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Wed Nov 29, 2006 5:41 pm

For those heading out for an alignment where the shop has no spec listings. Hope this is of help to some of you.

VW alignment specs borrowed from

Thing 71-74 and Type 1 60-68

T1 EXC SUPER AND VERT 69-77
T1 Vert 71-79
T1 Super 71-75
T2 68-79
T3 Fastback 66-73
T3 Squareback 66-73

T4 411,412 71-74
Vanagon models 80-86 including Syncro

SIDE SCUFF AND TOE CHANGE WEAR PATTERNS
Of the two most common wear patterns, one Is most often attributed to under inflation, which It could be, provided the tire has been driven that way for a very long period. Sometimes seriously low pressure or overloading can make the wear show sooner, as will hard cornering, of course. The second wear pattern Is usually blamed on incorrect camber. The interesting point here Is - how much is incorrect? On some vehicles, the preferred spec Is +l/2-degree, ±l/2-degree. Although many people, companies and text books have failed to acknowledge this fact for years,, It Is now being widely accepted that a more common cause of this wear pattern is weak shocks and/or springs due to resulting excessive side-scuff. Here's why. When the tire Is pulled Inward, due to excess control arm arcing, the tire's Inner tread ribs wear more because they are. In a sense, dragged under due to distortion as the tire Is pulled inward. This scuffing simply takes more rubber off the Inner tread ribs. Now, when the control arm comes back to the normal horizontal position. It pushes the wheel back outward. Now the outer edge or tread ribs drag under and therefore scuff more. You may wonder why this action doesn't cause a feathered Inner edge due to the distortion. It does In fact, but the "feather" Is promptly removed as the tire scuffs back In the opposite direction. Another common cause of this same "under Inflation" wear pattern Is dynamic, or load-toe change. Here's why. Suppose the car drops due to a dip In the road, or the wheels rise due to a hump in the road. In either cause, the control arm arcs up and the spring compresses. If there Is a mechanical problem that causes the wheels to toe out at this time, the tire tread tries to go out but can only go a small amount, of course. This distorts the side wall and sets up a scuff action similar to side-scuff with the same result - Inner tread wear.

Now, on the rebound, as the control arm straightens out and the car level Is out, the wheel toe comes back to zero. But as rebound continues (especially with weak shocks) where the car rises and control arms are downward, the same mechanical conditions may cause the wheels to toe In. This will cause the tire tread to track inward but Is restrained by the side walls and so scuffing of the outer tread takes place. Next, consider this. If a toe change problem exists, along with weak springs and shocks, you can see how this wear pattern would develop within a few thousand km. Does this mean that 1 1/2-2° will be excess, and will therefore cause wear? On the other hand, many vehicles today have +1 1/2° preferred with ±l° allowed. Does this mean that a tire on this vehicle will not develop camber wear until the camber exceeds +2 1/2°? And will It also develop camber wear if/the angle Is less than +1/2°? It Is very confusing to say the least!

Now let's look at this fact from another angle, so to speak. How many cars with Independent rear suspension (or front, nowadays for that matter) have you seen with several degrees camber (2° or more and negative or positive) and yet found either normal tread wear after thousands of kilometers, or (If It's got weak shocks and sagged springs) "under Inflation" type wear pattern? Since most of the time you will not see a "camber" wear pattern on this vehicle, we have to ask that when we do see a "camber" wear down do we know that camber is the real cause? The fact Is we don't. What you are most likely looking at when you see tire "camber" wear on independent suspension systems (either front or rear) Is in fact caused by toe change with up and down movement of the vehicle, or load-toe change as described earlier. The vehicle may have good shocks but most likely has weak parts. For some strange reason most vehicle owners and many automotive industry personnel seem to feel
that If the tires are worn, all the car need is an alignment and that this alignment will compensate for worn parts and sagged springs. In fact that's why most people believe the angles were, or are adjustable - to compensate for wear, etc.!

Nothing could be farther from the truth! Angles are in fact adjustable to allow the manufacturer to establish the designed-in angles during assembly, while assembling the vehicles from various parts that need not be, or are not, made to exacting specifications. In other words, adjustments were used to compensate for manufacturing tolerance, but were never Intended to compensate for wear. They also happen to be very useful to the mechanic when repairing the vehicle for the same reason; that is, to enable him/her to re-establish to designed-in operating angles. In recent years the manufacturers have Improved production methods to the point where they can assemble the vehicle with more precise parts to a more precise body or frame, and establish the designed-in angles without the need for final adjustments other than toe. And let's hope they don't take that adjustment away from us! That would be worse than hiding the mixture screws on the carburetor, or having no Ignition timing adjustment.

