Symmetric vs Asymmetric: A Davenport RV Shop’s First Year on a 2 Post Car Lift

Choosing a 2 post car lift for an RV and trailer service shop is a different problem than choosing one for a general repair bay, and a shop east of Davenport learned that the hard way before they ever poured a footing. They came to us in the spring wanting a single bay upgraded so their techs could stop crawling under tow vehicles on jack stands. Most of their work is tires, brakes, bearings, and wheel service on trucks and toy haulers — long wheelbases, heavy noses, and a customer parking lot that never empties. We spent two phone calls talking about arm geometry before we ever quoted a column. Here is what that first year actually looked like, from the concrete inspection through the first hundred wheel jobs.

Why the Davenport Shop Almost Bought the Wrong Lift

Their first instinct was to order the cheapest 10,000 lb unit they could find online and have it dropped on a pallet. That is a normal instinct and we do not blame anybody for it. The problem was the work mix. When the majority of what rolls into a bay is a three-quarter-ton pickup with a fifth wheel hitch in the bed, or a dually towing a horse trailer, the weight distribution is nose-heavy and the wheelbase is long. A symmetric setup puts the vehicle centered between the columns with equal-length arms, which is fine for a balanced sedan but pushes a long truck’s doors right into the posts.

We asked them to send photos of the bay and a list of the ten vehicles they saw most often. Eight of the ten were pickups. That single list changed the whole recommendation. An asymmetric configuration rotates the columns roughly thirty degrees and uses short front arms with long rear arms, which shifts the vehicle back so the doors clear the posts. For a shop where a tech opens and closes a truck door forty times a day, that clearance is not a luxury — it is the difference between a productive bay and a bay full of dinged door edges and irritated customers. We ended up spec’ing a Rotary asymmetric column set rated at 10,000 lb, which handled everything they described with margin left over.

Symmetric vs Asymmetric on a 2 Post Car Lift, Explained Plainly

The terms get thrown around loosely by online sellers, so here is the honest version. A symmetric 2 post car lift has columns facing each other straight across the bay, with all four arms the same length. The vehicle sits with its center of gravity dead between the posts, roughly fifty-fifty front to rear. That geometry is extremely stable and it is what you want for heavy, evenly loaded vehicles, box trucks, and older body-on-frame stuff where you are lifting on frame rails.

An asymmetric layout turns the columns inward and pairs short front arms with long rear arms. The vehicle sits about thirty percent forward, seventy percent behind the column line. You lose a little bit of the pure balance advantage and you gain enormous door clearance. Most modern general-service shops run asymmetric for exactly that reason. There is also a third option people forget: versymmetric designs from Rotary that let you swing the arms into either configuration depending on what is on the pads that hour. For a mixed shop that sees a Miata in the morning and a dually in the afternoon, that flexibility earns its keep. The wrong choice is not usually catastrophic — it is just a small annoyance repeated five thousand times a year until somebody finally calls us about swapping arms. We would rather have that conversation before the anchors go in the floor.

Concrete, Ceiling, and the Site Survey Nobody Wants to Do

Before we quoted the Davenport job we asked the two questions we always ask: how thick is your concrete, and how high is your ceiling. They thought the slab was six inches. We cored it and found four and a half in the area they wanted the lift, with an old expansion joint running right where the driver-side column wanted to sit. That is not unusual in a building that has been added onto three times since the seventies.

The fix was a pair of poured pads — roughly four foot by four foot, twelve inches deep, tied into the existing slab with rebar dowels and given a full cure before anchoring. It added about ten days to the timeline and a modest line item to the invoice, and it is the single most important thing they spent money on. We have been called out to enough failed anchor jobs across Iowa and Illinois to know how that story ends when somebody skips it. Ceiling height mattered too. Their overhead was a little under twelve feet with a light fixture and a heater in the way, which ruled out a standard overhead-beam configuration and pointed us at a baseplate model with the hydraulic and equalization lines running through a floor channel. Baseplate units get a bad reputation because of the crossover plate on the floor, but in a low-ceiling bay they are the right answer, and a well-installed floor channel disappears within a week of use.

