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How often alignment & how much change on settings?
I don't mean how much do you adjust the settings, I mean how much did they shift from where you set them and why?
This is for camber only so far.
LF chg -.1 deg.
RF chg 0.0
LR chg -.4
RR chg -.3
I have camber plates & good poly bushings, so there is zero slippage there.
I do not have a setup plate or hubstands so there is a good chance this is simply a measuring error due to putting the car in a slightly different spot where I do alignment. I do have specified marks that are leveled on my floor.
Is it also possible that ball joint and hub wear are a factor? All original (55k mi) except RR bearing.
Time between alignments is 3 months and six events on slicks & rough lots.
Is this within reason for a "garage alignment" or should I be looking for problems.
Tool is Smart Camber and I square it & zero it per instructions evey time I use it.
IMHO a lot of the difference is probably due to the way you are performing the alignments and lack of really precise measuring equipment. It is well within the margin for error. You are talking 10ths of a degree, if you had major shift, a degree or more then something is loose or wearing quickly. On my track car, I had a shop perform an alignment to my specs at the start of each season. Then marked the excentrics with paint so I could see if anything shifted when I had the car on the lift after each event. Usually only set it once a season (8-10 weekends) or if I had a particularly bouncy off track excursion.
Last edited by CHJ In Virginia; 08-26-2014 at 04:53 PM.
Your measurement accuracy and repeatability is probably fine. The difference is the ride heights which you do not have data for. Ride height changes camber, camber changes toe. So if the ride height varies everything else does too.
Poly bushing stiction can change ride height by a LOT.
Your measurement accuracy and repeatability is probably fine. The difference is the ride heights which you do not have data for. Ride height changes camber, camber changes toe. So if the ride height varies everything else does too.
Poly bushing stiction can change ride height by a LOT.
I do have different front tires but rears are same.
If ride height changes due to tire height does that change camber
I think it is just poly bushing stiction, especially since your largest changes are in the exact order of where the driver's weight goes. So your bushings are sticky and when you exit the car the sticky bushings keep the springs compressed, reducing ride height, changing the camber.
You can experiment with this -- either lift up or push down on a corner and see if the car settles at the same height. If it does not, remeasure everything and see how much it changes.
In my experience, you can raise or lower the car by half an inch easy at the rear, by hand.
Same principle goes if you jack a wheel off the ground and drop the car off the jacks with the suspension in full sag. You will raise the ride height a ton which is why you have to roll the car back and forth before you measure the alignment -- otherwise you get random ride heights and unreproducible camber measurements.
I think it is just poly bushing stiction, especially since your largest changes are in the exact order of where the driver's weight goes. So your bushings are sticky and when you exit the car the sticky bushings keep the springs compressed, reducing ride height, changing the camber.
You can experiment with this -- either lift up or push down on a corner and see if the car settles at the same height. If it does not, remeasure everything and see how much it changes.
In my experience, you can raise or lower the car by half an inch easy at the rear, by hand.
Same principle goes if you jack a wheel off the ground and drop the car off the jacks with the suspension in full sag. You will raise the ride height a ton which is why you have to roll the car back and forth before you measure the alignment -- otherwise you get random ride heights and unreproducible camber measurements.
I drive the car thru the ditch at the bottom of the driveway, but there is still my 185 lbs getting out, so I think i bounce it a few times after I get out, at least the driver side. The poly is well lubed but yes, there is still stick.
Good post!
I can roll the car back a bit but forward is hard for 1 guy against the "water heater" slope.
What about change in ride height adjuster vs tire ?
What about change in ride height adjuster vs tire ?
Changing the tire diameter won't change the alignment. But it will change your reference ride height which you need to know to make sure the suspension is in the same place when you measure the alignment.
Changing the tire diameter won't change the alignment. But it will change your reference ride height which you need to know to make sure the suspension is in the same place when you measure the alignment.
Thanks, I have not been checking ride height during camber settings as that also seems to change a mm or so whenever you move the car.
I guess I am looking for perfect which is hard to get to with my constraints on setup area and with a mostly street car.
I check everything before the track and then do it all again when I get back home. That's how I figured out that my poly bushings were going bad. My left rear wouldn't hold it's camber setting. It was almost a degree off. When I took everything apart this is what i found.
I check everything before the track and then do it all again when I get back home. That's how I figured out that my poly bushings were going bad. My left rear wouldn't hold it's camber setting. It was almost a degree off. When I took everything apart this is what i found.
I could not agree more, it blows my mind how many guys will just take a car onto a track at 3x speeds and maybe they aired up the tires (if they remembered) and that's it.
No wonder so many HPDE sessions are yellow/red flagged for breakdowns or s##t falling off onto the track.
I am constantly refining my alignment car set-up technique. One thing I learned was the best way to get reproducible results and make sure all the stichion was out of my suspension was to do my alignment while still on the scales. So when I dropped the car back onto the scales I settle the car by bouncing on the front and rear of the car and look to see that the corner weights are at the weights that I corner balanced the car at. That gives me real numbers very quickly and I'm not having to do what was suggested above which is to confirm ride heights which is a much more difficult task. Now I'm ready to measure and adjust camber etc. The only time I have to really shake the heck out of the car is the final time to confirm 50/50 cross.
The other thing I learned was why you want solid camber plates especially on the rear of the C5/6 vette. I never bothered to find out why all the angst if your ecentrics move a bit and you loose camber. Whats the big deal? Well the typical process to align a car is set your thrust to zero 1st. Then rear toe. The rear camber then move to front. The huge problem with an ecentric moving is not the loss or change in camber but the effect that change has on thrust and rear toe. A 1/2 degree change in camber will massively alter your thrust and make a car near uncontrollable. So on the C5 its set thrust, camber, toe and go back and check thrust again. Every change has some effect on the other settings. The take home message is use camber plates never the ecentrics or you could be in for a wild ride if one comes loose mid-race.
I am constantly refining my alignment car set-up technique. One thing I learned was the best way to get reproducible results and make sure all the stichion was out of my suspension was to do my alignment while still on the scales. So when I dropped the car back onto the scales I settle the car by bouncing on the front and rear of the car and look to see that the corner weights are at the weights that I corner balanced the car at. That gives me real numbers very quickly and I'm not having to do what was suggested above which is to confirm ride heights which is a much more difficult task. Now I'm ready to measure and adjust camber etc. The only time I have to really shake the heck out of the car is the final time to confirm 50/50 cross.
The other thing I learned was why you want solid camber plates especially on the rear of the C5/6 vette. I never bothered to find out why all the angst if your ecentrics move a bit and you loose camber. Whats the big deal? Well the typical process to align a car is set your thrust to zero 1st. Then rear toe. The rear camber then move to front. The huge problem with an ecentric moving is not the loss or change in camber but the effect that change has on thrust and rear toe. A 1/2 degree change in camber will massively alter your thrust and make a car near uncontrollable. So on the C5 its set thrust, camber, toe and go back and check thrust again. Every change has some effect on the other settings. The take home message is use camber plates never the ecentrics or you could be in for a wild ride if one comes loose mid-race.
I like that way, but I don't have scales yet.
When I finished toe, yesterday, I drove it and again (2x in a row) my steering wheel was perfectly straight!
I wonder why it used to be always crooked when I used to have a shop do it? I don't stake the wheel either, just center it & the column lock holds it. Same as staking I guess. Yeah I still have a column lock (2004) never had a problem.
What takes me the longest when I do toe is setting the strings perfect around the car, each change on one end changes the other. Grrr. Takes me an hour just to string it.
08-26-2014, 04:34 PM
How often alignment & how much change on settings?
