JL Rubicon caster measure

[whiskey jack]

Dang, that looks like it would be around 8.5

I think that puts it at 4.5

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[Headbarcode]

I have a stock height JLUR, but weighted down with armor, bumper winch etc. I also have the Mopar LCAs. When measuring the diff holes I get 88.7*, and measuring the flat spot under the knuckle I get 8.7*. Mine actually drives really nice, but may be lifting soon and want to get at least back where I am now.

I zero'd out my Klein digital angle finder at 90 degree vertical and it is now showing 1.3*. It looks like to be at 90* I need shorter LCA, or longer UCA.

I am assuming I am running about 7.3 degree caster correct? This is new to me and I am a little confused. I have adjustable UCA on the way to go with my Mopar Lift LCA so I can get this dialed back in after a lift to keep it driving as nice as it does now.

The surface you're parked on is likely throwing the #'s off

 

[AnnDee4444]

FWIW: Another way to measure caster at home is with a camber gauge and some math:

- Turn the steering wheel so the tires are 20° to the left and read camber.
- Turn the steering wheel so the tires are 20° to the right and read camber.
- Find the difference in the camber measurements.
- Multiply by 1.43 to get caster.

* if your vehicle can't get 20° steering angle, you can use 15° and multiply by 1.91

 

[Cypher]

The surface you're parked on is likely throwing the #'s off

Surface is level, or at least as level as any concrete surface can be. Verified before I took any measurements as I planned to account for floor slope ahead of time.

I used a 6ft level across the floor with my Klein digital angle gauge on top. Both the level and angle gauge were showing level.

I have a very oversized garage, and parked in the dead center to ensure I was not near the edge where it has a slight slope, and not to front or back for same reason.

 

[Headbarcode]

Surface is level, or at least as level as any concrete surface can be. Verified before I took any measurements as I planned to account for floor slope ahead of time.

I used a 6ft level across the floor with my Klein digital angle gauge on top. Both the level and angle gauge were showing level.

I have a very oversized garage, and parked in the dead center to ensure I was not near the edge where it has a slight slope, and not to front or back for same reason.

Just thought it was worth asking. I do my own installs and alignment on my Jeep. After it's done, I'll find a good place to have it put on a professional rack. Never having lifted a vehicle or gotten too in depth on road vehicle suspension, I almost dove right into disassembly. Fortunately, I remembered to get a base line front and rear axle angle, because the steering and lift parts were done on a gravel driveway.

 

[WagzDad]

FWIW: Another way to measure caster at home is with a camber gauge and some math:

- Turn the steering wheel so the tires are 20° to the left and read camber.
- Turn the steering wheel so the tires are 20° to the right and read camber.
- Find the difference in the camber measurements.
- Multiply by 1.43 to get caster.

* if your vehicle can't get 20° steering angle, you can use 15° and multiply by 1.91

This jives with the directions for the Longacre gauge, with the factor correction for scale compression. You can get the magnet gauge for under $20 and just attach it to the brake rotor as it is square to the spindle.

 

[AnnDee4444]

This jives with the directions for the Longacre gauge, with the factor correction for scale compression. You can get the magnet gauge for under $20 and just attach it to the brake rotor as it is square to the spindle.

I'm not sure where I got the info from, and I don't really know how they came up with the correction factors... I've been using it on vehicles where the magnet hub-mounted gauge won't work, so it's good to know that Longacre's numbers are the same.

