crappy ride with no weight

I put in some used RE 3.5 packs and they have settled to about 4 even on both sides. I greased up the bushings and tightened everything once on the ground. Whenever i have over 200 or 300 lbs in the back the jeep seems to ride much smoother and takes bumps much better. The shocks are not maxed out and nothing binds. My question is, Why does the jeep ride better with more weight in the back?

Same question, sort of. Did a search and found this thread, some help would be cool. I have stock rear springs with a full add-a-leaf and 1.5" block. I have a real rough ride in the back. Got new shocks (pro comp es3000) but I think they may not be up to the job. I too noticed a smoother ride with weight. Sorry to jump in you thread sir but maybe we can get our question answered by bumping up the thread.

Hi guys,
I have been running the RE 3.5 packs since i put them on with my 4.5in superflex lift, and i found the same thing was true, when i first got them they were as stiff as anything, when i added weight they were better. so, I talked to the guys at RE, and they explained that the 3.5 full leaf packs are heavy duty springs designed for off road bumpers + rear swing out tire carrier + roof rack, THEN, after all those are added, these springs are ready to be sprung off-road bent, twisted, and pushed...
so here i am I have 30,000 miles on my springs, they are settled, I ran with 400lbs of dog food in the back of my jeep for about 10,000 miles +plus off-roading with it...
They are still stiff, when i took the dog food out, but the ride height is down closer to level. I am in the process of getting my bumper mounted and my spare tire on there to help coushin the ride...
I am running RS3000 nitro, Truck shocks, so maybe depending on your shock, you might be able to break yours in faster... i know mine are kinda stiff, but i plan to haul a trailer around alittle and i do lots of large gravel roads and off roads....
hope it helps...
That's my 2.1 cents... (heh darn inflation)

To me this seems like a common sense question. The heavier a vehicle is the more force it can put on the springs (assuming equal spring rating). I had an old 1978 catilac that sailed like a ship over bumps. It was very heavy with relatively soft springs for its weight. FYI, They used to make vehicles heavy on purpose because it gave them smoother rides (all else equal--spring rating). This, of course, kills gas milage though.

I have RE 3.5" rear leafs and ES3000 shocks. The ride is rough. It is an off-road vehicle so I expected a rough ride. Softer shocks would likely help the problem as would adding weight. Before adding too much weight, consider that you have lifted your vehicle. Its center of gravity has been elevated. Adding too much weight raises that center of gravity even higher and will increase your chances of flipping your jeep over. Anytime you lift a vehicle you want the new springs to be stiff for safety reasons. A lifted vehicle should ride like a sport car, stiff, because both suspensions are built to decrease the chance of a roleover.

Clay

if you want a softer rate, go with tomken 4" leafs. $100 i think cheaper than RE. but i think the RE leafs are better for towing a lot. more weight gives the springs more to push up, and forces them to move more instead of the the body. my RE front springs are about 3.5" after 150lbs of bumper and winch, and they ride good, so...

paul, the rough ride you have in the rear is partially due to the blocks. the axle/block acts like a lever and when you hit a bump, it kinda twists the leaf backward. then moves back straight. which creates a foreward-backward vibration on the leaf. and that solid metal leaf does not absorb the lateral movement; the bushings/ body do. and because your aal is made to compensate the leafs, the still-kinda -weak part of the stock leaf is pretty much isolated to do most of the twisting, so the spring doesen't work as a whole to transmit the vibrations in the same manner. it's not gonna fall off or anything, it will just wear out your bushings a little quicker.

thanx guys

clay said:

Anytime you lift a vehicle you want the new springs to be stiff for safety reasons. A lifted vehicle should ride like a sport car, stiff, because both suspensions are built to decrease the chance of a roleover.

Clay

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ahh not really most people try very hard to find a spring rate that is not too stiff. the reason for this is so that when you off road and flexing on objects your axles can articulate and the body can stay level providing a nicer ride and also keeping the vehicle on all fours. if you have stiff springs like you describe "sports car" style your body will rise with the axle (not realy what you want) getting tires off the ground and getting the body out of level.

auto makers designed sway bars to eliminate the stiff up and down feel of a spring that is trying to keep the body from rolling. a sway bar allows the body to move up and down without much binding but keeps the body from rolling side to side at higher speeds.


with all that being said it is verry common for lift springs to be stiffer because the manufactures compromise ride quality for height (some come verry close to stock ride comfort)

how long have you had the leafs in your truck might take a little longer before they soften up also shock's are a huge part of the ride quality so look into what shocks you are running and if there are any improvements you can make there. take a leaf out of the pack to soften them up a bit

bj-666 said:

with all that being said it is verry common for lift springs to be stiffer because the manufactures compromise ride quality for height (some come verry close to stock ride comfort)

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Not really. Ride quality is mostly a function of spring (and shock) rate, and a spring with more arch for lift can be engineered to the same rate as stock springs. As someone explained above, most of the companies offering lift springs for off-road vehicles assume that the people buying their lifts will probably be adding heavier bumpers, maybe external spare tires, maybe a winch on the front ... in other words, weight. They engineer their springs with a higher-than-stock rate to accomodate this anticipated additional load.

