I've been determined to link the rear of my truck for over a year now and am just getting around to finishing it.
My truck is pretty different from most of the K5’s on here but I am still using most of the K5 frame and the methods I used to attach the links and springs could be useful for any K5 owner who is considering linking the rear of their truck.
**If you don't care about how to design a 4 link, pics of my setup are at the bottom**
Why would I want to switch to a link suspension? This is what the rear springs that came off of my truck looked like :
These two videos show the axle wrap that I dealt with for the last few years (34% for language)
(I was open in the front then, the "bolt" that fell off was just rust 
[youtube]i2TfF10-GWk[/youtube]
(I don't know why the sound is off)
I chose to replace the leaves with a double triangulated 4-link. A triangulated 4 link will locate the axle front to back and side to side and allows the springs to simply hold the vehicles weight. Using spherical rod ends (abbreviated as SRE’s, usually referred to as heim joints) or flex joints a triangulated 4 link will practically eliminate any unwanted movement. This means that the axle won’t “walk” under the truck when turning, the springs can’t wrap or bend, wheel hop is all but eliminated (if you set it up right), you can achieve better approach/departure angles, etc.
On a leaf sprung suspension you are depending on the leaves to locate the axle front to back, locate the axle side to side and resist the torque running through the axle. Generally leaves do a fairly good job of all of this but the desire for bigger tires, more flex and better performance can exceed their capabilities (as you can see by the bad axle wrap and wheel hop I've experienced). Leaf springs also allow the axle to move around a lot under the truck because they use bushings, the steering on my front end (I'm still running leaves in the front) will actually move the front of the truck (rather than the tires) through the first bit of steering travel
This is roughly my setup and shows you what a double triangulated 4 link looks like. It simply means that all 4 links are at an angle when looking from above, like the picture here (red are the lower links, blue are the uppers):
As long as the combined angles of the 4 links are at least 40 degrees you won’t need a track bar (panhard bar) to locate the axle side to side.
So what do you need to know to design a 4 link?
Each motorsport (drag racing, desert racing, mud bogging, competition rock crawling, recreational rock crawling, etc.) all commonly use 4-link suspensions but their design is different for their different purposes. The focus of this writeup is for a recreational rock crawler.
First, you need to understand a couple terms for the most important aspects of a 4 link suspension:
Anti-squat: Anti-squat is the force that actually “picks up” the rear end under power. As the truck accelerates, weight is naturally transferred to the rear and causes the truck to “squat”. Basically the links have to resist the torque running through the axle shafts and exert an equal and opposite force to the frame which will actually push up on the body of the truck based on how the links are setup.
Roll Axis Angle: When a 4 link suspension flexes it can create what’s called “roll steer”. To describe it, lets say (when viewed from the side) your tire sits centered in the wheel well at ride height. When the suspension flexes, each tire may move forward or backward from the center of the wheel well based on the roll axis angle. A zero degree roll axis angle would keep the tires perfectly centered in the wheel well throughout its travel.
That’s a REALLY basic run through but those are the major design constraints to watch.
My truck is pretty different from most of the K5’s on here but I am still using most of the K5 frame and the methods I used to attach the links and springs could be useful for any K5 owner who is considering linking the rear of their truck.
**If you don't care about how to design a 4 link, pics of my setup are at the bottom**
Why would I want to switch to a link suspension? This is what the rear springs that came off of my truck looked like :
These two videos show the axle wrap that I dealt with for the last few years (34% for language)
[youtube]i2TfF10-GWk[/youtube]
(I don't know why the sound is off)
I chose to replace the leaves with a double triangulated 4-link. A triangulated 4 link will locate the axle front to back and side to side and allows the springs to simply hold the vehicles weight. Using spherical rod ends (abbreviated as SRE’s, usually referred to as heim joints) or flex joints a triangulated 4 link will practically eliminate any unwanted movement. This means that the axle won’t “walk” under the truck when turning, the springs can’t wrap or bend, wheel hop is all but eliminated (if you set it up right), you can achieve better approach/departure angles, etc.
On a leaf sprung suspension you are depending on the leaves to locate the axle front to back, locate the axle side to side and resist the torque running through the axle. Generally leaves do a fairly good job of all of this but the desire for bigger tires, more flex and better performance can exceed their capabilities (as you can see by the bad axle wrap and wheel hop I've experienced). Leaf springs also allow the axle to move around a lot under the truck because they use bushings, the steering on my front end (I'm still running leaves in the front) will actually move the front of the truck (rather than the tires) through the first bit of steering travel
This is roughly my setup and shows you what a double triangulated 4 link looks like. It simply means that all 4 links are at an angle when looking from above, like the picture here (red are the lower links, blue are the uppers):
As long as the combined angles of the 4 links are at least 40 degrees you won’t need a track bar (panhard bar) to locate the axle side to side.
So what do you need to know to design a 4 link?
Each motorsport (drag racing, desert racing, mud bogging, competition rock crawling, recreational rock crawling, etc.) all commonly use 4-link suspensions but their design is different for their different purposes. The focus of this writeup is for a recreational rock crawler.
First, you need to understand a couple terms for the most important aspects of a 4 link suspension:
Anti-squat: Anti-squat is the force that actually “picks up” the rear end under power. As the truck accelerates, weight is naturally transferred to the rear and causes the truck to “squat”. Basically the links have to resist the torque running through the axle shafts and exert an equal and opposite force to the frame which will actually push up on the body of the truck based on how the links are setup.
Roll Axis Angle: When a 4 link suspension flexes it can create what’s called “roll steer”. To describe it, lets say (when viewed from the side) your tire sits centered in the wheel well at ride height. When the suspension flexes, each tire may move forward or backward from the center of the wheel well based on the roll axis angle. A zero degree roll axis angle would keep the tires perfectly centered in the wheel well throughout its travel.
That’s a REALLY basic run through but those are the major design constraints to watch.
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. Also very informative.
