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Rob 930 Rob 930 is offline
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Join Date: Dec 2002
Location: Seattle
Posts: 659
I'm considering a lift too, but I'm likely to get a 2 post lift. A 4 post lift is more of a storage lift, while a 2 post is more of a service lift. But a 2 post works fine for storage too, while a 4 post has big limitations for service work.

The advantage of a 4 post lift is that it is easier to drive the car on and off -- and perhaps better for doing a wheel alignment. But it requires more length, because of the structure at each end and the ramps (which are heavy but removable), though it requires less width than a 2 post lift. And with a 4 post lift, it may be easier to open the car doors while on the lift.

But for service work, the 2 post is much better. The wheels are lifted from the floor, so you can easily do wheel/suspension/brake work. The entire underside is clear of obstruction for simple tasks like changing fluid, or more involved projects like removing the engine or transmission. If there is exhaust or driveline work (especially for front-engined cars), the whole space is clear. And the issue of opening doors while on the lift can usually be solved by getting an "asymmetrical" lift that has the posts located forward somewhat, such that the rear lifting arms are longer than the front ones, and the car doors are able to swing open farther.

With a 4 post lift, it can be difficult to even change the oil, especially in a 911 variant, because of the wheel trays and cross members, but most people find a way to do it. Additional jacks can be used to lift the car on the lift somewhat, but I'd prefer to lift it from the floor if I'm going to use a jack. But if your primary goal is storage, then the 4 post may be for you. The two post takes a little more setup to lift the car -- the arms have to be placed under the lift points each time you put the car on the lift, which requires kneeling down and aligning them. But once you do that, it's every bit as stable, and every bit as good for storage, plus you have the added benefit of being able to do real service procedures.

A 2 post lift must be anchored to the floor. Recommendations vary, but most that I've seen require 4 in. of reinforced concrete capable of withstanding 3000 psi. The four post lifts I've looked at may have similar bearing requirements, but to my knowledge, they don't need to be anchored (or at least some of them don't). Some have wheels that can be extended so you can move them around should you need to.

Both types of lift require the same ceiling height, though there are some 2 post "clear floor" lifts that require much more height -- about 12 feet. This is because two post lifts require some means of side-to-side equalization, either mechanical or hydraulic. Those that have a mechanical equalization cable can be purchased with the equalizing cable going along the floor (which creates a small obstruction on the floor that may interfere with rolling a jack or oil receptacle) or across the top, which is 12 feet in the air. If you've got the ceiling clearance, you should probably have the latter. If you don't, then you can get one with floor equalization routing, because the posts are much shorter. There's one more option for low ceilings: Mohawk, PKS, and AMPRO make lifts with a hydraulic equalization. That means that there's a hydraulic line that goes from tower to tower, but it doesn't need to be at a prescribed height. You can route this small line across your existing ceiling, plus it gives you the flexibility to move the posts to a narrower (or wider) stance because you're not constrained by the the mechanical link. The AMPRO lift has columns that are just under 100 in. --so technically you could use one if you have 8.3 foot ceilings. But of course, you wouldn't be able to lift the car full height, and I doubt you'd be able to park a car underneath it unless it's very low. With the "low" 2 post lifts, the minimum ceiling height is dicatated by the height of the car you're lifting (and how much clearance you want underneath it), and perhaps by the height of the car below it if you want to use it as a storage lift.

Last edited by Rob 930; 01-16-2008 at 09:01 AM..
Old 01-16-2008, 08:58 AM
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