Eight Checks After You Put a Trailer Wheel Into a Curb

Check one is the tire and wheel. Look for a scuffed or cut sidewall, a bulge anywhere on the sidewall, and damage to the wheel rim flange. A sidewall bulge is a broken body ply and that tire is finished regardless of whether it holds air. On an aluminum wheel, look for a flat spot on the rim flange and for any crack radiating from a spoke, which is a scrap wheel.

Check two is lug torque, with a torque wrench. A strike can move a wheel on its studs and stretch the studs. Torque each nut to specification in the correct pattern, and note whether any nut moved before reaching torque. A nut that took a quarter turn to reach spec means it was loose, and a stud that reaches torque with a spongy feel is stretched and needs replacing along with its neighbors.

Check three is hub play, and this is the first one that finds serious damage. Jack the wheel clear, grip the tire at twelve and six oclock and rock it. Any perceptible movement is bearing play, which after an impact means either the preload moved or the bearing is damaged. Then grip at three and nine and rock it: movement there in the absence of play at twelve and six points at the spindle rather than the bearing. Then spin the wheel and listen. A dry grinding or a periodic click is a bearing that has been damaged.

Check four is brake drum runout. With the wheel off, mount a dial indicator or, failing that, set a fixed pointer close to the drum face and rotate it slowly by hand while watching the gap. A drum that wobbles has either been struck directly or is running on a bent spindle. On electric brakes, also look at whether the magnet has been contacting the armature surface unevenly, which shows as a wear pattern favoring one side.

Check five is the leaf springs and their hardware. Look along each spring pack for a leaf that has shifted relative to the others, a broken center bolt, and any crack at the eye. Then the shackles and bushings: grip each shackle and try to move it in the plane of the spring. There should be minimal movement. Elongated shackle holes and worn bushings show up as clunking under tow and as visible ovaling at the bolt.

Then the equalizer, on a tandem axle trailer. It is the pivoting link between the two springs on each side, and it takes the impulse from a curb strike directly. A bent equalizer changes load sharing between the two axles permanently, which overloads one and produces exactly the bearing failures that arrive six months later with no obvious cause.

Check six is the spring hangers and their welds to the frame. Clean each hanger area, because a hairline crack under road grime is invisible. Look at the weld toe all the way around each hanger, particularly the forward face of the forward hanger and the aft face of the rear hanger, which see the highest load. A crack presents as a fine dark line that does not wipe off, often with a slight rust weep because it has been breathing.

Also look at the hanger itself for deformation. A hanger that has been pushed will show a change in the angle of its leg relative to the frame, and comparing left to right at the same station is the quickest way to see it. Take a photograph of both sides at the same angle and compare on a screen, which catches differences your eye misses standing next to it.

Check seven is alignment, by measurement, and this is the one that actually determines whether the trailer tracks. Establish a centerline at the coupler, then measure from the coupler to the center of each hub, left and right. On a tandem, measure to both. Those distances should match side to side within about an eighth of an inch. A difference of half an inch or more will produce tire scrub and a pull under tow. Then measure hub face to hub face across each axle to check for axle bend.

A curb strike hard enough to move a hanger will usually also have put a load into the frame, and the frame carries the body. Measure the diagonals across the entry door opening and across the nearest window. If both diagonals are within an eighth of an inch of each other, the body has not racked. If one is longer, it has.

The practical version of this check requires no tape at all. Open and close the entry door, every compartment door on that side, and cycle any slide. A door that latches differently than it did last week, a compartment that needs a push, or a slide that hesitates where it did not before are all telling you the body geometry changed.

This check exists because it is the one that tells you the damage is not confined to running gear. A trailer with a bent spindle and a straight frame is a bounded repair. A trailer with a racked body has frame involvement, and frame and structural work runs $750 to $20,000 and up. Establishing which you have before authorizing anything keeps the scope honest in both directions.

Do not tow with a sidewall bulge, with perceptible hub play, with a cracked hanger weld, with a broken spring center bolt, or with a coupler to hub measurement off by more than about half an inch. Each of those is a progressive failure under load, and the failure mode is a wheel departing the trailer or an axle shifting under it. There is no speed at which those become acceptable.

Marginal findings are a judgment call and the useful question is distance. Getting a trailer twenty miles to a shop at 45 miles per hour on surface streets is a different risk than towing it 300 miles up the 5. If you are going to move it, move it short and slow, check hub temperature by hand at every stop, and stop for good if any hub is noticeably hotter than the others.

We are in shop only, no mobile or roadside service, so a trailer with a stop rule finding needs to be transported rather than towed. From San Clemente that is roughly 45 minutes to Yorba Linda via the I-5 or the 73. An RV systems estimate is $150 credited against an authorized repair, and a full measurement session on a trailer after an impact is the most useful money you can spend before deciding anything.