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Doing an underhood inspection recently, I noticed the right side upper control arm has an odd shim arrangement... the front mounting bolt has 3 shims but the rear bolt only has 1, plus this single shim is upside down and looks like it slid halfway out of it's mounting place but it is not loose. The left side UCA has 3 shims front and back, all right side up and looking proper. I've had the car professionally inspected and aligned a few times in the past, the technician did not say anything. (The car drives good, maybe wanders a bit on the highway but that's probably tie rods or something else, or could be grooves in the pavement that I'm not seeing... either way it's not a real problem.)
So... is this worthy of concern? Should I just drive the car, and point out the shim arrangement to the technician next time I take it for alignment? Sorry I did not take a picture at the time, I can provide one if it will help but I figure this description is adequate for anyone familiar with the UCA shim arrangement. Thank you all.
Doing an underhood inspection recently, I noticed the right side upper control arm has an odd shim arrangement... the front mounting bolt has 3 shims but the rear bolt only has 1, plus this single shim is upside down and looks like it slid halfway out of it's mounting place but it is not loose. The left side UCA has 3 shims front and back, all right side up and looking proper. I've had the car professionally inspected and aligned a few times in the past, the technician did not say anything. (The car drives good, maybe wanders a bit on the highway but that's probably tie rods or something else, or could be grooves in the pavement that I'm not seeing... either way it's not a real problem.)
So... is this worthy of concern? Should I just drive the car, and point out the shim arrangement to the technician next time I take it for alignment? Sorry I did not take a picture at the time, I can provide one if it will help but I figure this description is adequate for anyone familiar with the UCA shim arrangement. Thank you all.
I'd say you need to have it aligned and ask the alignment technician to explain FEA to you. So long as the 4 factory 'washers' are properly placed and aligned it isn't unusual for the shim counts side to side NOT to match. It would be considered ODD/UNUSUAL if they in fact did. There are alignment shims with a hole in the tab that allows them to be wired.
Doing an underhood inspection recently, I noticed the right side upper control arm has an odd shim arrangement... the front mounting bolt has 3 shims but the rear bolt only has 1, plus this single shim is upside down and looks like it slid halfway out of it's mounting place but it is not loose. The left side UCA has 3 shims front and back, all right side up and looking proper. I've had the car professionally inspected and aligned a few times in the past, the technician did not say anything. (The car drives good, maybe wanders a bit on the highway but that's probably tie rods or something else, or could be grooves in the pavement that I'm not seeing... either way it's not a real problem.)
So... is this worthy of concern? Should I just drive the car, and point out the shim arrangement to the technician next time I take it for alignment? Sorry I did not take a picture at the time, I can provide one if it will help but I figure this description is adequate for anyone familiar with the UCA shim arrangement. Thank you all.
Caster is adjusted by changing the angle of the ball joint axis, and I think that is what you are seeing.
The ball joint axis is changed by moving the upper ball joint forward or backward relative to the lower ball joint.
You move the upper ball joint center by adding or subtracting shims. Everything you described sounds normal to me, with the exception of the one shim being upside down.
Post a picture of it if you feel like it.
Last edited by PatternDayTrader; Jul 9, 2018 at 12:13 PM.
Upper Control Arm Shims
