Factory trailer hitch receiver bent, broken or weld failure

Applies toODI opened this Engineering Analysis based on allegations of hitch receiver failures in certain MY 2002 GMT800 series full size 2500 C/K sport utility vehicles and pickups.

On September 14, 2007, the Office of Defects Investigation (ODI) opened this Engineering Analysis (EA) based on allegations of hitch receiver failures in certain model year (MY) 2002 GMT800 series full size 2500 C/K sport utility vehicle (SUV) and pickup (PU) vehicles (subject vehicles).— [1]

Applies toThe models are the Chevrolet Suburban, Tahoe, Avalanche and Silverado, the Cadillac Escalade, and the GMC Yukon and Sierra, with the original equipment hitch receiver typically installed as part of the towing package option.

GM reports that it produced approximately 215,052 MY2002 SUV/PU subject vehicles equipped with original equipment manufacturer (OEM) hitch receivers typically installed as part of the standard towing package option. Models include the Chevrolet Suburban, Tahoe, Avalanche and Silverado, the Cadillac Escalade, and the GMC Yukon and Sierra vehicles.— [1]

Applies toThe design of the hitch receiver stayed the same throughout 1500/2500 GMT800 series production (MY1999-MY2006).

The design of the hitch receiver has remained the same throughout the 1500/2500 GMT800 series production period (MY1999-MY2006).— [1]

First signsThe opening complaints alleged bending or deformation of the pin box area while towing, failed welds around the pin box, and in one report complete weld failure of the pin box with full separation of the trailer from the tow vehicle.

Two owner reports allege bending/deformation of the pin box area while towing. One owner report alleges welds failed around the pin box area and another report alleges complete weld failure of the pin box leading to a full separation of the trailer from the tow vehicle.— [2]

First signsReported problems include hitch breakage, weld failures, bent hitch receiver and improper hitch installation.

Reported problems include hitch breakage, weld failures, bent hitch receiver and improper hitch installation.— [1]

First signsIn NHTSA VRTC's survey of owners with an OEM hitch receiver who tow, 3 reported a hitch strength/structure issue and 132 reported a rust issue (poor protective finish on the units).

Three owners reported hitch “strength/structure” issue, 132 owners reported a rust issue (poor protective finish on the units) and the remaining 173 owners expressed satisfaction with their products.— [1]

Why it happensThe OEM hitch receiver is made of welded steel tube and plates and is attached to the frame rail at the rear of the vehicle.

The OEM hitch receiver as shown in Figure 1 consists of welded steel tube and plates. The assembly is attached to the frame rail at the rear of the vehicle.— [1]

Why it happensThe receiver box is attached to the cross tube by welds at the slant steel plate interfaces and at the "U" shaped bracket (the upside down "hat").

As shown, the receiver box is attached to the cross tube via welds at the slant steel plate interfaces and at the “U” shaped bracket (upside down “hat”).— [1]

Why it happensThe unit is bolted to the bottom of the vehicle frame at both mounting brackets and fastened to the bumper at the top of the "U" shaped bracket.

The unit attaches to the bottom of the vehicle frame by mechanical fasteners (bolts) at both mounting brackets and with fasteners to the bumper at the top of the “U” shaped bracket.— [1]

Why it happensODI distinguished two kinds of high-speed receiver box failure: tear or breakage from trailer sway / extreme side loading, and weld failure from inadequate weld construction.

Hitch receiver box tear/breakage from trailer sway/extreme side loading and hitch receiver box weld failure due to an inadequate weld construction.— [1]

How to confirmSigns of an overload failure: the operator first noticed trailer sway, the failed part shows extreme lateral and twisting loads, and the tear/break line runs through the material and not at the weld interface.

Telltale signs for this overload failure condition include initial trailer sway as noticed by the operator, extreme lateral and twisting loads (from trailer tipping) in the failed part, and the part’s tear/break line to be at the material and not at the weld interface.— [1]

How to confirmSigns of a weld quality failure: the trailer separates first (the safety chain and emergency trailer brakes may or may not activate), loads are longitudinal with little lateral or twisting load, and the tear/break line is at the weld interface.

They would include initial separation of the trailer that may or may not activate the safety chain and emergency trailer brakes, longitudinal loads with little lateral or twisting loads in the failed part, and the part’s tear/break line to be at the weld interface (due to poor quality welds that is weaker than the parent material).— [1]

If leftIn the GM hitch design, when the receiver box assembly breaks away, the chain plate carrying the safety chain and emergency brake activation anchorages may tear off with it.

