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Caster Question

Old Mar 25, 2012 | 06:50 AM
  #11  
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^^^Bump^^^
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Old Mar 25, 2012 | 07:01 AM
  #12  
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Originally Posted by jesse0920
The higher the pinion angle the less caster correct?
correct

Therefore to obtain 6-8* caster the pinion would have to be parallel or actually pointing towards the ground correct?
correct. please be advised that 6-8° of caster is nice to have but, unless you are running stock gears, it's not something i would recommend especially if you're running after market drive shafts.

This being said I am in the process of installing a 3" long arm lift along with a JE Reel 1310 double cardin on my 2012 JKU Rubi. I'll be running 35's and its my understanding the additional caster over stock is to improve the handling with the lift and larger tires. The new drive shafts however, recommend the pinion be inline with the drive shaft thus having less caster than even the stock 4.2*.
NO, you ONLY do this for a rear drive shaft. not even a factory drive shaft on a stock JK is sitting in line with the front pinion. proper front end alignment needs to take precedence.

I know there has to be a compromise between good handling and drive shaft vibrations. My biggest fear is grenading my transfer case due to not enough pinion angle.. According to the Dynatrac caster write-up they mention even setting it back to the stock 4.2* could be enough to cause sever vibrations. Does anyone have any recommendations as to how much caster or what pinion angle to run with my setup? Thanks to the OP for letting me get that out and thanks for any help you guys may have. If you need more information please let me know.
factory caster would ONLY cause severe vibrations IF your drive shaft isn't balanced well and really, this is something that you would only really start to see if you were running 5.13 gears or higher. i would NOT run anything less than factory caster as that would cause your jeep to be flighty at highway speeds.

Last edited by wayoflife; Mar 25, 2012 at 07:03 AM.
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Old Mar 25, 2012 | 07:09 AM
  #13  
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Thanks for the help and clarification. I think I've finally got my head wrapped around it now. Hopefully ill get it finished soon so I can to drive it. I was hoping for the suds n grub this week but it doesn't look like it. Well back to the garage...haha
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Old Mar 25, 2012 | 07:26 AM
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Chech here- http://project-jk.com/jeep-jk-tech/j...affect-my-jeep

At zero pinion angle you'll have 6* of caster which is more than stock. This is a bad angle for your t-case (especially lifted) and can cause serious issues.
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Old Mar 25, 2012 | 07:43 AM
  #15  
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Originally Posted by Dynatrac
Chech here- http://project-jk.com/jeep-jk-tech/j...affect-my-jeep

At zero pinion angle you'll have 6* of caster which is more than stock. This is a bad angle for your t-case (especially lifted) and can cause serious issues.
Well now you have me scampering outside to double check everything. I believe I had set my caster to 4* on the passanger side. If I understand the article you linked correctly, after a lift you will have to reduce caster closer to zero to avoid driveline issues, correct? And to improve handling, you will try to increase the caster again? With 4" of lift, and stock driveshaft, what is the ideal caster to aim for? I thought you wanted to get something near 5-6*, but that seems counter-intuitive to the linked article (since it mentions trying to aim for 4* factory caster will wrench the drive train, and to aim for closer to 2*)
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Old Mar 25, 2012 | 08:03 AM
  #16  
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Originally Posted by Dynatrac
Chech here- http://project-jk.com/jeep-jk-tech/j...affect-my-jeep

At zero pinion angle you'll have 6* of caster which is more than stock. This is a bad angle for your t-case (especially lifted) and can cause serious issues.
in all fairness, i think the key word here is "can" - not "will". at 6° of caster and running a factory drive shaft, factory gears and on a smaller lift, i have not seen this to be a problem - ever. sure, on a JK running a tall lift, aftermarket drive shafts and running 5.13 gears or higher, 6° really is bad news just waiting to happen and one that you can feel immediately. but, assuming the drive shaft is well balanced, bringing it back closer to stock has always mitigated that for me. because no two driveways are the same and nobody seems to be able to measure things the same way, i do recommend that people try to get to about a 4° reading from the top of the ball joint or about zero at the pinion flange as that is a good starting point. and, if you still feel vibrations after that, well, you probably are still off about about a degree or two and, it should be addressed as needed. but of course, that's just how i've been doing it and what has worked for me.

so that it's clear to everyone, driveline vibrations should NOT be ignored and you shouldn't just set your caster to what you think it should be and assume that it must be right.

Last edited by wayoflife; Mar 25, 2012 at 08:07 AM.
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Old Mar 25, 2012 | 08:26 AM
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Thank you for the great info. I am subscribed to this thread and next month will be my install of driveshafts
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Old Mar 25, 2012 | 08:54 AM
  #18  
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So I just went out and measured, I have 1* of caster (measuring the top of the ball joint). Should I try to get it closer to 4*? (4" lift, factory axle, factory drive shaft)
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Old Mar 25, 2012 | 09:29 AM
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Originally Posted by sneck
So I just went out and measured, I have 1* of caster (measuring the top of the ball joint). Should I try to get it closer to 4*? (4" lift, factory axle, factory drive shaft)
just to verify, measuring from the top of the ball joint, your c is dropping toward the back of your jeep only 1°? if so, even assuming for a degree or two margin of error, you would still be under what factory caster should be at and your jeep should feel flighty at highway speeds. if you're okay with the way your jeep feels, leave well enough alone - as i always say, ride comfort and handling quality is totally subjective and having as little caster as you have now will pretty much ensure that you won't have vibes. if it were my jeep, i would be adding a bit more caster but, that's just the way i like it.
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