Lift installed!

Thanks! Appreciate the feedback!

 

This is a good point. The reason you drill the hole deeper when putting fasteners in concrete (be it a simple screw to hang a picture or an anchor to lift a #3k pound car) is so when you install the fastener the concrete debris that falls off the inside walls of the hole doesn't build up at the bottom and cause an early bottom out of the fastener. The extra 1/2" is essentially a relief area.

The instructions clearly say the slab needs to be min 4" & #3k psi. If your concrete was thicker than 4" you'd need that extra 1/2" for the relief. I'm not a structural engineer, but as long time home builder and remodeler I'm concerned about what was done here. I understand the thought process behind creating the thicker concrete and the idea of a reinforced "plug" with support under existing slab, but IMO the prudent thing would have been to just drill your existing concrete if it met Max Jax stated min of 4"

The instructions also say not to install over expansion joints, seams or cracks. I can't find it right now but I thought it also said mounting had to be a min of 12" away from any existing expansion seam, joint or crack. The base of the jacks will be surrounded by cracks created by the cuts for this hole. The plug and the existing slab will always be independent pieces. Whats been done here is the creation two independent (estimating) 36"x 36" mini slabs of concrete which IMO is not enough surface area to support a vehicle.

I don't mean to be a wet blanket on this project, and again I'm not a structural engineer, just a builder who has worked alot with concrete and wood for too long and I'm just compelled to mention my concern. I'm sure there are SE's on this site and if they or someone (even MaxJax) says this is ok then I'm totally fine with them saying my concerns are overactive or just plain wrong.

I've also seen on this site where people cut the slab in their garage, dig down a few inches, pour a mini slab and install a scissor lift so it's flush with the original slab. I cringe when I see them lifting a #3k 7'x14' car on surface which has less area than a piece of plywood.

I also have a maxjax which I bought just before we moved and our new house has infloor heat in the garage and I cant risk drilling into it and hitting a heating tube. I'll have to wait until I add on.

 

Tear down is really fast.

Putting it back up isnt bad maybe 45 min to get it set up bolted down and then to run it up and down and make sure its bleed well.

Even with the QDs it needs to be bled.

 

The MaxJax User Manual instructions I have dated 4/12/14 specifies drilling a 5 1/2" deep hole for the Power Drop Anchors. The anchors are hammered 5/8" below the surface of the concrete then drawn up to be locked in place. I'm getting ready to install mine.

 

I for one appreciate your voicing your concern. I think when thousands of pounds of pressure are involved (not to mention the value of the car - and your life), it's worth getting the expertise of an engineer. This installation may be perfectly fine, but I'd want a professional eval to give the A-Ok.

 

You raise a good point. There are a number of threads on the web about pouring concrete piers to support car lifts. Most seem to involve opening up a 2'x2' or 3'x3' hole in the existing floor, excavating at least 12" below it and 6" under the existing floor all the way around the hole. Most seem to use rebar to add more strength to the pier and extend it fill the hole.

What effectively is being done is putting a pier into a floating concrete floor. The weight of the lift is placed onto the pier not the floating floor. While it seems that spreading that weight over a "smaller" area is problematic.....it is not. Structurally a concrete pier is far superior to attaching a car lift to floating floor if there is any question about the holding ability of the anchors.

If you think about structural loading for a moment.....the weight of the lift is on the lift's pad (pushing down) and the torsional load is on the outside anchors (lifting up). Of the two loads, the holding strength of the outside anchors is the key to a safe installation.

 

Image Unavailable, Please Login I have had my lift for 15 years with zero problems. One of the best automotive type investments I’ve ever made.

 

Great lift (and cars)!

In your case, all your load is distributed vertically on four large plates. The MaxJax is a two post lift with articulating arms which places the loaded weight on the inside part of the lifting post. That's why the holding ability of the outside anchors is so important. Without them, the lift would collapse inward when loaded.

 

Right and these are the loads I'm concerned about the smaller cut in 3'x3' pad handling. I'm not concerned about the anchors pulling out, I'm concerned that the smaller pads don't have enough surface bearing on the soil to keep the jack towers from ending up looking like the leaning tower of Pisa.

 

Right. I see zero benefit to the concrete work. If you wanted to be safe, I would have broken out an entire pad and re poured it. I personally feel that 1 foot square is more dangerous.

I also have 4" in my garage. Remember, factor of saftey is built into the calculation. I don't plan to lift 7000 lbs with mine.


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You can do cores, or use a windsor pin or a manual hammer. They will all give you a reasonable idea.

 

Set a hockey puck on the lift pad you need to raise.

 

I designed my own cradles with hockey pucks - works great.

 

I own a shop and we could have made these but was too busy at the time.

Doing a single set would be expensive.

 

Pinch clamp. you will never worry about the car moving



xo
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I use hockey pucks with my MaxJax for the rear points for my 348. The pucks are smaller than the lift pads and fit the jacking points at the rear better. The pucks fit on solid metal and allow the under body panels to be removed easily.

 

beat me to it. Thats what the shop which recently PPI'd my ex 348 used. Took a couple tries to get comfortable (shop guy) with his set up, several shake tests near the ground but thats exactly what he did.

 

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I use these more expensive than hockey pucks but fit better
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