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OT 2 post auto hoist.

Joined
Nov 19, 2007
Location
marysville ohio
I was in the right place at the right time and got a 1 year old 2 post lift for free. Not enough height in the shop, plenty of height in the machinery shed but it has a dirt floor. I could put a concrete floor in but I have access to 2 pieces of 1" thick 4' x 8' steel plate. Will it be safe to bolt the uprights to the plate?
 
Should be fine as long as the ground isn't quicksand or soft and movable.
I would want the two plates to be touching in the middle if you can. Just to have a nicer surface to stand on and not trip.
But I would keep the metal plates for something more useful and do concrete floor.
 
What are the plates attached to? Dirt?

Even an 8' x 8' area is not enough IMO. I mean...it would probably work but keep in mind you will have people under the vehicles, presumably. Put a 20' long truck on it, start yanking around with a pry bar...nope.
 
If you want to use the metal plates they will keep it from sinking into the ground. If you are really worried, to keep the thing from tipping over you can brace the uprights to the wall or roof framing.
 
I was in the right place at the right time and got a 1 year old 2 post lift for free. Not enough height in the shop, plenty of height in the machinery shed but it has a dirt floor. I could put a concrete floor in but I have access to 2 pieces of 1" thick 4' x 8' steel plate. Will it be safe to bolt the uprights to the plate?

I started using a mechanic "now and then" instead of always 100% DIY just a coupla years ago. Gittin' a tad stiff...

He had just moved HIS garage into larger space and held an "open house". Showed me how he had to move a 2-poster further from the wall to accommodate longer W/B vehicles.

He had cut a large rectangle, poured serious concrete, new location to have a proper anchor for the bolting-down.

You can surely do that concrete work with holes in the dirt - no need to slab the entire shop. Even so, there seems to be a great deal more to it than just plate on the surface, "unknown" - potentially nasty surprise - as to changes in condition, under them.

"Non-trivial exercise" just bedding-down those plates, yah?

I'd be more inclined to rent a nano-trackhoe, trench, bury a pair of beams, heavy rod provided to smaller plates up-top, fill with concrete in an "H" shape .... with "great legs".

:)
 
Faq from a lift manufacturer:

Richard Bienvenue says:
April 2, 2017 at 3:39 pm
I’m looking into installing a lift on asphalt surface. We are cutting out the asphalt and pouring 4’x4′ and 8″ deep 3,000 psi concrete pads for a 9,000 lb lift. Do you think this will be ok?
Reply
eagleequip says:
April 3, 2017 at 12:19 pm
As long as you have the lift installed into the concrete at 8″, 3000 PSI you should be OK. Are you putting a lift outdoors ?
Reply

From here: Preparing For Proper Lift Installation : Eagle Equipment

Is 1" steel "stronger" than 8" concrete?
 
Concrete footings are definitely the way to go but it MIGHT be somewhat safe using the plates if they are tied together with heavy angle or channel bolted in place at each end. As mentioned if there were to develop a problem with the dirt floor later it would then become unsafe.

The real issue is that the plates are only 8 foot long. That is only 4 feet fore and aft of the post center line. While they might be OK for a smallish automobile a longer vehicle such as a nose heavy pickup could easily tip the rig.
 
If you really want to avoid concrete, at least level and compact the dirt where you intend the lift to be and a little beyond, and use earth anchors at the perimeter of the plates to ensure they don't tip or move.

American Earth Anchors - Official Site 1-508-520-8511

Talk to these guys (or a similar provider) about the right anchors for your purpose. Simply setting the plates down without anchors or surface prep doesn't sound good to me.

Depending on the lift design, you may want to use an asymmetric location on the plates, the two post lift I have is that sort (to clear front doors).
 
My two post is a Mohawk, which, at the time anyway, was USA made and the finest lift you could buy. Not sure if they still are made in the USA as they were making noise at the time about offshore manufacture. It's a wicked-ass stout lift.

I think they recommended anchoring into 6" concrete. I had the concrete poured 14" deep. Then I used Hilti threaded rods that go 12" into that, glued in place with Hilti glue.

A lift is something I ain't gonna mess around with. My lift...if we have a tornado, I'm hiding under it.
 
"Will it be safe to bolt the uprights to the plate?"

Yup. Not a bit of a safety issue there. However using the what's now a jerry rigged contraption to raise a vehicle is a WHOLE nuther story............Bob
 
No...

Steel may bend or bow...it will allow movement.

Out 2 post is on a bottom frame made of 2 inch solid square steel forming large h, many bolts into floor.

You need foundation that will not allow movement.

A structure on top of the steel may work but that really requires a real engineer if you wish to live long.

Only i
1 inch thick with the bolts engagement sounds sketchy as steel plate may be sub grade 2 nut.

The moment working against the bolts is huge, 6k pounds 6 feet up again We bolt pattern 18 inches square...

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
I think they recommended anchoring into 6" concrete. I had the concrete poured 14" deep. Then I used Hilti threaded rods that go 12" into that, glued in place with Hilti glue.

Good on yah!

Reasonably righteous.

For future reference, another old hairy-ears trick is to supplement those glue-ins with another pair drilled into the 'crete at opposing angles. Even 20 degrees each off the vertical and they ain't coming out atall easy, enduring glue down-hole or not.

Better - cheaper as well, no adhesive needed - is to 'crete in studs already bolted through a bar or ptate yah bury in the 'crete. Simple "disposable" wood template insures the working ends will be where they match their holes in the lift's base.

Worth doin' this stuff right, Day Zero onward. Too damned inconvenient to fix it later, coupla tons of vehicle settin' atop yer carcass!
 
Is there an attic above your shop ceiling? If so, is the current ceiling height 9+ ft high?

I have a couple of 2 post lifts. For both of them I bumped the ceiling up locally (pocket for the vehicle greenhouse to fit into when fully lifted). Not ideal but the only way I was going to get an additional vehicle "parked" in each of the garages. For one of them, a Rotary asymmetrical with the cross beam on top, the ceiling pocket is framed at about 11-3 ft up and the cross beam runs thru the attic, clearing the ceiling joist by about 1 inch. I relocated the bump rod to the underside of the ceiling. I get full lift on all my vehicles without contacting the bump rod/switch - but I don't own a van.

Using a floor jack and a couple of jackstands, I found the fore/aft balance point on the 5 vehicles in our fleet. For every one of them, the CG is within a couple of inches of where the windshield and roof meet (2wd 6 cyl PU, 4wd 4 cyl SUV, 4 cyl midsize FWD sedan, early '60s compact RWD sedan and a nose heavy 6 cyl LBC).
 
Here we go again, machinists giving advice that should come from structural and geotechnical engineers or from the manufacturer of the lift. Stepping outside your area of expertise could have disastrous consequences.
 
Here we go again, machinists giving advice that should come from structural and geotechnical engineers or from the manufacturer of the lift. Stepping outside your area of expertise could have disastrous consequences.

Thankfully lift installers aren't engineers!

If it's a 9k 4" is fine. That's what most manufacturers spec. Just don't use wedge anchors. Use epoxy.

Lifts are usually about 9 feet between posts so using two 4x8 plates would be a little tricky. More work than it's worth. Sell the plates for $1000 and there's your concrete cash.

I've seen a lot of guys go nuts over the concrete under a 2 post. It's kind of ridiculous. Most auto shops are lucky to have 5" and they rack vehicles constantly.

Only failure I have seen was with wedge anchors in a busy shop in a sub 4" slab. Took 5 years and a drunk on the job mechanic racking a new F-150 wrong to bust it loose.
 








 
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