 

[WagzDad]

Here’s a link that explains how to use a simple camber gauge to measure caster. The one I have has a scale-5 to +5 and I zero it on 2 or 3 to keep it on the scale In the most accurate area (mid 60%)

http://www.keep-your-car.com/WebRoo...4846/C0A8/2935/2299/77066_Instructions_GB.pdf

 

[Priherd]

After fighting my wandering steering and almost 2 inches of play in the steering wheel for several months I finally feel I have it under control. I have a teraflex 2.5 inch ST2 lift on my 2020 JLUR. I adjusted the steering gear about a 3/16 inch turn to the right which got rid of most of the play in the steering wheel and then I replaced the LCAs that came with the lift with a set of adjustable Teraflex LCAs. After installing them I couldn't get what I thought was a good reading of the caster angle so I decided to take it to a shop. I told them I wanted 7 degrees of caster and 0 -1/32 of toe out. Attached is the read out I got from the shop. My Rubicon drives and handles much better now. My concern is I ended up with 7.3 degrees of caster, is that to much caster considering the pinion angle? I asked the tech why it ended up at 7.3 and he said that if he rotated the LCA in a complete turn it would reduce the caster down to around 6 degree so he set it at 7.3. I like the way it handles now but I am concerned that I might be pushing it with the pinion angle. (I haven't measured the pinion angle but I think it's at about -1.3 degrees) Am I overly concerned? Should I leave it since it drives nice or should I turn the LCAs in a full turn and drop the caster down to 6ish degrees which will also drop the pinion angle down to less than 1 degree.

 

[Mikester86]

After fighting my wandering steering and almost 2 inches of play in the steering wheel for several months I finally feel I have it under control. I have a teraflex 2.5 inch ST2 lift on my 2020 JLUR. I adjusted the steering gear about a 3/16 inch turn to the right which got rid of most of the play in the steering wheel and then I replaced the LCAs that came with the lift with a set of adjustable Teraflex LCAs. After installing them I couldn't get what I thought was a good reading of the caster angle so I decided to take it to a shop. I told them I wanted 7 degrees of caster and 0 -1/32 of toe out. Attached is the read out I got from the shop. My Rubicon drives and handles much better now. My concern is I ended up with 7.3 degrees of caster, is that to much caster considering the pinion angle? I asked the tech why it ended up at 7.3 and he said that if he rotated the LCA in a complete turn it would reduce the caster down to around 6 degree so he set it at 7.3. I like the way it handles now but I am concerned that I might be pushing it with the pinion angle. (I haven't measured the pinion angle but I think it's at about -1.3 degrees) Am I overly concerned? Should I leave it since it drives nice or should I turn the LCAs in a full turn and drop the caster down to 6ish degrees which will also drop the pinion angle down to less than 1 degree.

If I am not mistaken, you generally want a small amount of toe in, not out.

 

[Priherd]

If I am not mistaken, you generally want a small amount of toe in, not out.

You maybe correct, I'm no expert. I think the print out shows that I ended up with a tad of tow in.

 

[Priherd]

I actually have 7.3 degrees caster as well and it drives great. I have read a few others on here running 7.5. I do plan to try and get mine dialed back down to 6.5 -7 degrees with an adjustable UCA after my lift goes on. I think the upper arm will let me get that sweet spot I am looking for.

Have you done any hard wheeling with it at 7.3? Just curious how it will act when she's fully flexed in 4 low, hoping there is no issue with the pinion angle. But's it good to know others are running 7.3 of caster. Thanks!

 

[AnnDee4444]

FWIW: The XJ & ZJ caster spec is 7 degrees +/- 1 degree

 

[Cypher]

Have you done any hard wheeling with it at 7.3? Just curious how it will act when she's fully flexed in 4 low, hoping there is no issue with the pinion angle. But's it good to know others are running 7.3 of caster. Thanks!

Yes, I have fully flexed it out and there are no issues. I am running 35s now, and it still drives great. (Better that factory Falcon M/T for sure). I have about 10,000 miles on it with about half being off-road. Has been all over AZ and Sand Hollow, and multiple places in Nevada with no problems.

 

[Priherd]

Yes, I have fully flexed it out and there are no issues. I am running 35s now, and it still drives great. (Better that factory Falcon M/T for sure). I have about 10,000 miles on it with about half being off-road. Has been all over AZ and Sand Hollow, and multiple places in Nevada with no problems.

Great! I'm in the Black Hills right now, heading to Colorado for a month in a couple weeks! Thanks for your feed back!

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