1.1° difference between Left and Right caster readings

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I am prepping for the next set of maintenance tasks while I wait for my Delta radius arms to arrive. My current readings show that caster is off by 1.1*, where the left is 1.7* and right is 0.6*. My specs that apply to the front end are below:
  • 94 fzj
  • 2.5 OME front heavy, rear medium, nitro shocks
  • Caster correction bushings that come with OME lift kit (will be replaced soon with Delta arms)
  • Whiteline HD front sway bar, dropped
  • New 555 TREs all around with Marlin DOM rods
  • New adjustable pan hard front and rear
  • Powerstop z36 rotors
  • 35" with 1.25 spacers
The car runs decent at both low and speeds of 70mph with toes in at 13* a side. Does not pull left or right at all, and hard turns feel great. Wheels are on solid after attempting to shake and move them jacked up. Nothing weeping at the steering knuckle, knuckle arms are all solid at 71ft lbs, no sounds coming from the birfs or front axle at all speeds.

All I can think if are that my radius arm bushings are off on one side, or perhaps trunnion bearings? Anyone run into a variance between left and right caster this big and have any ideas?

Readings below

tempImageGwD6oN.jpg
 

smritte

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Who did the alignment? 1 degree difference you would be turning the steering wheel to compensate . Who ever aligned it, probably didn't lock the brake pedal when he measured the caster. You steer the vehicle left and right and the machine calculates caster from how much lean the tire has when its turned. If the tire is allowed to rotate slightly, it will throw the reading off.
 

eimkeith

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@eimkeith - welp you were right. Just measured and the right side front and back is a little less than 1/4" lower than the passenger side.
I don't think that would account for it, but I'll draw it up real quick and see. (I was thinking like 1"+, maybe)

EDIT - that accounts for .44 degrees or so; so not your actual issue.
 

smritte

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Looking at your sheet, Rear thrust angle is .4 (vehicle is slightly crooked on rack), rear camber is almost .5 difference. The alignment head is slightly crooked.
Bottom line, we don't care about the rear, unless you were looking for a bent axle. It does bring up the question now of the accuracy of the front. If the vehicle tracks straight, don't worry about it.
If this sheet was accurate, your vehicle would be dog tracking slightly and going to the right.
 

eimkeith

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Looking at your sheet, Rear thrust angle is .4 (vehicle is slightly crooked on rack), rear camber is almost .5 difference. The alignment head is slightly crooked.
Bottom line, we don't care about the rear, unless you were looking for a bent axle. It does bring up the question now of the accuracy of the front. If the vehicle tracks straight, don't worry about it.
If this sheet was accurate, your vehicle would be dog tracking slightly and going to the right.
wonder if all the tires were aired up properly, based on that rear camber?
also - my rack uses the rear as a reference to determine the front values, I assume all of them do?
 

Delta VS

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Have been told by a couple alignment shops that this is how the OEMs account for the crown in the road. NOT claiming this idea to be true, but every single vehicle we’ve had measured shows .2 to 1* difference between sides.
 

mudgudgeon

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I’m going to take it to another place for another reading for comparison and make sure my tires are all aired up properly myself prior.

Thank you gentlemen for all the help! And yes, it’s drives pretty darn good and stable compared to how it did before :)

Maybe check front wheel bearings are good first too.
They can have a surprising amount of play before they affect driving feel significantly.
 

mudgudgeon

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Maybe check front wheel bearings are good first too.
They can have a surprising amount of play before they affect driving feel significantly.
Just did the front axle 2000 miles ago I’m really hoping it’s not that haha.

After my stock TREs were beat to s*** and melted with heat trying to get more toe in - I had to pick up some replacements quickly before a planned road trip so I ended up with the marlin steering kit since they were in stock.


So far so good, and feels quality. I’m sure they won’t live as long as OEM, but the DOM rods and 555 ends should last long enough.
 

landtank

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with the trucks getting old and who knows how many incompetent hands have touched them, some times it can be the weirdest thing. I'd still cycle the front end and make sure the front and rear stops on the knuckles are contacting the stops on the axle. Somebody might have botched centering a steering box and you are falling short in one direction.
 

mudgudgeon

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Just did the front axle 2000 miles ago I’m really hoping it’s not that haha.

After my stock TREs were beat to s*** and melted with heat trying to get more toe in - I had to pick up some replacements quickly before a planned road trip so I ended up with the marlin steering kit since they were in stock.


So far so good, and feels quality. I’m sure they won’t live as long as OEM, but the DOM rods and 555 ends should last long enough.

Thanks for the link. Will have a look. Mine has quite new TREs.
I had similar made for a previous vehicle
 
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with the trucks getting old and who knows how many incompetent hands have touched them, some times it can be the weirdest thing. I'd still cycle the front end and make sure the front and rear stops on the knuckles are contacting the stops on the axle. Somebody might have botched centering a steering box and you are falling short in one direction.
Good call out. I’ll play with it later today. Thanks!
 

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