5.0MX5

Rather than clutter Chris B's (crispy) shop life thread https://www.v8miata.net/shop-tool-ta...934/#post13500 I thought I'd ask my questions here. But first to Chris, VERY NICE!

I'm on the verge of pulling the trigger on a Dannmar D12, 12,000 lb. four post lift. In my poor boy wisdom back in about 1988 I scrimped on the floor in my shop and now am not comfortable with the safety concerns related to a 2 post lift. Since we have a couple Dodge Cummins diesels that'll be lifted occasionally, I'm leaning toward a four post lift.

Only real issue I have (and someone please chip in) is how much am I giving up in convenience while working on suspension and brakes. I know you can use a bottle jack or lift jack while the lift is raised, however I've never worked off a 4 post before so am not really sure how well that'd all play out.

Thanks, RR

GoKart

Just curious, what were your safety concerns with the 2-posts? From my understanding, the only thing that would make them unsafe would be improper installation, not a thick enough floor or a severely unbalanced load. 2-posts are used in professional shops everywhere for full sized trucks.

The 4-posts are great for storage but makes getting at the suspension pieces tough. Although, the lift you're looking at has a handy bridge jack option that lets seems like it might make it a little easier to get to things.

5.0MX5

[QUOTE=GoKart;13514]Just curious, what were your safety concerns with the 2-posts? From my understanding, the only thing that would make them unsafe would be improper installation, not a thick enough floor or a severely unbalanced load. 2-posts are used in professional shops everywhere for full sized trucks.

GoKart, you nailed it with the "not thick enough floor" comment. I remember what a financial stretch is was to build our 30x40 shop almost 30 years ago and we saved money at every opportunity. The only rebar used in in the floor was on the 1'x1' perimeter footing and wire in the floor is whatever used wire we could scrap up, fence wire, chain link, hog wire, what ever. The design thickness was only 4".

Although it's held up well over the years, there are a very few minor cracks in the slick finish. All this makes me nervous when thinking about one of the trucks setting up their with that heavy Cummins, homemade Ranchhand style bumper with winch and four-wheel drive assembly hanging off the front.

Must be getting cautious in my "experienced" years.

GoKart

Nothing wrong with being cautious. I won't put anything over 3,000 lbs on my 6,000 lb lift, haha. I plan on cutting a big section out of my floor and re-pouring a thicker slab so I don't have to worry about it. 4-posts definitely have their advantages, too.

crispy

I remember reading somewhere about pouring footings for a lift also. The footings would have to be underpinned IIRC, with a web of rebar. If you go the route of pouring a new slab, be sure that you record the locations of the rebar. Those concrete bits don't like rebar. Just a thought.

5.0MX5

Quest over....pulled the trigger on a 9k Rotary lift at a State auction yesterday. Now to get it home, make a template of each post's base and locate exactly on the shop floor, then drill holes and see whats to see. That'll tell the story on the next step.

5.0MX5

Well, after moving the Duster and 51 Chevy out I discovered Unintended consequences were biting my backside again. I left many trees standing near the shop almost 30 years ago and they provide welcomed shade in the Hot Southern summer, however tree roots are the enemy of concrete shop floors.

After making templates of the lift post bases and locating on the floor I discovered a small crack within a very few inches of two bolt holes....not good. So, rent a water fed walkbehind concrete saw... cut out a 5'x15' concrete slab.... find tree roots... remove said roots... dig down 3 inches... dig under the existing slab to key the new concrete to the old... drill 1/2" holes 6" into the old concrete on 18" centers to pin the new to the old... install #4 rebar on 1' centers...pore 2 yards or 8" of 4,000 lb. concrete..... cover with plastic watering twice a day for 4 days.....now wait 30 days to install the lift. What fun.

charchri4

Wow didn't see that one coming. What a PITA! On the other hand my car is sitting on 4 jack stands and I have been crawling around on the floor doing bushings the last few nights sooo...



The end result will be worth it!

GoKart

Nice looking work! Did you hand mix all that or have it delivered? I'm looking to do the same thing to mine sometime soon.

5.0MX5

Thanks GoKart, I did run the numbers on Quickcrete and it was very near the same as having the minimum 4 yards delivered. So... the neighbor got a gift of 2 yards of 4,000 lb. mix and helped with my little pore. All the lift manufactures recommend not mixing your own. Obviously concerned someone wouldn't know what they're doing and a subsequent catastrophic event.

charchri4

The lift cycle is pretty slow but I had her up working on my four poster last night.

5.0MX5

You likely wouldn't believe how many times I've gone through that routine. Heck, I remember the day when a concrete floor was only a dream. A pneumatic roll around lift would be great in your shop....PTC Auto Accessories Co.,Ltd._ABF-5.

5.0MX5

After what seems like a lifetime (which it sorta was)....the Miata defies gravity!

Now to continue de-junking the shop so I can make max use of the small 30x40 area.