Rear Upper Control Arms vs Front Track Bar

[Don Bulee]

Hello, I just bought a set of 4 Rubicon Express 4.5 inch springs with some Rancho's RS5000X, my TJR 2006 already had a lift kit when I got it, front total 4 inches by springs and a 2 inch lift puck and rear 3 inches with only the springs, (16 inches front and 11 inches rear according to the TJ lift chart) it has the 4 non-adjustable skyjacker lower control arms and the 2 upper front control arms so I'm trying to get rid of all skyjacker stuff and I started with the springs... my TJR has the rear bracket for the relocation of the rear track bar, the drill in the front for the stock track bar to be relocated (the wheels are pretty much aligned) and I add some washers in the TC to eliminate vibration..

The 64,000 question would be.... in most-important vs can-wait-a-little-longer scale... what would be first... to get a new front adjustable track bar, to get a rear adjustable upper control arms to adjust the pinion angle (current I have stock upper rear control arms) and may reduce vibration, to add a MML, save some money for the double cardan DS (since it is a rubicon, no SYE will be needed) or start replacing the non-adjustable lower control arms from skyjacker..

Extra info:
- I dont know what lower control arms are the ones in my rig (I know they are skyjacker but I dont know what size or model)
- I have skyjacker quick-disconnect in the front sway bar so no issues there
- I did get a new set of rear sway bar links for the 4 inch lift
- I may have some vibration (not that bad) but since the TJ has always been like that and that's the only jeep I have ever driven, I have no point of comparison
- It is my DD and I'm a weekend warrior but, where I live is really small so I dont usually drive more than 6 miles to get anywhere.. maybe once per month I drive more than 40 mph, the rest is really slow
- I measured with an angle app in my phone and the angles from my pinion and driveshaft were 22 degrees vs 11 degrees (something like that)
- The TC drop are only 4 washers, less than half an inch

 

[eastbloc]

Bad pinion angle will have most consequences

 

[Don Bulee]

Bad pinion angle will have most consequences

like... the breaking things kind of consequences?

 

[CharlesHS]

IF I understand the pinion to driveshaft angles you posted; I would replace at least the rear upper control arms before you destroy the rear driveshaft. There should be as close to 0* difference as possible.

 

[pagrey]

Rear adjustable uppers seems like a great idea. I think you also might be hitting the front track bar on that rather large diff cover. You could look into getting a cover that's not so big before you play with the front track bar or at least check to see how much room you have.

 

[Don Bulee]

Thanks! I'm gonna be having a transfer case drop while saving for some rear upper control arms...

@pagrey I think those dents were already there when I bought my rigg.. maybe before the low front CA were installed but agree..... I will check if there is no hitting between the trackbar and the diff cover

 

[Don Bulee]

IF I understand the pinion to driveshaft angles you posted; I would replace at least the rear upper control arms before you destroy the rear driveshaft. There should be as close to 0* difference as possible.

let me try to take a picture of the angles and post them for betteer understanding..

 

[CharlesHS]

The picture below is a 1* difference between pinion and driveshaft with a double cardan joint driveshaft.

 

[Don Bulee]

I was not able to measure the angle... But it looks like this.... I think that the rear upper control arms will definitely help my rig with the 4.5 inches of lift... I found the adjustable rubicon express for 160 bucks on Amazon... I think Im gonna get those....

 

[Don Bulee]

Just to conclude with this thread, I got the upper adjustable control arms... hell!! that was night and day difference! really recommend them... due to the angle of the axle I had to include a relocation bracket for the shocks.... nothing fancy but... need them to avoid any damage....

still have some vibration in the 20/30 mph range but I would get a MML to try to reduce them.... (still haven't purchased the DC driveshaft)