Add-a-leaf vs. driveshaft angle

[Armo325]

I need some help from all you lifted suspension experts.  I did a quick search but the info is pretty dated.  I'm currently riding on a 6" Gen 2 Fabtech suspension lift.  The lift also levels the truck but I prefer the factory rake.  I'm planning on adding a leaf in the rear to raise it slightly.  My questions:

 

1. Do I need to change anything else in the rear suspension to account for the changed driveshaft angle that will come from the added leaf spring?  I currently have the "standard" tapered block that comes with the kit - I'm going from memory but it's around 5" on the thicker (back) end.

 

2.  Assuming the previous answer is "yes," will I need to get a different block or add shims? I know the change in angle is small but I'd like to give my U-joints the best angle possible.

 

3.  Finally, what are your thoughts on other, possibly better ways to raise the rear end slightly?  I'm looking for a small difference from the current stance - to raise the rear end 1 to 2 inches, at most.

 

Thanks in advance.

[Darksky]

My FabTech lift provided plenty of angle to accommodate the addition of a leaf to the pack. 

 

I would avoid using an “Add a Leaf” in favor of finding a shop that makes springs/suspension components. Have them make you a single full length leaf to add into your existing pack with the correct spring rate. They will have the correct spring information in a database and should be able to make you a leaf pretty inexpensively. Probably cheaper than an add a leaf kit.

 

In in my experience, just adding a short, thick leaf  makes the spring rate weird, so that the springs get very stiff after being compressed past a certain point. This makes the ride suffer. Add a leaf or overload springs are designed to keep the springs from “bottoming out” while under heavy load, not just to give you additional height.

 

With the addition of the heavier coil overs in the front, I was glad to beef up the rear springs a bit instead of just adding a block. I have 50K miles on my suspension since adding the FabTech lift and the additional leaf, without any issues and my truck rides like a dream.

[FootballCoach53]

7 hours ago, Darksky said:

My FabTech lift provided plenty of angle to accommodate the addition of a leaf to the pack. 

 

I would avoid using an “Add a Leaf” in favor of finding a shop that makes springs/suspension components. Have them make you a single full length leaf to add into your existing pack with the correct spring rate. They will have the correct spring information in a database and should be able to make you a leaf pretty inexpensively. Probably cheaper than an add a leaf kit.

 

In in my experience, just adding a short, thick leaf  makes the spring rate weird, so that the springs get very stiff after being compressed past a certain point. This makes the ride suffer. Add a leaf or overload springs are designed to keep the springs from “bottoming out” while under heavy load, not just to give you additional height.

 

With the addition of the heavier coil overs in the front, I was glad to beef up the rear springs a bit instead of just adding a block. I have 50K miles on my suspension since adding the FabTech lift and the additional leaf, without any issues and my truck rides like a dream.

Are there AAL kits that actually add the long spring as opposed to the short spring?  I'm actually considering the AAL because I did the 6.5" lift from Zone, but I don't want to have any sag when I tow the boats/load the bed.

[Armo325]

9 hours ago, Darksky said:

My FabTech lift provided plenty of angle to accommodate the addition of a leaf to the pack. 

 

I would avoid using an “Add a Leaf” in favor of finding a shop that makes springs/suspension components. Have them make you a single full length leaf to add into your existing pack with the correct spring rate. They will have the correct spring information in a database and should be able to make you a leaf pretty inexpensively. Probably cheaper than an add a leaf kit.

 

In in my experience, just adding a short, thick leaf  makes the spring rate weird, so that the springs get very stiff after being compressed past a certain point. This makes the ride suffer. Add a leaf or overload springs are designed to keep the springs from “bottoming out” while under heavy load, not just to give you additional height.

 

With the addition of the heavier coil overs in the front, I was glad to beef up the rear springs a bit instead of just adding a block. I have 50K miles on my suspension since adding the FabTech lift and the additional leaf, without any issues and my truck rides like a dream.

 

This is great.  Thank you.  Did you use"off the shelf" springs for the front or have a shop fabricate those, too?

[Darksky]

The FabTech lift kit uses Eibach springs on the coilovers.  Eibach is pretty well known for their suspension products.

[Darksky]

Football Coach;

it is my understanding that AAL are usually a thick, arched short spring designed to fit at the bottom of the spring pack. As the factory springs are compressed they settle down onto the AAL and it supports them providing a longer “footprint” for the springs to rest on than the factory pad or the top of the block. The AAL is thicker and stiffer, that’s how it supports the factory springs, but it is also where potential problems can arise.

-the factory spring is designed to flex with it only being supported in the center, by extending the support out to the end of the AAL, it is creating two new points along the spring where the bulk of the weight is now concentrated, this potentially causes wear issues to the factory spring. Some guys have even described cracking to the factory springs at that point.

- having that thicker, more rigid spring under the pack, limits range of movement by changing the flex point to the spots above the ends of the AAL. That makes the springs have softer factory spring rate until the spring bends enough to rest upon the ends of the AAL, then the spring rate becomes very stiff. The ride then suffers, because once they compress enough to rest on the AAL, it gets much stiffer.

