I'd like to understand how a couple of little bolts can adjust caster in the JK. Can anyone shed some light on this?

Also, the black diamond 3" kit is looking a little too good to be true. It addresses axle shift, caster, the rubicon front swaybar issue and comes with shocks, all for about 700 bucks. So what's wrong with it? If it solved all those problems and had a great ride, wouldn't everyone wanting 3" or so of lift be using it? Why go OME when they solve none of those problems and cost about the same?

 

Yeah, I asked someone the same question but was left confused

 

Oh, and I thing Rough Country has a similar item.

 

I have the Black Diamond 3" and love it. The ride is better then stock and not a single issue.....except the esp but thats the tires not the lift

 

I installed the CAM bolts but later changed to the SuperLift (same company as BD) Rockrunner lower arms. Since the length of the arms are adjustable, cam bolts are no longer needed.

The problem occurs as the frame is lifted away from the axles as the lift height increases, the lower arms pull the bottom of the axle towards the the back. This changes the steering castor/kingpin angle, to a more upright position, making the steering less stable and making death wobble more likely and more severe. The cam bolts rotate the axle to its original position, pitching the lower control arm bracket forward. Another way to look at it this; if you were to remove the passenger front tire and look down the length of the axle. When the lift in added, the bracket welded to the axle to mount the lower control arm is pulled back as the axle is rotated clockwise (from the passenger side, CCW from the driver side). Since the kingpin is welded to the end of the axle, it is also rotated to a more up and down attitude reducing the castor angle/kingpin angle/steering angle. This has the effect of making the steering more darty. In order to return the geometry to its original (and safer) angle, a longer lower control arm or cam bolts are needed.

Now installing cam bolts suck. The reason is that the lower control arm brackets must be slotted to allow the bolts to slide back and forth as the cam is rotated. The stock brackets come from the factory with a square hole through which the stock bolt goes. In order to adjust castor, the stock square hole must be slotted left to right to allow the bolt to move back and forth as the angle is set. The stock bracket is extruded so that it looks like the slots can be knocked out with a punch and hammer. I tried mightily to knock them out and gave up. I used a plasma cutter to cut them out. Now thinking about it, there is no point in cutting the forward section of the slot out, as the point is to regain lost castor and the center of the bolts will need to be moved towards the back of the vehicle. So I would advise cutting only the rear portion of the slot (and half the work). I understand the most of us do not have plasma cutters in the garage. In that case I'd want some sort of power tool, possibly a jig saw as the blade must be small enough to pass through the existing square hole.

Once slotted, slide the lower control arm into place, put one washer on the cam bolt and slide it through the bracket and arm. Install the other washer on the other side of the bracket. Tighten the bolt enough that the washer on either side sits between the two extruded tabs.

I know it seems like a lot of info but it will make sense during the install.

 

Could yo have the same caster angle correction installing a lowering transfer case kit???... I wouldn't like to slot the control arms brackets to install the cam bolts...

 

Thank you!

Still not quite seeing it, though... (at this point I'm more interested in how it works and why it works than how it install it)

So essentially you slot the mounting bracket so that the arm can be mounted further back, offsetting the tilt of the axles? If so, where does the cam bolt itself come into play? Cant' you just slot the hole and mount the stock bolt further back?

 

Sorry, but no, this will only make the drive shaft angle shallower, which is a good thing but the steering angle must still be corrected. Besides the two items, cam bolts or a longer lower control arm, the only other option is to leave to steering angle uncorrected and I do not consider this a viable option as JK Jeeps are already notorious for the deaded death wobble.

GL

 

THe bolts have a "D" shape that fits in two large washers with the same "D" hole punched in them. This D is not located in the center of the washer but off to one side. Now imagine that the outside of the washer is held in place, meaning that it can rotate but not move backward or forward, only turn. Well as the head of the bolt is turned, the centerline or long axis of the bolt will move back and forth if held in a slot. Likewise, if the hole is not slotted, turning the head of the cam bolt will have no affect other than jamming the D shape of the bolt into the D shaped hole in the washer and the steering angle will not be corrected.

Hope this helps

By the way, your logic is exactly correct, you are slotting the hole so that the center axis of the bolt can be mounted farther back. Since so much force is exerted on suspension components supporting 3000 lbs in the air and if the bolt were only tightend in the slot and not fixed in place, then it would almost certainly shift in the slot. Since the cam washer with the D shaped hole is fixed in place as long as moderate tension on the bolt is maintained, it is much more secure. It is also much easier to make changes to the bolt location, as only the head of the bolt need be turned to move in front and back, making reading an angle finder and making corrections as needed rather than tapping the axle forwards and backwards.

 

Think of it like a clock. Looking at the front axle from the side. The upper and lower ball joints make up the steering axis. How the ball joints are inclined is the caster angle. If the ball joints are true verticle as viewed from the side, then the caster angle is zero degrees. the Jeep comes from the factory with positive caster built in. This means that viewed from the side, the top ball joint is further toward the rear from verticle, and the bottom ball joint is further toward the front from verticle. You might say that the axle comes "rotated" just a tad, because actually, that's the case. By allowing cam bolts to be installed, we can get back some of that positive caster the lift kit removed. As the axle drops as with a lift kit, the axle also rotates, causing the upper ball joint to move closer to verticle as well as the bottom ball joint. This is moving caster more negative. Negative caster is usually not desired on a street driven vehicle. Positive caster gives us the good returnability to center we feel when we make a turn and release the wheel. It comes back to center almost all by itself. This also adds high speed stability. Take away some of the positive caster, and we also remove some of those good qualities. Now, if we were driving our Jeep on the NASCAR circiut, negative caster might be more desirable. LOL