Jackstand Safety ?

[GeorgiaSnake]

While most of you are working on getting to the fling I'm working on my car. I was thinking about cranking it for the first time while it's on the jackstands which would give me better access to check for leaks. A buddy said not to do it because the car would likely jump off of the stands from the torque. Any advice from the more experienced would be appreciated.

Randy

[BB427]

Before a race we usually put a jack under the rear end and lift the tires 2-3" off the ground. We warm the engine,trans,and rearend to operating temp. The driver stays in the car with his foot hovering over the brake pedal. This is as far as I feel comfortable with.

I hate that what if feeling. Ya know

[A Snake]

Follow your buddy's advice. Don't take the chance. Jack stands are dangerous enough when the car is not running.

That said, if you have a pair of ramps, get two more. Get one end of the car up on ramps then raise the other end and put ramps under it. Still not the best, but much safer than jack stands.

The simplest and safest, is to get out your trusty flashlight for seeing into dark places under the car. If you have any appreciable leakage, you'll see it on the floor pretty quickly. Oil filter and cooling lines (if any) are the most likely leakers. There shouldn't be any water leaks, if you put the hoses on properly and didn't ding the radiator or forget a thermostat gasket. The only thing left is the fuel line and that you can see from top side.

If you have or are going to prime the oil system with a drill motor, there is opportunity to spot big leaks while doing it. Other oil leaks probably won't show up until internal oil pressure is at operating levels.

Al

[aumoore]

I started my Cobra while on jackstands a couple of times but it kind of felt funny so I did not rev it over about 2000 rpm. Jackstands are pretty good for weight placed directly down on them but they do not like sideways forces applied to them like engine torque and vibration.

[CRZN427]

I have started my car several times on jack stands.

I have done that to check for leaks when I reworked the oil lines to the remote filter and several occations to check the filter after an oil change.

When I rebuilt my headers I ran the car to check for exhaust leaks in the pipes, collectors and mufflers.

Whenever I put my car on the jack stands I stand off to the side and "try to rock it off the jacks" just to make sure they are firm.

I also have a 2" thick wood base under my jack stands and I try to use a wood block under the frame. If I can't put wood under the frame I make sure the steel head of the jack stand can't move anywhere on the frame member. When I put them under the a-frames I have the shock bolt in the saddle of the jack stand to prevent any metal to metal slippage.

Engine torque will not cause the car to fall off properly installed jack stands, neither will high rpm. After all, the jack stands are the safety divice we use to keep from crawling under a car that is just on a jack.

For a jack stand to tip over, unless it fails structurally, the car has to go up a slight amount. Gravity does a pretty good job of limiting that action. Think of a right triangle, one leg is the distance form the outside of the base, of the jack stand, to the center, the vertical leg is from the center, at the bottom, to the point of contact on the car and the hypotenuse is the distance from the point of contact on the car to the outside edge of the base. The difference in length of the vertical leg and the hypotenuse is the amount the car has to go up for the jack to fall over.

I bought a set of ramps, my son and his friend went to use them, they collapsed when the friend drove up the ramp too fast and slamed on the brakes to keep from going over the end.

After that I welded some angle iron braces to prevent any such action in the future.

The problem I have with ramps is that they are hard to keep in place while getting the car up on them, especially on a smooth surface like a garage floor, that is why my son's friend was going a little too fast, trying to get the car on the ramps in one operation.

If you can put a brace from the ramp to something solid then it can't slip, or put some concrete anchors in the floor to secure it in place.

Another alternative is to have some kind of mesh, cable, chain etc. attached to the foot of the ramp and drive on it while getting on the ramp. That means that the extension has to be under both wheels on one side (on both sides) to keep the ramp planted while going up the slope. I have had the ramps slip even when the drive wheels are trying to go up the slope.

The other thing I don't like about ramps is that they don't quite get the car high enough to work comfortably under it.

As ususal, one persons opoinion. Don't try this at home without adequate supervision and don't "pop the first Bud" until the car is securely up on the stands.

[Jack21]

First of all, you're using decent, well constructed jackstands.

Engine torque with the engine running has no effect on the car on jackstands unless someone is revving the engine. Even then, the jackstands will hold the car in place. If it were me, I would lift the rear wheels off the floor to insure that no forward or rearward motion could be imparted to the car with me under it.

The worst hazard to you under the car while the engine is running is if you have the flywheel or flexplate exposed. The flywheel teeth will do a nasty job on hands, forearms, and forehead.

[GeorgiaSnake]

Thanks for the response guys.

I have very good jackstands and I have tried to push the car off of them, fortunatly without success. I never feel completly safe under a car even after checking for stability. I have the jackstands under the shock mounts as directed by Alan Weaver and the car seems very stable. The wheels are off and it seems like I could fire it up without an incident. however I my just put the wheels on it and take it off the stands. That way I can drive it out of the garage if all is well.

Randy