Custom Build Jeep YJ 4 Link Suspension

Years ago I built a lot of full width axle Jeep YJ’s while starting another company. Oddly enough one of the first builds I am putting together as I start a new company is a built Jeep YJ. In years past the builds took on a different form. In those days the hot thing was 1/4 elliptic suspension or buggy springs.

This Jeep YJ build is going to feature many new Motobilt parts you guys/girls will be able to purchase in kit form. We are going to 4 link the Jeep front and rear and install KING Coilovers front and rear. The suspension is something I have been thinking about for a long time. If everything goes as planned it will produce a kit that will be easier to install and set up for at home builders. The rear section of the frame has already been cut off. The plan there is to build a back half kit to make room for coilover shocks.

The Jeep has a Chevy Dana 60 front and 14 bolt rear. The tires are Super Swamper SX 43″ on 17″ Allied Beadlocks. The engine is the stock 6 cyl, stock auto tranny, and a Atlas t-case. I am not sure if the customer will change out the engine and tranny but I have a feeling he will at some point in the future. (Update: the customer has installed a chevy LS series motor and it does fit!)

I will do my best to update this post all along with pictures of the progress and parts used.

 

 

Here is a BEFORE picture of the Jeep as it was delivered to us:

custom Jeep yj build pictures
This is how the Jeep showed up to the shop

 

Be sure to check out the build pictures as we progress through the project:

jeep yj project build

We are working on a new product for this build because the rear section of the frame was cut off to make room for the long travel coilover shocks. Part number MB3001 will soon be our Motobilt Jeep YJ Back Half Kit. This part is CAD designed for precision fit. This image is a work in progress the actual product will look a little different. The kit will include parts for new frame rails sections and the back bumper. The kit is going to require cutting the body in the rear of the Jeep to allow the frame rails to pass through just above where the factory bumper is located.

jeep yj back half kit
This is a 3D model of the Jeep YJ back half kit.

 

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The Chevy Dana 60 front axle mocked into place.
Jeep YJ Back Half Kit by Motobilt
The Jeep YJ back half kit is now available online. Just click the picutre
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Mocking everything into place.

 

 

The new Jeep YJ Back Half Kit went together well.  We will be adding this new part to the Motobilt online store very soon.  If you have any questions let us know.  Were are here to build parts and help you build.  Update (The YJ back half kit is now available click here!)

motobilt-jeep - yj-back-half-kit
The YJ back half kit is the most complete on the market and consists of 7 pieces.

We have been busy working on a couple different builds in the shop in addition to this one.  One project we are excited about is the new 14 Bolt Axle Truss Design we are working on.  This too will be a production made part available on the website for purchase.  We will be adding it to the line up very soon.  The new Motobilt 14 Bolt Axle Truss was designed to give strength to the axle and provide a solid place to mount upper links on the 4 link suspension.  Check it out.

14 bolt axle truss for 4 link

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We have been slammed out in the shop working on a few different projects the YJ project is coming along.  We are working on developing more new Motobilt products during this build.  This picture illustrates a 4 link kit we are working on for the Jeep YJ.  We have the front truss assembly turned off in the pic. The rear is a Corp 14 Bolt with a full width Motobilt truss system.

jeep yj 4 link kit
Update This kit is now available just click the picture!

I thought I would give an update on the build.  We are currently installing the 4 link kit pictured in the above 3D rendering. The parts turned out very well and we are excited about being able to offer the Jeep YJ 4 LInk Kit to the public very soon.  This 4 link mounting system will greatly reduce the time needed in the shop to fabricate and install a custom linked suspension. (Update the kit is now available online. Click here.)

