2 Post Lift Dilemma

[NoSloCoupes]

Start off by saying my shop was built on an existing slab that was poured many years ago in 3 sections....11' x 36' on either end and 12' x 36' down the middle. Where i want to put the lift, obviously, is on the 12' wide section.

So, i'm looking at the OH9000 with an overall width of 11' 3" which would leave roughly 4 1/2" - 5" from the edge of concrete to the single center anchor. The 2 other outside anchors would be roughly 5 1/2" - 6" from the edge. See this for the base plate anchor positions and scroll down a bit.... http://cdn.gregsmithequipment.com/documents/manuals/2postlifts/OH9000N.pdf

Now, would you guys see any issues with this install? What about not using the furthest outward anchor and drilling another centered between the gussets? Or 1 on the inside of each of the gussets?

http://gsmith.s3.amazonaws.com/photos/ATPK-OH9000-15.jpg

 

[NHBandit]

Re: 2 Post Lift Dilema

Gonna be tight. I hope you're not planning on doing any CV shafts or rear wheel drive axle bearings in there...

 

[NoSloCoupes]

Re: 2 Post Lift Dilema

Sorry, should have clarified... shop is open with no walls and 34' x 36'.

In this pic, you can see in the bottom left corner, where the 12' section begins and goes to other side of the car.

*edit, having problems with image showing normal size...all thats working is this smaller one.

 

[Bob C]

Re: 2 Post Lift Dilema

I believe it will fit.

 

[NoSloCoupes]

Re: 2 Post Lift Dilema

Thanks for the pm also Bob. What do you think about not using the outward anchor and drilling the base for another between the gusset? Or just not worry about it and install normal?

 

[coljar]

Re: 2 Post Lift Dilema

If I was doing it, I'd have to cut the concrete out to a size and depth recommended by the manufacturer. I think you are too close to a seam, but call them and see what they say. I've had to call Bend-pak a couple of times to get answers to questions when I was installing mine.

 

[pattenp]

Re: 2 Post Lift Dilema

My Challenger 9000# lift install instructions say not to drill mounting bolt holes any closer than 8 inches to the edge or joint in the concrete. Drilling new holes in the base plate to me doesn't seem to be a wise thing to do. You should call the manufacturer before you do any mods to the base plate bolt pattern.

 

[skyking]

Re: 2 Post Lift Dilema

Mount it in a normal fasion .....Hell you arent lifting a dump truck.If you position your vehicles properly there is no stress on the bolts anyway.

 

[cyamaha2007]

Re: 2 Post Lift Dilema

There are tables in place for this exact situation. The joint between concrete slabs is considered a un supported edge. If the anchors are installed too close together, it can cause an interaction of the forces, thus reducing the holding power of the anchors. As a rule of thumb, the concrete anchor industry has established a minimum standard of ten (10) anchor diameters for spacing between anchors and five (5) anchor diameters from an unsupported edge. You will be fine as long as you have 4in concrete @ 3000 psi. I believe your lift uses 3/4in anchors. So 3/4in anchor x factor of 5= 3.75 inches from un supported edge. You have a good amount of wiggle room. If your still worried about it. A friend adapted this to work on his lift even tho it was meant for another model we just had to drill/tap 2 holes in each column base of the lift prior to installation of the post http://www.gregsmithequipment.com/Atlas-Baseplate-Extension-Kit

 

[NoSloCoupes]

Re: 2 Post Lift Dilema

Thanks for posting that cyamaha. Leaves me to wonder why some want to stay min 8" from an edge, liability concerns? Would still have room with a 7/8" anchor, don't know if that would help or not tho? Def. won't be drilling new holes in the base plate. Cutting it out is an option i can do no problem.

 

[Bob C]

Re: 2 Post Lift Dilema

Nice info cyamaha2007. Judging from what you stated NoSloCoupes, I'd just install it normal. When you torque down the anchors, you will know IF the lags will pull or not. Most require 150 foot pounds per anchor. Worse case senario, you will need to cut and pour a slab under each post with any anchors that do not hold. I have drilled in an alternate location on the baseplate, but that too brings complications to how the lift reacts to stress. Have you punched a test hole? What was the consistency of the dust?

