Alright, everyone... I need your collective wisdom, because I run short of experience and intelligence myself.


Background:
       I recently bought a bunch of different parts to switch out and do a lift on a Wrangler.  I also bought a good jack and
some stands and set up an agreement with a buddy to use his garage space to do the work. I would help him gut and redo
a spare room in his house and he would provide the work area and a set of extra hands when I needed them on the lift.  

       Well, fast-forward a few weeks, and he has no plans yet to start the room... this means, then, that the garage is quite
full of boxes waiting to be set up in their new home (the spare bedroom.)  I, unfortunately, live very much in town and as such
have only a bit of gravel for a "driveway".  

       So, I started looking for solutions to safely sit the Jeep on stands, on gravel.  I learned that, in amateur racing, the
teams paddock is occasionally just an assigned patch of grass, and in these cases, (and sometimes even with asphalt paddocks,
regulation seems to be the that the stands mustsit on a minimum 18" pad to prevent sinking/tilting/falling.  These cars are
much lighter, though, so their usual methods, I don't feel directly apply... so, here's my plans... tell me how idiotic they are.


The Plan:
       My plan was to take 24" square, 3/4" plywood from Lowe's, cut it down to the 18" square, and then use the leftovers to
make a sort of barrier square for the jack stands to sit inside of, to keep them from sliding without having to slide the whole
pad with them.  I wasn't sure if that much weight on the surprisingly thin legs would simply shear through.  A second plan
was to buy 2 pads per stand, glue and screw them together, giving 1-1/2" of pad.  I could also double the height of the wall
around the stand base this way, as well.

       The Jeep Wrangler JL Unlimited weighs around 4,500lbs, but I don't know the weight distribution.  It is safe to say,
though, that each jack stand should have less than 1,250lbs. at any given time.  Consider too that I will have a floor jack
providing support to the front/rear axle since I need to droop it to replace the springs. If I work the math for a worst case
scenario, though, measuring the skinny-ass feet I end up with only about 0.211in^2 footprint per foot x 4 = 0.844in^2,
which would make that 1,250 close to 1,500PSI!  If it settled in about 1/4", the footprint would increase to 3-3.5" and that
figure would drop to 350-425psi, less than pine or Douglass fir, which should be easy for it, I would think, but there's no
way for me to guarantee that is safely/smoothly sinks that 1/4".  


Perhaps I am overthinking this, or maybe I'm an absolute moron and I am completely off base here.  The days of, "Fuck it,
let's see what happens," ended when I became a dad, so now I am genuinely trying to do this right and stay alive.  

Do you think this idea is fine?  Do you have a better suggestion?  Or should I just be patient and wait for the garage space to
become available?

Thanks all!

With the car stands (about 8x8 base stance), I used to use squares of 2x12 pressure treated pine when I didn't have concrete.
Never a problem with car weight loads on them. The legs dug into the wood a sixteenth or an eights, and the stands weren't sliding anywhere.

If using the bigger truck stands, 2x12 might be too small.
I'd double the 3/4 or buy 1 1/4 ply, but that's just me.

The safest option would to be wait till the garage space is available of course. Just spit-balling here:

1. rent a storage place with a concrete floor for a month?
2. what is your grassy area like? Flat of course. How far down does the dirt under the grass go? If its not too far before you hit
clay. Like a foot or so of dirt like my yard has. Buy a bunch of these cheap pavers, dig out the dirt and stack up the pavers to put
your jack stands on. Now your safe and it'll only cost you 50 bucks probably and 4 small holes to fill in later.

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Well the guy I bought my trailer palace from worked for the RR and left a bunch of those steel plates laying around that the tracks normally would sit on.
So I put those under my 3ton Jack stands when I need to use them.
My driveway is scoria which is sort of a fired clay found on the coal burn line. Ceramic if you will.
So I am not a lot of help in your situation.
When I want to use a Jack, I take a piece of 3/4" plywood and lay it down for the jack.

It's not ideal but I did the whole front end and even swapped engines in my drive to work junker all by myself while my buddies stayed home.

Well, you did math, so you're already way ahead of me.

If it were me and knowing in advance that I'm math challenged, I would do this:

Half of 24 is 12, so I would go buy some 2X12s at the home center, cut them to 24" long, and glue/screw them in between two 24X24 plywood pieces.  Like an ice-cream sandwich (I'm not ice-cream sandwich challenged).  Once you build these you will have shoring blocks that you can use on the trail for jacking and any other uses around the house (like leveling a ladder).  Screw a loop of webbing into the side to make carry easier.

I always lower the jack to put the weight of the vehicle full on the jack stands, then pump the jack up until it's firmly touching but not supporting the vehicle.  Some people will not get under a vehicle without shoring in addition to the stands.  If I'm going under the truck, I use extra stands and/or shoring blocks (I've seen folks use firewood) - the thought here is backup to the stands just in case; if the vehicle falls off while you're pounding on something it will fall on the other stands, the shoring (or firewood) and not mash you flat.  You might need to replace a bent component underneath, but you'll be alive to do so.

