Gate Swings Free Off Hinge But Binds On Bypass Vs Normal Decision Tree

Why this matters

A customer says a gate binds when they swing it. You pull a hinge pin and swing the gate by hand to bypass the hinge load and the gate moves freely. That isolation result is a powerful diagnostic moment: when the gate frame swings free off the hinge but binds back on the hinge, the bind lives in the hinge system or in the geometry of the two posts (hinge and strike), not in the gate frame itself. Read the bind wrong and you replace the frame on a problem that is at the hinge post or the latch geometry. This tree walks the bypass-versus-normal logic so a 10 minute isolation test becomes a defensible diagnosis.

Symptom presentation

Characterize the bind with both states ready to compare:

• Bind only on hinge: gate hangs square on the hinge but the post offset is wrong.
• Bind on hinge and off hinge: gate frame is racked or the frame itself is the cause.
• Bind only late in the swing (latch approaches strike): geometry between hinge and strike posts.
• Bind early in the swing (right off the hinge): hinge fit-up or hinge post twisting.
• Bind only in one direction (inswing free, outswing tight): hinge post tilted out of plumb in the direction that resists outswing.
• Bind only at certain temperatures or after rain: wood gate frame swelling, not a hinge problem.

Capture which state binds and where in the swing arc.

Quick checks

1. Run the bypass test. Pull one or both hinge pins and swing the gate by hand, supporting it. Note where it binds, if at all.
2. Check the hinge post for plumb at the top hinge while a helper holds the gate open at the latch end. Movement is hinge post twist.
3. Sight from above between the hinge and strike posts. Are they parallel? Posts that are not parallel cause an arc bind.
4. Measure the gap between the gate frame and the strike post at the top and bottom. A widening gap top to bottom is a sag, not a bind.

Isolation tree

• Bypass test free, normal hung binds: the bind is at the hinges or post geometry. Go to the hinge system branch.
• Bypass test binds, normal hung binds: the gate frame is racked or undersized. Go to the frame branch.
• Bind only in one swing direction: hinge post tilted. Go to the post plumb branch.
• Bind only at the very end of the swing: latch and strike geometry. Go to the geometry branch.
• Bind only seasonal: wood swelling. Go to the seasonal branch.

Hinge system branch:

• Hinge pins galled, bent, or out of axis: replace with matched hinges. Lubricate sparingly; a sticky hinge will read as a bind.
• Hinges installed at different vertical spacing on the post versus the gate (top hinge inward, bottom hinge outward): pull and reseat hinges in axis.
• Hinge post and strike post not parallel within roughly 1/4 inch at the top: re-set one of the two posts.

Frame branch:

• Measure both diagonals. Mismatched diagonals on the gate frame say racked.
• Wood frame: rebuild corners with bolted or mortise-and-tenon joints; tension the diagonal brace from top hinge to bottom latch.
• Steel frame: weld a diagonal if missing; this is a structural defect of original construction.
• Vinyl frame: a deformed vinyl frame does not unrack reliably. Replace.

Post plumb branch:

• The hinge post leans toward the inswing side: outswing binds because the gate top arcs into the strike.
• Re-set the hinge post to plumb. A small lean at the top compounds at the latch end.

Geometry branch:

• Bind only at the strike says strike position is wrong. Move the strike or shim the latch, not the hinges.
• Confirm the strike post is plumb and the strike hardware is on the latch axis.

Seasonal branch:

• Wood gate frame swells in wet weather. A clean 1/4 inch reveal between gate and strike at install can disappear after a rain.
• Trim the latch edge of the gate to restore the reveal, or upsize the reveal at install for wet climates.

Confirming diagnosis

• Hinge pin pull is the cleanest single test in the diagnostic kit. Bind state reverses with the hinge in or out: hinge system.
• Plumb check the hinge post with a 4 to 6 foot level. A 1/4 inch lean over 6 feet of post moves the latch end of a 4 foot gate noticeably.
• Sight the post pair from above. Two posts that are not parallel cannot host a clean swing.
• Seasonal check: revisit in dry weather with a measurement. A bind that disappears in dry weather confirms swell.

Remediation

• Hinge system: replace hinges, re-axis if needed, post-pair re-parallel.
• Frame: rebuild or replace; the gate frame is a structural member and patches do not hold.
• Post plumb: re-set the hinge post.
• Geometry: adjust at the strike, not at the hinges.
• Seasonal: trim the latch edge to restore reveal.

Bypass test gotchas

The bypass test is powerful but easy to misread. Three gotchas come up regularly. First, supporting the gate yourself during the bypass changes its loaded geometry; have a helper hold it at the same height it sits when hung, not at a comfortable height. Second, a hinge pin that is bent in service may pull out cleanly but mask the bend until you reinstall it; inspect every pulled pin before reuse. Third, an outswing gate that binds only when wind pushes it shut is a wind-load test, not a static-bind test; the bypass test cannot replicate the wind, and you will need to add a stiffener or a closer rather than rebuild the frame.

Documenting the diagnosis

Record the bypass-test result in writing on the work order. The customer will not see the difference between "binds at the strike" and "binds at the hinge" without the test, and a paper trail of which state you tested protects you on a callback. Photograph the gap measurements, the diagonals, and the post-pair geometry; these are the artifacts that turn a felt complaint into a numerical finding.

References

• ASTM F537, Standard Practice for Design and Installation of Fences Constructed of Wood and Related Materials (gate frame and post setting).
• ASTM F900, Standard Specification for Industrial and Commercial Steel Swing Gates (gate hinge and frame requirements).
• ASTM F1043, Standard Specification for Strength and Protective Coatings on Steel Industrial Fence Framework (steel gate post and hardware).
• ASTM F567, Standard Practice for Installation of Chain-Link Fence (chain-link gate installation and post requirements).