicle suggests the failure to be a result of wear out of the mechanical part and probably not a defect.  The insured also showed lack of care in correcting the problem, which leads to an assessment that subrogation potential against the vehicle manufacturer in this case is relatively low.   


Figure 4


Figure 5

Figure 5 is a view of a utility tractor, which was being worked on by a maintenance person, when it suddenly lurched forward, striking the individual and causing an injury. The tractor was parked with the ignition off, in gear and wheels not blocked, which was contrary to the recommendations in the manufacturer’s manual.  Inspection of the tractor revealed that an intermittent circuit was closing between the battery contact and starter contact in the starter ignition switch, causing the vehicle to lurch forward while in gear. Figure 6 shows the disassembled switch. Corrosion of the battery and starter contacts was evident along with evidence of an electrical path between the contacts. According to the insured, the starter switch was replaced with an after-market part by a local repair shop. The replacement starter switch was not waterproof, unlike the original equipment. A vehicle of this type is often parked outside and exposed to the elements. Consequently, a waterproof starter/ignition switch is essential.  


Figure 6

Certainly the shop that replaced the waterproof factory equipped starter/ignition switch with a non waterproof after-market switch deserves criticism. The tractor manufacturer is also subject to criticism, since an interlock to prevent start-up in gear was not designed into the tractor, as is typically available on most tractors. Probability of successful subrogation against the repair shop and vehicle manufacturer is relatively high.


Figure 7

Figure 7 is a view of an after-market automotive wheel that became detached from the vehicle, causing a severe roll-over accident. Fretting patterns on the lug nut holes suggest loosening of the wheel, despite testimony that the nuts were periodically tightened.  One difference between the after-market wheel (Figure 7) and the original equipment wheel (Figure 8) is the inside diameter of the hole where the axle hub fits.  The hole of the original equipment, as indicated by the green arrow, is similar to a pilot hole that fits over the axle hub. The wheel is actually partially supported by the axle hub. The wheel hole in Figure 7 (red arrow) is too large and does not take advantage of the support provided by the axle shaft hub. Consequently, the wheel in Figure 7 is prone to loosening over time on this axle hub, despite repeated tightening of the lug bolts, which is a design defect.  It should be noted that there is a problem with this wheel on this particular axle.  Many after-market wheels are designed to fit a variety of axles, therefore a problem with this axle does not imply a problem with another axle.   

Figure 8

Four case studies on automobile related failures and the possibility of subrogation have been presented. For additional case studies, see the references cited below. Copies of References 1 through 7 are available in Adobe Acrobat format by email request from


1.      “Motor Vehicle Accidents Caused by Mechanical Failures,” Claims Magazine, January 1988, p33f.

2.      “Analysis of Seat Belt Malfunctions,” Claims Magazine, April 1988, p63.

3.      “Failure Analysis of Automotive Vehicle Wheels,” Claims Magazine, December 1995, p54f.

4.      “Truck Component Failure Analysis,” Claims Magazine, August 1996, p64f.

5.      “Rodent Damage to Automobiles,” Claims Magazine, December 1996, p35f.

6.      “Throttle Mechanism Failure Analysis,” Claims Magazine, May 2001.

7.      “Automotive Suspension Failures,” Claims Magazine, June 2002, p46f.

8.      “Motor Vehicle Fires from Oil Leakage,” Subrogator, February 2004, p108f.

9.      “Improper Reverse Engineering,” Subrogator, Winter 2005, p102f.

10.  Technical Aspects of Insurance Claims Investigations, Roberts Publishing, 2002, ISBN 0-9715050-1-2.


Published in Subrogator Magazine