Would You Trust This Jack Stand?

[DerbyDad03]

I'm not looking to start another discussion related to the proper techniques for jacking up and supporting a vehicle. That subject has been discussed ad nauseam.

My question is quite simple: Would you feel safe working under a vehicle that was supported by either of these jack stands, assuming of course that you stayed within the 2 ton rating of the device.

Based on the date that this first video was published, I think this is the newest version of the RennStand.

Video Published on May 10, 2017

The following appears to be an earlier version of the RennStand, based on the date that the video was published:

Video Published on Oct 13, 2016

Maybe it's just me, but both the angled welds and the curved sections of the support bars seem like dangerous points of failure.

[Dean Hoffman]

It would seem stronger without the angles. Also, wouldn't the jacks be a bit simpler to make if there was just a 90º angle at each end?

[clare]

If reasonably built both would be very safe. Poorly built, even the "best" current designs are dangerous.

[Stormin' Norman]

The angled and curved pieces are types of arches. The load is easily transferred through those structures to the abutments resting on the ground. As long as the welds are created properly (can be said about everything which is welded), the structure of the jack stands appears quite sound.

[clare]

You are looking at "cheman engineering" - when did simple to construct win out over elegent design?? (other than the first beetles.

[Meanie]

If I had to compare it to architectural designing, the arch support entryway is stronger than the basic square (90 degree) entryway. The same for arch bridges. The weight is distributed more evenly in all angles than compared to all the weight at the ell angle.

I would use it but I prefer the the conventional jack stands.

[DerbyDad03]

But most arch support entryways don't have 4 welds as possible points of failure. It's not the arch shape that bothers me, it's the welds.

[DerbyDad03]

I understand how arches work/transfer the load. It's not the arch shape that bothers me, it's the welds. Since I didn't do the welds, I'm not sure I want to trust my life to them when a "straight down to the ground" option exists.

I'm sure they're fine, I just don't want to be worrying about them while I'm under the vehicle.

[clare]

Architectural arches are often made of MANY parts - tied together with lime cement (mortar) A GOOD weld doesn't scare me.

[clare]

The arch weld is likely a better solution than the legs being welded to the end of the top tube, and 2 angled welds are likely stronger than a single weld holding the leg to the bottom of the cross tube. Look at the load distribution - combination of compression and shear.

They actually look pretty good to me. Any structural engineers out there??

[Stormin' Norman]

I am glad you understand arches.

I wonder, do you worry about all of the welds you "didn't do" throughout the course of every day? All of the vehicles on the roads, airplanes, trains, elevators, staircases, bridges, etc, when you are in a position to be harmed by a failure?

I hope not.

The fact of the matter is, in modern manufacturing, a great percentage of welds are made by robotic welding apparatus. Whereas they are not perfect, I suspect they create welds which are far superior to the average human operator.

[rbowman]

I'd feel safe but I'd also feel safe with a jack stand that doesn't cost $140. If you're worried about the welds I'm surprised you're not looking at the pins and wondering what their shear strength is. Ultimately that's what is going to hold the weight up.

[micky]

I bought the shop manual for my 2004 Sebring, and it has 95 pages of Location of Welds.

I don't understand it. They need to know where the welds go when they build the car, but when people fix it, how often do welds break? And if a mechanic finds a broken one, he should reweld it.

He's certainly not going to check out the welds before they break.

[DerbyDad03]

I don't need to wonder about the shear strength of the pins because the spec is given in the video.

[Ed Pawlowski]

You trust your life to welds most every day crossing bridges, using elevators. I don't crawl under a car unless it has two supports though.

[Ed Pawlowski]

Body shops and junk yards cut off sections from one car and weld it on to another. I imagine they would want to know where they are.

[micky]

Okay. Makes sense.

Still annoying to spend so much space on this when there are other things that are ignored. I've had shop manuals for about 7 other cars from GM, Ford, Chrysler (84, 88, and 95), and Toyota, between 1966 and now, and none of them had a separate section for this. I don't remember if they were indicated elsewhere. This 2004 chrysler sebring manual has mostly instructions on how to use the fancy tester I don't have. ($3000 second hand, iirc), and the Haynes manual, which used to just be excerpts from the shop manual is now probably more useful to me than the shop manual.

[rbowman]

If you had an Austin-Healey 3000 you would be very interested in welds...

[micky]

I had a set of jackstands, maybe from Western Auto, and a friend who didn't weigh more than 160 was sitting in the drivers seat with his legs out of the car, a Chrysler K-car that didn't weigh more than 3000 pounds, and had 3 wheels on the ground so the stand was supporting only a little more than a quarter of the car, and the jackstand collapsed on him.

Not this brand but something like this:

I took it back but didn't want to spend extra for bigger, so like an idiot, I accepted another box of the same thing that failed once.

A few years later when I was changing the right half axle on my car and the ball joint, I was so afraid another would collapse that I used both stands, another one, and 2 floor jacks and a scissors jack all at the same time so I wouldn't get crushed. It was hard to get it to rest on all of these at the same time.

[Stormin' Norman]

Many modern passenger cars are designed and built using unibody construction instead of the frame construction (ladder, X, etc.) used on cars of yesteryear and still used on trucks, vans etc.

Unibody construction is far more dependent upon each weld in the vehicle. Having a manual that provides details about each weld certainly makes sense when an auto body repair shop needs to repair and ensure the safety of a vehicle that has been involved in a crash.

Unibody might sound like a gimmick or a cluster f*ck, but, compared to ladder and X frames that minimize damage to a vehicle, unibody limits injury to occupants by absorbing and distributing collision forces over much more of the vehicle. Sacrifice the vehicle to save the occupants, a good trade if you ask me.