E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > Tuning & Tech > Suspension & Braking Forum by BimmerWorld

Suspension & Braking Forum by BimmerWorld
Have some questions about suspension or brake setups for your E46 BMW? Get all your answers here!
Sponsored by BimmerWorld

Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 12-03-2016, 09:16 PM   #1
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
Wheel Alignment Angles Explained

This is my steering and alignment post.
I do not know everything, but I will at least tell you what I do know and maybe it might help someone.
To start I would like to say that the dealership has all the correct alignment equipment to do wheel alignments the proper way. This includes weights, ride height measurement tools, etc. If your vehicle was in an accident then a BMW certified body shop could check it on their frame machine. The outside shops that do alignment have machines with adjusted specifications in order to do the alignment. This is within approximately 1% of measured angles so your alignment will come out just about the same. There are some shops that do alignment for body shops. Usually these guys know what they are doing. If your vehicle was modified then you may want to find a shop that does lowered / raised vehicles.
If you want to have tire longevity and even wear, then an alignment will correct bad tire conditions.


Tires should be the same size per axle front axle / rear axle. Different tread patterns will have an effect on driving conditions as the contact patch between the tire and the road are different. Before any adjustments are to be done on the vehicle. The most important thing to do is to make sure that your tires are properly inflated. Conditions caused by under inflated tires is that both outer and inner edges are worn and the middle has more tread. This also has an effect on fuel economy and will cause the vehicle to drift / pull to the side with the lowest pressure. Conditions caused by over inflated tires is that both outer and inner edges have more tread than the middle of the tire.

Suspension components that are worn, bent or damaged will have an effect on the outcome of your alignment. If you know something is defective then change it. Also the technician working on your vehicle should have checked your front end and suspension before they do the alignment. If not then ask them to do so.


The 3 most common angles / adjustments used in alignment is Toe , Camber , and Caster. Afterwards there is SAI Steering Axis Inclination , Included Angle , Thrust Angle , etc.

The most adjusted angle to correct an off centered steering wheel is called "TOE". Not the one on your foot but you can also use that for reference. Toe alignment is the measured difference between the front of the tire and the rear of the tire. This is the same for the front and rear wheels. An even Toe alignment will straighten your steering wheel for you.


Toe adjustments that are out of alignment will cause "feathering" of the tires and increase tread wear. Also if extremely out of adjustment will cause tire noise while driving and steering stability problems.
"Toe In" or "Positive Toe" is the front of the tire pointing in towards the center line of the vehicle. See below illustration.


Slightly increased Toe-in will reduce over steer, steady the vehicle and improve handling at higher speeds.

"Toe out" or "Negative Toe" is the front of the tire pointing out away from the center line of the vehicle. See below illustration.


Slightly increased Toe-out will reduce under steer during initial turn in or while entering a corner at higher speeds.
Attached Thumbnails
Click image for larger version

Name:	Tires.jpg
Views:	167
Size:	23.6 KB
ID:	646402   Click image for larger version

Name:	Bent suspension parts.jpg
Views:	157
Size:	33.3 KB
ID:	646403   Click image for larger version

Name:	Toe.jpg
Views:	155
Size:	71.0 KB
ID:	646404   Click image for larger version

Name:	Toe In.jpg
Views:	155
Size:	57.3 KB
ID:	646405  

Click image for larger version

Name:	Toe Out.jpg
Views:	161
Size:	56.0 KB
ID:	646406  

Last edited by Swiff; 12-03-2016 at 09:29 PM.
Swiff is online now   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 12-03-2016, 09:16 PM   #2
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
Camber is the inwards or outwards tilt of the wheel. Out of adjustment camber will cause uneven tire wear on either the inside treads of the tire or the outside treads of the tire. There are camber adjustments on the front and rear of our vehicles.


Excessive camber can cause the vehicle to pull to one side. Also if extremely out of adjustment will cause tire noise while driving and steering stability problems. Your Camber adjustment also directly affects Toe. If no other adjustment is touched then Positive Camber will give you Toe-in and Negative Camber would give you Toe-out. This is because our vehicles have the steering ahead of the front axle. If our rack and pinion was behind the front axle the opposite would be true. If no other adjustment is touched then Positive Camber will give you Toe-out and Negative Camber would give you Toe-in.

Positive Camber is the the top of the wheel pointed away from the vehicle center line. Excessive Camber will cause accelerated tire wear on the outside tread area of the tire. See below illustration.


Negative Camber is the top of the wheel pointed towards the vehicle center line. Excessive Camber will cause accelerated tire wear on the inside tread area of the tire. See below illustration.


Caster angle is for the front of the vehicle only. Caster helps with tracking and allows the steering wheel to come back to center when coming out of turns. Caster directly affects Camber while turning. While turning the steering wheel you will see Camber gain. The outside wheel will go Negative Camber and the inside wheel will go Positive Camber. Caster is the forwards or rearwards tilt of the steering knuckle. In our cars we have struts. So the angle of center strut bolt in relation to the lower ball joint. On vehicles with SLA (Short/Long Arm) suspension, the relationship between the upper and lower ball joint is where the measurements / adjustments will be taken.


Positive Caster would be the strut top leaning more towards the rear of the vehicle. This would cause the vehicle to pull / drift to the side with the least amount of Positive Caster. Positive Caster also allows the wheels to come back to center out of turns and improves directional stability. See below illustration.