 

There are overload springs, that you can buy, which ride on top of the existing pack, they have clevises that hook onto the factory springs and support the pack from the top, these certainly work better, but you won’t get any height from them.

 

if you look at a 3/4 or 1 ton truck they have a thicker spring pack with more leaves. I believe my 1500 High Country only had three full length leaves.  The local truck spring shop literally took less than an hour to look up  the spring stats on my truck, cut two additional full length  leaves, drill them for the pins and  pads on the upper side of each end so they wouldn’t squeak. He also gave me new threaded pins and keepers. He told me to put the new leaves under the lowest of the main leaves, but above the shorter, thick leaves.  All of this for $60 bucks.

When the lift kit was being installed , the tech took a couple of extra minutes to add the extra leaf.  NOw my rear spring pack looks more like a 3/4 ton. Easy Peasy.

[FootballCoach53]

Football Coach;
it is my understanding that AAL are usually a thick, arched short spring designed to fit at the bottom of the spring pack. As the factory springs are compressed they settle down onto the AAL and it supports them providing a longer “footprint” for the springs to rest on than the factory pad or the top of the block. The AAL is thicker and stiffer, that’s how it supports the factory springs, but it is also where potential problems can arise.
-the factory spring is designed to flex with it only being supported in the center, by extending the support out to the end of the AAL, it is creating two new points along the spring where the bulk of the weight is now concentrated, this potentially causes wear issues to the factory spring. Some guys have even described cracking to the factory springs at that point.
- having that thicker, more rigid spring under the pack, limits range of movement by changing the flex point to the spots above the ends of the AAL. That makes the springs have softer factory spring rate until the spring bends enough to rest upon the ends of the AAL, then the spring rate becomes very stiff. The ride then suffers, because once they compress enough to rest on the AAL, it gets much stiffer.
 
There are overload springs, that you can buy, which ride on top of the existing pack, they have clevises that hook onto the factory springs and support the pack from the top, these certainly work better, but you won’t get any height from them.
 
if you look at a 3/4 or 1 ton truck they have a thicker spring pack with more leaves. I believe my 1500 High Country only had three full length leaves.  The local truck spring shop literally took less than an hour to look up  the spring stats on my truck, cut two additional full length  leaves, drill them for the pins and  pads on the upper side of each end so they wouldn’t squeak. He also gave me new threaded pins and keepers. He told me to put the new leaves under the lowest of the main leaves, but above the shorter, thick leaves.  All of this for $60 bucks.
When the lift kit was being installed , the tech took a couple of extra minutes to add the extra leaf.  NOw my rear spring pack looks more like a 3/4 ton. Easy Peasy.

Thanks, man! I’ll double check and see if my shop can do that.


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[Tyy1907]

On 02/04/2018 at 6:05 PM, Darksky said:

Football Coach;

it is my understanding that AAL are usually a thick, arched short spring designed to fit at the bottom of the spring pack. As the factory springs are compressed they settle down onto the AAL and it supports them providing a longer “footprint” for the springs to rest on than the factory pad or the top of the block. The AAL is thicker and stiffer, that’s how it supports the factory springs, but it is also where potential problems can arise.

-the factory spring is designed to flex with it only being supported in the center, by extending the support out to the end of the AAL, it is creating two new points along the spring where the bulk of the weight is now concentrated, this potentially causes wear issues to the factory spring. Some guys have even described cracking to the factory springs at that point.

- having that thicker, more rigid spring under the pack, limits range of movement by changing the flex point to the spots above the ends of the AAL. That makes the springs have softer factory spring rate until the spring bends enough to rest upon the ends of the AAL, then the spring rate becomes very stiff. The ride then suffers, because once they compress enough to rest on the AAL, it gets much stiffer.

 

There are overload springs, that you can buy, which ride on top of the existing pack, they have clevises that hook onto the factory springs and support the pack from the top, these certainly work better, but you won’t get any height from them.

 

if you look at a 3/4 or 1 ton truck they have a thicker spring pack with more leaves. I believe my 1500 High Country only had three full length leaves.  The local truck spring shop literally took less than an hour to look up  the spring stats on my truck, cut two additional full length  leaves, drill them for the pins and  pads on the upper side of each end so they wouldn’t squeak. He also gave me new threaded pins and keepers. He told me to put the new leaves under the lowest of the main leaves, but above the shorter, thick leaves.  All of this for $60 bucks.

When the lift kit was being installed , the tech took a couple of extra minutes to add the extra leaf.  NOw my rear spring pack looks more like a 3/4 ton. Easy Peasy.

Nice tip.  I'm contemplating this avenue.  Only possible drawback would be when ur springs wear out (which takes quite awhile granted) you'd have to put in another custom leaf.  Whereas a higher block won't wear out.

[sdeeter19555]

I've seen main leaves bent from using AALs and some moderate offroading... they have their place, but are not perfect.

2012 2500hd 6.0l CCSB 4wd