A question for the wrenching Oppos.

"The Crazy Kanuck; RIP Oppositelock" (jukesjukesjukes)
03/09/2019 at 00:50 • Filed to: None

About air bag jacks.

I’m not super experienced in wrenching, so anything to make or easier is very welcome. I bring up air bag jacks as I could lift all 4 corners up in one shot with out a hoist(then jack stands of course). I could see at the track these being great, I will have an air compresser this year so it could double for the air bags. Also they seem more compact then a floor jack, so it free up trunk. space. To me it seems like a good idea.

DISCUSSION (14)

Discerning > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 01:05

They’ve been around for a while. They are more expensive than a conventional jack and I'm not sure I see the benefit.

So would you have access to a compressor at a track? I’ve never seen one accessible unless you planned on borrowing one. Or bringing your own and then plugging it in to a power source. At that point you might as well use a normal floor jack imo.

The Crazy Kanuck; RIP Oppositelock > Discerning
03/09/2019 at 01:07

I would think a good 12v compressor that uses the 12v socket from my car be plenty capable for the task.

WRXforScience > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 01:44

I don’t see how you’d lift all four corners at once, multiple jacks with multiple air lines filling at different rates and possibly dropping the car don’t sound like the best way to lift a car.

I just use an aluminum floor jack and jack stands. I can lift an entire side of the car at once and get two jack stands under the car before moving to the other side (I can do left, right, front, or back depending on what I need to get at). It only takes a few quick pumps of the handle and the car is in the air and it’s relatively compact and fits in otherwise unused void space between tires or in the spare wheel well.

The only pneumatic jacks I’ve seen at the track are the Quick Jacks and they’re mainly used because they get the car higher than typical and lock in place serving as their own jack stands (they’re expensive and too big to fit in a car but are easy to store in a trailer under a car) .

I’m not sure a 12v system is going to be ideal for inflating the air bag jack since they typically require about 100psi. They also look to be almost the same size as a floor jack and definitely weigh more than an aluminum one. I think you’d be better off investing in a tire trailer if you are hurting for space.

The Crazy Kanuck; RIP Oppositelock > WRXforScience
03/09/2019 at 02:06

Looking at some 12v pumps some can go to 150psi max. I have jacked up one side before no problem. For putting it in the air I prefer jacking the front, I use front sub frame so problem. As for the rear there is no good jacking point in the middle. The rear tow hook (the one attached to the sub frame) is close to right side so it won’t lift even.

Eury - AFRICA TWIN!!!!!!! > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 04:41

I think they are a neat concept, but you are vastly underestimating the amount of time it’d take to pump one of those up with a 12v compressor.

diplodicus forgot his password > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 06:59

Its not just psi but s cfm that matters.

diplodicus forgot his password > WRXforScience
03/09/2019 at 07:01

You'd have to run a line to a manifold first to equalize pressure to all the bags. But I agree a 12v compressor won't be ideal.

shop-teacher > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 08:12

No. Not even close. You’d need a big ass air compressor to fill these in any reasonable amount of time. Don’t be fooled by the pressure rating on a compressor. Every tiny piece of crap can get to 150 psi. The volume of air the compressor puts out, is what’s important. Look at the CFM rating, that’s what will tell you what a compressor can really do. To li ft all four corners of a car at once, you’d need a big shop compressor. And then you’d need to monkey around with multiple air lines. It almost certainly would not lift evenly either.

No, just get one of those aluminum floor jacks for the track.

BigBlock440 > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 09:55

For reference, a decent 12v compressor (not great, just not the bottom of the barrel) takes an hour to pump up a truck tire from 10 psi to 55, 265/75R16. You’re not moving a ton of air with them. To fill up an inner tub for snow takes an hour or two with a cheap HF 12v compressor.

Spamfeller Loves Nazi Clicks > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 10:41

DO NOT DO THIS, IT IS ENTIRELY UNSAFE.

Air jacks require a specific pressure and a specific flow rate to deliver a specific lift rate. Just ‘Tee’ing one compressor into four jacks will result in an uneven fill rate, resulting in the load shifting, resulting in breaking the car or you. DON’T. DO. IT.

Further, 150psi ain’t shit . 12V pumps CANNOT DELIVER THE REQUIRED AIR. It’s CFM AND PSI. Not one or the other. The 12v compressor I’ve EVER seen that isn’t a fire hazard could deliver a whole 150psi @ 0.2CFM. An impact gun requires 90psi @ 24cfm . 12V pumps aren’t shit. Unless you are ready to drop SERIOUS money on a SERIOUS compressor, you are sure as shit not filling up air jacks - which eat a CONSTANT 150psi+ @ 4 0cfm+.

gogmorgo - rowing gears in a Grand Cherokee > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 10:52

What is the primary advantage of this sort of jack? I’ve never seen one before.

We do have air-powered jacks in our shop, as most heavy equipment shops do. But they’re not using the air directly to lift the vehicle, they’re just air over hydraulic.

Having worked with air systems on trucks, brakes, suspension, etc., I’m not sure I’d trust an airbag jack with my life. The only reason trucks can get away with air systems is because they’ve got a big compressor on board (when I say big, I mean a truck will air itself up faster than we can do it with our shop air) and there’s always a mechanical backup. None of our trucks will hold a full system overnight, and the older ones will dump everything within a four hours. And this is all within commercial inspection standards. You’d need to have whatever compressor you’re using running almost constantly to keep the air up, and most 12v compressors don’t have the ability to push enough cfm to do that. I remember once when I was a kid with my grandpa trying to fill all four tires on a vehicle that had sat over winter. We ran the compressor on the first tire and it was taking so long I decided to hurry things up and got out my bike pump. I managed to get the other three tires filled all the way up from sitting on the sidewalls and then unhooked the compressor and filled that one tire up the rest of the way too with my cheap bike pump.

HammerheadFistpunch > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 12:09

You can get a PUMA, or one of the nicer VAIR but I still recommend going aluminum jack and jack stands.

HammerheadFistpunch > The Crazy Kanuck; RIP Oppositelock
03/09/2019 at 12:10

I can tell you that you will find NO compressor that goes in a 12v cig that is even worth buying for anything but beach toys. You’re looking at a $100 MINIMUM level compressor.

Jake - Has Bad Luck So You Don't Have To > The Crazy Kanuck; RIP Oppositelock
03/12/2019 at 23:48

Bolt four of them under the car so it can lift itself.