Basically in a suspenion lift you are increasing the distance between the axles and the frame of the vehicle. This allows for more articulation of the axles, and will allow room for bigger tires, which will give you greater ground clearance.
To understand the basics of a suspension lift, we need to look at all the parts involved. We need to look at how the axles are connected to the frame, and what we can do to increase the distance between them.
On the stock bronco the axle is attached at several places:
- Radius arms
- Tracking bar
- Pitman arm
- Drive Line
The Radius Arms attach to the frame rear of the front axles, and to the axle via a "c-bushing" to wedges on the front axle.
The Coils are retained in cups attached to the axle and the frame
The Tracking bar connects to the passenger side of the axle, and to the frame on the drivers side.
The pitman arm attaches the steering via the drag link to the steering box.
The shocks attach to the radius arm and to the frame.
The front driveline connects to the front axle at the pinion and to the frame through the transfercase.
There are only a couple things holding the axle to the frame in the rear:
- Leaf Springs
- Drive Line
The Leafs Springs are attached to one spot on the axle and two spots on the frame at each side.
The rear shocks are attached to the axle and the frame at one spot each for both sides.
The rear driveline is attached to the axle at the pinion and to the frame through the transfercase.
To address these components, there are the following options:
Coils - These are available in progressive rate, and linear rate, and available in various sizes according to the lift you are after (ie. 2-2 1/2", 3.5", 5.5").
- Linear - Coils are spaced evenly through the range of the spring. This provides a fairly consistent spring rate throughout the full travel of the spring.
- Progressive - Coils are wound tighter at the top of the spring. The result is that on compression the springs progressively get more stiff. On extension the opposite occurs. (The more they are extended the softer they become)
Radius Arms - There are extended radius arms available which help with articulation, and can be used from stock to any lift you can imagine. What needs to be addressed in a basic suspension lift is the "c-bushing" that is sandwiched between the axle and the radius arm. These come in different degrees to match the new angle of the radius arm to the frame.
Tracking Bar - There is a drop bracket available as well as an adjustable trac bar. The drop bracket will help retain the factory geometry for lifts 3.5" or more. The adjustable trac bar will help center the front axle under the frame. This has been used on lifts as small as 2", but generally speaking is only necessary on larger lifts. Also, the adjustable trac bar and the drop bracket are usually used in conjunction with each other.
Pitman Arm - The stock pitman arm is good for a lift of 2.5" after that, you need to look at a drop pitman arm. This will compensate for the lift, and keep the drag link in the proper geometry for steering.
Shocks - These need to be matched to your lift. They have variable rates of travel, but the stock shocks won't work for a lift over 2.5", and even then are pushing it.
Leaf Springs - The distance here can be increased by adding a block under the stock leafs, adding an add-a-leaf, or by completely replacing the leaf pack with a built in lift.
Drive Lines - The drivelines may need to be changed to offer more articulation. They are available in longer lengths and with longer splines to allow the driveline to articulate. The stock drivelines should not be an issue until getting into lifts of greater than 3.5"
There are various systems or kits available through the major bronco vendors, and there are many more custom options out there. Good luck with your lift, and I hope this helps your understanding!
If you have anything to add to this FAQ please respond below:
Last edited by DebosDave'72; 07/19/06 at 08:00 PM..