Simple Safety Question - Chocking Front Wheels While Jacking Rear End

I've never worked on cars much, except my MG, so I'm not sure about how to approach this.

The floor in my garage is concrete and has a slick finish. I have a good floor jack and jackstands, and I want to raise the rear end of my car so I can easily grease the u-joints and driveshaft. I'm going to put the jack under the differential to raise the car, and then put jackstands under the axel. I feel like I need to chock the front wheels while I'm under the car. However, I'm sure the chocks won't hold since the floor is so slick.

Suggestions?

Thank you.

Either the jack or the car should be able to roll unless the car is on a grade, then only the jack. If one of them can't move the jack will pull itself from under the jacking point.

chocks shouldn't be needed unless the floor is sloped. then put chocks in after the car's up. either in front of or behind front wheels, depending on which way the slope is.

Yep. I wouldn't worry with chocks if the car is on jack stands on level floor. But I'd still be careful not to push on the car.

there are also, what I would refer to as "parking guides" Basically they are a sheet of heavy weight rubber with a bump at one end. They are designed to drive on and let you know where to stop driving when the tire hits the bump, so you don't hit the garage wall or junk piled in front of the car. Once the car is parked on them, the weight of the tire will keep them from slipping out.

I did a google search on parking guide and this is an example of what I came up with:

http://www.amazon.com/Racor-Parking-Yellow-PPK-1L-PPK-1R/dp/B000077CPH

18 bucks and it would probably prevent rolling either way.

I do say, that I feel comfortable on a level garage floor with a floor jack and jackstands without chocking the wheels, but you should do what you are comfortable with.

If the jack is the common low profile roller type then you wouldn't have any problem lifting the car with the front tires chocked. If you're using a scissors or bottle jack then you don't want the front tires chocked, as the front of the car will have to roll back slightly as the rear is raised. If the front tires are chocked the rear of the car will tend to creep forward and possilby tip the jack. The same applies to jacking the car when one end is lifted and on jack stands, it can't move so the jack has to be mobile. You can make that lift with a bottle or scissors jack, but you have to do it in several small steps, placing jackstands under the rear and resetting the jack each time. As already stated, with a smooth level concrete floor I don't think you need to worry about the chocks until you get the car lifted. I've been quite surprised that simple wood blocks work very well as chocks even on smooth floors, but if you can find some rubber chocks they will be better. You can get an inexpensive rubber chock at Harbor Freight. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96479

I still chock the fronts. t work the floor is slick Like at my work I use ones with rubber feet. Thy can be found/made.

Call me what you will, but I use chocks whenever I raise my car to work under it. The old adage comes to play "Better safe than sorry". I've been doing that for many years with all my cars both MG's and Healeys. I also carry a set of wheel chocks when I travel. I made them out of a piece of 4" x 4" pressure treated lumber left over from a deck project I had been doing. I cut a piece of 4x4 about 5 inches long. Then on my band saw I cut it diagonally on the 4 inch dimension. Now I have two chocks to put under the wheels whenever needed and they take up virtually no space whatsoever. I got the idea when I saw a friend but a rock under one of his back wheel while parked on an incline. Granted the parking brake should work but. . . . .better safe than sorry.

FWIW only

George Herschell

While we're talking safety...I always put something else under the car even when its up on jack stands when I plan to get under the car. Real easy for a quick job is to slide the wheels you take off under it. Just so that if something unexpected happens you won't wind up with the full crushing weight of the car on top of you.

This winter, as the car has been up for welding in a new cross member and floors (lots of banging and moving around)I put wooden blocks under the front cross member and one under the diff. as well as jack stands at the usual places.

My list of "Stupid Car Things" that we all shared on the forum a little while back also includes cars rolling off a jack and a Bug Eye landing on my foot. (Just lucky for me that my Mother and Sister could lift the Sprite. Lucky for all of us that I wasn't into big American muscle cars...

I always chock my front wheels when jacking up the back end,even on my flat non slippery garage floor. 10 seconds of work is better than a bad accident. Joe

Safety first!!!! :)

You're NOT supposed to chock the wheels when jacking up one end of a car. The wheels need to roll with the movement of the car. I learned this the hard way. After I refreshed my engine, I was lowering the front. I had my jack under the front crossmember and the e-brake engaged. The jack while lowering hit a crack and stopped. Since the rear wheels were locked, it caused the car to slip of my jack and crush my oil pan and pump. That sucked big time. I learned the hard way.


EDIT: I just re-read your post. Definitely chock your car after you lift it, just not while your jacking it up.

Thanks for all the replies.

My jack rolls, but there ARE some cracks in the floor, so I won't chock it until its in the air. I can make a big enough mess of a job without dropping the car!

Looks like I need to get some of those rubber chocks from Harbor Freight.