Is this one of those "grammar" comma placement things?

Help my Uncle Jack off the horse...Or help my Uncle, Jack off the horse?

Thanks for the first-hand knowledge!  

I might have to call around to the local lumber yards and see if they don't have something thicker in stock... 3/4" was just that best that
Lowe's had to offer.  I will say too, my reasoning for the ply was that it couldn't split down the grain and fail spontaneously...
Do you think that that is an unfounded fear, or a legitimate concern?

I welded some 1/4" plate squares to the base of my jacckstands when I was running Wissota a dirt track track modified car 20 years ago. I ran the plate 1" over the base dimensions.

Always have TWO sources of support.

Won't get under a vehicle with only one source of support.

Having a bunch of new Fencepost trimmings we cut the 4"x4" scraps into 1' long 'sticks' that we can then quad out under the vehicle as a 2nd support system (cribbage) if the primary were to fail.

For the On Gravel aspect, the concrete pavers would work if you smooth out the surface under as flat as possible.  The concrete pavers don't have any steel inner reinforcements rebar, so they are susceptible to fracture if enough force is applied unevenly.

I did some work on my f150 the other day in my sorta muddy back yard.
I used 2 2x6x18 treated scraps laid side x side to set my jack stand on.
I doubt your stands will slide on wood.
I'd use 2x material instead of plywood.

My yard is terrible!  I feel like some areas have sank 8 inches since I bought the property 6 years ago.  

I feel that one day my house will be on the news as it has fallen 400 feet down an enormous sinkhole! I do like your idea, though.




You brought up another concern that I had.  Given that the ground isn't perfect, do you all think that I would be better served getting
the Jeep up on 4 stands and flat?  Or just one end lifted with the wide tire patch on the ground, but the Jeep obviously at a slight tilt?

Interesting... that makes me feel like I'm not too far off track here, then.  

Thanks!

Hmm... I think I see what you're saying.  

I had considered cribbing and just lifting the whole dang thing up on 4 boxes, but thought buying $250 worth of 2x4s and 4x4s may be
overkill, but this is an alternative.  

Thanks!

I started off my post by telling you I am not that smart!  Don't draw attention to my mistakes!

Oh!  

Just 1" over the base, and you obviously didn't die, so that makes me feel more confident in the pad size, even if the material is
drastically different.  

Welding isn't an option for me, at the moment, though a good welder is one of the items that the friend is wanting to buy for his
garage when it's cleaned out!

The correct answer is "cribbing".  Simple to make, and the "footprint" is actually larger than your tires.

Yes!  I had considered some fail-safe cribbing, or even cribbing itself as the main mode of support, but thought that 200k pounds worth of support
under a wrangler may make me seem like a crazy person!  I would still have the usual, throw the removed tires under it, backup, as well... that is
just something that I have always seen done, and just feels right now.

Well, your F150 is almost certainly heavier than the Wrangler, and perhaps considerably so, so I would feel pretty good using
a setup that worked effectively under that.  

Thanks!

I do feel like the smartest option would be to just splurge for the cribbing, and if the garage project doesn't happen fast enough,
and the itch to do the lift gets too severe, I just might talk myself into the expense, just to be confident in the support.

Nice space, btw!  Have you considered something like a 2-post lift?  A nice lift in a good garage is a goal of mine!  Someday...

Napa Jack Stands

Get a set of these, I use them (and the 20 ton versions) off road on fire trucks all the time. Worth the money.

I have a shell driveway. I just use pieces of 3/4" plywood underneath my jack and jack stands.

We use 6x6 cut into 2' lengths stacked as cribbing under the trucks at the gravel yard.

Plywood sheet cut into squares.

Pavers can fracture unexpectedly.

My suggestion as well. I would even recommend doubling the plywood, wood grain rotated 90°.

I wouldn't, but you do you.

Be sure to have a spotter with a cellphone in hand.

You can build thickness with additional layers of plywood but I wouldn't do that unless they are bonded together.  Do that and you can build additional bending stiffness and strength.

Plywood is a laminate with grain orientations rotated by 90 degrees between plies.   That is why it is dimensionally stable and flat (unless the plywood is very thin with a only a few plies).

This looks easier and better than my idea. (Didn't know what cribbing was) Since your yard is
soft you could use something heavy and flat to tamp down the area where the support is needed. Make sure its reasonably level etc.. I was originally
thinking the jack stands would cut into the boards but since the load is distributed that looks like a false concern.

My dad 'borrowed' one to put a trailer tongue jack on, I found out after it'd been outdoors for at least a year.
The next time I used that one it split in half as I was lowering the car down on it. I bought another 4' 2x12, made another set, and gave my dad the three old ones.

Yep, I've had this happen with a 12x12 paver with a bottle jack, which is admittedly more focused force than jack stands.

I use jackstands under my 1-ton trucks in my gravel driveway all the time.  I have a well established (re: hardpack) driveway with #68's for gravel (smaller, 1/2" - 3/4" size).  

I just slide them under the truck and do my thing.  No sinking, never a problem.


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Use 2x10 cribbing under the jack stands.