Install Day: What Actually Happens

Install on a straightforward two-column job is a one-day event for our crew when the site is ready. We show up early, verify the layout chalk lines against the manufacturer’s spacing spec, and set the columns before anything gets torqued. Anchor bolts get drilled to depth, cleaned out properly — and yes, cleaning the hole matters more than most people think, because dust in the bore cuts holding value dramatically — then set and torqued to the manufacturer’s number with a calibrated wrench, not by feel.

From there it is the carriage assembly, cables or chains depending on the model, hydraulic lines, the power unit, and electrical. We ran their power unit on 220V single phase off a dedicated circuit their electrician pulled the week before. Then comes the part that separates a real install from a drop-and-run: cycling the lift unloaded a dozen times, equalizing the carriages, checking that every safety lock engages audibly at every height on both sides, and then running a loaded test with an actual vehicle. We had the shop owner and both techs stand there while we did it, because the person who operates the equipment every day needs to hear what a properly engaging lock sounds like. That way, eight months later when one side sounds different, they call us instead of ignoring it.

Tire Rotation and Wheel Work: Where the Arms Earn Their Money

Six weeks in, the Davenport shop called with a good problem. Their tire volume had jumped because techs could get a truck up, all four wheels off, and rotated in a fraction of the time the floor jack routine took. On a 2 post car lift the wheels hang free, which is exactly what you want for rotation, balance checks, bearing inspection, and brake work — the whole reason a two-column design beats a drive-on for this kind of service.

The asymmetric arms turned out to be the right call for another reason we had not emphasized enough: on long-wheelbase trucks, the drop-end front arms reach the factory pinch weld or frame pickup point without the tech having to lie on the floor guessing. Rotary’s telescoping arm design with screw-up pads lets you dial in height at each corner, which matters on vehicles with running boards or rocker cladding. They did add a set of tall adapter stacks after the first month, because RV tow vehicles and lifted trucks sit high enough that the standard pads leave you short. Those adapters run a modest amount and are the single most common accessory we ship after install. If you are ordering a lift and your work mix includes anything with a lift kit, buy the adapters up front. You will use them the first week. We keep them in stock and can ship them the same day, along with pads, arm restraint gears, and the small parts that wear on any two-column setup.

The First Service Call and What It Taught Them

Around month nine they called because one carriage was drifting slightly out of level with the other over a full raise. This is the most common non-emergency call we get on any two-column unit, and it is almost never a failing lift. It is equalization cable stretch. Cables and chains break in over the first several hundred cycles, and the fix is a straightforward adjustment at the sheave ends to bring both carriages back into sync.

We did that adjustment, greased the columns, inspected every anchor for torque, checked the hydraulic fluid level and looked for weeping at the fittings, and pulled the arm restraint gears to confirm the teeth were clean and engaging. Total shop downtime was under two hours. What that visit taught the owner was that a maintenance rhythm beats an emergency. We set them up on an annual inspection, which is also what ANSI/ALI guidance recommends for commercial lifts, and gave them a short daily checklist for the techs: look at the cables, listen to the locks, check for fluid on the floor, and never bypass a safety. If you want more on that, our writeups on car lift maintenance and two-post lift cable replacement cover the same ground in more detail. The shops that stay ahead of small adjustments almost never see a big repair bill.

What We Would Tell the Next Davenport Shop

A year in, that shop is running the same equipment with no complaints and is talking to us about a second bay. If we compressed everything we learned on that job into advice for the next RV and trailer shop shopping a 2 post car lift, it would be four things. First, pick your arm configuration based on the ten vehicles you see most, not the one exotic thing you might see once a year. Second, core the concrete before you buy anything. A slab that fails spec does not mean you cannot have a lift — it means you need pads, and pads are cheap compared to a column that walks.

Third, buy capacity you will not use. A 10,000 lb rating is plenty for most tow vehicles, but if your shop is edging toward one-ton duallies and service bodies, step up to 12,000 or 15,000 and stop thinking about it. The cost delta between capacity tiers is far smaller than most buyers expect, and nobody has ever regretted having margin. Fourth, buy from somebody who will pick up the phone in month nine. Plenty of outfits will drop a crate in your parking lot and disappear. We install across Iowa and into the Quad Cities, we stock parts for Rotary, Challenger, BendPak, and Atlas, and if something on your 2 post car lift is not behaving right, we would rather diagnose it over the phone than have you guess. Call 800-674-9302 and describe what it is doing. Usually we can narrow it down in five minutes.