Jack Stand or Jack - which one weighted?

[clarkebd]

So got to thinking while I was under my truck changing the oil.

I have always placed the jack and jack stands as such (but I leave the weight of the truck on the jack itself).

Is it safer to lower the truck until the jack stands take the weight and leave the jack in place as a backup -- Or just continue like I have done, and let the jack have the weight and the two stands as backup if the jack fails?

Also, on a side note, thought some might find this handy. Ever stay in a hotel and they have those disposable shower caps in the bathroom? Well they work GREAT for putting over your funnels to keep the dust/dirt out. The one I have below is really old and the elastic has stretched out too much, but when new they grab good and don't fall off either.

 

[tdkkart]

Imo, the weight should be resting on the stands. Of you jack the vehicle up and slide the ayands under without letting the vehicle down on them, how do you know if the weight will be properly supported when/if the jack fails??

I almost always put the full weight on the stands and remove the jack completly as its usually in the way.

 

[clarkebd]

It's hard to see in my picture, but I have about 1" between the vehicle frame the top of the jack stands. The stands are rated well above the vehicle weight.

But technically, you are correct in that unless they are field 'tested' I cannot be 100% certain they would hold.

 

[Super Sport]

The jack is both more likely to fail and more likely to move. IMO a vehicle on stands is much better supported. I lower my vehicles down on the stands, and occasionally leave the jack ~1" lower as a secondary safety.

 

[Steven67fr]

Yeah - you definitely will want to position the stands then lower the jack so the stands are supporting the weight of the vehicle... you can always leave the jack in place as a fail safe, but not bearing any load.

As the others have said - you will want to know for sure that the stands are positioned and bearing weight properly.

 

[Professur]

On the stands, always. You can leave the jack in place holding some of the weight if you like ... but if you lift the car and leave the stands under with a gap and the jack fails .. the car's weight is going to be multiplied by the acceleration of it's decent ... and you might well have given a stand a kick while moving about under there, displacing it.

 

[ajchien]

I put the weight on the jack stands. My jack is often on the lift point touching, might be carrying a little weight, not much.

 

[jacked_72]

I wouldn't leave the stands just sitting there to catch the car in case the hydraulic jack has a catastrophic failure. That would result in a shock load hitting those jacks and although they're rated for 3 tons total, the shock load can be higher and cause welds to break or metal to sheer.

 

[#1SomeGuy]

Weight on the jack stands for sure...you definitely don't want the weight of the vehicle falling down onto them, they're likely to fail that way. Also the jack itself could move (it's on wheels after all) and then the jack stands might not line up.

I usually also just snug up the jack (very lightly so it's touching the frame but not holding any weight really) after lowering onto the jack stands as a backup if the jack won't be in the way for the job I'm doing. I'll also throw wheels under the frame if they're off as another backup to the stands. Frankly I don't care what breaks or gets destroyed if heaven forbid a vehicle ever falls, so long as I'm not pinned under it.

 

[clarkebd]

Ok, good to know! I will switch what I'm doing and place the main weight on the stands from now on.

Thanks guys for the consensus!

 

[SMKS]

The jack is both more likely to fail and more likely to move. IMO a vehicle on stands is much better supported.

This.

 

[03protege]

It's hard to see in my picture, but I have about 1" between the vehicle frame the top of the jack stands. The stands are rated well above the vehicle weight.

But technically, you are correct in that unless they are field 'tested' I cannot be 100% certain they would hold.

The issue would be if the jack moved and the vehicle didn't come straight down on the stands. That could result in them being tipped over and the vehicle going down to the ground.

 

[redwrench60]

Think about this: The only thing holding back all that hydraulic fluid and your heavy *** truck is a rubber seal. Think of the stress and wear you're putting on your jack by having it support the load while you work. Kinda makes those STEEL stands seem like a better choice for bearing a load.

Besides, if the jack fails and the truck falls it might spit out those stands or break them. They're not made for shock loads.

 

[clarkebd]

Yep, got it all and totally agreed that I have been in the wrong in my setup. I will for sure change over next time I have it up.

Thanks!

