Reverse bags?

[metalshapes]

It seems both airbags and hydraulics have their drawbacks, so I was thinking about a different way of doing it.
Maybe I can get some feedback from you guys...
What if you lower the car so it has a nice stance, but is still driveble and clears speed bumps, etc.
And then use Bags working against the springs to lay rockers and to drive it ultra low.
That way you would not have to relocate shocks. In regular "drive" mode the body would not have any extra lean ( like when the 2 bags on the same axle are connected )
And when a bag or a line fails, the car just pops up to its regular ride hight, so you can drive it home.

[Unkl Ian]

OK.......I understand the basic concept,but how do you make it work?

[Muttley]

That's a damn good idea, but you gave me a brain cramp trying to figure out how to do it. http://www.jalopyjournal.com/ubbthreads/images/graemlins/crazy.gif

[mikes51]

You could mount a bag low on the frame, have it pushing up against the top A-arm. It would be located as close to the a arm as possible. Like lots of other ideas, it comes down to will it fit. Would it interfere with your front wheel turning. etc.

[DrJ]

A few winters ago a guy built a sedan with adjustable suspension. actually several guys did. (Ledbetter? the guy who built the AlaKart clone and "Posies" Fenical, I think) anyway, the car rides on a coil-over but the frame end of it is attached to a belcrank that the other end of is hooked up to an electric screw jack, not unlike the screw jack that works the horizontal stabalizer, the tail, of a passenger jet. It always has the same spring rateand travel, just the upper mount point is adjustable relative to the frame from a switch at the drivers seat.

No, you probably can't hop it.... http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif

[metalshapes]

Unkl, the way I see it, the car would have the best ride quality at normal ride height. And you can play with spring rates and shock stiffness if you would need to.
Drawback would be all the extra shit on the suspension, since you would not replace the spring with the bag, but adding it on.

[kustombuilder]

i think hydraulics cylinders would be easiest for what you are proposing. hydros would also work in place of the actuators in DR.J's setup too.
if you set bags up "correctly" it would still be driveable when all the way down so that if you blew a line you could stil limp it home on the bump stops. problem is nobody ever sets em up that way (not even me) cause we want them to "lay out".

if you take the time and really do it right you should'nt have any failures. the line and everything is the same as is used on semi trailers for their air brake systems. when i used to do suspension work the only time we had to repair an air line was when we burned it with the torch trying to remove something near it. when you blow a line on air brakes the brakes lock up RIGHT NOW! i think i'll do a post listing the dos and don'ts of setting up an air ride suspension...

Mike

[ELpolacko]

If you look at the tag axles on heavy load hauling trucks they use a pair of airbags to plant the axle and to lift it off the ground when not needed. Interesting idea but expensive and complicated to adapt to a hotrod.

Instead of air or hydraulics, there is annother option. It is still very young and has the capability of replacing all of the above suggestions an once developed by the right minds will be more compact than it is now.

Liquid Springs (http://www.liquidspring.com/)

I saw this demonstrated a couple years ago, amazing. Please read as much as you can from their website it is informative.

[Rocket88]

Elpolako, that is a cool website. I see that the new Cadillac SUV's have a similar arrangement with their shocks, electronically controlled dampening.

[Alford]

A few years back a guy built a late model ex-cab chevy pickup where he used the same idea but with hydraulics in the front. It was build by a shop called "R Customs" either in cal or arizona. I forget. Tangerine with crazy graphics and a channel job I think. Its a cool idea. I wonder if the springs would lose their integrity a lot faster?

[daddylama]

seems like it would work OK, BUT...
A few people around here have done it... with hydraulics (like the R-Customs truck, built in so-cal), airshocks, and some other methods... all to pull the suspension down to make it low. All seem to ride like total shit when it's low, and all would not allow the suspension have it's downward movement (so the vehicle can go up, yet the tire remain in contact with the road) into even the slightest dips... effectively causing some f*'d up wheel hop and unpredictable handling at any kind of motion.
The first i saw was a mini-truck about 12 or so years ago... airshocks to pull the suspension down to the ground. I can show you where it hit a telephone pole at 30mph...

The bellcrank, screwjack and other methods that DONT pull the suspension down seem to work a hell of a lot better... and are safer.
There's a couple oldtimers that ive seen use screwjacks on otp of coil springs, just like on nascar... and one that's screwjacks are electircally operated. Only took about 5 seconds to lay the rockers.

[DrJ]

GOOD: lose juice to a screw jack, it just stays where it's at. If that happens to be when you're going down the highway at 80mph, the suspension stays put wherever it is. No loss of control, no more sparks or pavement gouging than before.

NOT SO GOOD: Car suspended on compressed air or pressing on contained hydraulic fluid. Rupture any of many feet of tubing or have a connector come loose and drop one corner of your car into the pavement and you could be killing the babies in the car in the next lane before you regain control, if you do at all.

(I worded it that way because I don't want to even hear from all the immortals who "aren't afraid to die" in their death rods)

PS. Trucks don't lay frame if they have a bag failure.

[Scotch]

The way to do this is to have the slave cylinder (hydraulic or airbag) work against a rocker arm/bellcrank to push down against the spring. In this manner, when pressure is at zero the car would be at "normal" ride height. When pressure was increased, the bag/cylinder would push down against the spring to stiffen the ride and lower the ride height.

It would require sufficient under-vehicle space to accomodate the rocker arm assembly and necessary linkage. It's certainly possible, and I've heard through the grapevine that a system like this is currently being marketed for the Subaru WRX. For performance reasons, this adjustable suspension allows the driver to increase suspension stiffness and lower the center of gravity while driving. The ride quality will suffer (we know about that) but the addition of pressure to the system will lower, not raise, the car. So, it's a double-edged sword toward the positive. Heaven forbid you develop a leak, but if you do, the car goes up instead of down. Should you choose to drop it down, pump up the pressure and it'll slam.

