A third-generation family garage in West Des Moines called us with a very specific question about the 31000/2: symmetric or asymmetric arms for a shop that spends a lot of its week on engine oil pan gasket work. It’s a good question, and one we don’t think gets answered honestly enough online. The short version is that arm configuration changes how a technician gets under the pan, how the vehicle balances on the lift, and how much walk-around room you have once it’s in the air. This deep-dive breaks down the real dimensions and trade-offs so you can make the call for your own bay.
Compare symmetric and asymmetric two-post lift configurations built for engine and pan work, with install and parts support across Iowa.
What Symmetric Arms Actually Give You
On a symmetric setup, the arms swing out equally front and back from the columns, and the vehicle sits centered between the posts. The 31000/2 in a symmetric configuration is the more forgiving choice for a shop that services a wide mix of vehicles, because the center of gravity stays balanced no matter what pulls in. For oil pan gasket work specifically, this matters less about door access and more about stability once the vehicle is at full height, since a lot of pan jobs mean working directly underneath with both hands occupied and no free hand to catch a shifting vehicle.
The trade-off with symmetric arms on the 31000/2 is door clearance. Because the columns sit closer to the vehicle’s centerline, opening a driver’s door on a wider truck can mean the door meets the post before it’s fully open. For a shop doing high volume of quick in-and-out oil pan work where the driver rarely needs full door swing while the vehicle is up, that trade-off is minor. For a shop that also does long service visits where techs are getting in and out of the cab repeatedly, it adds friction.
What Asymmetric Arms Give You
Asymmetric arms on the 31000/2 shift the front arms further forward and the rear arms further back relative to a centered vehicle position, which pushes the columns effectively further from the door line. In practice this means more usable door swing and easier driver ingress and egress while the vehicle is elevated, which matters if your techs are hopping in to move the vehicle, check pedal feel, or grab tools from the cab mid-job.
For the West Des Moines shop, the appeal of asymmetric arms was less about door swing and more about where the arms land relative to the oil pan and crossmember. With the vehicle shifted slightly forward on the pads, there’s often more open space directly under the engine bay where the pan sits, since the front arms aren’t crowding that zone the way a centered symmetric setup can on some longer wheelbase trucks. That extra few inches of clearance is the difference between comfortably swinging a drain pan and wrench versus working around an arm.
Real Dimensions That Matter for Pan Work
Numbers help make this concrete. On a typical 31000/2-class two-post lift, you’re looking at roughly 40 to 47 inches of adjustable arm reach depending on symmetric or asymmetric geometry, and rise heights in the 60 to 72 inch range at full extension. For pan gasket work, the working height that puts the pan at chest-to-shoulder level for a technician of average height typically lands somewhere in the 55 to 65 inch range, well within either configuration’s usable travel.
Where the dimensions diverge is in the front-to-rear arm offset. Symmetric arms on the 31000/2 typically hold a near-equal offset of somewhere around 6 to 10 inches front and rear from the column centerline, while asymmetric geometry pushes that split to something closer to 4 inches rear and 12 to 14 inches front. For a longer engine bay or a truck with the pan set well back on the block, that extra forward reach on asymmetric arms can be the difference between the arm sitting clear of the pan versus needing to reposition the vehicle to get a straight shot with a socket wrench.
How the West Des Moines Shop Decided
This particular shop runs three generations of family history and a customer base that’s heavy on older trucks and SUVs that come in for oil pan gaskets, valve cover gaskets, and similar underside work. After walking through both configurations on the 31000/2, they landed on asymmetric arms, mainly because their fleet mix skews toward longer wheelbase trucks where the extra forward arm reach kept the arms out of the way of the pan and crossmember.
They also weighed shop habits built up over decades. Their techs are used to hopping in and out of cabs while vehicles are elevated to check things, and the improved door swing on asymmetric arms fit that habit better than a symmetric setup would have. We walked their bay dimensions against both arm geometries before ordering, since column spacing and drive-in width can make one configuration awkward even if it looks fine on paper.
Maintenance Differences Between the Two Configurations
Arm configuration on the 31000/2 doesn’t just affect day-to-day use, it also affects maintenance routines slightly. Asymmetric arms, because they carry more offset weight distribution, tend to see marginally more wear at the arm restrictor pins and the arm pivot bushings over years of heavy use, simply because the load isn’t distributed as evenly front to back. That’s not a dealbreaker, but it does mean a slightly tighter inspection interval on those components if you’re running high volume.
Symmetric arms wear more evenly across the pivot points, which for some shops means a marginally longer interval between component swaps. Either way, we recommend checking arm restrictor pins, pad adapters, and pivot bushings at every safety inspection regardless of configuration, since both setups on the 31000/2 will eventually need these wear parts replaced. Keeping a small stock of adapters and pins on hand, especially for a shop running daily volume, avoids downtime waiting on parts.
Which Configuration Should You Choose
If your shop’s day-to-day work is mixed general repair with a wide range of vehicle sizes and body styles, symmetric arms on the 31000/2 are usually the safer default, since the balanced geometry handles unpredictable vehicle mix without much compromise. If your shop, like the West Des Moines garage in this case study, leans heavily toward pan and underside work on longer vehicles with techs who need to get in and out of the cab often, asymmetric arms are worth the trade-off in door clearance.
There’s no universally correct answer, which is why we walk through actual bay dimensions, vehicle mix, and daily workflow with every shop before recommending a configuration. The 31000/2 performs well either way mechanically, so the decision really comes down to fit for your specific work, not lift capability.
Related Reading
For more on choosing lift configurations for your bay, see our guides on two-post lift buying considerations, installation checklist basics, and arm and pad maintenance tips.
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