Negative Caster would be the strut leaning more towards the front of the vehicle. This would cause steering instability at higher speeds especially with wider wheels / tires. There will be more of a tendency for the vehicle to track the road that is grooved. See below illustration.
Attached Thumbnails
Click image for larger version

Name:	Camber.jpg
Views:	136
Size:	31.9 KB
ID:	646407   Click image for larger version

Name:	Camber Negative.jpg
Views:	137
Size:	45.4 KB
ID:	646408   Click image for larger version

Name:	Camber Positive.jpg
Views:	134
Size:	43.3 KB
ID:	646409   Click image for larger version

Name:	Caster.jpg
Views:	143
Size:	53.6 KB
ID:	646410  

Click image for larger version

Name:	Caster Negative.jpg
Views:	135
Size:	79.2 KB
ID:	646411   Click image for larger version

Name:	Caster Positive.jpg
Views:	144
Size:	65.6 KB
ID:	646412  

Last edited by Swiff; 12-03-2016 at 09:40 PM.
Swiff is online now   Reply With Quote
Old 12-03-2016, 09:16 PM   #3
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
SAI (Steering Axis Inclination) is the distance from the center strut nut to the tires true vertical center line. SAI is the strut top tilt inwards or outwards to the vehicle center line. It is always a positive measurement. Increased SAI would give you better steering stability. SAI is a front end measurement *non-adjustable only.


Increased SAI directly affects Camber. Positive SAI in turns will cause the Camber to go positive on the outside wheel and negative on the inside wheel. This is not good for cornering at higher speeds and will cause the outer treads of the tire to wear out faster. SAI will usually be the same amount on the left front and the right front. If the numbers are off by more than a 1.5 degrees then most likely something is worn damaged or bent in the front end.


Notice in above picture how the Tire is straight but the strut is facing more inwards even though the tires are vertical.

Included Angle is the combination of SAI and Camber. If the Camber angle is negative then the Included Angle will be less than the SAI. If the Camber angle is positive then the Included Angle will be more than the SAI. See below illustration.


Attached Thumbnails
Click image for larger version

Name:	SAI Steering Angle Inclination .jpg
Views:	140
Size:	36.6 KB
ID:	646413   Click image for larger version

Name:	SAI Steering Angle Inclination Positive .jpg
Views:	137
Size:	61.8 KB
ID:	646414   Click image for larger version

Name:	Included Angle1.jpg
Views:	136
Size:	36.3 KB
ID:	646415   Click image for larger version

Name:	Included Angle2.jpg
Views:	139
Size:	52.2 KB
ID:	646416  


Last edited by Swiff; 12-03-2016 at 09:49 PM.
Swiff is online now   Reply With Quote
Old 12-03-2016, 09:16 PM   #4
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
Thrust Angle measures the direction that the rear of the vehicle wants to go. When aligning the rear of the vehicle the rear Toe numbers should be the same amount positive or the same amount negative.


If the rear Toe is out on one side, it will cause the vehicle to want to travel in the direction of the highest Toe angle.




Well that's it.
THE END.
Attached Thumbnails
Click image for larger version

Name:	Thrust Angle.jpg
Views:	129
Size:	71.1 KB
ID:	646421   Click image for larger version

Name:	Thrust Angle1.jpg
Views:	133
Size:	75.0 KB
ID:	646422   Click image for larger version

Name:	Thrust Angle2.jpg
Views:	135
Size:	72.7 KB
ID:	646423  

Last edited by Swiff; 12-03-2016 at 09:56 PM.
Swiff is online now   Reply With Quote
Old 12-03-2016, 09:17 PM   #5
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
Finished posting. Thought I needed more room. Well if I do then I still have this one. If this is in the wrong section please relocate.

Last edited by Swiff; 12-03-2016 at 10:00 PM.
Swiff is online now   Reply With Quote
Old 12-03-2016, 10:54 PM   #6
lllRazorlll
Modded ///Member
 
lllRazorlll's Avatar
 
Join Date: Jul 2012
Location: Philadelphia, PA
Posts: 2,160
My Ride: '00 328i
Nice visual explanation. Helps those of us who learn best that way
__________________
lllRazorlll is offline   Reply With Quote
Old 12-04-2016, 06:43 PM   #7
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
Quote:
Originally Posted by lllRazorlll View Post
Nice visual explanation. Helps those of us who learn best that way
Thanks. It took a while for me to figure out MS paint. As you can see I like to doodle and I know that
Swiff is online now   Reply With Quote
Old 12-18-2016, 07:16 PM   #8
Swiff
Registered User
 
Join Date: Dec 2013
Location: New York
Posts: 205
My Ride: 2002 330xi
I will be changing some of the pictures from this design to this because it is a better representation of the E46 chassis.


Well at least the E46xi chassis.
I still have to put the tires on. What do you think?
Attached Thumbnails
Click image for larger version

Name:	4WD system.jpg
Views:	58
Size:	33.1 KB
ID:	647343   Click image for larger version

Name:	E46xi Chassis.jpg
Views:	56
Size:	35.9 KB
ID:	647344  
Swiff is online now   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 11:59 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
(c) 1999 - 2016 performanceIX Inc - privacy policy - terms of use