I’m looking for some guidance on the strength of “standard” pine cribs for working under a vehicle. I’ll be under an SUV tha weighs approximately 3 tons. I was planning to use yellow pine 2x4s in the stacked configuration I see in all the guides topped with a solid board, with bumpers for the tires, the size of the whole crib for the wheels to sit on. I’ll probably have to lift in sections so was thinking of screwing a 2x4 to the outside of the crib once at full height. Would that construction be strong enough? Is there anything I should do to make it stronger or more stable?
Crib Strength
- Thread starter Phrank308
- Start date
mike93lx
ALLIANCE MEMBER
Why? There are so many properly engineered solutions available for this.
jack stand
Well-known member
How high do you plan to go?
iagsxr
Well-known member
^^^ That's my question as well. How high and what do you plan on doing while it's on them?
I personally wouldn't have any trouble working under something on cribbing as long as it's on a solid, fairly level surface.
If I was going to go way high or maybe getting aggressive working on the vehicle like pulling an engine or trans I'd think about sheathing two sides of each crib with plywood. Like outside and front of the front two and outside and rear of the back two. My feeling is you couldn't push the vehicle over if you tried once that was done.
Here comes the safety police, but railroad bridges used to be built out of wood. I think what you're proposing can be done.
Higgins
Well-known member
Across the yrs I’ve collected a number of 4x4 and 6x6s that I just stack under the vehicle and let the vehicle down.
With that said, I did have a 4post lift which normally did away with using cribbing, however there were occasions when I would use 6x6s on the jack bridge for some additional height!!!
Not planning to go too high, 12-18 inches, or doing anything crazy, oil changes and ATF filter.
There are two reasons I’m thinking about using cribs.
First they seem more stable for getting the suv in the air. I’m lifting a Range Rover and the wheels have a lot of articulation so if I get them off the ground at one end the car is at quite an Angel which seems unsafe when lifting the other end. I figure if I use cribs I can lift the front in one go then come around to the rear and lift it in one go as well. But I haven’t seen them used on SUVs in the DIY guides so just wasn’t certain about the weight limits if building out of yellow pine.
Second I have a low sports car I need to get under for oil changes. I’m not worried about weight as it’s light. However, it does not have multiple jacking points to allow me to put it on stands easily. I figure lifting it at the Jack points then cribs under the wheels is like race ramps but cheaper.
There are two reasons I’m thinking about using cribs.
First they seem more stable for getting the suv in the air. I’m lifting a Range Rover and the wheels have a lot of articulation so if I get them off the ground at one end the car is at quite an Angel which seems unsafe when lifting the other end. I figure if I use cribs I can lift the front in one go then come around to the rear and lift it in one go as well. But I haven’t seen them used on SUVs in the DIY guides so just wasn’t certain about the weight limits if building out of yellow pine.
Second I have a low sports car I need to get under for oil changes. I’m not worried about weight as it’s light. However, it does not have multiple jacking points to allow me to put it on stands easily. I figure lifting it at the Jack points then cribs under the wheels is like race ramps but cheaper.
strutaeng
Well-known member
I've seen what I think you are calling cribbing and I've been kinda wondering the same.
I was doing a rear main seal on my 06 Suburban 2500 recently. Using 6 ton jackstands. I was think the cribbing may be a bit more stable and maybe can be made a little higher? The question is how high? At some point you are limited on high you can lift the vehicle to set it on the cribbing, right?
It probably depends on more on stability rather than material strength. A 2x6 lumber, say 12" long loaded in compression on the flat edge has an allowable bearing stress of about 300-400 psi, depending on species. So that's 20,000 to 26,000 lbs.
I was doing a rear main seal on my 06 Suburban 2500 recently. Using 6 ton jackstands. I was think the cribbing may be a bit more stable and maybe can be made a little higher? The question is how high? At some point you are limited on high you can lift the vehicle to set it on the cribbing, right?
It probably depends on more on stability rather than material strength. A 2x6 lumber, say 12" long loaded in compression on the flat edge has an allowable bearing stress of about 300-400 psi, depending on species. So that's 20,000 to 26,000 lbs.
That’s a good point on stability. I also worry about the drop in suspension when lifting for an SUV which may explain why I only ever see sports cars being held up this way. I may need to just put my Jack under there and lift it all the way up to see how far the wheels get off the ground. It may be a moot point for everything but oil changes.
iagsxr
Well-known member
I was thinking in terms of stackable sections rather than one piece to get to the final height.
Jack your SUV up. Say you can get a 6" tall section under the tires. (Just making up a number.) Make a 6" tall platform for your jack to sit on and you should be able to lift the vehicle 12" total with two 6" tall sections under each wheel.
Jack your SUV up. Say you can get a 6" tall section under the tires. (Just making up a number.) Make a 6" tall platform for your jack to sit on and you should be able to lift the vehicle 12" total with two 6" tall sections under each wheel.
I put my corvette on ~14" of cribbing, I used 2x3s.
Put it up in virtually 1 lift, drove up on 3" ramps (so I could get a jack under it, dang vettes are low), lifted the front onto the cribbing, then lifted the back onto the cribbing.
It was more unnerving getting it up there but the truth is, it was very stable going up, sitting there, and coming down.
Put it up in virtually 1 lift, drove up on 3" ramps (so I could get a jack under it, dang vettes are low), lifted the front onto the cribbing, then lifted the back onto the cribbing.
It was more unnerving getting it up there but the truth is, it was very stable going up, sitting there, and coming down.
Wood is fine for cribbing, i semi regularly put 9600 tons on lumber. Yes that is the right number. Yellow pine would not be my preference but should be fine for a car.
Make sure you have a wide base and each level is stable on its own. If you can give it a good shake unloaded and nothing falls over you should be fine loaded. Apply load slowly and watch the members of the cribbing stack. If any start to fracture, stop and reevaluate.
Make sure you have a wide base and each level is stable on its own. If you can give it a good shake unloaded and nothing falls over you should be fine loaded. Apply load slowly and watch the members of the cribbing stack. If any start to fracture, stop and reevaluate.
strutaeng
Well-known member
19 million pounds?! Yikes! Curious...What are you lifting that weighs so much? What wood species are you using?
nadogail
Well-known member
I would not make planed or painted lumber my first choice, better would be rough sawn.
iagsxr
Well-known member
Sitting on oak.
That's just awesome.
Garage Junkie
Well-known member
Here is a table that might help with crib capacity-
Renegade1LI
Well-known member
Why not use ramps or jack stands, would be faster for an oil change. Or jack it up and use some 2' pieces of 6 x 6 under the wheels.