JL Rubicon caster measure

[Kev84]

I just found this in the description of the kit I bought with those arms in it...

• Preset front lower Sport Control Arms balance front caster and pinion angles on 2.5” lift kits
• 1.5” lifts = more caster; 3.5” lifts = less caster

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[2Wheel-Lee]

The pumpkin is 6 degrees off of the caster. So if the caster is at 6 degrees, the pumpkin will be at zero (or a vertical 90, depending on how you set your gauge).

I haven't checked to make sure the lower knuckle surface is a good place to measure, but based on the measurements noted above, they corresponded to being 6 degrees off of what was read on the pumpkin, so the lower knuckle does appear to be a good place to measure caster. .

 

[Cypher]

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.

 

[blnewt]

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.

Haven't heard of any unlifted Rubis that only added the Mopar LCAs w/ caster over 6 degrees, I would think there may be a degree of error there.

 

[Cypher]

Haven't heard of any unlifted Rubis that only added the Mopar LCAs w/ caster over 6 degrees, I would think there may be a degree of error there.

I thought so too, I set the digital gauge with a level and square, same results. I can zero it out and it reads 1.3, or just use it as is and it is 88.7 I have done thins about 10 times and it is always the same.

my JLUR is a pig, it is really weighted down and on 35s, so that may be throwing it off a bit. Side by side with another JLUR on 35s with no lift I am about 3/4 to 1" lower. I may play around later and jack the front end up to simulate a 2.5" lift to see where it measures at, or how much I need to lift it to get to an even 6 degrees.

 

[blnewt]

I thought so too, I set the digital gauge with a level and square, same results. I can zero it out and it reads 1.3, or just use it as is and it is 88.7 I have done thins about 10 times and it is always the same.

my JLUR is a pig, it is really weighted down and on 35s, so that may be throwing it off a bit. Side by side with another JLUR on 35s with no lift I am about 3/4 to 1" lower. I may play around later and jack the front end up to simulate a 2.5" lift to see where it measures at, or how much I need to lift it to get to an even 6 degrees.

That weight would alter the caster angle and 1" lower would equate to about a .75 degree change, so maybe your caster is closer to 7. Sorry but I skipped right over the drop your extra weight was causing

 

[jeepingib]

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 knuckle reading is easy to get a incorrect reading on. The 7.3 is probably correct. The only real way to find it would be an alignment performed by someone competent. With the Mopar lift having longer lower control arms, and you ordering adjustable upper control arms, and the current portly stance of your Jeep, I think that you will be just fine. The Mopar arms aren't always long enough to get the caster corrected, but with your Jeep sitting lower currently due to the weight, you aren't likely to get 3.5 inches from the lift that some folks get. So you should be able to get your caster back to 7.3 or very close, and be happy with it.

 

[blnewt]

Honestly I am not sure I would want to lower it down to 6 degrees. It really does drive amazing now. It drove nice before with the Mopar LCA and Fox ATS stabilizer, but the @Clayton Off Road Adjustable track bars took it to the next level. I worry if I drop it back to 6 degrees it may wander a bit more. Right now even my wife is amazed driving it as it really does drive pretty much like an f150. Still no Grand Cherokee, but really good for a 4x4.
I will evaluate it after the lift goes on to see where it is sitting, and how it drives. I think it may be about perfect with the Mopar lift as far as getting back to 6 degrees, but if it tracks worse I know how to get it back to 7.

I'm a fan of heavy caster, I can see why you'd want to stay as-is, and if I were to lift mine any further I'd opt for more adjustable parts to gain even more caster. Just don't want to get into pinion angle issues so there is a line that can be crossed, but seems like all is well w/ your ride

 

[BCalvin]

I have a M186 front axle and as a data point, i have 7 degrees castor with the mopar lift arms.

 

[cactusflier]

I have a stock 2020 Rubicon and using the measure app on the iPhone I am getting 1 degree at the pumpkin and 7 degrees on either knuckle. So is that telling me I have 6 degrees caster? I was under the impression stock Rubi's are around 4.5 degrees. I was going to order the Mopar Lift LCA's but now I don't think so.

 

[Cypher]

I have a stock 2020 Rubicon and using the measure app on the iPhone I am getting 1 degree at the pumpkin and 7 degrees on either knuckle. So is that telling me I have 6 degrees caster? I was under the impression stock Rubi's are around 4.5 degrees. I was going to order the Mopar Lift LCA's but now I don't think so.

I read in the past that the 2020s had more caster built in. I am starting to think there may be something to this from your experience, mine and a few others recently. I know for sure my 2020 is 100% better than my 2018 or 2019 was. I wish I took some measurements before I had the LCAs swapped. I did it pretty much right off the lot though since I had issues with my other ones.

 

[blnewt]

I read in the past that the 2020s had more caster built in. I am starting to think there may be something to this from your experience, mine and a few others recently. I know for sure my 2020 is 100% better than my 2018 or 2019 was. I wish I took some measurements before I had the LCAs swapped. I did it pretty much right off the lot though since I had issues with my other ones.

Would be interesting to get an alignment verification off a bone stock 2020 JL Rubi as a baseline. That need for 6 degrees caster may have made it to production???

 

[whiskey jack]

Would be interesting to get an alignment verification off a bone stock 2020 JL Rubi as a baseline. That need for 6 degrees caster may have made it to production???

Bone stock rubicon on the diff.

 

[whiskey jack]

Bone stock rubicon on the diff.

Sorry, it's a 2020MY, feb build

 

[jeepingib]

Sorry, it's a 2020MY, feb build

Dang, that looks like it would be around 8.5

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