I have a two post car lift to install in my shop, obviously the posts need to be perfectly vertical. The problem is, the entire floor slopes toward the center floor drain.
The base of the posts are 24" square, the floor drops about .25" over that distance, where the lift will be mounted.
My three idea's for a fix so far are...
1. A tapered shim under the base.
I want the base to be fully supported, so the shim or shims would have to be quite large. I have not come up with a reasonable way to produce such a shim yet.
2. Build a form and pour some type of harding filler where the base sits.
I don't know what, if any material would strong enough to do the job at less than .25" thick.
3. Using a masonry wheel, grind the concrete level under the base.
This is the method I am leaning toward now, but I don't like the idea of making the floor thinner under the base.
Any and all thoughts or suggestions on how to accomplish this, are appreciated.
My neighbor had his garage floors poured the same as yours when they came to install the lifts they used plastic shims that were about 2" in diameter under the base plates at each bolt .The lightest of these lifts is 10000 lb capacity they have been there for 5 years of constant use with no problems .Bill
Install it with a space under the footplates, plumb the columns, trowel a grout the consistancy of mashed potatoes in the space. "Por-Rok" is a material I've seen used in this connection.
What do the instalation instructions tell you to use for bolts to to hold the floor plates?
What does it say about the concrete slab?
Perhaps hydraulic cement?
8,000 PSI compression strength.
Do me a favor. If you use shims, make sure you anchor them in some way, epoxy or cement. If you draw a sketch of the mast, shim, and floor you will see the shim as a slight triangle. Now, going back to your high school physics, vector the forces. If the shim is too steep, the lateral forces will overcome the friction holding the shim in place.
Can you say shrapnel?
I've installed the Rotary 12,000 # lift in my shop. Rotary supplied U shaped plastic shims to use under the 3/4" anchor studs torqued to 150 ft.lbs. I have not seen any problems even when loaded to capacity. Max
Along the lines of retaining shims, when you realize the final height, you can tack weld the compressed stack or simply measure and add the thicknesses and make a custom 1-piece shim with your shop equipment [img]smile.gif[/img]
If everything is square and plumb, what difference does 1/4" make in that distance. I have 6 lifts of 2 different brands in my shop and they have been trouble free for 25yrs. Each side is adjustable if needed. I bet where you pick up the vehicle is further off than that.
Another idea would be to use a cerro-bismuth based metal. Melting temp varies from 150 to to about 300f. I saw a big planer mill (60x15 feet) leveled with it.
Forest has the answer (of course). Almost nothing is mounted to a concrete slab without some form of leveling grout.
However, you raised another concern. If you are concerned about the slab being too thin after grinding off a 1/4 inch, then it is already too thin. I have never installed such a lift but I would guess that the proper installation calls for several inches of embedment of the anchor bolts and an even thicker, steel reinforced slab in the area of the anchor bolts.
I have installed heavy machinery and the way I would anchor and plumb the lift would be to epoxy all thread anchors into the floor, then use a leveling nut under the plate and one on top of the plate to anchor the plate with the post vertical. I would then grout the plate with a hydraulic cement which does not shrink. By putting leveling nuts under the plate, you are allowing enough room to get the hydraulic cement to fill the complete bottom side of the plate and provide full support.
I got a question
What if he was to use the method that modern traffic light collums use, i.e. the column's base itself doesn't rest on the ground but rather there are nuts threaded onto the bolts and these nuts sit between the column base and the ground.
He could allways then fill the inbetween space if needed.
If you see in this picture, you'll notice the gap I am referring to,(not a great picture but couldn't find any better).
If you use leveling bolts under the pads then you are going to loose that much clearance for the lift arms to swing under low cars.I can speak from expierience, these arms need to damm near touch the floor when swinging ! I installed mine with just small steel shims under the corners that needed them.
I like the idea of grinding the floor. Get a transit and start at the lowest point,grind everything off that is higher than that. Good luck....Randy
I would be more bothered about the vehicle rolling about before it is jacked than the posts being plumb. Obviously you want brakes off / out of gear before it is lifted. Not sure that 1.5inches in 10 ft would allow the vehicle to roll, may be worth experimenting before the lift is positioned?
Yes I agree with Steve post, he really expose his idea very well...
Originally Posted by Steve Riley
My floor is pitched towards the doors. My two post came with a bag of U shaped metal shims just for that possibility. I plumbed the posts using the shims and have not had any kind of problems. No need to over think this..............Bob
This is the best answer. I helped install a two post that is in a shop space I share and this is exactly what is done. I would ask the manufacturer for the correct shims and get it reasonably level and call it good.
Originally Posted by maxk
I have never seen the requirement to release brakes and have a car out of gear prior to lifting the vehicle unless the work had to do with the drivetrain and having to rotate things like drive shafts or half shafts. Same for my son that was a dealership mechanic. 99% of the time the cars were in park if it was an automatic.