In my opinion, it's how these systems should have been engineered all along. I predict this will be the direction the airbag/hydraulic market will move toward next, since low stance is something everyone wants, but a move to bags/juice systems has always required a sacrifice of handling performance. This way, performance could actually be improved and the cool stance we're after can come with more benefits. It just plain makes sense, if it can be packaged effectively.

Scotch

[gowjobs]

A really interesting idea I saw on another board:

Guy is using a combination air/hydraulic setup. At each wheel, he is utilizing a narrow hydraulic cylinder, hooked up with braided line to another cylinder that he has mounted in a remote location. That cylinder is hooked at one end to an airbag... in this way, he has air adjustablity and spring, with little or no visible method of suspension up front (also makes for gobs of wheel clearance if you use a wheel with heavy positive offset.)

It's an interesting idea... and makes for adjustable ride height on a fenderless car without big coil springs or bags visible. Imagine using cylinders of different bores on either end of the transfer line so that five inches of adjustment at the bag could mean 12" of stroke at the cylinder.

Dave

[JamesG]

[ QUOTE ]
seems like it would work OK, BUT...
A few people around here have done it... with hydraulics (like the R-Customs truck, built in so-cal), airshocks, and some other methods... all to pull the suspension down to make it low. All seem to ride like total shit when it's low, and all would not allow the suspension have it's downward movement (so the vehicle can go up, yet the tire remain in contact with the road) into even the slightest dips... effectively causing some f*'d up wheel hop and unpredictable handling at any kind of motion.
The first i saw was a mini-truck about 12 or so years ago... airshocks to pull the suspension down to the ground. I can show you where it hit a telephone pole at 30mph...

The bellcrank, screwjack and other methods that DONT pull the suspension down seem to work a hell of a lot better... and are safer.
There's a couple oldtimers that ive seen use screwjacks on otp of coil springs, just like on nascar... and one that's screwjacks are electircally operated. Only took about 5 seconds to lay the rockers. [/qute]






I have bags on my delivery and you just have to find a happy medium. The best way to set it up is to slam the car and use your bags to lift it so you can drive. Now keep in mind that the lower you go suspention and body wise, thats if you channel it, the higher the bag will have to lift meaning more air preasure and a shittier ride.

[DrJ]

"Guy is using a combination air/hydraulic setup. At each wheel, he is utilizing a narrow hydraulic cylinder, hooked up with braided line to another cylinder that he has mounted in a remote location. "

Sounds almost as good as a half century old Citroen suspension.... http://www.jalopyjournal.com/ubbthreads/images/graemlins/wink.gif

[praisethelowered]

I need screw jacks. Where can I find them?

I have a spin on this one too. My current project is a lowered 2-ton '54 delivery truck. In order to safely carry that much weight I am looking at dropping the body over the frame untill it hits the ground, then lifting the truck from the rear shackles of the parallel leafs connected side to side with a balance bar and a panhard (it has parallel leafs front and rear). So the truck will raise up about 12" without affecting the spring rate at all- the truck ride with its normal spring rate when raised. This idea should work on the back of a sled.

I figured I would set up hydraulics and rig a back-up manual jack at the same point so I wouldn't be stuck if the hydro's failed- but an electric screw jack sounds like the ticket since if it ever failed you could unplug it, unbolt it and put in a rebuilt one without having to look for a leak or clean up a bunch of spilled fluid. I've never heard of a screw jack before- anybody know where I could get some?

[scooter]

Interesting idea there shapes ? where did it come from sounds very familar ...

[DrJ]

Here's a couple I found with a quick search;

http://www.joycematerialift.com/jacks/jack_mach_screw.php

http://www.nookind.com/ProductsHome.cfm

Not sure if these would be applicable but its a start in finding the right part...

[metalshapes]

I dont know where it comes from, and I'm sure people have done it with more and with less succes.
Some time ago I happened to be driving behind a late model front wheel drive Custom job that has Hydraulics, And I could tell that the driver had memorised every bump in the road. ( he needed to or he'd be fucked )
The couple of times I have seen airbags been put in cars, determening the rideheight and springrate seemed to be a hit or miss kind of thing. ( I'm sure thats where experence comes in )
By using the bags only to lower the car, the suspension would be unaffected in "drive" mode, and it would have a real positive stop getting there from "lowered" mode.
Lowering it that way would make the springrate less ( the bag and the spring are fighting each other ) making the ride softer, untill it pushes the suspension against the bumpstops. ( then there is no movement at all )
At the end of the day, the system ElP showed would be the ultimate, depending on cost.

[metalshapes]

PS...
The "lowered" mode would not be for driving, just for Stylin' and parking.

[daddylama]

as long as the "lowered mode" was for the vehicle being parked or driven slowly (over flat ground), it would probably be fine. But imagine going up an off-camber driveway, your right rear wheel coming off the ground because there's no downward movement to the suspension with the bags filled (pulling the suspension to it's bottom).

Ive seen the R-Customs built chevy truck driving around... pulls a nice 3 wheel motion over the slightest dips...

as for the standard use of airbags, ive had 'em in more than a few of my drivers... never had a problem. Im not saying i wasnt thinking "man, it sure would suck if a bag went out right now" while driving to vegas through death valley...
and ive been debating putting them on my current driver, because of that exact reason. Ive never had a problem, but there's always a first time.

As for jackscrews- speedway has 'em... in steel and aluminum. Or want an electric jackscrew? Look at camper jacks... some of the better ones are really well built (but expensive).

This topic rocks, btw... good to see a good on topic discussion... and what the hell do i know, anyway... im running torsion bars and happy about it.