The Lumpskie Build - '96 5-speed

Have you looked at Rancho or Skyjacker? Both of those companies have been making leaf packs for years and they just work. I like Skyjacker personally, they seem to have one of the better rides for full size vehicles, Rancho's are reported to be a little stiff.

 

I'm confused...
Not looking to argue but rather to understand.

I thought that unless you changed the mounting point or got different length shackles or flipped the shackles or otherwise changed the geometry that you would want the same length top leaf.

I thought that by lifting your vehicle you were just changing where the ride height sat in the natural cycle of the leaf springs.

Essentially, that's what I did in making my bastard packs. I reused the top leaf of my stock pack and added leafs to make it sit higher at ride height and retain a better arch.

School me on what I'm missing here..

 

Arching a pack of leafs pulls the eye to eye closer together, which in turn pulls the shackle angle to a negative angle. Lengthening the main spring will alleviate the shackle angle.

In Lumpskies case, his springs are under the axle. Stacking leafs has no lift effect at all, it's all about the arch. The arch has to be increased so much to achieve lift that the main leaf needs to be longer.

On the Tacoma's, it's a spring over, so stacking leafs will increase lift by the thickness of the leaf as well as any arch that happens to be in the leaf. There should still be a longer leaf in this case to maintain the lift but as most of the lift is achieved by extra leafs, it's minimal at best. This is the biggest drawback I am seeing to factory lifted leafs for Tacoma's is the lack of proper arching and length. I see lots of thin flexy leafs stacked together, rides great at first but unable to maintain the arch and they end up with a "wavy effect" over time.

 

Actually I think the Wagoneer has spring under in the front and spring over in the rear. But The main leaf still needs to be longer in either case. I guess what I'm getting at is a lifted set of springs should have just enough leafs in it to control the ride, hold a load and still be long enough to have the shackles perform as they should.

Edit:
This guy says it better than me. First paragraph.
http://www.4wheelparts.com/buyers-guide-reviews/lift-kit-how-to-leaf-springs.aspx

 

But a longer spring, given the same shackle length and frame mounts will necessarily limit compression no?

Greater chance of breaking things if springs won't flatten to full length?

 

Yes, it will limit compression, but you also have bigger tires, so you don't need all that compression. This is why there are longer bump stops available.

However, in most cases where the lift is designed correctly, you will get more range of motion with the lift, IE: more wheel travel.

 

so what you're after is the same shackle angle at ride height?

to change the ride height, I can see that you're either going to have to change the shackle angle or the arc length of the spring.

 

I drew a little picture to help me understand and visualize...

Green is ride height... Blue is droop... Red is compression
each arc is the same length end to end along the path of the arc.

 

Excellent visual aid.

 

I would think you'd want to be careful about going too much longer with the springs...

I was at a shop just yesterday and they had gotten some springs for a nissan (spring under if that matters) and they were too long. It caused it to actually sit lower. I think the fix was shorter springs with a greater arch.

Here's the same picture as above with the addition of a longer set of leafs.
The yellow lines are the longer set with the shackle at the same 3 angles.


1. It looks like longer leafs will give you a smaller range of travel overall
2. If the top spring can't flatten/go inverted at full stuff it seems like you'd better limit the uptravel as you mentioned with some tall bump stops or you're likely to break stuff.

of course this is all just theory in my head combined with geometry and autocad

 

There comes a point of too much arch and length. Like trophy trucks that have a half circle of leaf spring to get 18" of lift. Looks cool but useless outside of the arena. Its a delicate balance for sure on the main leaf length, arch, shackle position/length, travel, etc...however there are known lengths ands Arch's for certain early iron 4x4s. Jeeps, scouts, Chevy, ford, dodge all had manufacturers of lift kits that offered similar levels of lift.

 

I edited my last post with additions to the drawing after you replied.

It seems your reply fit with my edited post though


Now add the wrinkle that 2nd gen tacomas use an inverted shackle and you muddy the waters even further.


makes me want to draw my rear suspension to correct dimensions and see whats what

 

You would want to match spring length to shackle length though. Doesn't make sense to change spring length on the same shackles. Similar reason as to why you shouldn't change shackle length on the same springs, as I learned. Do that same drawing, but add longer shackles to the longer springs. Longer springs will give you more travel with longer shackles.

 

You shouldn't need longer leafs man. Bolt them on, they will be fine.

Basically what happens, as in every lift, you are basically move the axle down the travel. So with 2" of lift your loosing 2" of droop bit gaining 2" of up travel. If that makes sense. You aren't going to gain any travel with a stock length spring and stock shackles. You should only lengthen the leafs if your lengthening the shackles

or you'll have to move the actual shackle mounts themselves to compensate for the arch on the leafs.


Id slap them in. I bet they are just fine.


All aside. Nice chatting with you! Sorry I didn't get to meet up. Just got into town

We wI'll meet up sometime!

 

Good replies here! Like you guys already discussed, there are two ways to make a lift spring.

1. Make a stock length spring and arch it more dramatically. This draws your two mounting points together. (you can flatten the spring with a floor jack to install... typically) At ride height you shackle angle will be changed when you do this. (It will be at the same angle as if you drooped your axle the same amount as your lift)

2. Add length to the main leaf so that you have added height and your two mounting points are in the same position as stock. This approach maintains stock shackle angle.

So, this situation is a little more complicated than a 1st gen taco setup because the Jeep uses an inverted shackle (like second gens) and also mounts the shackle in a short "box". This box has raised edges for structural rigidity. The stock shackle angle is basically straight up and down at ride height. The problem I have is that, to line my shackle up with the narrower mounting points on the spring, I have to pull my shackle all the way forward. THEN I have to jack the truck up (when the spring end shimmed) and put all the weight of the truck on the spring to flatten it out to get the eye to line up. (I still can't get it to line up) If you do that, you preload the spring, just like a 5100 will do on your front end. Also, on extension my shackle will imping on the front of the box... just like on install. I really need the shackle to have a stock-like range of motion to keep that from happening.

Kind of like what Brett and Brett said... If you go with a longer shackle without changing the spring length, you'll affect the angle. Also, if you shorten the eye to eye length of the spring, without changing the shackle length, you'll affect the angle.

At least that's my theory... we'll see what Bill says today.

 

I test fit the front springs yesterday. They fit fine. I had to flip the shackle but I could get everything to line up.
If the rear springs fit like this, I would just run them:

So I called Bill and told him my issue. He said he'd build me a new main leaf to my specs, for free. I'll pick them up in Grand Junction on Thursday. (really I can't complain about Alcan's customer service, they are always eager to help) I'll let you guys know how everything turns out when I install them.

 

If you don't mind me asking, what kind of shape are those old waggy springs in, and what are your plans for them after the new ones go in? If you are interested in parting with just the front (ill take all 4 if the price is right), PM me if you want to sell them im looking at running waggy springs for my SAS.

 

^The fronts are in really good shape... and I'd be interested in selling to you. I'll send you a pm.

 

Some truck random shots from my last trip: