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Ask two installers how to set up a two-post hoist and you’ll often get two answers: one swears by perfectly plumb columns, the other chases dead-level contact pads. Knowing how to level a two-post hoist correctly comes down to understanding which of those actually keeps a vehicle safe in the air – and on most workshop floors, it isn’t the one people reach for first.
This guide walks through the principle, a real-world slope example, the safest installation method, how to check your work, and the engineering that explains why a little out-of-plumb is nothing to lose sleep over. The figures and procedures here are drawn from BendPak’s own technical guidance, rewritten for Australian workshops and converted to metric.
The single most important outcome of a two-post hoist install is that the four frame contact pads finish level with one another. Plumb columns are nice to have; level pads are non-negotiable.
If your slab happens to be genuinely flat, then plumbing the columns and levelling the pads amount to the same thing, and you should absolutely check both. But the moment the floor slopes – and most do – those two goals pull in opposite directions. Plumb your columns to a sloped floor and your pads end up at different heights. That’s the unsafe outcome, because a vehicle lifted on uneven pads loads one side before the other.
So the rule to carry into every install is simple: the columns must be parallel, and the pads must sit as close to level with each other as you can get them. Perfect plumb is secondary to both.
Here’s the catch – a floor can look dead flat and still throw your pads out. Consider a slab that drops 25 mm (1″) from one side to the other, with the high side under the right-hand column.
A typical two-post hoist measures roughly 3,680 mm (about 145″) across the outside of its base plates. Spread that 25 mm of fall across that width and you’re looking at under 3 mm of slope for every 300 mm travelled – a gradient almost nobody would clock by eye. Yet because a two-post hoist’s arms reach well out to the sides, even that gentle lateral fall translates into a meaningful height difference at the pads.
Worth noting: it’s side-to-side (lateral) slope that causes this, because that’s the direction the arms extend. A front-to-back fall in the floor is a separate consideration and isn’t what we’re correcting here.
Faced with that 25 mm of lateral fall, an installer has three broad options. Only one of them is sound.
Option 1 – Shim only to plumb the columns. Stand the hoist on the slope as-is and add shims purely to bring the columns vertical. The columns look textbook, but your pads are now 25 mm out, left to right. Depending on where the arms sit under the vehicle and the spread between pads, that 25 mm can translate into a dramatically tilted load and a genuinely dangerous lift. Avoid.
Option 2 – Lift the whole low column up to match. Set the high-side (right) column straight onto the slab, then pack the low-side (left) column up by the full 25 mm with steel shim plates and plumb both. On paper this works — columns plumb, pads level. In practice it carries real downsides: stacking that much shim means roughly 25% less embedment on the anchor bolts (unless you’ve bought longer ones), it can leave the pads sitting too high to slide under low vehicles, and any residual unevenness still risks one side’s pads contacting the chassis before the other. Usable in theory, but rarely the right call.
Option 3 (⭐recommended) – Shim until the pads are level, keeping the columns parallel. Don’t fixate on perfect plumb. Shim each column until the four contact pads are level with one another, and make sure the two columns stay parallel. This is the method that delivers a safe, even lift, and it’s the one to default to — within the limits below.
When this method isn’t appropriate: if the floor has considerable pitch, or the job would need more than about 12 mm (1/2″) of shims, stop. That’s a sign the slab itself needs attention – sort the floor or get engineering advice before proceeding. Check the concrete foundation requirements for BendPak hoists for the minimum slab specs before you pour or anchor.
Levelling the pads is only half the job; you also need to confirm the columns are running parallel. There’s a quick measurement that proves it:
If the columns are parallel, that pad-to-pad figure won’t change between the floor and full height. If the two measurements differ, the columns aren’t parallel — readjust and re-check until they match.
Say a hoist was set up with a spirit level, both columns confirmed dead plumb – and you later find the two left pads sitting 25 mm (1″) higher than the two right pads. You don’t need to start again. Correct it like this:
Splitting the correction across both columns – half down on the high side, half up on the low side – keeps the adjustment small and the structure balanced, rather than forcing it all into one column.
This is where installers tend to over-worry. The honest answer, backed by the engineering, is: not meaningfully. Walk through the worst case.
Take a two-post hoist rated to 5,400 kg (12,000 lb) and shim it 13 mm (1/2″) under just one edge of a single base plate. That one edge shim works out to roughly 50 mm (2″) of vertical change at the contact pads – which is exactly why, in normal installs, shims thicker than about 5 mm (3/16″) are almost never needed for pad-height adjustment.
That 13 mm shim tilts the base plate about 1.35°, so the column leans 1.35° off vertical. As the carriage climbs its full 1.78 m (70″) of travel, that lean swings the arms about 45 mm (1.78″) horizontally from where they started.
Now the load path. A loaded arm reaches about 1,146 mm (45.1″) from the column centreline to the centre of the pad. The 45 mm horizontal shift stretches that effective lever to 1,191 mm (46.9″) – an increase of 4%. So the moment fed into the column and down into the base plate also rises by 4%.
In anchor terms, that nudges the bolt tension from about 1,257 kg (2,772 lb) to 1,307 kg (2,882 lb). For context, a single 19 mm (3/4″) Wej-It anchor set 127 mm (5″) deep into 20 MPa (3,000 psi) concrete is rated to 5,440 kg (12,000 lb) or more in tension. With the columns and main structural components engineered to safety factors above 400%, a 4% increase in moment loading is, in practical terms, negligible.
The takeaway isn’t “plumb doesn’t matter” – it’s that chasing level pads is the right priority, and a small, deliberate amount of out-of-plumb introduced to achieve level pads won’t compromise a properly anchored hoist.
Getting the install right starts well before the shims come out – with the correct hoist for your vehicles, a compliant slab, and proper anchoring. As the exclusive Australian distributor for BendPak, Genesis Equipment supplies and supports every BendPak two-post hoist sold into Australia with local stock, Australian-standard compliance support and installation guidance, so your hoist is specified, anchored and levelled correctly the first time.
Browse the two-post hoist range, check the concrete foundation requirements for BendPak hoists before you pour or anchor, or contact the Genesis team for advice on the right hoist for your shop or home garage.
Genesis Equipment is your exclusive Australian source for BendPak hoists – supplied from local stock and backed by Australian support, warranty and installation guidance.
