Why lower a truck?

[othrgrl]

Take a spring. Compress it. It becomes stiffer. Spring rate is the same but it's like having it flexed out. You lose travel and it wraps the rear of the leafs about 5". Your putting the spring way further into it's operating capacity than without a shackle. Your truck corners better due to a stiffer rear. Less body roll comes with that too

Shackles don't compress your springs, they simply move the rear eyelet up. Once again you still have the same spring and the same weight, therefore the spring is loaded the same amount and operating in the same area of it's capacity.

Longer shackles will give you more travel - offroaders have been using longer shackles for years to get more flex out of leaf springs. The shackle should be at a 90* angle to the spring with the truck static, as the spring compresses the rear eyelet gets further from the front, as it arches it gets closer - the longer the shackle the further the spring can flatten and arch and the more flex you will get. If anything longer shackles will remove binding from the rear suspension and make it softer. Go read around on some offroad sites about suspension geometry and the physics. Here is one place to start.

Here is my Bronco II, without longer shackles I would have never gotten near this flex out of the spring pack I had on it. I had to keep them in the hole for the shortest setting to keep the tire out of the fender (purposely causing it to bind and limit flexing):

My truck corners better because the center of gravity is lower, the wheelbase is wider and the traction bars being preloaded stiffens the rear suspension.

If you still don't believe me take something flat and lay across the top of the spring eyelet to eyelet and measure down to the top of the spring pack, then install drop shackles and do it again - the measurement will be very close to if not the same because the spring is compressed the same amount.

 

[TrentNell]

When you put longer shackles on it the spring is compressed more because it has to go higher up to mount which would make it ride stiffer...This is my thinking towards it. My truck rides way stiffer then it did with stock shackles.

weight is the only thing that can compress a srping more not mounting. a shackle is simply moving a mounting point . i am not debating that your truck rides stiffer just trying to figure out why . now spring angle might affect the arc of the suspension travel due to the extra length of the shackle but usually as long as the front spring eye has not changed it is what determains the arc.

 

[Utahski]

These trucks have quite a bit of rake. A 53 gal fuel tank is about 6' long and mine has a completely flat bottom with no bevel up forward. There're probably at least 5 or 6 gallons the pickup never even sees. I'll be lowering the truck to get the fuel tank more level.

 

[othrgrl]

These trucks have quite a bit of rake. A 53 gal fuel tank is about 6' long and mine has a completely flat bottom with no bevel up forward. There're probably at least 5 or 6 gallons the pickup never even sees. I'll be lowering the truck to get the fuel tank more level.

That's one reason I've never heard or thought of.

 

[Big Block 88]

I don't see how moving the mounting position of the spring affects anything. I have lifted trucks never lowered them, and all a new shakle does is move the mounting point up or down on the truck. How can the spring be more compressed when the shackle oves up? Did you have to bend the spring into position? I would bet that the harsh ride is because of the shocks, usually the more they compress the stiffer they get. How close are you guys to your bump stops?

 

[RENODMAX]

You are only moving one mounting point. The spring is still bound to the axle and the front hanger. If you were moving two mounting points thatd be a different story.

Edit: for those of you that are in dsagreement, look at leaf spring curve rate. Ill find some stuff on that for you to, or do your own reading. I am not against drop shackles, but they absolutely change the curve rate of a spring, thats how they lower the truck. If you have ever honestly looked into building your own leaf spring setup and want a smooth ride, you look for a relatively smooth even curve rate in a spring. When you lower our trucks with shackles the front half of the spring is near flat while the rear comes up at a steep angle towards the shackle. Go look at your lowered trucks leaf spring pack.

 

[Utahski]

That's one reason I've never heard or thought of.

With such a long tank on a slant there's always several gallons in front of the pickup that can never be used. On a trip it'll go about 900 miles between fillups without worrying, but I'd still like to use more of the fuel in there.

 

[Fat_Robi]

You are only moving one mounting point. The spring is still bound to the axle and the front hanger. If you were moving two mounting points thatd be a different story.

Edit: for those of you that are in dsagreement, look at leaf spring curve rate. Ill find some stuff on that for you to, or do your own reading. I am not against drop shackles, but they absolutely change the curve rate of a spring, thats how they lower the truck. If you have ever honestly looked into building your own leaf spring setup and want a smooth ride, you look for a relatively smooth even curve rate in a spring. When you lower our trucks with shackles the front half of the spring is near flat while the rear comes up at a steep angle towards the shackle. Go look at your lowered trucks leaf spring pack.

The reason the front is relatively flat and the rear comes up at a steep angle is not because it is bending it up but because it is rotating the back of the spring up bringing the axle up which makes the front part of the spring flatter and increases the angle of the rear portion. The curve of the spring does not change. Here is a rough drawing, same curve it just looks steeper. Now it is possible that changing the orientation of the spring makes it stiffer, not the change of the curve. If the same spring were rotated up 45 degrees is would function entirely different.

Where is killerbee to give an overly technical explanation when you need him.

 

[Bentley]

When you change the angle of the spring you have also changed how the axle pushes against the spring. A leaf spring works best when weight is applied at a 90* angle, when we add drop shackles we effectively change this angle to say 80-85* so when we hit a bump some of that energy will not be absorbed by the spring. Thus giving you a "stiffer" ride.

 

[Turbo Buick 6]

As the angle of the spring changes the ride would become more stiff, if you take it to an extreem, but the few degrees a we are dealing with won't make a difference.

 

[Bentley]

As the angle of the spring changes the ride would become more stiff, if you take it to an extreem, but the few degrees a we are dealing with won't make a difference.

That's just the point I am trying to make. But I do think some of the energy is being transferred to the frame because the spring cant absorb it. With my drop shackles I feel the little bumps are more pronounced now, but the big ones feel the same.

 

[Turbo Buick 6]

That's just the point I am trying to make. But I do think some of the energy is being transferred to the frame because the spring cant absorb it. With my drop shackles I feel the little bumps are more pronounced now, but the big ones feel the same.

I was screwing around while posting so your post was not up when I started:rofl:

Same idea. I have not noticed a difference. With the drop shackles on my farthers lightning the ride got smoother. In theory if you can get the front of the spring a little higher than the back it would ride the smoothest since a bump not only thrusts the axle up but also slightly back.

 

[NJ_LLY]

What are you doing for shocks with a 3" drop in the rear?

 

[Righteyeblind]

What are you doing for shocks with a 3" drop in the rear?

I left mine the same with plenty of travel left. Probably be the best bet to get shorter shocks

 

[paint94979]

I left mine the same with plenty of travel left. Probably be the best bet to get shorter shocks

I believe Pat was looking for a shorter shock with no avail?

 

[TrentNell]

I believe Pat was looking for a shorter shock with no avail?

i couldnt find any either that were vaved for a 3/4 ton truck anyway . plenty with the right length . the bilstiens i ended up runing in the rear are actually a shock used for the front with the dual shock kit they work quite well but are not a direct bolt up a little to short for the passenger side mounts . for all looking for shocks measure the passenger side it is longer by a few inches maybe 3-4". but as stated 3" drop the stock length still work .

 

[Fat_Robi]

I was screwing around while posting so your post was not up when I started:rofl:

Same idea. I have not noticed a difference. With the drop shackles on my farthers lightning the ride got smoother. In theory if you can get the front of the spring a little higher than the back it would ride the smoothest since a bump not only thrusts the axle up but also slightly back.

Somebody should try moving the front hanger up on the frame instead of a longer shackle in the rear to lower it and see how it rides.