SteveG

Probably more work is done under cars in the winter, but Spring is here and this needs repeating; people know better, but it keeps happening. If you are under a car, make sure the damn thing is safe. A 34-yr old near where I grew up (Lancaster, OH) died yesterday when the car he was working on fell on him. He was savy and this should never happen. Such a tragedy.

hacker-pschorr

I added a new garage rule after my rod bearing job: "No working under the car after midnight".

I fell asleep, when I woke I sat straight up (or at least tried to) forhead meet crankshaft........

Also, I almost never have the car up on four jackstands. Instead two of the wheels are on Rhino Ramps with the usual removed wheels under the car for additional safety.

Cannot be too safe under there.

linderpat

Agreed. I use jack stands at each jack point, plus an extra set under the rear control arm pivot points, plus stacked RR ties under rear tranny cross member, and under each pivot point in the front suspension. If my primary jack stands fail, then I have sufficient back up.
I think it was Dr Bob that said very little twisting/torque is required to unseat a car from jack stands, especially as they are raised higher - so as we lay under our cars and strong arm stuck bolts, accidents can happen. I don't want that fate to befall me. Also, I live in an earthquake prone area, so I don't want some random act of nature to kill me under the car either - thus, many failsafes!

Edit - I actually use the lift bars, with the jackstands located under the 4 jack points - I think the lift bars are safer than just the stands.

dr bob

No such thing as "too safe". Can't use the word "overkill" in this context, but you get the idea.

The thumbnail rollover value for the fully-extended 3T jackstand was 175#, assuming the pull is inside the square footprint of four stands and they are all at the same height, 3500# car on a level floor. Move the application point outside the footprint and the number shrinks some. Good news for me is that the only way I can get 175# of lateral force on something on or under the car means I'm somehow braced against the same car somehow. That negates most of the the force immediately.

The original discussion was around the use of railroad ties, stacks of 2x4's, whatever, on top of the jackstand. This was before the liftbars were popular, when folks were building little leaning towers of lumber as scaffolding to get the cars up to working height. Very scary!

Using stands is fine, s long as you recognise their limitations. A small footprint at full extension means the vehicle weight has fewer vertical inches per horizontal inch to overcome to roll off. Imagine a circle with the center at the edge of the stand where it hits the floor, and the radius is the distance from that point to the contact point with the car. Consider the arc section of that circle between where the car contact point is, and the point on the circle directly over the edge of the stand at the floor. That's the motion of the car required to push it over and off the stand. The initial force needed has some vertical compponent to it, so the weight of the car is helping. Once it starts rolling, the required lateral force decreases until the point where the car contact point at the top passes over the floor contact point, at which point the gravity starts fighting you instead of helping.

So if you plan on working under the car, support it well for the tasks you have planned. Changing the oil and filter? The small stands will be fine. Dropping the rear suspension and the gearbox? The expected effort on wrenches, potential for big things moving around, and the extra height requirement point to bigger stands as a minimum requirement.

Bottom line is to think about what you are doing, maybe before you do it.


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Almost two decades years ago now I was visiting a company I'd purchased in Illinois. A neighbor came running over to get help lifting a truck from where it had fallen and pinned her husband. He had raised it with a bumper jack sitting on a stack of wood blocks insidee the garage, and it had rolled off and squeezed him against the wall. We were too late. It squeezed him so he couldn't breathe, and couldn't call for help.

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I admit that I was a very late adopter of the current style of jackstands. Even after the tube stands were withdrawn from the market, I used my old tube stands regularly. Until I had one split while changing rear brakes on the Explorer. The jack was still under the pumpkin, but that stand split end to end in seconds, with no warning. My little feet weren't in the path of destruction fortunately, but it was a real wake-up call. New modern stands that afternoon, before doing the front brakes.

Imo000

[QUOTE=Hacker-Pschorr;7407692]..........with the usual removed wheels under the car for additional safety........QUOTE]

I do the same thing and keep the hydraulic jack under one corner for just in case and I do not go under a car when I'm alone in the house. I also as my wife to check on be on a regular basis when I'm in the garage.

