Jeep Enthusiast Forums banner
41 - 57 of 57 Posts

·
Mopar Nut
Joined
·
586 Posts
Airbags (air springs) need a different shock valving than a regular coil spring.
Just to clarify - what I am referring to as an "air bag" in this thread are the AirLift helper springs that are inserted inside the existing coil, not replacements for the coil.

Furthermore, I would agree with a higher spring rate if this is a regular issue for the OP. In my case, towing and hauling gear up north 6-8x a year isn't enough for me to change my ride quality overall. The load assist bags serve my purpose just fine....
 
  • Like
Reactions: Delta0

·
Registered
Joined
·
368 Posts
Just to clarify - what I am referring to as an "air bag" in this thread are the AirLift helper springs that are inserted inside the existing coil, not replacements for the coil.

Furthermore, I would agree with a higher spring rate if this is a regular issue for the OP. In my case, towing and hauling gear up north 6-8x a year isn't enough for me to change my ride quality overall. The load assist bags serve my purpose just fine....
We are on the same page.

How much do you ballast up your WJ (in pounds)? If you know?

If you need an air bag (air lift coil spring) to handle the additional load, you have enough load on there that I'd consider figuring out your axle weights empty and full, and recalculating your tire pressure accordingly.
 

·
Registered
Joined
·
2,424 Posts
We are on the same page.

How much do you ballast up your WJ (in pounds)? If you know?

If you need an air bag (air lift coil spring) to handle the additional load, you have enough load on there that I'd consider figuring out your axle weights empty and full, and recalculating your tire pressure accordingly.
Tire pressures are easy peasy.

Work out the ground to rim distance from the static loaded radius.
Then blow the tyres up to the pressure needed to get that distance with the load you have on the tyre.

You will almost certainly end up with different pressures across the axle.
 

·
Mopar Nut
Joined
·
586 Posts
How much do you ballast up your WJ (in pounds)? If you know?
I can't state exactly, as I never actually weighed it. But I am fairly good at estimating. I'm also pretty careful about keeping my loads balanced. When I go up north, I generally carry 1000Lbs of gear, which nearly completely compressed the rear springs. She would wander on the freeway, and a good "whoop" would hit the bump stops. When I towed my gear trailer or boat, all the gear is in the trailer/boat. Trailer has a tongue weight of 350, boat 500. Both sunk the springs a bit, but not enough to hit the bump stops. None the less the boat would give the tail a bit of waggle and sway (no load distributing hitch on either the boat or trailer).

With 30psi in the bags, I have carried 2000Lbs of gear and firewood in the cargo hold. While the springs still sagged, I never hit the bump stops on my 120mi ride up north. With just the 1000Lbs of gear, there is about a 1.5" of sag (Keep in mind the full 30psi with no load will raises my rear .75", so we are really only sagging by .75" from factory). With the boat, there is no noticeable sag, and minimal sway from the tail. Your barely even notice she is back there on the freeway.

I think my 2000Lbs estimate is pretty accurate, as I also once carried 32 bags of 60Lbs mulch in the cargo hold and roof rack up north which comes to 1920Lbs. Once again, keep in mind this is NOT what these bags are deigned for - I am abusing the bags and the Jeep. AirLift makes no claims of increasing load capacity, and I am clearly overloading my Jeep....

I usually only haul all this gear and tow in the summer. Assuming roads are dry, I generally run my tires pretty firm in the summer, up to 44psi. I think the factory spec is 29psi. 44psi gains me about 0.5mpg. I have not looked at tire psi or sidewall bulge when I carry all this stuff, probably a good thing for me to check next time.
 
  • Like
Reactions: Delta0

·
Registered
Joined
·
2,424 Posts
I can't state exactly, as I never actually weighed it. But I am fairly good at estimating. I'm also pretty careful about keeping my loads balanced. When I go up north, I generally carry 1000Lbs of gear, which nearly completely compressed the rear springs. She would wander on the freeway, and a good "whoop" would hit the bump stops. When I towed my gear trailer or boat, all the gear is in the trailer/boat. Trailer has a tongue weight of 350, boat 500. Both sunk the springs a bit, but not enough to hit the bump stops. None the less the boat would give the tail a bit of waggle and sway (no load distributing hitch on either the boat or trailer).