In addition, in the GM hitch design, when the receiver box assembly breaks away from the hitch receiver, the chain plate containing the safety chain and emergency brake activation anchorages may also tear off with the receiver box assembly.— [1]

Why it happensIn one weld incident GM and the supplier, Production Stamping, found that two of the welds lacked proper penetration/fusion; the supplier improved its quality control from January 2002, with fewer hitch issues on vehicles built in the latter part of MY2002.

GM and Production Stamping quality personnel retrieved the part for post failure analysis and determined that two of the welds lacked proper penetration/fusion. Because of this incident, Production Stamping made improvements to their quality control process starting in January 2002 that have resulted in fewer hitch issues from vehicles built in the latter part of MY2002 when compared with vehicles built prior to January 2002.— [1]

Why it happensEight returned parts showed overload failures from severe side loading, generated during high-speed trailer sway, low-speed maneuvers or sudden stops.

Eight returned parts showed overload failures from severe side loading. The side loads were generated during high-speed trailer sway, low-speed maneuvers or sudden stops.— [1]

Why it happensOf the bent hitches VRTC inspected, the downward bent one had towed a utility trailer that can weigh over 5,000 pounds without a weight distribution hitch, likely exceeding the 600 lbs tongue weight on the receiver's placard; the two upward bent ones had towed 12,000 pound travel trailers, likely with an improperly adjusted weight distribution hitch.

The owner of the downward bent hitch towed a utility trailer that can weight over 5,000 pounds but did not use a weight distribution hitch and likely exceeded the trailer tongue weight of 600 lbs as stated on the placard located on the hitch receiver. Both owners with upward bent hitches towed large 12,000 pounds travel trailers and are likely to have improperly adjusted the weight distribution hitch.— [1]

Why it happensIn VRTC's dynamic towing tests, hazards like deep chuckholes or running over curbs produced torque loads of 3,000 ft-lbs (= 4,067 N·m) with peaks of 4,000 ft-lbs (= 5,423 N·m); with the 4,000 ft-lbs (= 5,423 N·m) peak applied in fatigue testing the hitch receiver failed at only 10,000 cycles.

However, hazards like deep chuckholes or running over curbs can produce high torque loads of 3,000 ft-lbs with peaks of 4,000 ft-lbs. When the peak torque load of 4,000 ft-lbs was applied during follow-on fatigue testing, the hitch receiver failed at only 10,000 cycles.— [1]

How to confirmODI notes that prior metal damage or cracks should be detectable before the final failure or separation, and that a bent receiver shows in a side view of the hitch receiver with the vehicle on level ground.

As evident from the failed parts, prior metal damage or cracks should be detectable by the operator before the final failure/separation of the part. As for inspection and detection of a bent receiver, a side view of the hitch receiver (with vehicle on level grounds) should indicate this condition.— [1]

RepairIn one low-speed weld failure the owner repaired the hitch by re-welding the receiver box onto the crossbar section and reported no further problems.

The owner repaired the hitch by re-welding the receiver box onto the crossbar section and reported no further problems with the hitch receiver.— [1]

CautionVRTC's sectioning of welds and material analysis of the inspected units showed proper weld quality and steel material; it found no weld quality issue in its survey, vehicle inspections or parts analyses.

The results showed proper weld quality and steel material. VRTC found no weld quality issue during its survey, vehicle inspections or parts analyses.— [1]

CautionAs of April 2008 ODI identified 41 owner complaints and 89 warranty claims, 130 reports in all, for all issues associated with the hitch receiver on the subject vehicles.

As of April 2008, ODI identified 41 owner complaints and 89 warranty claims totaling 130 reports for all issues associated with the hitch receiver.— [1]

CautionODI concluded that the design and manufacturing process of the OEM hitch receiver in the MY2002 2500 C/K vehicles appear to be adequate but without any excess capacity.

The design and manufacturing process associated with the OEM hitch receiver installed in the subject MY2002 2500 C/K vehicles appear to be adequate but without any excess capacity.— [1]

CautionImproper hitch/trailer setup and overloading of the hitch were the primary causes of the majority of the hitch bending issues.

Improper hitch/trailer setup and overloading of the hitch were the primary causes of the majority of the hitch bending issues and they too did not provide indications of a safety defect trend.— [1]

CautionThe investigation did not identify any defect trend with the OEM hitch receiver in MY2002 2500 series SUVs and pickups.

This investigation did not identify any defect trend with the OEM hitch receiver in MY2002 2500 series SUVs and PU vehicles.— [1]