Scissor Lift Install - over-engineering?

[widebody911]

So here's how I'm installing my lift:

Yesterday I built a 4x8 frame out of 2x6+3/4". The frame will be set into the slab as a sort of reverse form. After the slab has set up, I'll remove the 3/4" piece, then set a piece of 23/32 plywood into the hole, onto the 2x6, with appropriate supports across the middle.

Today I dug a 5 1/2' X 9 1/2' X 12" pit for the area below and around the lift.

The lift itself is only 36x80, so this gives me a few inches of extra room in the pit around the lift, which will make putting on the little pads easier. The pit is several inches wider than the 4x8 frame, to prevent creating a score line at the corners of the pit.

Next I have to dig a channel for 2" conduit to the wall, to run the hydraulic line and control cable through.

Does this seem over-engineered? Underengineered? Am I missing anything obvious?

[RoninLB]

Hi Thom...
I would make the lift floor perfectly level.. and I'd figure in a perfectly level area where the tires would sit when driven in for future wheel alignment and rake adjustment.. and I'd rebar the lift floor, and at least 6in. of concrete.. an accelerator will speed up curing from 28 days to one week.. maybe $50 for entire floor.. just tell the delivery guy in advance so he has it on the truck.. and measure the tire/wheel spread.. 48in. seems to wide a hole width ........Ron

[ChrisBennet]

What about drainage? You don't want your lift sitting in water.
-Chris

[Rot 911]

If it was me I'd use concrete. Supports much better than dirt. I agree with Ron, 48" seems awful wide.

[RoninLB]

Originally posted by Kurt V

I agree with Ron, 48" seems awful wide.

Thanks Kurt...

my lift is 37in. wide, including the arm pin which sticks out a little.. so the hole is 39in. wide, which allows a pry bar for lift adjustment.. then a 1in. wide grove to allow 3/4in. plywood to sit flush with floor for a total of 41in. to the floor... and my itty bitty 205X55X16, on all 4s, barely span the width.. I even have a tennis ball hanging from the ceiling to allign with the windshield mirror to center the 911.

and because the lift legs concentrate the weight on a small concrete area I have mucho bird cage deep concrete under the lift floor.. then a sheet of 1/8in., [I think], steel to help prevent stress cracking.. which may show up much much later.. thus, because I live on a sandbar, a big wave will wash away every house, but the 911 will be submerged sitting on the extended lift.

[RoninLB]

Originally posted by ChrisBennet

What about drainage? You don't want your lift sitting in water.
-Chris

I didn't think in rained in Calif.

but I have a massive drain on each end of the lift pad.. hurricanes are a PIA.. a drain into my sandbar world is another story.. but they sit under diamond plate to allow proper crawling underneath. the plate sits into the same grove as the plywood.

[RoninLB]

[BGCarrera32]

So Ron, how many times have ya changed oil right into that drain?

[RoninLB]

Originally posted by BGCarrera32

So Ron, how many times have ya changed oil right into that drain?

LOL... 12qts. of oil would clog it up.. toulene flows better..

in the 60s the street sewer drains were acceptable behavoir for an oil change.. I should have taken a pic of my '69 Vette sitting on the sidewalk & street for the 2,000mi oil change... now HAZ Matt gets called in for a car for that drops over 5 gal. of gas on the street.. and a home boiler guy got fined big bucks for dumping a few gallons into the street drain.. there were all kinds of agencys comming around all day inspecting the drain, and even set up an oil trap where the sewer drains into the bay/channel............Ron

[widebody911]

Sorry, I'm a little late getting back.

I went and narrowed the width to 41" and the length to 91"

Do you still think 41" is too wide?

My lift is 36" wide. I'll have 2x6 on either side, (my builder talked me out of doing the little lip thing) so that would be 39" with the lift squeezed in. I figured I'd want some space for 'adjustments' so I went to 41".

I think the tightest I'd want to go would be 39 1/2"

What do you guys think? Trim another inch or 2 out of the width?

[Wayne 962]

Hey Thom, not to throw a monkey wrench, but you may want to rethink the scissors lift idea. I thought about one of those (still thinking about it) and decided it would be too difficult to work in the center of the car with one of those. They are excellent for brake and suspension work, but just try to get into the center with one of those...

-Wayne

[widebody911]

I spent quite a bit of time mulling over my options. A two-poster would have actually been cheaper. (BTW, I know of a used one for sale in the Sacramento area)

I thought about the types of stuff that I do with my cars. On the 911, most of what I do is brake and suspension stuff. The engine stuff on the 911 is basic tune up/oil change stuff. Several people on this board have scissor lifts and have done 911 engine drops with them. An engine 'drop' in the bus is more of a 'slide the engine out the back' - you don't need to raise the car at all.

I only have 25x25 to work with. A two-poster would mean that one of the posts was pretty close to the middle of the garage, which would limit what I could do with that area. If I'd been allowed to build the garage one bay wider, I would have gone with a two-poster, and had a dedicated lift bay.

When I'm not using the lift, it will be covered, and I can park on it, push cars across it, etc. In the small space I have, I couldn't do that with a 2-post.

On the VW's, most of what I do is bodywork and metal repair. I rarely need to get under the center of those. The lift will make doing things like rockers and corners nicer, and it will be a dream to pull the front beam or steering box with the bus on a lift.

There's absolutely nothing under the center of the 911 that many of us care about.

Originally posted by Wayne at Pelican Parts
...but you may want to rethink the scissors lift idea.

[RoninLB]

"Do you still think 41" is too wide?"
--- try the 41".. you can always do a little cement work later if needed.. but the large cement blocks I use for getting under all the car just fit.. you don't need much more width that the lift width.. just enough to get a pry bar in there.. maybe 1" on either side.

" (my builder talked me out of doing the little lip thing)"
--- why did he do that?

[widebody911]

Ok, I squeezed it down to 40" wide

Ron - I don't remember how he talked me out of the lip. It sounded right at the time.

Looks like we're going to do the footers on Thursday.

[RoninLB]

maybe Thom.. if you don't recall why no lip.. then maybe it wasn't a logical answer??

like for a top covering you could use some Alum. diamond plate when necessary.. a few marine hatch handles and you would have a class act, IMO

anyway. your looking good.. your building a very respectful world for your mean machine to hang out ...........Ron

[RoninLB]

how about some more rebars crossing/lengthwise thru the lift floor.. I think any stress between the present bars/ by the lift legs is doable.. running lengthwise will keep the slab tight, IMO

[widebody911]

Originally posted by RoninLB
how about some more rebars crossing/lengthwise thru the lift floor.. I think any stress between the present bars/ by the lift legs is doable.. running lengthwise will keep the slab tight, IMO

The rebar shown was just to hold up the box for the picture. The real setup will be across the bottom of the pit and around the edge of it. I just wanted to suspend it somehow to show where the pit really will be in relation to the hole.

[widebody911]

Here's the rebar grid for the bottom of the lift pit:

[RoninLB]

Originally posted by widebody911

Here's the rebar grid for the bottom of the lift pit:

COOL

[catuck]

Keep that rebar 3" above the bot. of concrete and 3" in from the sides. You should be fine structually, we use a footing like that for a 40' tall masonry chimney! If you use an accelerator in the concrete, you should know that it will weaken the concrete. You should be fine, but the longer the conc. takes to cure the stronger it will be.