Farmwithjunk
Super Member
GeneD14 said:A few years ago I had my 3,800 lb Allis D14 sitting up on 4 Sears jack stands rated at 4,000 lbs each. I thought the safety factor was more than enough...wrong.
As I was working on the tractor with the 4 wheels off: one of the rear tires which weigh about 200lbs gently tipped over and hit the side of the tractor. That small side impact was enough to make all 4 jack stands crumple and the entire tractor slammed down on the floor! It scared the @*%&%$#) out of me!
Now even when I'm under a 3,000 lb car I use a set of heavy duty jack stands (rated for 5 tons) or I use solid blocking.
I saw a demostration (done at a local Police Dept) once where a former auto thief took 4 of the old (10 oz. I THINK) Coke bottles and placed them under the suspension of a car. He then removed all the lug nuts. Next, he let the air out of the tires. The cars weight was supported by the Coke bottles. That allowed him to remove all 4 wheels and tires. Then he gave a shove to a rear quarter panel. That shifted the cars weight ever so slightly, crushing all 4 Coke bottle. Down went the car. He said he'd stolen HUNDREDS of tires and wheels that way.
The old car hit the ground with quite an impact. It doesn't take a lot to hold up dead stationary weight, but add a little movement and BANG.
I keep several 6"X6"X12" wood blocks in the shop. Jack stands may fail, but those blocks won't if they're placed correctly.