Jeep YJ 4 Link Kit
Here you can see the upper link mount easily
Jeep YJ 4 Link Kit
As you can see the skid plate uses counter sunk hard ware for a perfectly smooth belly pan.
Jeep YJ 4 Link Kit
Nothing to get hung up on with this kit’s smooth pan.
Jeep YJ 4 Link Kit
This is the upper link mount before it gets welded.
Jeep YJ 4 Link Kit
As you can see their is ample room for just about any drive train combo.
Jeep YJ 4 Link Kit
After we have welded the link mounts solid.
Jeep YJ 4 Link Kit
Here you can see both frame rail sections and how the skid plate holes are used to align the kit.
jeep yj 4 link kit
This is the complete kit and what will ship when you order the bracket system.
jeep yj 4 link suspension
Another look at the actual link mounts all welded up and ready for install.

I posted some pics of the rear 14 Bolt Truss on Instagram a few days ago and have been getting swamped with emails.  The 14 Bolt Axle Truss design features multiple layers of construction for strength.  Basically it is creating box at the point where the upper links mount and also ties to the pinion support off the front of the axle.  This 14 Bolt Axle Truss extends the full length of the axle tube on both sides leaving enough room to bolt on the disk brake brackets.  Check out the pics.

14 bolt axle truss
You can see how the pinion guard and inner truss tie together
14 bolt axle truss
The truss spans the majority of the axle tube span for the ultimate in strength.
14 bolt axle truss
There is a large flat section on top to mount your upper link mounts or any other mounts such as bump stop pads.

More progress is being made on the Jeep YJ 4 link suspension.  The 14 bolt truss is complete.  The upper and lower suspension mounts are installed on the 14 bolt axle.  The axle side brackets are CNC laser cut and formed from 5/16″ plate.  On a race rig we would go lighter but on a trial rig to keep maintenance issues down we opted for a heaver bracket to resist damage contacting the rocks. The lower links are 2″ OD x 1/4″ wall DOM tube and the uppers are 1-3/4″ x 1/4″ wall DOM tube.

Jeep YJ 4 link suspension
The Jeep YJ back half kit can bee seen quite well here
Jeep YJ 4 link suspension
The back half kit gives you the room needed with the larger rear axle being stretched further back
link tube adapter install
These American made tube adapters can be purchased on our site. Click the picture to find them
Jeep YJ 4 link suspension
Look at all that room for flex due to the back half kit

We have been busy in the shop and have not kept up with the updates like we should. The front Chevy Dana 60 axle truss was a huge success. The new Motobilt design allows the PSC Motorsports double ended steering ram to sit very low allowing more clearance for the frame rails.
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When building a custom Jeep it seems the more you change the more you need to modify. This Jeep YJ needed a custom aluminum fuel cell to fit behind the seat and above the floor. Because the rear axle was 4 linked and stretched to the rear there was little room to build a custom fuel cell under the Jeep. This fuel cell will be available for purchase on the website. The fuel cell is TIG welded aluminum. It features a top mounted pick up, return and vent with built in roll over valve.

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This tank holds approximately 18 gallons. Please note we changed the design of this tank and the mounts are no longer welded onto the tank.
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Here you can see how well tank fits behind the rear seat while maximizing fuel capacity. Please not we no longer weld the mounts to the tank as shown here.
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You can see here how the tank is sloped so that the factory rear seat will still fit.

One of the goals with this Jeep YJ build was to keep the 16 inch KING Coilover Shocks covered. The main reason for this was keeping the back seat in the Jeep. If the Coilovers were exposed it would be a real hazard for pinching fingers off in the coils. Another major goal was to keep the overall ride height as low as possible. In doing so we needed to move the wheel opening up. The Motobilt answer for this was to build custom sheet metal parts to relocate the inner fenders up roughly 4 inches. Check out the following pictures. You will see the upper coilover mounts coming together as well.

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Here you can see the new Jeep CJ/YJ fender tops, the GYJU coil over tops, and the behind the seat YJ fuel cell

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Underneath the roll cage plate with 4 bolts is an actual coil over mount. PN GYJU the cage plate will be tied into the roll cage for additional support

In the above pictures you will see the custom aluminum fuel we built for this project. The bolt plates on top of the inner fenders are to locate the upper coilover shock mounts. They will be attached to the roll cage. We will be posting updates soon. (Update You can purchase this mounts now by clicking here.)

