Lowering pickup on HWY, raising for off road/snow?

[stillsearching]

Some of us live in nice climates and can drive things like a scooter, small motorcycle, or low slung economy car year round. And then there are those of us who dont. :) When I finish a move to the country sometimes I have to go places that even a big tire upgrade wont take you. If this can be done with the same one vehicle it's alot better because all other MPG upgrades will be built into it since offroading is uncommon.


I'm still trying to figure out the best way to modify/reengineer the suspension of a 4x4 pickup so that it can ideally be raised up when you need to fit large tires for ground clearance, and actually be LOWERED (not just stock height) when you are on the highway.

It is possible that a solid axle suspension would be more suited to this - because the geometry changes with an independant suspension which is cranked down to some mid-way position (for the highway drop) is likely to create problems. However if anyone with either an engineering background or understanding independant suspension geometry has ideas to the contrary i'm all ears. Since i've never modified or changed any suspension ever i'm not even fully sure whats involved though, only played around with powertrain stuff so far.


What i'm thinking about is some way to first increase the total suspension travel of a live axle vehicle, air bags could provide variable spring rates, but i'm still not sure of the best way to change ride height. The ideal would be something like 14 inches of travel - where I could either force it to use the bottom 7 inches (highway slam) at a higher spring rate, the top 7 inches (tallest tires) or the full range of travel (medium tires) with softer spring rate for working in fields, getting through snow and similar. It doesn't have to be 14 inches (and the lowest to highest difference is 7 inches) thats just a random example of ideals I had in mind. Some tough strong way that will take everything from off roading to heavy towing, and not just cranking down springs throwing the geometry all out of whack messing up highway or higher speed stability. It doesn't have to be an instant change - even something I manually crank up or down would be tolerable, though automatic could be more convenient of course.

This is just a brainstorming and source finding post, seeing if anyone has random relevant ideas or has seen things elsewhere that could work.

[cRiPpLe_rOoStEr]

Unless you were willing to spend on a double-A arms setup, seems like a solid axle is really the most cost-effective option. It would only make it harder to smooth out the underbody around the axles, but everything has its compromises anyway.

[JRMichler]

Forget airbags. I tried them once, and they made the car ride hard as a rock even with zero pressure. And they rub against the springs and chafe, so die young.

Possibly some sort of air over oil shock absorber setup inspired by some lowrider hopper system? If the air over oil system replaced the springs, then the spring rate would have minimal change between high and low settings.

[MkVer]

You could do a complete airbag conversion. AirFlex and AirBagIt both make kits. Kinda pricey though.

Firestone used to make a kit called R4tech that removed all but your minimum load leaf spring with a supplemental airbag to handle heavier loads. The kit had a built in bleed for "kneeling" the rear end of your truck. That might be doable on a home built system. Remove a few leafs until your truck drops then install airbags between the axel and frame to lift it up. You may have to put traction bars on though, spring wrap might get bad.

[me and my metro]

My 06 Navigator has factory air ride. There is 2" range between park and low range in the transfer case. Normal ride height is in the middle. It kneels in park and airs up when put in drive. Two wheel drive, four wheel auto and high stays at the mid height. Four wheel low it raises 1" for more clearance. Independent front suspension so there is limited acceptable height range and alignment range available.

[cRiPpLe_rOoStEr]

Air suspension is not bad at all. Nowadays, even some big rigs use a full-air setup.

[oil pan 4]

You left out drive shaft angles.
If you go up 7 inches you will be changing rear U-joints every oil change or running around like one of those idiots with a 4x4 with no front drive shaft because they shell out front U-joints every 500 miles.

You will also need something like a anti sway bar disconnect like the dodge power wagon has. Its an electronic anti sway disconnect, you can switch between on road and off road mode on the fly. It auto reconnects above 35mph so you don't pull off the trail and on to the highway, change lanes, lose control, go off into the medium, flip the vehicle and die.
The Powerwagon gets 10mpg highway from what I hear.

My mechanical engineer says everything he learns about raising a vehicle up significantly and/or putting much bigger tires on a truck or SUV the more he hates the idea.
His off road Toyota and towing excursion have stock height suspension and tires that are stock size or very close to it.

He would love to lift his excursion and Toyota and put huge tires on them and if there was a way to keep the vehicles as strong, stabile, reliable as they are in stock form he would have already done it.

I think this is what you need to meet all your specifications aside for fuel economy, which just isn't going to happen.

https://www.youtube.com/watch?v=cDoRmT0iRic

All you need is 300,000 British pounds and pass a background check to make sure you are not some kind of villain.
Only problem I see is the wind screen wipers are not lion proof and the tire can not withstand 7 pounds of C4.
It seems that it sets off car alarms when it drives through brick walls.
And they should have been playing the A-team theme song through out the whole clip.

[JRMichler]

My brother uses his F250 off road a lot. For work, not playing in mud. When the snow gets deep enough that the differentials are plowing snow, it does not matter how high the body is lifted.

He carries chains for all four wheels. With practice, all four can be chained up in five minutes. If you can't get there with four wheel drive and chains on all four, you won't get there if the body is lifted. That's for a working vehicle. Playing in mud holes is different.

[stillsearching]

Multi responses...

I know a 7 inch lift by itself is considered problematic to driveline axles (i've generally read 4 is fine, 6 is too much, i'm not an offroader and havent investigated it alot though) but was wondering if the physics was any different if part of the inches are LOWER than stock, I thought the problem was the transfer case side being too high not too low. 4 up 3 down without a loss of travel was my ideal - but if that's not feasible maybe just aim for 4 inches like a more normal lift? (if it is still feasible like to keep it on the table)

Any ideas how I get more travel in the first place? That would seem to be kind of my first barrier, then up to how much i'm willing to raise spring rates and how little on-road travel i'm willing to accept. I've seen the aftermarket A-arms to give longer travel for offroaders, but like it was said - a little expensive. Wondering how the offroaders normally get more travel for solid axles.

As to differentials dragging snow, that's what the big tires are for. Alot of the need for lifts period is fitting bigger tires. Really my 'target offroad competence' would be 4 inches of suspension lift max and possibly 2-3 inches of body lift (possibly because it may be required by a cummins diesel or exotic transmission swap anyway) and then i'd like to take as much of that lift back out again for being on the highway. Or even lower it a bit.


Btw I never even heard of an electronic sway bar disconnect, how does that work? Is there a manual alternative?

[oil pan 4]

I have never seen the powerwagons sway bar disconnect, just the guy who had one bragging about it when he wasn't crying about getting 10mpg with almost $4/gal gas.

Manually unbolting the sway bar for maintenance is fairly simple but not overly easy, I have jack, remove the wheel then use a 9/16 air ratchet and a wrench to remove the link bolt and spacers and related bushings.
Then the anti sway does not go back together as easy as it came apart.

Lowering the vehicle can be good for drive line angles, putting them at almost 0 degrees, or if the angle goes negative its usually no more negative than it was positive, which means its fine.
But then lowering screws up tire camber angles on the tires (if you have IFS or IRS). If you have a solid front or rear axle don't worry about the camber.
If your camber is out then you ride on the inside shoulder of the tire when you go low or if you set the camber with the suspension down it will ride on the out side edge when up, riding on the shoulder with bad camber wears the tires out a lot faster and compromises handling.

Independent suspension gives more ground clearance. That's why they used them on the HMMWV.

Actually I have never looked into how to raise or lower the vehicle aside from rear solid axle to frame air bags.
I would not mind being able to adjust the rear ride height with a load or leave the front end down for 99% of normal driving then lift it an inch or 2 when the weather turns or if I go off road.