 

[pattenp]

Re: 2 Post Lift Dilema

Mount it in a normal fasion .....Hell you arent lifting a dump truck.If you position your vehicles properly there is no stress on the bolts anyway.

Well hell, if that's the case then just use some construction adhesive and glue it to the floor.

 

[NoSloCoupes]

Haven't drilled it yet, might run over there later or tomorrow. Also looking at the Danmar 10AC Symmetric with an outside base width of 10' 7/8" from asedeals.

 

[wssix99]

Re: 2 Post Lift Dilema

So, i'm looking at the OH9000 with an overall width of 11' 3" which would leave roughly 4 1/2" - 5" from the edge of concrete to the single center anchor. The 2 other outside anchors would be roughly 5 1/2" - 6" from the edge.

If the both base plates are entirely within the control joints and the manufacturer doesn't give you a spec to stay away from them, you should be fine. (The manufacturer should be able to confirm, though.)

What about not using the furthest outward anchor and drilling another centered between the gussets? Or 1 on the inside of each of the gussets?

This would definitely make the lift weak and would be dangerous. Those outboard anchors are key to the lift transferring bending loads to the slab as they tend to tip/bend inward and forward/rearward (depending on the balance of the vehicle) as cars are lifted.

Leaves me to wonder why some want to stay min 8" from an edge, liability concerns?

It all depends on how the manufacturer does their calculations and how their lift is engineered. They may need this additional space to counteract bending forces under the post legs. You should be able to call the manufacturer and confirm this spacing if they don't give it in the instructions. (Their bases could be engineered so it isn't an issue at all.)

Edges of slabs and areas adjacent to control joints can be weaker due to a curling phenomena. As the slab curs and shrinks, the control joins crack (as they are intended) and the slab edges and slabs along the joints will slightly curl up. (Just by a hair.) This is do to the top of the slab having more moisture on it as the aggregate presses down on the mass and squeezes a little bit of the excess water to the top. This causes additional shrinkage at the top of the slab, causing the curl. If the slab curls, there is a small void beneath, which can lead to more cracking under loads.

I wouldn't worry about this too much, though. The vertical loads a good lift put on a slab are no greater than what a regular vehicle puts on it sitting on its tires. Curling is more an issue for forklifts and heavy industrial equipment.

Cutting it out is an option i can do no problem.

This requires some additional homework as you could make the floor much weaker than it started. Typically, cut-out pads will need to be pinned or keyed to the larger slab.

 

[Bob C]

Re: 2 Post Lift Dilema

This requires some additional homework as you could make the floor much weaker than it started. Typically, cut-out pads will need to be pinned or keyed to the larger slab.

I guess this can be a case, however lifts usually require no more than 5000PSI concrete. When the pad is cut, it is easily keyed under the old edges of existing concrete. Every lift maker I've dealt with has this method as an acceptable solution. I suppose if the guy is an absolute idiot, he could mess it up and make it weaker.

 

[wssix99]

Re: 2 Post Lift Dilema

I guess this can be a case, however lifts usually require no more than 5000PSI concrete. When the pad is cut, it is easily keyed under the old edges of existing concrete. Every lift maker I've dealt with has this method as an acceptable solution. I suppose if the guy is an absolute idiot, he could mess it up and make it weaker.

There are lots of posts on this site where people marvel at their wonderful "footers" where they cut and don't key or pin. I wouldn't go as far to say they are idiots, but they are definitely unaware of the consequences...

 

[pmiranda]

Re: 2 Post Lift Dilema

Well hell, if that's the case then just use some construction adhesive and glue it to the floor.

I've always thought of "baseplate" 2-post lifts, where the only function of the overhead bar was to carry the hydraulic lines and a limit switch, but I guess the overhead bar is structural on these and holds the two posts apart in compression. Still, if the vehicle center of gravity is not exactly between the posts the bolts will be under load, so the strength of the concrete does matter.

 

[cyamaha2007]

Re: 2 Post Lift Dilema

There are lots of posts on this site where people marvel at their wonderful "footers" where they cut and don't key or pin. I wouldn't go as far to say they are idiots, but they are definitely unaware of the consequences...

I agree if the new footer is not pinned all your doing is a making a expensive counter weight.

