Rear HD Control Arm Mounts + Adjustable Long Arms

Myke

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I keep killing bushings in my rear control arms and tri-link. These things were just never meant for the amount of repetitive flex I put them through. I also want to have the rear ready to go for when I do the SFA swap as I will be replacing the c8.25 with a 1 ton axle (D60, Sterling 10.50, 14Bolt).

My main goals are to have a much flatter/straight travel arc for the rear axle with more lift and reliability/strength.

Today I started cutting out the frame side control arm mounts. Stock looks to be 1/8". I used 1/4" plate for these.

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My first design was just a simple bracket.
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I felt I could make it stronger and I also wanted it ramped so it can slide over an obstacle. So I ended up cutting these out. Considering I don't have a plasma cutter yet I feel these came out pretty sweet.

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This is as far as I got before having to head into work. This next image I used paint to give you an idea for the rest of the mount design.

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For the lower links I plan on using 2" .25" wall DOM tubing.

On the axle mount end I was going to use 1.25" heim joint from Ruff Stuff but for the price I can just run one of the joints below on both ends. The Metal Cloaks offer the most misalignment at 34 degrees per joint vs 30 degrees of the other two. I plan on running these over heims because they will be quieter and are rebuildable.


Compared to the kit JBA sells mine will be way stronger, allow more articulation, and will be quieter without the heims in it..
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I may end up cutting off the axle mounts and moving them up so they don't sit below the axle but Idk if the extra effort and $ will be worth it since I don't plan on keeping the c8.25 for much longer. If I do move them I will still have sufficient vertical link separation because the mount I'm going to make for the upper links can just sit higher off the top of the differential.
 

Myke

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Today I finished the assembly of the mounts. I just need to order the joints and tubing. Once I get home from work tonight I'll get them cleaned up and primed.

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(ignore my ghetto muffler hanging down)
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The width of the mount where the joint sits is 2.72" on one and 2.83" on the other. The specified mounting width of the 2.5" Johnny Joint is 2.82". The one is spot on but the other I will need to spread apart 0.1" if it's too tight on the joint.

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Although the JJ is "the standard" for rod ends I think I am going to go with Duroflex joints as they how lower NVH levels. They are 2.62" wide so I may need to tack on a washer inside the mount.

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Ran out of mig wire halfway through but luckily the welding supply store is right up the road. Went and picked up a 10lb spool of Lincoln wire.

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Not sure on how long I'm going to make the lower links yet. I would like to open up the rear of the wheel well into the bumper to do a 4-5" stretch. Will need to look into how I can reinforce the back end and if it's doable without a cage yet. I may need to build a subframe or plate the unitbody frame.

For now I'm just going to order a 7' section of tubing. This will be plenty as I expect link length with no stretch to be in the ~38-40" range.

Once the joints and tubing are in I'll drill the mounts. The JJ use a 3/4" bolt and the Duroflex use 9/16" bolt.
 

Myke

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A quick update. I received all of my tubing for the rear links.

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The lower links are going to the stock axle mounts then to the mounts I made in the previous post.

Wasn't sure what I was going to do for the top but I've decided on using a Ruff Stuff truss and Ruff Stuff 4 link mount for the axle side. The frame side I'm still unsure. I have a few ideas but will wait til the truss is in and I can mock stuff up.


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Myke

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Ended up getting Enduro joints from Barnes4wd for the upper links.
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Myke

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Ignore the ujoints and adapters. Joints are in and should have the upper links done this week once it stops raining.
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Myke

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Got the inner truss section tacked on. Started to rain so had to call it an early day. Will have to wait til tomorrow.

These are the Barnes Enduro joints I ended up getting the tube adapters and jam nuts from them too. The bolts are 9/16" grade 8 from the local fastenal. The Enduro joints have a ton of adjustment on them. Easily rebuildable with low cost internals. No special tools needed.

The Ruffstuff 4 link mount is all 1/4" and runs the joints with the bolt vertical which is a stronger setup. If I need to I can cut 2 small plates out of 1/4 and run them with a horizontal bolt setup.
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Myke

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Going to make the frame side upper mounts tomorrow and paint everything then bolt it up. Going to make them so the bolt is horizontal.

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Myke

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Drilled a new hole for the vent. Used a 1/4npt tap and put in an air hose fitting I had it fits my extended breather tube perfectly. Going to remake the brake hard lines and cut the head off a bolt and weld it to the axle so I can slip the brake link junction box over it and secure it with a nut.
 

Myke

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I got the upper mount on the driverside in. I have the pieces cut out for the passenger side just need to weld them on tomorrow. I ended up changing the way the bolt goes on the upper body side mount. I built them off the lower arm mount. I'm also going to cut out a couple of gussets for the frame side mount and a piece to box them in from the front.
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Myke

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The pinion angle is perfect at ride height up to full bump. At full droop it starts to lift a little but that will be solved when I make the lower extended arms.

Right now upper arms are 20" in length with room to goto down to 19" and up to 24". The lowers will end up being 35"-ish. I need to re measure and punch the numbers into the 4 link calculator. Should end up with 100-150% antisquat.
 

Myke

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Plenty of clearance at ride height for up travel. The tires will stuff before this gets close to anything.

Right now it has a ton of antisquat so the rear lifts up on acceleration. It drives and handles so much better. Everything is firm. I used to think my rack was going but it was all slop in the boomerang.

The great thing about them being adjustable is if you unbolt them and the body shifts to one side you can extend the one side that doesn't line up and then spin the tubing after loosening the jam nuts and it will pull the body back into alignment.
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