 

[FTG-05]

The jack is both more likely to fail and more likely to move. IMO a vehicle on stands is much better supported. I lower my vehicles down on the stands, and occasionally leave the jack ~1" lower as a secondary safety.

This is what I do. Redundancy is a good thing when holding up thousands of lbs over your noggin.

 

[OccupantRJ]

I lower the vehicle onto the stands, then raise the jack back up enough to load it. Unless the jack is in the way, I leave it as a backup.

 

[zkling]

but if you lift the car and leave the stands under with a gap and the jack fails .. the car's weight is going to be multiplied by the acceleration of it's decent

That would result in a shock load hitting those jacks and although they're rated for 3 tons total, the shock load can be higher and cause welds to break or metal to sheer.

The cheap, rough, porous castings those stands are made from do not tolerate impact loads at all. Especially off axis loads. Lift with jack, rest on stands. I would put a piece of wood or something to catch it. I'm not sure how well a jack would tolerate a impact load either. The pressure spike may just be high enough to actuate the relieve valve, thus rendering it useless as a safety catch. if you really want to use the jack as a safety catch, I would put it up high enough just so it is in contact, but not loaded. Just my 2¢

 

[atikovi]

So got to thinking while I was under my truck changing the oil.

I have always placed the jack and jack stands as such (but I leave the weight of the truck on the jack itself).

Why are you even using a jack and jack stands in the first place for an oil change? Much quicker and easier to drive up on ramps.

 

[silentpoet]

I use jack stands alone usually. Might leave the jack in place if the height works for where the safety pin is. Also often leave tires under frame. Once I get it on stands I give the car a solid shove or three before I get under it. I really put my shoulder into it and try to move the car. Any movement and the stands get repositioned before I test again then get under it.

 

[Dick in Wisconsin]

Never support the vehicle on the jack and crawl underneath or remove a wheel and work on it. Only support the vehicle on the jack stands.

As discussed above, SO many things can happen. You could get underneath and inadvertently kick one jack stand out and have the vehicle come down on top of you.

The primary reason to go under the vehicle it to wrench on it ... right? So support the vehicle with the jack stands ... relieve the pressure on the jack. Wrenching on the vehicle could cause the jack to roll over.

Anyone who says anything different is just industrial strength stupid.

 

[JBradley500]

On the stands, just like setting the lift on the locks. Momentum can do odd things.

 

[back2class]

On stands and with jack with maybe 200lbs of load on it for added insurance. No reason not to.

 

[cgv69]

As stated, the weight should be on the stands. I lower the vehicle down on the stands then raise the jack to where it's just kissing the jacking point

 

[rsanter]

Most weight on the stands
Some weight on the jack

Bob

 

[CNGsaves]

Also need wheel blocking as critical part of safety, AND set the emergency parking brake.

+1 to put full weight on stands and jack can serve as backup.

 

[graffix000]

I'm with CNG. All of the weight should be on the stands and the wheels chocked. I also place the jack slightly below the jack point as a secondary safety measure.

 

[mrjaw14]

I have a few old scissor jacks that I will use sometimes to suppliment jack stands. usually on uni-body cars where I'm having to use a block of wood with a slot cut in it to fit in the jacking points and I'm concerned about the weight of the car cracking the wood causing a failure. I"ll use a bottle or scissor jack in that situation to suppliment the jack stands. Where human life is under the car, have no less than two supports per side. if the whole front or rear is in the air, there's a minimum of 4 support methods total.

also, chock the wheels on the ground, if its a manual ****** put it in gear if you can, and have the e brake on if possible.

 

[cinco]

Everyone else seems to have covered it (on the stands, jack as a backup if it's not in the way, chock the wheels, etc.) so I'll just mention something only tangentially related. Last night I had a dream that a car I was working on at home (think it was a Camaro) was slowly descending due to the bottle jacks it was supported by giving way. What I was doing working on a Camaro and why it was only supported by bottle jacks I'll never know, but that's my scary jack dream of the week.

I guess I need to quit reading about cars before bed. Maybe I'll start looking at pretty ladies - I wouldn't mind being pinned under one of them.

 

[clarkebd]

Yes, I always chock the wheels and have the parking brake set too.