 

[wssix99]

Re: 2 Post Lift Dilema

I agree if the new footer is not pinned all your doing is a making a expensive counter weight.

And punching a ticket to the Darwin Awards. lol

 

[NoSloCoupes]

Ok, i hate having CRS syndrome,lol...couldn't even remember dimensions of my shop!

Some new info i just flat out forgot. This property used to be for rail cars and the rails are still in place. We built 3 structures on existing slabs, this one being 100'+ long, we just walled off a section in one for my shop....thats where the 36' comes from. So, that 12' section has two rails going down the center, i don't know if it was poured in a full 12' width and the rails being on concrete, or if in 3 different pours?? Where the bases of the lift would be the concrete is only about 42" wide. Still have yet to drill it for thickness. But in saying it is 4"+, would this change your decision of just installing or cutting it out? Here is a better picture showing it, one rail goes under the car. The lighter area is the rail, one base would be in the 42" section drivers wheel is on.

 

[cyamaha2007]

UHH that changes things. Is the rail filled in and patched over with a skim coat of crete?

 

[NoSloCoupes]

There was an inch wide gap(2" down) on one side between rail and edge i filled and feathered a couple years ago to ease rolling of jacks,engine stands,etc. I'm guessing this slab is 6"-8"+ considering a rail is 5 1/2" tall. I'll get off my **** and drill it sometime.

If i have to cut it, no problem. 4' x 4' 10" deep and pinned.

 

[cyamaha2007]

Cut it. I was in the no cut club since i work with concrete every day and before the rail came in i was sure it was safe. If the slab has rebar in it only cut 1.5in deep then bust it up with a sledge or jack hammer. This will leave your rebar intact. now just dig a hole in the dirt and pour the concrete.

 

[wssix99]

Definitely need to cut, but can a concrete cutter go through solid rail? Maybe a diamond blade is required?

 

[NoSloCoupes]

Think they need cut? If they do, i'll just fire up the torch.

Just figured it would stay and the new pour would be fine pinned to the 3 sides? At least cutting it, i can go with my original plan of the OH9000W (extra wide).

 

[cyamaha2007]

I dont see why you need to remove the rail. Just bust the concrete out around it.

 

[wssix99]

Think they need cut? If they do, i'll just fire up the torch.

Just figured it would stay and the new pour would be fine pinned to the 3 sides? At least cutting it, i can go with my original plan of the OH9000W (extra wide).

It depends on the footprint of the new pinned slabs and where they fall in relation to the rails.

The pins on the inside, forward, and rear of the posts are the most critical. Without the pins, the new slabs won't be able to resist (as well) the tipping forces the 2 post lift will create.

BTW - If you can tear up those rails, you might be able to sell them and pay for the whole job!

 

[NoSloCoupes]

LOL, theres 350'+ of rail on this property.

 

[NoSloCoupes]

Bringing this back up. I finally made a purchase, used asymmetrical Rotary SPOA10.

Did a layout of where the base will be(and if needed, the 4'x4' cutout). With the lift at standard width of 11' 5 3/8, the closest hole is 5" from edge and post will be 18" from the rail.

Drilled 3 holes to check thickness. The ones above and below the drill in picture bottomed the bit at 9 1/2" and never hit dirt! The other hole thats kinda centered a couple inches below the rail hit something that wouldn't go any further...it stopped at 6".

Drilled another hole that was between the 2 rails(as seen in older pic below...the left wheel is between the rails) and hit dirt at 6".

With the concrete being so thick, i really don't want to cut it now,lol. Think it would be ok with standard width? I could also use the narrow option of the lift which will move posts 1 1/2" in(total of 3") if need be.

 

[NoSloCoupes]

Bumping for any installers advice.

 

[HoosierMark]

I bought one of the rotary lifts out of Detroit a few months ago. The guys who took them down told me when you install them, put one post up first then the top bar and then the other post. They said that many people put both posts up first and then the top post but their method was much easier. I am not mechanical enough to tell you anymore or the logic behind this method. I plan on having a professional install mine. Good luck.

 

[wssix99]

Bumping for any installers advice.

Doesn't Rotary give you a spec for this in the install instructions?