With 30psi in the bags, I have carried 2000Lbs of gear and firewood in the cargo hold. While the springs still sagged, I never hit the bump stops on my 120mi ride up north. With just the 1000Lbs of gear, there is about a 1.5" of sag (Keep in mind the full 30psi with no load will raises my rear .75", so we are really only sagging by .75" from factory). With the boat, there is no noticeable sag, and minimal sway from the tail. Your barely even notice she is back there on the freeway.

I think my 2000Lbs estimate is pretty accurate, as I also once carried 32 bags of 60Lbs mulch in the cargo hold and roof rack up north which comes to 1920Lbs. Once again, keep in mind this is NOT what these bags are deigned for - I am abusing the bags and the Jeep. AirLift makes no claims of increasing load capacity, and I am clearly overloading my Jeep....

I usually only haul all this gear and tow in the summer. Assuming roads are dry, I generally run my tires pretty firm in the summer, up to 44psi. I think the factory spec is 29psi. 44psi gains me about 0.5mpg. I have not looked at tire psi or sidewall bulge when I carry all this stuff, probably a good thing for me to check next time.
AS I see it, your boat's 500 on the hook puts about 750 on the axle.
If you want to work it out, multiply boat's nose weight by 1+(distance from hook to axle centre divided by wheelbase)
 

·
Registered
Joined
·
83 Posts
How many cars have factory airbags, Dump trucks, Rvs? There is no right spring for a variable weight. Springs have fixed rates of compression, even progressive springs, Air bags insert into the spring as a system that allows you to vary the springrate by air pressure. They are specifically designed and used for load handling and reduce squat from acceleration or weight. Plus it's cheap and easy to install
 

·
Registered
Joined
·
83 Posts
How many cars have factory airbags, Dump trucks, Rvs? There is no right spring for a variable weight. Springs have fixed rates of compression, even progressive springs, Air bags insert into the spring as a system that allows you to vary the springrate by air pressure. They are specifically designed and used for load handling and reduce squat from acceleration or weight. Plus it's cheap and easynstall
 

·
Registered
Joined
·
2,424 Posts
How many cars have factory airbags, Dump trucks, Rvs? There is no right spring for a variable weight. Springs have fixed rates of compression, even progressive springs, Air bags insert into the spring as a system that allows you to vary the springrate by air pressure. They are specifically designed and used for load handling and reduce squat from acceleration or weight. Plus it's cheap and easynstall
Is "Springs have fixed rates of compression, even progressive springs"
strictly correct when you apply it to airbags please Br?

To my way of thinking,
when you load your suspension
until your airbag is half it's original height,
you get twice the original spring rate.

I see the above as one of the big pluses to airbags.

If I've got that wrong, please tell me where I've gone wrong?
 

·
Mopar Nut
Joined
·
586 Posts
Do you blow your tyres up to 30psi before you load up please Mr B?
I usually only haul all this gear and tow in the summer. Assuming roads are dry, I generally run my tires pretty firm in the summer, up to 44psi. I think the factory spec is 29psi. 44psi gains me about 0.5mpg. I have not looked at tire psi or sidewall bulge when I carry all this stuff, probably a good thing for me to check next time.
 

·
Mopar Nut
Joined
·
586 Posts
Factory Spec in my Operating Information booklet for 235/65HR17 tyres is 33psi Mr B.
It says the same on the Driver's B-post.
Factory "recommend" spec. I have my own spec. Soft in winter, hard in summer. Been running like that for 30+ years. Especially with chunky tread block truck tires. Slight MPG improvement in summer, a little more compliant in cold weather. I also run 245/70-16.
 
  • Like
Reactions: Delta0

·
Registered
2002 WJ 4.7
Joined
·
2,484 Posts
Discussion Starter · #57 ·
Here's an update. I installed some Clayton 4.5" coils I got from Kolak and fabbed some steel to fit Timbren bump stops (PN ABSJFTJ). I haven't tested it on any trails yet but that should happen soon. However, going over this huge dip in the road by my house, I can definitely tell the difference and the bump stop engagement feels much better. Thank you all for the suggestions.

Automotive tire Shelf Tread Synthetic rubber Gas
 
41 - 57 of 57 Posts
Top