Adjust control arms after 4.5 inch lift

idpagal

New member
Hi Eddie,

My husband and I took your advice replacing JLU Sport axles with Rubicon axles. Now those Dana 44 axles feel much better than Sport stock Dana 30+35 axles. In addition, we increased the lift to 4.5 inches to accommodate BFG KM3 37 inch tires.

We notice the coil springs are slightly bowing. The front ones are bending backwards at the axle (see pictures). The rear ones are bending forward at the axle. I wonder if this issue is caused by the 4.5 inch lift? Can this be resolved by adjusting control arms? I have all 8 adjustable control arms. I need guidance on how much the control arms need to be adjusted to get the geometry correct.

Many thanks!

~June
 

Attachments

  • Front Driver Coil Spring_20211028_2M.jpg
    Front Driver Coil Spring_20211028_2M.jpg
    276.7 KB · Views: 6
  • Front Passenger Coil Spring_20211028_2M.jpg
    Front Passenger Coil Spring_20211028_2M.jpg
    372.7 KB · Views: 6
Hi Eddie,

My husband and I took your advice replacing JLU Sport axles with Rubicon axles. Now those Dana 44 axles feel much better than Sport stock Dana 30+35 axles. In addition, we increased the lift to 4.5 inches to accommodate BFG KM3 37 inch tires.

We notice the coil springs are slightly bowing. The front ones are bending backwards at the axle (see pictures). The rear ones are bending forward at the axle. I wonder if this issue is caused by the 4.5 inch lift? Can this be resolved by adjusting control arms? I have all 8 adjustable control arms. I need guidance on how much the control arms need to be adjusted to get the geometry correct.

Many thanks!

~June
Hey there! It looks like no pics got uploaded. You definitely need all the arms adjusted and probably every other part on your rig. Both track bars need to be adjusted to recenter your axles under the body. Then you need the front wheel’s toe reset on the tie rod so it’ll all go straight.

Find an alignment shop who can go over it for you and get everything squared away with a computer.
 

Sorry I see the pics now. You need to push the lower fronts out until the springs are straight and the adjust the top arms out as well, but leaving 4-5 degrees of caster on the front axle. Still need the track bars and toe adjusted too for the new tires and ride height.
 

idpagal

New member
Sorry I see the pics now. You need to push the lower fronts out until the springs are straight and the adjust the top arms out as well, but leaving 4-5 degrees of caster on the front axle. Still need the track bars and toe adjusted too for the new tires and ride height.
Hi - The front and rear track bars were adjusted to center the axle. Toe was adjusted at an alignment shop, but probably needs readjustment once the control arms are done. We were thinking of lengthening out the front lower control arms. Thanks for confirming that. We are also thinking of replacing stock spring pads with Rock Krawler front spring correction pads to firm up the seating on the front axle as well.
Regarding the caster angle, I read 6 degrees would be better than 4-5 degrees, though FCA has it as 5 degrees. What about the pinion angle? Let me know your thoughts on this. Many thanks!
 

Sorry for the late reply. I’ll be forthcoming, I’ve not built a Jeep up past 3”. I’ve certainly read plenty and daydreamed about it, but I’m NOT an expert.

You seem to be going in the right direction. I didn’t want to over-recommend in your caster angle. My JL was 3”+ and I ended up around 4.75 degrees and I was happy with it. Given your height you may also be pushing how far your driveshafts can extend which will limit what you can do with axle angles. I never adjusted my rear axle.
 

Top