2007-03-25 11:01:03 · 6 answers · asked by carboy_carlover 1 in Science & Mathematics ➔ Engineering
Read the operator's manual supplied by the manufacturer!
2007-03-25 11:05:19 · answer #1 · answered by NJGuy 5 · 0⤊ 0⤋
There are two important things to consider.
1) What do you need access to?
2) How many points of contact are there?
If you only need to change a front tire then there will be 4 contact points to consider( front tire point, jack point, and the 2 rear tire points).
If you need to lift the two front tires then you will have only 3 points of contact with the ground.
In the case of one tire, the best spot for the jack is the point on the frame of the car closest to the tire you are changing.
In the case of lifting half of the car, the best spot is under the car on the motor support, the beam {desn't look like a beam though} that connects one side of the frame to the other, and is directly under the motor.
When doing this make sure to block off the rear wheels so it doesn't roll though.
This spot is ideal for this type of jacking because the bracket is designed to withstand the weight of the motor, which is a downward force, and you are applying an upward force and just like in math where:
(-4lbs+4lbs=0)
The resulting applied force at that point of contact is the same, although it is more like
(-800(engine)+1700+a) (force at the jack point)-900cos(theta)/2(weight of car/2 without engine)
the -900cos(theta)/2 represents the weight of the car the higher you jack up. Remember half the weight is supported at the rear wheels.
What this means in laymans terms is that if your jack point is on a bar that gets 100% of the engines weight, then as far as that bar is concerned it only experiences half the cars weight minus the engine when you are jacking it up.
2007-03-25 19:07:59 · answer #2 · answered by howard a 2 · 0⤊ 0⤋
Always the user's manual. In older times when cars had actual, visible, chassis it was possible to just look for something strong. Now, with the chassis gone and replaced by welded body construction, jacking in the wrong place can have serious consequences. The old VW bug had a socket on the side; my old TR3 had a plug in the floor and you jacked through the floor panels.
2007-03-25 18:07:30 · answer #3 · answered by ZORCH 6 · 0⤊ 0⤋
The manual is a good place to begin, however, I generally don't use it. I find a safe spot under the axle, front or rear. The axle is designed to take the weight of the vehicle, so this is a good lift point. If you misread the manual, you could damage the body, or frame by bending it. Use the axle, it's a lot safer.
2007-03-26 00:01:41 · answer #4 · answered by Anonymous · 0⤊ 0⤋
If there's no marks or manual, find the most accessable flat portion OF THE FRAME (make sure it's not part of the suspension, transfer case, or turning apparatus)
2007-03-25 18:05:56 · answer #5 · answered by Chad P 3 · 0⤊ 0⤋
the user manual.
or often, there is a dent with an arrow on the chassis.
2007-03-25 18:03:46 · answer #6 · answered by Anonymous · 1⤊ 0⤋