I am aware that many people on this site look for soft, lifted springs. Unless you are trailering or towing you rig to the trailhead, having soupy springs on a lifted vehicle is not safe. In addition to raising the center of gravity and increasing the amount of airflow under your vehicle (thus producing air lift), soft springs will allow the body to roll (magnifying the lateral forces) around corners. At high speeds this means trouble, plain and simiple.

Most of us ditched our rear sway bars when we lifted our vehicle. You can do that with stiff springs, with soft springs you are asking to be rubber side up. Can't really argue with physics.

Clay says "I am aware that many people on this site look for soft, lifted springs. Unless you are trailering or towing you rig to the trailhead, having soupy springs on a lifted vehicle is not safe. In addition to raising the center of gravity and increasing the amount of airflow under your vehicle (thus producing air lift), soft springs will allow the body to roll (magnifying the lateral forces) around corners. At high speeds this means trouble, plain and simiple.

Most of us ditched our rear sway bars when we lifted our vehicle. You can do that with stiff springs, with soft springs you are asking to be rubber side up. Can't really argue with physics."

Maybe you could rephrase your post so it doesn't sound like you're saying that:

1) soft springs raise the center of gravity
2) soft springs increase air flow
3) aero lift is a problem on a Jeep
4) body roll magnifies lateral forces

Can't really argue with physics :exclamati

Basic question, if you have two identical XJs each with 4 to 5 inches of lift one has soft springs and one has stiff springs which one is more likely to roll?

hasta

clay said:

Basic question, if you have two identical XJs each with 4 to 5 inches of lift one has soft springs and one has stiff springs which one is more likely to roll?

hasta

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Its moot, because it doesn't address Max's accurate assessment of your theories...

Back to the original question; why does added weight improve the ride? Every vehicle has a natural suspension frequency determined by the amount of sprung weight and the spring rate at the wheel, including the tire (ride rate). Your perception of ride quality is based on this frequency. If ride comfort is a high priority, engineers shoot for a frequency a little over 1Hz. For a stiffer suspension to improve handling or load capacity, frequencies around 2Hz and above are considered.

Suspension Frequency = 0.159 * SQRT(Ride Rate / Sprung Weight * Acceleration of Gravity)

An increase in sprung weight(more passengers or cargo) or a lower ride rate (softer springs, lower air pressure)will result in a lower suspension frequency and consequently, a softer ride. For a given vehicle, the spring rate will be dictated by the weight of the vehicle and the target suspension frequency.

MaXJohnson said:

Back to the original question; why does added weight improve the ride? Every vehicle has a natural suspension frequency determined by the amount of sprung weight and the spring rate at the wheel, including the tire (ride rate). Your perception of ride quality is based on this frequency. If ride comfort is a high priority, engineers shoot for a frequency a little over 1Hz. For a stiffer suspension to improve handling or load capacity, frequencies around 2Hz and above are considered.

Suspension Frequency = 0.159 * SQRT(Ride Rate / Sprung Weight * Acceleration of Gravity)

An increase in sprung weight(more passengers or cargo) or a lower ride rate (softer springs, lower air pressure)will result in a lower suspension frequency and consequently, a softer ride. For a given vehicle, the spring rate will be dictated by the weight of the vehicle and the target suspension frequency.

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ooohhh you're soooo smart..... really though, thanks. i've wondered before how exactly they determine that.

Put on a nice fluffy set of 12.5/33 TSLs and run em at 20 psi :laugh3: .

Sorry I couldn't resist....I'll go away now :sunshine:

For those who don't know, Acceleration of Gravity = 9.81m/s^2

clay said:

Basic question, if you have two identical XJs each with 4 to 5 inches of lift one has soft springs and one has stiff springs which one is more likely to roll?

hasta

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depends. WHO is riding in the passenger seat ? Oprah, or Jessica Simpson ?

While I like neither of the 2 I'm going with the one Oprah is riding in. Especially if that rig is making a left turn.

Flinstone all the way..