Also, using larger than required stands is a good idea. Go with a 3ton, they are better built than the base model 2Ts

dr bob

Imre--

The 'baby' stands I have are 3T. Anything that involves mrs dr bob's hubby doing serious work under the car means at least the 6T stands are there holding the car up. If nothing else, there's room for me on a creeper on the bigger stands.

The undercar spaces seem to get tighter and tighter as the years pass. Wonder what might be causing that. Hmmmm.

Tom in Austin

Amen all! I always put a wheel under the frame rail when the car is on stands, and if it takes more than two stands or up more than a couple clicks, I take it to Sean ;-)

Life is too good to take chances with stuff that can kill you.

dr bob

A lift sounds better and better all the time, doesn't it?

linderpat

Just for clarification Tom, what do you mean by frame rail? If it's the lateral channels running under the car on each side, those aren't frame rails - they are the seat channels, and they are non structural, which is why the car should never be jacked up from those rails (and where you can see in many cars where prior owners did it wrong, because those rails are all deformed).

I don't have a picture handy. What rails are you referring to? I didn't think the 928 had a frame, per se, but was instead a unibody construction.

UncleMaz

I forget to operate sometimes in the safest manner. Thanks for the reminder.

mj1pate

I made stacks of blocks by screwing 6 2x12s together to make each block. I usually have each wheel resting on a pair of blocks. When doing work that involves wheels-on-car and car elevated, I like the idea of the car tires resting on solid platforms. When the wheels are removed, I use jackstands, backed up by blocks under the rails.

I use Porkens excellent liftbars during the elevation process. Early paranoia instilled a slower lifting pace, until familiarity bred laziness. While speedily raising the car last year, one of the liftbars blew out from the passenger side during raising and the car fell about 9 inches. A little cautious observance would have seen this coming and saved the rocker panel from a dent caused by a floor jack laying under the area. I've slowed way down since.

928autobahndreamer

I have a.set of 6Ts and a set of 3Ts.
I need another set of 6T stands. They are so much more substantial. It actually makes me nervous to be under the end supported by the 3Ts when the car is up front and back.

But, I always put a wheel under each side as extra protection.

I appreciate the reminders of what can go wrong, as it is easy to get lazy. One time is all it takes.

Jerome Craig

I use two sets of 6 ton jackstands at the lift points for most work. I also keep both of my 3 ton floor jacks engaged and have been known to also use my 1.5 T floor jack as a backup under the front or rear crossmember - according to which end I'm working on. The 6 ton stands usually don't need to be extended higher than the second notch. When I did the motor mounts I used 4 6T stands plus two 3T stands plus a bottle jack and two 3T floor jacks.

Sometimes I spend more time securing the car than I do being under the car....but I've only got this one life....so I guess it's time well spent. Even with all those precautions, I still do some of my best praying when I'm under the car.

sprio

I haven't done much under the car yet - I do have a set of liftbars, and 4 3-ton stands, but I have to become comfortable with getting the car up on the stands. When I make that first lift, it seems so dang high - I've thought about getting a set of 2-ton stands, so I can incrementally lift the car, but then I'm worried about stability during the lift process. I imagine I'll get there, one day. Better safe than sorry.

linderpat

That's what I do - lift one side up onto the lower 2T stands, then around to the other side and up on the higher 3T, then back over to the first side and lift again to get the car on 4 3T stands. Once it's up on all 3T stands, then I lift to desired height. I do it this way because the 2T stands are lower than the 3T stands, and I prefer the incremental lift as well. Also, it doesn't take much longer to do it this way, especially with the liftbars. MAKE SURE YOU HAVE THE CORRECT LIFTBARS FOR THE CAR THOUGH IF YOU DON'T BAD THINGS COULD HAPPEN - see this thread for details: https://rennlist.com/forums/928-foru...car-today.html

I think with the liftbars, the car is up safer than without them.