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On-board air jacks


RebekahsZ

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I need a little help with terminology so that I can start searching and learning.  What do you call this on-board jacking system?  I work on my car constantly and it would be great to be able to pull into the shop and save a little time doing a tire swap to get the car ready for the next event (often a different venue) faster, or even to be able to do a tire swap with the car still on the trailer (maybe a little iff-y on this concept.  Maybe cost prohibitive, but I'd like to at least look into putting a system like this on the Z in order to make it just a little more fun and a little less hassle.  Anybody with experience with this type of system, feel free to contribute to my madness.

post-5903-0-80055400-1414940495_thumb.jpg

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^Not nearly as heavy as I expected, although that's not exactly cheap. But you've still got to find a way to mount them solidly enough to lift the entire car.. I would think 310mm would be enough travel to do wheel changes if they were mounted low enough in the car.

 

True, you'd have to do some strengthening where they mount, as well as making sure all 4 were at the same mounted height.

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I'm gonna tolerate small increases in vehicle weight until such time that weight becomes enough of a priority that I am willing to do what I need to do with the driver's weight.  If I lost 30# off of the driver, I could add a lot of neat gizmos.

[sharedmedia=videos:videos:252]

 

 

The jacks in these videos come down awfully fast - I wonder if that could be modulated.

Edited by RebekahsZ
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Could just put a jacking point in the rocker on both sides, then you can jack up one side at a time without getting under the car. I did this on my car and it's made life a lot easier. Even when I need to get the car up on jack stands, I can jack one side way up there and then it's really easy to get the other jack to the center of the xmember or onto the diff.

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I hope you have an air compressor that will output 300+PSI, or in the case of those AP jacks, 400+PSI.

 

( [weight of car] / [# of jacks] ) / [area of piston] = PSI required at bare minimum to stay up

 

I can't think of any shop air supply that goes over 175PSI.

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I hope you have an air compressor that will output 300+PSI, or in the case of those AP jacks, 400+PSI.

 

( [weight of car] / [# of jacks] ) / [area of piston] = PSI required at bare minimum to stay up

 

I can't think of any shop air supply that goes over 175PSI.

3000 lb vehicle weight with 4 jacks comes to 211psi if you jacked the entire car up at once.  It should be a decent bit less if you are doing one side at a time to swap wheels/tires.  

 

All you would need is a co2 tank and regulator to jack them up.  

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You don't want the exact amount of PSI, there is no safety margin. That is the pressure it takes to hold it as is. If you sit in it or drop a load? I would want at least 1.5x the capicity so if the car is 2400lbs, plan on a pressure to hold 3600lbs. That's just me.

 

With those AP jacks @ 54mm bore, 4 jacks @ 3600lbs, would be ~255PSI. Any smaller bore or less jacks means pump up that pressure.

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Just my opinion but investing in a CO2 system and all sorts of gizmos so you can change your pads fast in the garage over the weekend, is a bit over the top. Then again, I'm a cheap bastard.

Edited by josh817
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Yeah, in my searching I found the references to the high psi required for this system.  Gonna look (just for fun) at larger diameter airbag systems that could work.  Remember, I'm just looking and learning about what is out there.  I did a tire swap this morning before work and I did it the old fashion way-with a jack.

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Keith,

 

I have some experience with these.  All of the cars in Grand Am and now Tudor use air jacks.  The stated pressures are high.  We ran 150psi off the bottle.  Granted the RX8s and Daytona Prototypes we ran were only ~2400lbs but you likely wouldn't need much more for the Z.  We also ran no valve so as soon as you remove the wand the car crashed down.  Good times for the driver changer.  A lot of the Porsche cars used a valve which lowered the car more gingerly.  One cautionary statement: on really hot days the feet of the air jacks would sink into black top.  If you weren't careful you could damage the system by attempting to drive away with one stuck in the asphalt.  Luckily the vast majority of pit boxes are concrete.

 

If you are serious and need specific information give me a call or shoot me a message.  I'll get whatever info I can from the race team.

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I'm glad you weighed in. I noticed on YouTube (becoming more valuable than google), that not only are the pressures high, but the air tanks they are using are pretty large. I don't know if that means that high volumes are needed too or what? Yeah, the videos all show the cars crashing down. I'm just fact finding (and I'm finding more facts since posing the question).

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A few additional comments concerning how we used the jacks that you may want to factor in your decision.

The regulator pressure setting we used was enough to get the car to jump up quickly since elapsed time for changing tires was paramount. For non-racing situations I don't see why a lower pressure couldn't be used.

We almost never worked under the car when only elevated using the air jacks. We used bottle shaped braces that slid around the shaft of the air jack. It was mandatory by Grand Am/Tudor rules. About the only time I would go under the car while on air jacks was to change camber or toe while on the scales. It was easier since the car was going up and down a lot to check then change settings.

If you do end up adding a set to your car make sure you lubricate them often. They will stick in the down position.

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Here is a basic kit for these from my favorite supplier. https://www.pegasusautoracing.com/productdetails.asp?RecID=6208 Fairly expensive, and you have to think about how you plan to attach them. A caged car and this is no problem, anything else and it might be interesting. 

 

I imagine they are really only useful for quick suspension adjustments or swapping tires, but sounds like that is your stated usage. 

 

Their bottles are large because its more cost effective to buy large bottles, and if you are charging the system multiple times a day, you probably go through that quantity of gas. 

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