WARLOCK

ok I see, Maybee I red incorrectly on the mc web site but now I understand they provide guideline length for control arms to get around 5 deg caster.

I saw the front upper arms are kept at the factory length and the front lower are 7/16" longer hence the reason of the increased caster.

I don't know if the same adjustments can be done with RK arms.

kjeeper10

Why wouldn't they be? of coarse.

Usually lower arms push your wheelbase out back to stock and uppers set pinion/caster. Same as the rear if using both sets.
RK will actually push the rear back 1"
Arm lengths should always be used as a base. No two jeeps are going to be set up the same.

Space Monkey

Hey guys,

Wish I kept the print out, but I know it went along these lines:

Toe - .128"
Camber - 0FL & 1FR - No rear readings
Caster - .08 degree

I have attached some pics for you Bunny. Just FYI - You need to replace the LCR front and rear when upgrading to X-Factor from Flex. The LCA are longer in comparison to push the axle back 1" of stock. Note the 2 different sku's on the rock krawler site when you go to purchase the arms separately.

I also added some pics for fun so you guys can see the whole setup basically. If theres something i should know about please let me know!

Thanks for everyones opinions on this.


Thanks,

2climbbig

If you could take a picture of your knuckle, that would be great. Hard to see your caster from that picture. If he put you caster at .08 degree's, that definately needs to be changed.

That said, how is it handling?

towel33

So the short answer is don't let that shop touch your jeep anymore. In a perfect world, people run 4-6 degrees of caster. You've still got your stock drive shafts that can tolerate a more substantial difference in pinion angle and drive shaft angle so there's no reason for you not to be running in that range.

If/When the day comes that you upgrade to aftermarket drive shafts, you'll have to do a little compromising as the aftermarket shafts need to have the pinion angle as close to the drive shaft angle as possible. With a lift, that means the pinion needs to be set steeper as you go higher and higher. Since a JK only has 6 degrees separating caster and pinion angle, this usually has you running in the neighborhood of 2-4 degrees caster. It's a bit of a compromise but it sure as hell isn't Zero. At zero the jeep is going to be super flightly.

Id suggest you get a magnetic angle finder and a couple of come-alongs and fix it yourself. You can measure off of the drive shaft flang and subtact 6 degrees and that will ROUGHLY represent your caster. IE pinion at 0 caster at 6, pinion 1 up - caster 5, 2up-4 and so on. It looks in the pics like they bottomed out your lowers and the axle needs to rotate longer in that direction anyway, so THIS TIME ONLY I'd set caster with your lowers which will have the double benefit of centering your tires better in the wheel wells at the same time. It'll only involve removing two bolts and its super easy to use the come alongs to rotate the axle forward/back as needed.

DunnyBunny

Thanks. I have all the arms. Just my rear lowers are shorter. Looks like I need to contact RK about some different lowers

Space Monkey

2climbbig - Honestly its handling fine. My current problem is more of the truck vibrations above 60MPH and i know its not the DS. Im getting my wheels balanced again tomorrow, since i may have knocked a weight lose while wheeling.



towel33 - I will go grab a magnetic angle finder and see what it says. Will post up some pics when i do it to make sure im reading it right.


DunnyBunny - You have all new arms or the lowers are from the Flex kit? The Flex kit lowers are made short because they dont come with the uppers in that kit, so it has to match the OEM uppers.

Invest2m4

Hard to tell from the picture, but your rear pinion angle looks high. Stock driveshafts are not designed to run with the pinion pointing at the t-case. They need to run at an angle. Ideally, the t-case output and the pinion yoke should be at the same angle. Most lift instructions assume you have a DC shaft and most shops aren't familiar with the rzeppa joints.

WARLOCK

If I look at the last pictures on the right we can see the pinion angle from the front axle and I believe my JK as a steeper pignon angle than this. My caster is at 4.3

So I think the caster need to be properly set within reasonable range between 4 and 5 deg.

IMO, You should really set all the suspension and steering properly before going any further in diagnosis of driveline or wheels vibration.

did you have vibration before ? Since when you have it ? What has been done since vibration appeared ? Has it been done correctly ?

If your wheel alignement guy has not done the alignment correctly you should ask him to redo it or maybe change to another shop.

With adjustable controls arms and track bar there is a lot of things that can be adjusted other than the caster like setback, wheelbase and track center line.

Also you should note if the aligner is using an 8 sensors or a 3D aligner wich is the only way to fully cover the perimeter of the chassis.

2climbbig

The reason why I was asking about the kuckle is because the pinion angle does not necessarily reflect the caster angle. I know on the dana 60 I am working with, the pinion angle and caster angle have a 1.7 degree variance.