This can't be safe right?
 

First off, I want to say I do not recommend anyone support a vehicle this way, much less get under a vehicle supported in this fashion.

A few days ago, I needed to get all 4 stock wheels off, so I could get them powdercoated black with machine lips. I didn't have proper jack stands, so I screwed a few 2x6 boards together. Despite being an engineer and understanding the compressive strength of solid wood, I've been paranoid (hence the two scissor jacks in the rear). The car seems very sturdy so far and no signs of damage to the wood. I'm supposed to get my wheels back on Saturday and will post pictures.

https://cimg7.ibsrv.net/gimg/www.6sp...72e19a8ad1.png


https://cimg5.ibsrv.net/gimg/www.6sp...71d047cec3.jpg

Yes it can be safe but only when done right. Wood cribbing is used by fire departments and rescue teams all the time. They take 4x4's or 6x6's and cross them to build a tower to support heavy loads. Here's a link with FEMA's load guidelines for cribbing: http://www.boronextrication.com/2011...ibbing-basics/
Fire & Rescue:
https://cimg5.ibsrv.net/gimg/www.6sp...302ac2b304.jpg

Note a single layer 4x4 can hold 6000 lbs at one corner, or 24000 lbs total. Your car is in the low 3000 lbs mark as a reference, well below what a single corner of a proper cribbing structure can hold. Generally you are not to exceed a 1:1 width to height ratio to remain stable as you build your tower.

Wood cribbing is used to hold cars up too, in place of jack stands, but only when done right. There must be a stack of wood from top to the floor directly under the load, no open "bridges" at the point of contact. Hard wood is better than soft wood, paying attention to lengths to avoid end splits. I've built wood cribbing jack stands in the past to do clutch & transmission work, similar to the photo below, much cheaper than buying a lift for a single job. All pieces are secured together with deck screws and construction adhesive. Jacking the car takes stages as most jacks don't go high enough. Jack one corner/side, then the other, then rotate back and forth sometimes even cribbing the jack if needed. Keep the 1:1 width ratio in mind. Note the stack of wood in the center under the primary load location for good examples like the Nissan one. There are no bridges all the way down to the floor at this point. The Camero could be better.

Porsche 914 Crib Blocks Video:
https://cimg4.ibsrv.net/gimg/www.6sp...9938721626.jpg

https://cimg3.ibsrv.net/gimg/www.6sp...1408655493.jpg

https://cimg8.ibsrv.net/gimg/www.6sp...420f85a141.jpg

https://cimg9.ibsrv.net/gimg/www.6sp...89ae91814b.jpg

https://cimg1.ibsrv.net/gimg/www.6sp...09c7f71f62.jpg


Do a google image search of car wood cribbing. As always proceed at your own risk:
http://www.myturbodiesel.com/wiki/wo...o-jack-stands/
http://www.nastyz28.com/forum/showthread.php?t=242069


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Thanks for the awesome reply Semicycler! I didn't know cribbing was such a thing. These examples put my simple stacked 2x6's with a small 2x4 section on top to shame! Mine seems to be holding up okay though. With the car level, the wooden stands are only in compression. Just a few more days until I can put my baby back on the ground with her new kicks!