larry0071

I run a ProRock 44 Unlimited on stock arms with Rock Krawler 3.5" springs and I am setting at 5 degrees of caster and 5 degrees of upward pinion angle. It drives perfectly, no driveline issues with an aftermarket driveshaft in place of the factory one that the boot burnt off of.

larry0071

I had bought the RK adjustable lower arms and adjusted them to the prescribed length for a 4" lift and the springs were bent like a crazy S and nothing looked good. Also the pinion and caster angles were jacked. I pissed with it a bit and got frustrated and decided to toss the factory lowers back on and take measurements.... That is where I left it. With the corrected housing, if you tried to run the RK arms length as prescribed to correct a stock housing you get craziness. Going to stock arm length, everything is just peachy! So I decided I would run stock arms with no-maintenance bushings and leave the RK arms in the box on a shelf until I decided I need to use them for some reason or another. So far, after 10K miles... the stock arms are killing it. If I bend them, I guess I'll have to decide if I want to use stock length RK arms or find some Craigslist factory take-off arms.

Stock arms on Unlimited housing, pinion angle.


RK arms at whatever the recommended length is on an Unlimited housing, pinion angle.


Big Willy

mikesoffroad

Well got the Senrgy lower control arms mounted and fully retracted. I still end up with almost 9 degrees read off the ball joint machined surface. From what I have read should this number be in the ballpark of 6? to get there I am also guessing I need to purchase upper adjustable control arms. Then adjust them out until my indicator reads 6 degrees ish. As I stated earlier I am running a 4.5 " AEV without the drop brackets and a Prorock unlimited 44 with the built in extra caster.

Rebar-7

You very well might need upper adj arms too. Try getting a measurement off pinion flange like Larry0071 pic.
Measuring off top of ball joint isn't that accurate IMO.....

mikesoffroad

I was thinking that but can I do it with the unlimited dynatrac housing? I was under the impression that extra caster was built into the Dynatrac housing which would mean if I set the pinion up wouldn't the C's be way off? I have the lower arms adjusted to the point that they are just under the size of the stock arms. But looking at my reading I am sitting still a bit back on the C. She is real floaty to drive if that makes any sense.

nthinuf

Down here, it's not all that hard to find alignment shops willing to do free checks - they just throw it on the rack and print the 'before' specs without doing the full alignment. It may be worth a few calls to see if one of your insanely expensive shops would be willing to do that for you? At least that would give you a good baseline for your further measurements and adjustments.


Floaty is generally associated with low caster, not a word that gets said at 9 degrees.

I haven't actually put the angle finder on my pr44 since it was installed. I am running very high caster, but after some messing around and adding brackets, I'm not actually sure where it's at. If I get a chance I'll take a few measurements and see what it shows.



Just put the angle finder on the same spot at the upper balljoint. Looks like mine are sitting right around 9.7-9.8*. A bit higher than yours, anyway, assuming your jeep is sitting level. (looks like it's on stands?) Been meaning to get out there and adjust the arms, now that I see how high the caster is I think I'll go ahead and get to it...

mikesoffroad

Yes mine was on stands but I tried to set it up at ride height and made sure that it was zeroed with the floor. Maybe floaty is not the word. I find I am always playing with the steering to keep it tracking straight.

larry0071

Since you know that the PRU has 10 degrees of separation, if you get the pinion to 5° like I show above, you obviously also have 5° of caster.
That's a given.
So drop the front shaft and use the machined surface of the bolt flange to get accurate measurements. I did also put the gage on the top machined surface of the C and read 5 degrees there, so it verified what I already suspected.

From what I have seen with mine, the axle ends up right where it needs to be in relation to caster/driveshaft with stock length arms, so if you put a longer arm on the bottom and stock on top, you rotate out of position. You would need to put all 4 arms the same amount longer to push the axle forward and center it (if you desire), but you then run into issues that you don't have with stock arms. The issues I saw were that the Fox shocks with the larger body mounted upwards hit the shock tower, the spring moves forward and contacts the Synergy pitman brace. By keeping the stock arms, the spring is bent into a bit of an "S" at rest, as you compress it passes back into alignment, as you drop the axle the axle moves further back (circular motion of arms) and the bottom spring pad is even more behind. By adding longer arms you straighten the spring at rest, but the axle passes in front of the upper mount as you compress... so you give and take no matter what you do.

You are not working with vertical motion here. Everything is traveling in an arc and moving fore/aft as it moves up/down.

TxJeepers

I know you already have them, but I'd sure see about returning the lowers for some upper adjustables. Sounds like you need just a little adjustment and that would come better from the uppers. Use your stock lowers.

mikesoffroad

Thanks Larry 0071, When I get back into town this weekend I will drop the DS and see where I am at. Thanks for the help.