Way soft suspension - arrg!

[rcamacho]

Folks,
I'm running front 4" 3-leaf springs on my '87. I assume they are Tuff-Country Ez-Ride springs due to the very soft rate and number of leaves.
http://coloradok5.com/springratetable.shtml
Shocks are Rancho 5012's on cut-down Ford Superduty towers. Bump stops are set ~3" from the spring plate pads to keep the shocks from bottoming out with the low lift.

So here's the deal. The front suspension is entirely too soft with a BBC and winch on the front. I regularly hit the bump stops on road much less off road. Of course it flexes great and has plenty of droop on the trail. I would move the towers up and increase the bump spacing but the springs would go into negative arch.

So, here's the Q: What's the group recommendation for stock length front springs w/BBC and winch up front to firm up the ride but preserve articulation for what amounts to a dual purpose vehicle?

 

[89GMCSuburban]

I'd swap out springs for a higher rate. You have a lot of weight up there, and HD Tuff Country doesn't even bring the rate back up to stock. Skyjacker is next on the list here on CK5 in the tech section. I love mine, and look at the pic, still flexes pretty well with no mods other than shocks for the lift and the springs.

 

[resurrected_jimmy]

I love my skyjacker 6" springs, I have a warn 12000 and they hold it just fine and still flex well. If you call skyjacker and tell them what you want they will work with you to get the correct spring rate for the amount of weight you have over that axle.

 

[Greg72]

The "HD" Tuff Country springs are about 100 Lb/in stiffer than the EZ rides....from what I recall, they were intended for trucks with heavy winch bumpers (or BBCs).

 

[89GMCSuburban]

Yep, clicky

And the Skyjacker are 100 more over the HD Tuff Country

 

[mtnman210]

on that chart what does "free arch" mean?

 

[Hossbaby50]

The only difference between your current TC EZ Rides and EZ Ride HD's is 1 small leaf on the bottom. Find that 4th leaf and used on here or call TC and see if you can order it. I have HD's on my truck with a heavy winch bumper and a Warn 12K winch. The combo is very heavy and the HD's seem to handle it fine. They have sagged a little but not a hell of alot. If that isn't enough on stiffening then get some Rancho 9000's.

Harley

 

[blasterD]

I run the Skyjacker 4" springs on the front of mine. It has a Diesel and the utility bed puts a lot of weight on the front. My front end weighs 4100 Lbs by its self . The skyjackers ride well with the increased weight, and I only hit the bumps when I really work it offroad. They are also very stable on the road. I am running rancho rs9000 shocks set to about 2 or 3 on the front. IMHO, I don't think that the Rancho 9000s alone will firm it up enough to keep you off the bumps.

 

[Greg72]

on that chart what does "free arch" mean?

Free arch is the amount of arch in the spring (from the spring eye centerline to the bottom of the leafpack) BEFORE they are installed and have any weight on them...

A soft spring will typically have a LOT of free arch, because so much of it is lost once they're installed. If you don't believe me, take a look in my gallery photos... I've got a set of 4" lift springs with almost 9 inches of free arch!!!!

http://www.norcalbigdawgs.net/Gallery/album73

 

[mtnman210]

Free arch is the amount of arch in the spring (from the spring eye centerline to the bottom of the leafpack) BEFORE they are installed and have any weight on them...

A soft spring will typically have a LOT of free arch, because so much of it is lost once they're installed. If you don't believe me, take a look in my gallery photos... I've got a set of 4" lift springs with almost 9 inches of free arch!!!!

http://www.norcalbigdawgs.net/Gallery/album73

ok that makes sense. I just couldn't figure out what it was--thanks

 

[79k20350]

you can buy just the 4th leaf from ord to stiffen up your pack, cheapest/ easiest way...

 

[beater_k20]

If that isn't enough on stiffening then get some Rancho 9000's.

shocks arent designed to carry weight, that's why you have springs. if the AAL to upgrade to TC HDs isnt enough, you need to look into a stiffer spring. trying to compensate with a stiffer shock will wear the shock out prematurely, or break the mounts. either way, not a good way to try and fix the problem.

 

[79k20350]

using stiffer shocks will slow the compression of the spring, allowing you ro use slightly softer springs, have you heard of people having problems with 9012 shocks because they were to stiff?

 

[Triaged]

Just move the bump stops up some. Going into negative arch isn't the definition of what will ruin a spring.

 

[mouse]

The only difference between your current TC EZ Rides and EZ Ride HD's is 1 small leaf on the bottom. Find that 4th leaf and used on here or call TC and see if you can order it. I have HD's on my truck with a heavy winch bumper and a Warn 12K winch. The combo is very heavy and the HD's seem to handle it fine.

Harley

I'm in the same boat....Maybe someone has removed the extra leaf and could sell it to you.

 

[ntsqd]

Just move the bump stops up some. Going into negative arch isn't the definition of what will ruin a spring.

Have to disagree there. Reversing the arch is the best way to kill a leaf spring short of kinking it. May not break it right away, but it will take the set (ride height) out of them. Anyone over @ Deaver Spring will confirm this. Ideally the limits are set so that they never can go to perfectly flat, should always have a little arc left in them - even when bottomed metal to metal.

 

[Triaged]

Have to disagree there. Reversing the arch is the best way to kill a leaf spring short of kinking it. May not break it right away, but it will take the set (ride height) out of them. Anyone over @ Deaver Spring will confirm this. Ideally the limits are set so that they never can go to perfectly flat, should always have a little arc left in them - even when bottomed metal to metal.

Then how do you explain the factory leaves They are at negative arch at ride height. The guys at Deaver (just like everyone else) go by that as a guestimate. I don't see how arch would have anything but a secondary influence to spring strength.

I will have to dig out the equation for leaf spring stress. Thinner leaves will lower the stress in the leaves.

From Race Car Vehicle Dynamics p.772

Bending Stress = 6lF/nbt^2 , psi

They also state that yield for a typical passenger car spring is from 90,000-100,000psi.

If you rearrange the formula to solve for the force (F) you could then get the deflection from the spring rate and the free arch.

 

[89GMCSuburban]

The factory springs have no arch to them when new, so there's no pre-set arch to actually reverse. That's why they are ok to run like that.

Harder shocks may slow compression of the spring....but the springs will still sag in the end. Shocks won't change that.

 

[Triaged]

The factory springs have no arch to them when new, so there's no pre-set arch to actually reverse. That's why they are ok to run like that.

So if you bought some 2.5" springs that have just about no arch to them and are flat at ride height should you make the bump stop not allow any bump travel? This just isn't a logical line of thinking. Arch isn't anything "special". There is nothing "special" that happens when a spring inverts.

 

[89GMCSuburban]

Those springs are close to flat, and most instructions do not require bump-stops to be lowered. You said it yourself, "They don't have much arch and are level at ride height." The idea that it's ok to invert a spring that has 5 to 6" of arch isn't exactly sound.

You want logical proof? Go get a spring pack with that kind of arch and put it in a press. Load it down till it goes into negative arch and then let it back up and tell me if the spring is ok...if it doesn't fly out and kill you first. Just look around online. People have problems when springs invert, including the shackles locking the spring in that inverted state. If anything is logical, it sure ain't your thinking on this topic.