Project Built to Cruise

Page 4

   
 

Previous Update

As mentioned in the previous update lowering the tire pressure seemed to tighten up the steering but the front end wobble soon reappeared.  As per the various death wobble check lists I picked up some cam bolts to give the front end a bit more caster, as it sat I had approximately 5 degrees.  Dialing the cam bolts to the max really tightened up the steering feel but seemed to make the wobble worse.  At this point this whole problem was really getting aggravating so I decided to position my bullet cam under the Jeep to film various positions in the hopes of seeing exactly what was happening. 

After a few days of filming I was able to eliminate the steering gear as a culprit as well as the ball joints.  When the wobble occurred you could clearly see the whole axle shudder back and forth.  I pulled my track bar one evening and closely inspected everything but didn't find anything that had play in it.  Next up was the control arms.

I hit pay dirt on the drivers side arm.  One of the standard check items on the various death wobble checklists is to make sure all the bolts are tight on the control arms.  In this case it looks like the bolts may have been too tight since the ends of the ball in the misalignment joint were crushed down.  This could have been caused by the wobble itself. 

I will say that no matter what caused the damage, the slot in the lower control arm mounting bracket will cause this issue again as only a small portion of the misalignment ball rests against the control arm (note the indents).  The reason for the slot is to allow the use of cam bolts to adjust the caster on the front axle which ironically are not supplied with the vehicle from the factory. 

On the other end of the control arm is another glaring design flaw.  Here we have a stepped bolt which in no way locates the arm to the mounting bracket without a ton of slop. 

When I pulled the upper control arm I discovered the same thing as the lower control arm, the bolt is way to small for the hole in the bracket.

Not one for half-ass fixes I have determined I will need to replace the lower control arm brackets with a pair that have a single hole in them as well as properly sized bolts.  Next a set of adjustable lower control arms will replace the existing ones so I can adjust the caster as needed. Since the cost of a pair of adjustable lower control arms is only slightly less than the cost of a new set of lower long arms I am going to take this opportunity to upgrade the front end.  The longer arms will eliminate the steep angle on the front links and provide a much nicer ride.  I have sourced a set of Rubicon Express Long Arms (RE4000 & RE4010) and some new control arms mounts from Ballistic Fabrication (frame end) and Currie Enterprises (axle end) for the conversion.  I should be able to re-use my existing upper arms with the new long arms and eliminate the oversized mounting hole at the frame end.

Here's a comparison shot showing the existing short arm and the new long arm. 

To accommodate the added length of the new control arms I need to remove the stock mounting bracket and attach a new one back by the TeraFlex belly-up skid plate.   I am pretty sure I can tuck the bracket in ahead of the first mounting bolt for the skid plate so the two are independent.  After mocking up the drivers side link I can see I will need to lengthen the upper control arm slightly to get the bracket mounted out by the frame rail.  For reference it looks like the angle on the lower control arms will go from just over 20 degrees to 5 degrees.  

To lengthen the upper control arms I am planning on sleeving  them.  This will also allow me to build in more caster adjustment (if needed).

After discovering the rod ends in the track bar I had made were already loose after just a few months usage I decided to go back to the Rubicon Express track bar. The RE track bar used a rubber bushing at one end which I tried to eliminate to cut down on all play in the track bar but the two piece rod ends wore out much faster than I expected. I also used a 3 piece rod end like the RE track bar had initially.  With this change I gain back some clearance between the track bar and front diff cover, despite moving the straight track bar around and adding longer bump stops I still managed to rub the front diff cover when the drivers compressed fully.

The rig is also sporting some new shoes, a new set of Mickey Thomson MTZ's.  These things are much quieter than the MTR's they replaced and so far they seem to work as well if not better off-road.  I don't notice as much side to side tire slippage when climbing over obstacles. 

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