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These coil over mounts are listed on the site as PN GYJU

The upper coilover shock mounts will be located at the bottom side of the new inner fender tops in the rear. We took the extra time to mount them this way to make it safer for someone riding in the back seat. The coilover mounts we designed to tie into the roll cage as well as the Jeep frame. With the Motobilt Jeep YJ Back Half Kit Installed we have plenty of room to work with mounting the shocks. The picture below shows the part laying on the fabrication table ready to weld out. It flips over and mounts to the bottom side of the inner fender.

We have received a few emails asking about the wheelbase and departure angle. The below image shows a few things. Check out the departure angle, the custom “comp cut” fenders, and you can see how much we moved the wheel well opening up. If you are custom building a 4 linked Jeep YJ hopefully this build will inspire you more.
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The front coilover shock towers have been finished up on the Jeep YJ. They were fabricated using 1.75″ OD x .120″ wall DOM round tubing. We formed the tubing with our JMR Manufacturing hydraulic tube bender. The cross brace over the engine was made using the same material. The cross brace is removable using the Motobilt 4 bolt tube flanges.
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The backside is painted and back together. With the exception on a couple small projects most of the fabrication is complete at this point. Now it’s time to do the finishing work like plumbing the custom aluminum fuel cell, running hydraulic hoses to the PSC Motorsports steering pump and double ended ram. More updates coming soon.
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The front Dana 60 axle truss has been welded out and painted. The front axle is bolted back to the 4 link suspension and back under the Jeep YJ. The picture below shows both the front and rear 4 links at full droop or fully extended.
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We are getting very close to sending this Jeep YJ home with its owner. Keeping a low center of gravity takes a lot of effort.

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Jeep shown at full bump

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FINISHING A PROJECT….
Finishing an in depth project is always a bittersweet moment. On one hand you have the excitement of presenting the build to the owner and sharing in their excitement. The difficult part is a true craftsman can always think of more they can do or would do. I am happy for the owner of this Jeep project and looking forward to seeing he out on the trail.

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If you have any questions about this build please give us a call or email us at info@motobilt.com
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We now offer comp cut corners at Motobilt.com

This build has been a huge hit with our customers.  Since building this Jeep we have sold MANY YJ 4 link systems to customers around the world combined with many other parts from this project.  We were recently contacted by the owned of this Jeep YJ to custom fabricate a custom roll cage.  The cage needed to fit and flow with the original design of the Jeep.  The cage needed to be functional as a trail rig.  We talked over building a flat roof design to allow the customer to add a flat metal to the roof at some point in the future.  Check out the following pictures from the roll cage build completed in December 2015.

7 thoughts on “Custom Build Jeep YJ 4 Link Suspension

  1. This suspension set up was designed to be used with full hydraulic steering. The front on this build we have a double end PSC ram mounted. The suspension link system we are developing on this build is not meant for street driven vehicles and was designed for larger tire builds.

  2. Looking at your 4 link. Is it a triangulated front 4link or are my eyes deceiving me. If it is the triangulated front what effect would this have on running stock steering

  3. Dan.. Your killing it on the Solidworks modeling! How are you getting the frame rails and axle housing modeled? I’m starting to get the hang of SW, but its a hell of a steep learning curve!

  4. […] of the install process and clearances very soon. Link the the build this is being installed on: Custom Build Jeep YJ 4 Link Suspension and back half kit by Motobilt | Motobilt Metal Fabrication Bl… Listed in the online store here: Jeep YJ Four LInk Suspension Kit and Skid Plate Motobilt, Inc. […]

  5. […] of the install process and clearances very soon. Link the the build this is being installed on: Custom Build Jeep YJ 4 Link Suspension and back half kit by Motobilt | Motobilt Metal Fabrication Bl… Listed in the online store here: Jeep YJ Four LInk Suspension Kit and Skid Plate Motobilt, Inc. […]

  6. The axle trusses would work with the CJ. The chassis side brackets are going to be specific to the YJ. I will be working on versions for the CJ and TJ very soon.

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