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Can anyone confirm if you get a 4 wheel alignment done at the dealer that they check thrust angle and SAI? I've seen the dealership alignment readout sheet and it doesn't show these measurements but maybe they're just calling it by a different name? I attached an example of what the dealer readout looks like.
Can anyone confirm if you get a 4 wheel alignment done at the dealer that they check thrust angle and SAI? I've seen the dealership alignment readout sheet and it doesn't show these measurements but maybe they're just calling it by a different name? I attached an example of what the dealer readout looks like.
Yes, they do and yes different alignment machines have different terms as well.
Can you tell me which term is thrust angle and which is SAI?
geometrical driving axis = thrust angle
SAI on the other hand is all integrated with measurements at 20°. Then, final measurements at 0°
Those measurements include SAI/IA and toe out on turns.
If any of the measurements are out of spec for SAI/IA it will show red and won’t let the tech complete the alignment.
SAI on the other hand is all integrated with measurements at 20°. Then, final measurements at 0°
Those measurements include SAI/IA and toe out on turns.
If any of the measurements are out of spec for SAI/IA it will show red and won’t let the tech complete the alignment.
Awesome thanks for all that info. I'm going to have my cars alignment checked because I'm sort of paranoid maybe the subframe got tweaked or something. I bought it as a certified pre-owned (frame and alignment should have already been checked) only a couple months ago, completely clean carfax. It's hard to explain what I'm feeling when driving but the car seems to kinda sway back and forth every so often, maybe has to do with little road irregularities but I don't exactly know what causes it to feel that way. And the car seems to be really sensitive to crosswind, you can really feel it. Another strange thing I noticed is whenever I park as straight as possible in a parking spot, the driver side rear looks crooked but the passenger side looks completely straight. I can't figure out how that is even possible lol. Either way the alignment check should tell me if there is something to worry about like a tweaked subframe correct?
With Extended Mobility Tires - yes - at times you will feel a quick "Fan-Tail-Dance" - sidewalls have much less flex and that energy has to move something..
Awesome thanks for all that info. I'm going to have my cars alignment checked because I'm sort of paranoid maybe the subframe got tweaked or something. I bought it as a certified pre-owned (frame and alignment should have already been checked) only a couple months ago, completely clean carfax. It's hard to explain what I'm feeling when driving but the car seems to kinda sway back and forth every so often, maybe has to do with little road irregularities but I don't exactly know what causes it to feel that way. And the car seems to be really sensitive to crosswind, you can really feel it. Another strange thing I noticed is whenever I park as straight as possible in a parking spot, the driver side rear looks crooked but the passenger side looks completely straight. I can't figure out how that is even possible lol. Either way the alignment check should tell me if there is something to worry about like a tweaked subframe correct?
Well, these cars do come with Crosswind Assist as standard. Do you feel like your “ping-ponging” in your lane? Did your car come with Driver Assistance Package? If it did, you can turn the Active Steering Assist off. Mine came with the Driver Assistance Package and it does give that “ping-pong” effect when it’s on. So, I just Keep it off until I use the cruise control.
Also, the front and rear track are different, so if you’re gauging the distance when you park against the parking stripe, it may look crooked... worse when you have wider staggered after market rims.
You can also ask a friend to drive behind you... like 5 car lengths behind. If there’s something wrong with your chassis, the car behind you will see you tracking to the left or right like a crab walking sideways.
Well, these cars do come with Crosswind Assist as standard. Do you feel like your “ping-ponging” in your lane? Did your car come with Driver Assistance Package? If it did, you can turn the Active Steering Assist off. Mine came with the Driver Assistance Package and it does give that “ping-pong” effect when it’s on. So, I just Keep it off until I use the cruise control.
Also, the front and rear track are different, so if you’re gauging the distance when you park against the parking stripe, it may look crooked... worse when you have wider staggered after market rims.
You can also ask a friend to drive behind you... like 5 car lengths behind. If there’s something wrong with your chassis, the car behind you will see you tracking to the left or right like a crab walking sideways.
My car does not have driver assist. So is the front track wider than the rear? That's what it would look like in the picture, but still strange the other side looks completely straight lol. Would the alignment check pickup if there was something going on with the subframe that needs further looking into?
My car does not have driver assist. So is the front track wider than the rear? That's what it would look like in the picture, but still strange the other side looks completely straight lol. Would the alignment check pickup if there was something going on with the subframe that needs further looking into?
Yes, if the technician is meticulous he should be able to catch it. The alignment machine definitely will, but if the tech ignores it... worse, overrides the machine’s findings.
Yes, if the technician is meticulous he should be able to catch it. The alignment machine definitely will, but if the tech ignores it... worse, overrides the machine’s findings.
By override do you mean purposely change bad readings to good? Not sure what advantage they'd have by doing that.
You can measure yourself. Height from ground to the top of the wheel housing, clearance between the tire and the wheel housing. Driver side and passenger side should have the same height and clearance.
You can measure yourself. Height from ground to the top of the wheel housing, clearance between the tire and the wheel housing. Driver side and passenger side should have the same height and clearance.
Finally got the alignment done and everything was able to be moved into the green so looks like I don't have any subframe damage! I'm guessing with subframe damage you'll notice the geometric driving axis out of spec but that was good from the start.
So interestingly enough I noticed the back and forth sway symptoms after they performed the below attached recall steering gear bolt replacement. While it doesn't require a front wheel alignment on mine like the other vehicles, it's a little suspicious the front toe was so far off especially compared to the rear. My guess is they really should in fact be doing alignments to the front on the w205's even though the procedure says otherwise, or maybe the tech who did the recall disconnected more stuff than he should have causing the toe to get all messed up.
Edit: Actually they had to replace the steering gear on mine, not just the bolts which means they should in fact have done the alignment on the front of my car.
Last edited by Bmarcinczyk14; 02-01-2020 at 05:25 PM.
With Extended Mobility Tires - yes - at times you will feel a quick "Fan-Tail-Dance" - sidewalls have much less flex and that energy has to move something..
What exactly is a fan tail dance? I got the car aligned and I felt like for a couple days I didn't notice this swaying back and forth feeling over slight road imperfections but then it came back again. Sometimes it even causes the car to start pulling slightly to the left or right. I'm definitely not a fan of this feeling almost makes the car not feel as solid as it should. Hopefully it's just a normal phenomena with the run-flat tires and something isn't messed up with the suspension or something. Does anyone else feel what I'm describing?
What exactly is a fan tail dance? I got the car aligned and I felt like for a couple days I didn't notice this swaying back and forth feeling over slight road imperfections but then it came back again. Sometimes it even causes the car to start pulling slightly to the left or right. I'm definitely not a fan of this feeling almost makes the car not feel as solid as it should. Hopefully it's just a normal phenomena with the run-flat tires and something isn't messed up with the suspension or something. Does anyone else feel what I'm describing?
I used to get that exact road feel in my Jag XJ6 a few years ago. Determined that it was something called tramlining, where the tires have a tendency to follow road imperfections/lines and makes the car feel like it is pulling slightly side to side in the lane and causes a general unsteadiness.
In my case a brand new set of tires immediately fixed it and the behavior went completely away.
I used to get that exact road feel in my Jag XJ6 a few years ago. Determined that it was something called tramlining, where the tires have a tendency to follow road imperfections/lines and makes the car feel like it is pulling slightly side to side in the lane and causes a general unsteadiness.
In my case a brand new set of tires immediately fixed it and the behavior went completely away.
They are the original run-flat tires. Do they have a tendency to "tramline"?
01-25-2020, 12:19 PM
