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1983 380SL, ivory/dk brown, 46k miles, dual roller timing chain. 1986 560SL, red/white, 190K mile.
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Discussion Starter · #1 ·
I've thought about a Lift, but how do you prevent this ...

Tire Wheel Automotive parking light Land vehicle Car
 

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1991 300SE W126 Collector owned, maintained 90k mi
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Simple poor anchors or depth of concrete. Mohawks are the finest lifts out there and are generally used in municipal and gov't facilities. There are also the most expensive and ALI rated at 150%. They also have the largest base of 20 x 30" and 100% US made in NY. No rubber hoses or cables and 3/4" steel throughout. How do I know? I own one!
 

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Don’t bolt it in to concrete less than 5” thick, no visible cracks or control joints within 5 feet of the pads, and when lifting the vehicle be certain to understand the center of the weight, which is usually about 60 40 on a front engine car. They also have 2 post lifts that attach both posts above the car tying the posts together.
The lift pictured, isn’t tied together above, and either too short of an anchor was used, or the concrete was too thin.
 

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1998 MB E300TD, 1997 MB E36 AMG, 2001 MB E55 AMG. 2011 BMW 335d
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As to the one in the picture, short anchor and poor quality concrete will do that. Mostly anchors.

When I had to replace the lift in my old shop, the guy installing it used 18" anchors. He had a hammer drill that could drill through concrete and he used every inch of it. By the time he was done there was only 1" sticking out after the lift was installed and bolted down and counter nut installed.
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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I've thought about a Lift, but how do you prevent this ...

View attachment 2774423
Mowhawk is about the best lift you can get. Looks like poor concrete. This is one of the things that I always feared with a 2 post lift but its also the first time I have seen a picture of it actually happen. I will probably be getting a 2 post lift for my new house and will probably do something like placing a 16" channel under the concrete with welded nuts on the underside.

I notice Bendpak specifies a minimum 4.25" thick 3000PSI concrete floor for there 2 post lifts. That seems pretty sketchy, but that is what they design to. Problem is getting concrete to actually be 4.25" and 3000PSI when poured at your house without taking core samples and having them analyzed at a laboratory and having contract clauses that hold the contractor accountable, good luck with that. It is also unlikely that you have 4.25" 3000PSI concrete in a standard residential garage unless you are around to specify it before construction. If starting from scratch best to specify a minimum of 5" 3500PSI rebar reinforced.

The Bendpack 4 post lifts only require 3.5" 2500PSI concrete, which is more like standard residential construction. The 4 post is pretty much the safest bet for standard residential construction
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Don’t bolt it in to concrete less than 5” thick, no visible cracks or control joints within 5 feet of the pads, and when lifting the vehicle be certain to understand the center of the weight, which is usually about 60 40 on a front engine car. They also have 2 post lifts that attach both posts above the car tying the posts together.
The lift pictured, isn’t tied together above, and either too short of an anchor was used, or the concrete was too thin.
One of the things I like about most clear floor 2 post cable operated lifts is the sturdy beam across the top. Mohawk does not have that but belive me thay are not lacking in there designs.
 

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1983 380SL, ivory/dk brown, 46k miles, dual roller timing chain. 1986 560SL, red/white, 190K mile.
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9,088 Posts
Discussion Starter · #13 ·
My residential garage was built 28 years ago.
It was damaged during construction and the contractor came back and poured another 1 to 2" of concrete on top of it because the finish was fubared.
This is my worry about a 2 poster lift.
 

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1991 300SE W126 Collector owned, maintained 90k mi
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Pour a minimum of 8" to be sure and it has to cure for a minimum of 30 days. No need to put a channel with welded nuts. Look up "wedge anchors" for 3/4" diameter and you will be impressed by the holding power of just one bolt itself. The Mohawk System 1 has 12 of them on their 20 x 30" base with only a single overhead stainless steel hydraulic line to feed the opposite hydraulic cylinder which by the way is 4" in diameter. The warranty to the first owner is 25 years. Yes, 25 yrs. Try to find one used. I put my Suburban and Rolls-Royces on the lift (5,800 lbs) and there is absolutely no movement in the posts. No need for an overhead stabilizer bar if the lift is well designed. BTW, the posts have "fork lift" steel channels that the 3" steel rollers travel within and never need lubrication. Each post weighs close to 1000 lbs.If in doubt about your depth, drill a test hole and measure.the depth
 

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Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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I notice Bendpak specifies a minimum 4.25" thick 3000PSI concrete floor for there 2 post lifts. That seems pretty sketchy, but that is what they design to. Problem is getting concrete to actually be 4.25" and 3000PSI when poured at your house without taking core samples and having them analyzed at a laboratory and having contract clauses that hold the contractor accountable, good luck with that. It is also unlikely that you have 4.25" 3000PSI concrete in a standard residential garage unless you are around to specify it before construction. If starting from scratch best to specify a minimum of 5" 3500PSI rebar reinforced.
Ah yes...the beauty of knowing what you want ahead of time.

I knew I wanted a 2 poster before I built my house. I knew the 4.5" / 3000psi recommendation beforehand, as well.

What I have is 9" / 3000psi in the garage....no rebar but extra reinforcement screening.

I am not worried.
 

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Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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Now that everyone has expounded on proper installation of the lift, let's hear some creative suggestions as to getting the truck back on the ground without any further damage.
I think I would try to winch that post back slowly while lowering the truck (if the lift in fact still works.)
 

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1986 560SL with M120 V12 Engine, 1988 560SL Stock
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Pour a minimum of 8" to be sure and it has to cure for a minimum of 30 days. No need to put a channel with welded nuts. Look up "wedge anchors" for 3/4" diameter and you will be impressed by the holding power of just one bolt itself. The Mohawk System 1 has 12 of them on their 20 x 30" base with only a single overhead stainless steel hydraulic line to feed the opposite hydraulic cylinder which by the way is 4" in diameter. The warranty to the first owner is 25 years. Yes, 25 yrs. Try to find one used. I put my Suburban and Rolls-Royces on the lift (5,800 lbs) and there is absolutely no movement in the posts. No need for an overhead stabilizer bar if the lift is well designed. BTW, the posts have "fork lift" steel channels that the 3" steel rollers travel within and never need lubrication. Each post weighs close to 1000 lbs.If in doubt about your depth, drill a test hole and measure.the depth
My point is quality control of the concrete. The 4.25" and 3000PSI is probably fine if its done correctly. But dealing with concrete contractors can be very risky. So you need to do thinks that will insure marging for poor quality concreate that may not be obvious when first pored. Go thicker, go with rebar at least in the area where the lift will be and go with a higher PSI concrete. And if you can put a channel under it, its cheep insurance. Wedge anchors only work good in good concrete no mater how thick it is.
 
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