- First Name
- Sep 4, 2019
- Reaction score
- Patterson, ca
- 2019 jlur
We are kidding ourselves if we think any kit, or even the oem suspension was perfectly engineered. Almost none of the kits from budget spacer to $4k+ system address the roll center in the front as changing the track bar angle requires changing the drag link angle to match. A lot of the kits raise the rear track bar mount to help with the roll center. The bracket to do the same can be had for as little as $50 from various sources. Adjustable control arms will do very little to address any geometry other than caster angle. Toe won’t change regardless of lift, as the tie rod isn’t effected (not to mention the oem is adjustable). A perfect example of the fallacy of oem engineering, all models run the same suspension components aside from springs. A sport sits ~2-2.5” lower than an XR and yet they run the same control arms? Obviously better shocks are an improvement, but a budget boost with shock extensions is no worse than stock. If you want to go 3+” you’ll need to do a lot more toward suspension geometry, but a budget boost is no different performance wise than a stock XR in my opinion. If we are pretending stock was some gold standard of engineering, it fits the bill(and is easily improved upon). We started out with a budget boost and have since made multiple changes, some for driveability, some for off road performance, some for durability, and some for all of the above. We are now at ~4” of lift, front drive shaft is replaced for improved down travel. Rock sport shocks, budget friendly long travel. Synergy drag link flip and track bar relocation bracket for improved droop, better roll center, and improved steering angle. Rubicon express adjustable LCA’s up front for better caster, more flex, and added strength. Rear track bar frame side drop bracket for better roll center and more down travel. With the new springs and all the other upgrades we are at ~$2k in to the suspension, but the front drive shaft and steering correction doesn’t come with even the most expensive kits out there. Jeep drives, handles, and performs well. Off the shelf kits are built to be “good enough” and leave plenty of room for improvement just like the oem in my experience. Of course your expensive kit will have better control arms and joints than my still stock front uppers and rear upper and lowers, but that does nothing for the geometry.When you change one item on the suspension all the specs will have new measurements. Sure the budget can do it’s it’s best to put back into almost oem alignment. A good lift will have 500k miles of on/off road R&D and will need over a year of testing.
Roll Center - Both front and rear suspensions have a Roll Center. This is an imaginary point around which the body of the car will rotate in a turn. The attachment points of the suspension components determine the Roll Center.
Roll Axis - A line between the front & rear Roll Centers.
CG (Center of Gravity) - The center point of the vehicle's mass.
Understeer - When the front tires lose traction first.
Oversteer - When the rear tires lose traction first.
Neutral Steer - The ideal balance when the front & rear tires gradually give up traction at an equal rate.
Spring Rate - Expressed in pounds per inch, it is the force necessary to compress the spring, i.e. a 200 lb spring requires 200 lbs to compress it 1 inch, 400 lbs to compress it 2 inches, etc.
Motion Ratio - Specifically we usually refer to the relationship between the motion of the wheel and the motion of the spring; i.e. If the spring is half the distance from the control arm pivot as the wheel is, the motion ratio relative to the wheel is .5 to 1.
Wheel Rate - The combined effect of spring rate, motion ratio, friction and/or binding of other suspension components measured at the wheel
Roll Bind - Any binding of suspension components that occurs as the body of the car leans over in a turn
Roll Steer - Generally refers to a steering effect on the rear axle as the car leans over in a corner. Caused by the rear control arms pivoting around their forward mounting point, drawing the axle forward as the arm moves up or down.
Bumpsteer - Toe change as the suspension moves up & down
Ackerman - Or in other words Toe out in turns. When turning the inside tire must turn more than the outer tire because it is turning on a smaller radius
Camber - Expressed in degrees, it is how much the tire leans in or out
Caster - The forward inclination of the spindle or strut - like the forks on a bicycle
Toe - The difference in the distance between the leading and trailing edge
Testing and making sure the geometry for all the above is on point takes time.
The Bronco is cheaper than the Jeep when comparing MSRP, mine is about $2k less. I had no issues with how my 12 Rubicon drove on road.