QUESTION - I need to do some work under my car. I have never used jack stands. Can someone give me a primer about what to buy and how to use them?

ANSWER - I claim to be fairly good at it. As proof I offer the fact that my TR3 was on jack stands during the '89 Loma Prieta earthquake and it stayed up on the stands. I live about 1 mile for the surface of the epicenter.

Kinds of Jack stands:

There are two basic kinds of jack stands. One kind has a vertical rod with a flat 'Y' at the top that adjusts upward from a base. This is meant to support a frame rail or axle. There are two common construction types. One is stamped sheet metal with a hollow tubular raising centre tube. Centre tube adjustment is usually done by a removable pin through a set of holes. The other common construction is cast steel. The raising centre rod is solid cast steel with a row of teeth on one side. Adjustment is via these teeth and a catch.

Of the two types, the cast design is usually stronger and rated for higher loads. A general rule of thumb is to get the stand with the highest load rating and the widest base that will fit under your car.

The other kind of jack stand is basically a rectangular box, with or without a ramp, with or without a raising centre post. This type is designed to support a wheel when you are doing work that does not require wheel removal. This type is a LOT more stable than the narrower adjustable rod jack stand and should be the type of preference any time you need to work under a car and do not need to remove a wheel from that corner. Some companies are now making this kind of stand out of nonmetal materials. I have never used one that is not metal. Pay close attention to the load ratings and read the safety part of the user instructions before purchasing.

Jack stands will break/bend if you overload them. If you are getting the adjustable rod type get, the biggest one (widest base) that will fit under your car at your jacked up working height. The lower the adjustable rod is the more stable the jack stand is. An adjustable rod type at it's fullest extension can be fairly unstable.

Use the right tool for the right job. Do not use bricks, cinder blocks or any other similar materials in place of a jack stand. These materials are prone to breaking under load. Be wary of logs or any other handy material. The top surface of your jack stand was carefully designed to centre the weight and keep it from sliding off. Other "sturdy " objects may allow the weight to slide off.

Stacked boards, even under weight, tend to become unstacked when sideways pressure is applied.

Never go under a car with just a jack holding it up. Jacks were never meant to substitute for jack stands and are a lot less stable than jack stands. This includes the hydraulic floor jack. Don't fool around with your life. Use the right tool the right way. The best jack stands you can find.

I have both kinds of jack stands and use the wider, stronger, more stable box type any time I can. Get a set of the adjustable rod type and at least two of the box type that supports wheels. Two full sets would be best.

Placing a jack stand:

Your jack stand resting surface is critical. If any corner of one jack stand base should sink it can quickly destabilize all the other jack stands and bring the car crashing down.

Flat level cement is best. Asphalt looks stable but is not. A jack stand will sink into the asphalt, especially on a warm day.

If you are working on any surface other than flat cement you need to add a stable "floor" between the jack stand and the ground/asphalt/blocks/bricks/whatever. I suggest wood at least 1/2 inch thick that reaches at least six inches in any horz direction from the outside base edges of the jack stand.

If you are on a grade you will need to tie the uphill end of the car to a stationary tie point. I had my TR3 on a few degree slope. I sank a 17 inch iron water pipe with a 'T' at the top into the soil as a tie point. I used a come along to connect the car frame to the tie point then put a slight tension on the wire.

Special situations:

If you are in an earthquake area, orient the car lengthwise to the normal direction your nearest fault moves then tie it at each end to tie points. In my case the car was on a slight slope, pointed in the direction of movement. Gravity kept it from falling over uphill and the tie kept it from falling off downhill. I had box style stands under the rear wheels and the adjustable rod type on the front with the front wheels removed. The car was on dirt with plywood under each stand.

The fireplace in my house literally exploded, the kitchen sink fell through the counter. The refrigerator and stove walked out into the middle of the kitchen and were almost in contact. I had to replane the house doors to get them to close into their sills. We had a great deal of damage from a 7+ force earthquake almost directly under us.....but the TR3 remained up on the jack stands. If I were under it at the time of the quake, I would have very much appreciated it.

If you do not know the normal movement direction of you nearest active fault look in the phone book for an earth quake preparedness centre or a geologist. If you are in earthquake country it never hurts to know how the earth will move. Tall furniture is more stable if it is oriented lengthwise to the movement of the earth.

I know that an earthquake is very unlikely to happen when you are under your car, but it does happen. Just like people just happen to be on or under a bridge or raised roadway when it collapses. You can not predict it. You just need to decide if you want to be prepared for it or not.

If you live in an area with strong afternoon wind gusts, point the car nose or tail into the wind and anchor the upwind end.

Jacking the car up onto the stands:

Different cars have different constructions. Always check your car's user manual for jack point recommendations. Usually the frame is the best lift point. The differential of a solid axle car is normally another good lift point.

Jacking a car onto jack stands is done one end at a time and not one side at a time. This provides the least lateral force when jacking up the second half.

The adjustable rod type of jack stands should be set under a main frame section or a solid axle as close to the corner as possible. Stay away from sections that are not normally horizontal to the ground when the car is on it's wheels.

Any time you jack a corner you should block the opposite corner wheel. Same when you jack up one end of the car. Jack up one end, set the stands and any boards. Do the same to the other end. THEN go back to the first end and jack it back up again, verify stand placement, then lower the jack. When you jack up the second end you very frequently put a lateral force on the first set of stands. This means the first stands may be cocked a little and unstable. Resetting the first pair eliminates any instability caused by lifting the second end.

Once the car is on the stands give it a firm shake from a side and from an end before going under it. If you have the car up on multiple days, do it every day you crawl under it. If the car does not feel stable reset the stands. Check the stands for damage or bending, check the surface under the stands.

When you are under a car and trying to get something off or on, do not do a lot of hard pulling or pushing in any direction other than up or down. I read a story once about a guy who was replacing his exhaust system under jack stands. He was having a hard time getting pipe sections to separate & pulled so hard he knocked the car off the stands onto him.

Each year people die when their car falls on top of them. I doubt that suffocating with the weight of the car on your chest is all that pleasant of a way to go. You would probably have between one to two minutes of consciousness to reflect upon that before you die. So spend the extra money to purchase the best jack stands that you can get then spend the extra effort to set those stands up for maximum stability under likely and unlikely conditions.

All this takes a little extra time & expense. But there is only one you and you have to decide how important seeing the next morning is to you. If you are not willing to go through the effort and own a nice condition 1800 or 2000 Triumph Roadster, please, will it to me before you go under your car?

Best of luck & stay safe

Return to the FAQ contents          Return to the page top