Motobilt Tech Thursday “YJ & TJ 4 Link Conversion”
The Motobilt Jeep YJ 4 link bracket system has been a major hit since its debut 3 years ago. As of late, the addition of the Jeep TJ 4 Link system has been release as well. The purpose of this segment is to answer many of the questions that are frequently asked about these kits.
To start we have to explain the story behind the purpose of the 4 link bracket system. Dan DuBose, the owner of Motobilt, has a long history with custom suspension designs for Jeeps and tube race buggies. His many years of experience in suspension design and his specific skill set are not something that many shops or consumers have these days. So, he took it upon himself to develop a bracket system that would be race inspired but trail worthy.
In designing the 4 link system there are many different attributes that have to be addressed, such as: link separation, roll axis, anti-squat and much more. With each of the many factors to consider, he wanted a system that created the proper geometry and placed everything for the end user. This type of design would net a vehicle that would perform at the race course as well as on the trail.
The YJ and TJ bracket system not only give you a well thought out suspension design, but it makes it possible to install accurately and quickly. You do not have to measure and calculate, position parts, test fit and then check. The bracket system is located using the existing holes in the frame for the skid plate. This makes sure that it fits every time and speeds the entire process up dramatically.
In order to attain the correct suspension geometry that would perform to its fullest potential, the link system was designed with an integrated skid plate. The skid plate and brackets provide for a completely smooth bottom surface so that it will slide over the rocks and not get hung up. Often there are custom builds or other manufactures that try and make a belly-up system. The major problem is twofold with this type of system. If you move everything up, including the link mounts, then you are sacrificing the correct suspension geometry to do so. If you leave the link mounts low and only move the skid plate up then you create a hook to grab obstacles off road.
The bracket system is set up to a create a true 4 link system front and rear. If you are planning on running a traditional steering box on the road, then you will want to modify the front 4 link and use it as a 3 link system with a track bar. This will eliminate bump steer. Also, if you are running a 3 link, they we suggest running a driver’s side drop front axle so that there is room to mount a track bar bracket onto the axle.
We also suggest running a wider axle then the factory units as you will need the room for coil overs, link triangulation and other systems. You can keep your factory wheel base or stretch it.
Our system utilizes a 1.25” x 1" heim joint for the lowers and a 7/8” x 3/4 heim joint for the uppers. We offer many other components to complete your 4 link conversion such as heim joints, back half kits, coil overs, axle trusses, link mounts for the axle, coil over mounts, rear fender tops, YJ behind the seat fuel tank etc. The pocket mounting width for the lowers is 2.63" and the uppers is 1.75".
If you have any questions, we have several experts at Motobilt to help you before, during and after the conversion process.