When one arm of your two post lift creeps ahead of the other, or the carriages won’t lock at the same height, you’re dealing with an equalization problem, and two post equalization troubleshooting is exactly what gets a lift back to lifting straight and safe. We’re Auto Lift Services, based in Ames, Iowa, and we install and service two post lifts in shops all over the state. Equalization issues are one of the most common service calls we get, and while the symptom looks scary, the fix is usually straightforward once you know where to look. This guide walks through the causes in the order we check them ourselves.
Cables, sync cylinders, and lock components in stock for Rotary, Challenger, BendPak, and Atlas lifts, backed by our Iowa install team.
What “Equalization” Actually Means on a Two Post Lift
Two post lifts use a mechanical or hydraulic link between the two columns so both carriages rise and lock at the same height at the same time. On cable-equalized lifts, a steel cable runs from one carriage, over a sheave near the top of the opposite column, down through the base, and back to the other carriage. On hydraulically equalized lifts, a small sync cylinder or crossover line does the same job with fluid instead of cable. Either way, the goal is identical: keep the vehicle level as it rises so it doesn’t tilt.
Two post equalization troubleshooting starts with understanding which system your lift uses, because the failure points are completely different. Cable systems fail from stretch, fraying, or a cable jumping its sheave. Hydraulic sync systems fail from air in the line, a leaking sync cylinder, or a clogged orifice. Before you touch anything, pull your lift’s manual or the tag on the power unit to confirm which type you have. Guessing wrong wastes time and, on a cable lift, can mean adjusting the wrong side entirely. We keep both cable and sync cylinder assemblies on the shelf in Ames because this is such a routine repair.
The First Symptom: One Side Lifts Faster
The most common complaint we hear is that one arm rises noticeably ahead of the other, sometimes by several inches before the operator stops and lowers the lift back down. On cable lifts, this almost always points to cable stretch on the slower side, not the faster one — the side that seems fine has actually pulled ahead because the other cable has stretched and has extra slack. Check both cables for visible fraying, kinks, or rust while you’re under there, since a cable close to failure needs replacing regardless of adjustment.
On hydraulically synced lifts, uneven rise is more often air trapped in the sync line after a fluid change or a hose replacement. Bleeding the system per the manufacturer’s procedure usually resolves it. If bleeding doesn’t help, the sync cylinder itself may have a worn seal letting fluid bypass internally. This is a case where two post equalization troubleshooting really diverges by lift type, and it’s why we always ask customers what kind of lift they have before we start diagnosing over the phone.
Checking and Adjusting Cable Tension
Most cable-equalized two post lifts have an adjustment nut or turnbuckle at the base of the equalizer cable. With the lift empty and lowered to the ground, most manufacturers want a specific amount of cable deflection when you press on the midpoint with moderate hand pressure — check your manual for the exact spec since it varies by model. Adjust the slack side until both cables show equal tension and both carriages sit at the same height with no load.
Don’t try to fix a stretched cable by cranking the adjustment nut past its designed range. If you’re out of adjustment thread and the lift still won’t equalize, the cable has stretched beyond its service life and needs to be replaced, not tightened further. We see shops try to squeeze another year out of an overstretched cable, and it almost always ends with the cable snapping or jumping the sheave during a lift cycle. A full cable set is inexpensive compared to a dropped vehicle, and we stock replacement cables sized for the major commercial brands.
Safety Locks and False Equalization Readings
Sometimes what looks like an equalization problem is actually a safety lock issue. If one locking pawl engages a notch on the rail while the other doesn’t catch cleanly, the carriages can appear unequal even though the cable or hydraulic system is fine. Inspect the lock bar, the return spring, and the release cable on each column. A sticky or bent lock mechanism needs cleaning, lubrication, or replacement before you assume the equalization hardware itself is at fault.
We also see false readings caused by uneven concrete under the lift base plates. If one column has settled or was installed on a slightly low spot, the carriages can look unequal even when the mechanical system is perfectly synced. A basic level check across both columns rules this out fast. This step gets skipped constantly in two post equalization troubleshooting because it feels unrelated to the cable or hydraulic system, but foundation issues cause more callback visits than people expect.
Hydraulic Sync Cylinder Problems
On lifts that use a hydraulic sync cylinder instead of cables, the most common failure is an internal seal leak that lets fluid pass from one side of the piston to the other without doing its job. This shows up as gradual drift over several cycles rather than an immediate, obvious fault, which makes it sneaky. If your lift equalizes fine when new but drifts worse every week, suspect the sync cylinder seals before anything else.
A clogged orifice fitting in the sync line is the second most common cause, especially on lifts that haven’t had a fluid change in years. Debris in the hydraulic fluid restricts flow through the small orifice designed to meter fluid evenly between sides. Flushing the system and replacing the fluid, then rechecking equalization, resolves this more often than people expect. If you’re already deep into two post equalization troubleshooting on the hydraulic side, it’s worth reading our two post lift hydraulic troubleshooting guide, which covers power unit and line issues in more depth.
When It’s Not the Equalization System At All
We get calls where the customer is convinced they have an equalization problem, but the real issue is arm restraint, tire slip on the pads, or an overloaded lift trying to lift more weight than it’s rated for on one side, like a heavy diesel with uneven weight distribution. None of these are equalization failures, and adjusting cables or bleeding sync lines won’t fix them. Before you dig into the equalizer hardware, confirm the vehicle is centered, both arms are set to matching positions, and you’re within the lift’s rated capacity.
If the lift also shows other symptoms — slow rise, chattering, or one side that won’t move at all — the root cause may be broader than equalization. Our general two post lift troubleshooting guide and our two post lift won’t lift troubleshooting guide both cover adjacent failure modes that get mistaken for equalization trouble, and it’s worth ruling those out before you order parts. A quick diagnostic call to our team can often narrow it down before you order the wrong component.
When to Call In a Technician
Equalization problems involve the part of the lift responsible for keeping a vehicle level over your head, so we’re conservative about what we recommend as a DIY fix. Cable tension adjustment and basic inspection are reasonable for a shop’s own maintenance staff. Cable replacement, sync cylinder rebuilds, and anything involving disassembly of the locking mechanism are jobs we recommend scheduling with a certified lift technician, especially on lifts still under warranty.
We service and troubleshoot two post lifts across Iowa and keep equalization parts — cables, sync cylinders, lock hardware — in stock for every major brand we carry. If your own two post equalization troubleshooting has hit a wall, or you’d rather have someone else’s eyes on it before the lift goes back into daily use, give us a call. A lift that equalizes correctly every single cycle isn’t optional equipment; it’s the whole point of a two post design.
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