The result of all this to some service shops is that an "alignment" now takes a little longer. Since there are no camber and caster adjustments on some cars, they feel they have to create them by bending or shimming components that should not be tampered with. And of course, there Is always the so called "specialist" out there that feels he has to set the angles to his "time proven" settings, even though they may be somewhat different from those recommended by the manufacturer. The point here Is that if we replace the proper worn parts and restore the vehicle to the right height, the angles will usually be within spec.
If not, there's likely a bent frame or component that was not detected.

Alignment Angles Explained

Ride Height:
Alignment geometry Is based on vehicle height and If height Is Incorrect, an alignment should not be attempted.

Camber:
Purpose
1 Maximize tire life
2 Isolate road shock
3 Enhance stability
4 Maintain bearing load
5 Reduce stress on suspension components

Caster:
Purpose
1.Obtain desired stability
2.Project vehicle load
3.Improve steering wheel return
4.Improve cornering

Toe:
Purpose
1 Bring about a running toe of zero
2 Reduce stress on steering components
3 Minimize tire wear
4 Centre steering wheel

S.A.I.:
Purpose
1. Keep wheels In straight ahead position
2. Help. wheel return from turning
3. Improve directional stability reducing the need for
additional positive caster
4. Helps In placing more load on larger Inner wheel bearing
5. Assist In maintaining straight line control when braking
On vehicles with long short control arms, the average S.A.I. Is 7 to 10 degrees. On strut suspension, the average S.A.I. is from 10 to 17 degrees. This may explain why some vehicles with a large amount of camber difference don't seem to pull.

QUICK CHECK
S.A.I. and Included Angle

* Is a directional control angle
* Is a built In angle

a) * On vehicles that have camber adjusters on bottom of the strut, S.A.I. angle does not change.
* If S.A.I. angle Is wrong on this type of front end. It would indicate a bent shock tower, bent lower control
arm or bent cross member, etc.
b) * On vehicles that have camber adjusters at the upper or lower control arm, or at the top of the struts, S.A.I. will
change, but Included angle will remain the same. If INCLUDED ANGLE Is Incorrect, a bent spindle or MacPherson strut Is Indicated.

Included Angle:
Purpose
To give technician diagnostic Information to determine If the vehicle has bent parts. Included angle can be changed on front wheel drive vehicles that have adjusters provided at the base of the strut housing. Also, Included angle can be changed on 4X4 when around tapered shim is placed behind the spindle and steering knuckle. To read a true included angle on these types of vehicles, you first have to adjust camber the same on both wheels.

Set Back
When one front wheel Is mounted further back on the body than the other. It may occur from damage or It may be Intentional on some front wheel drive vehicles to help over come torque steer. Turning Angle or toe out on turns: Purpose
1. Reduce tire scuffing on turns
2. Reduce tire squealing on turns
3. Improve handling on turns

Scrub Radius:
Purpose
1. Provide the driver a feel for the road.
2. Project vehicle load to larger Inner wheel bearing.
3. Assist Is providing stability under adverse road conditions.
4. Work In conjunction with static toe settings to help bring about a running toe of zero.

Most rear wheel drive vehicles have positive scrub radius. This Is one reason most rear wheel drive vehicles specie static toe setting of toe in.
Some front wheel drive cars have positive scrub radius, thus, dictating the need of static toe out settings.
Other front wheel drive cars have a negative scrub radius. Therefore, dictating the need for a static toe-in setting.

Reduced Scrub Radius - easier steering

Any bump or cornering force that Is applied to the tire can exert a twisting force on the steering that Is proportional to the length of the scrub radius.
If the scrub radius Is zero, the twisting force will be zero.
Cars with zero scrub radius usually can be driven without assistance of power steering.

Factors that affect scrub radius are:
1. wheel offset
2. brake rotor width
3. design of steering knuckle
4. increased S.A.I. angle will able reduce scrub radius

Roll Centre
The roll centre height is determined by drawing a line from the tire contact print through the Instant centre of the control arms, which Is where we measured the swing arm length. For a given swing arm length, the roll centre height can be raised or lowered by moving the intersection of the control arm lines up or down. If we establish a given roll centre height, this will dictate the Instant centre height and that will determine the angle of control arms.

Alignment Reading & Mechanical Checks
Part of Good Diagnosis
Vehicles are designed to have zero or minimum toe change and side scuff when:
1. The vehicle is at correct ride height statically and dynamically.
2. All related parts are operating within normal wear tolerances, and
3. The steering and suspension components can operate at the proper alignment angles.

Countless books and service guides have been produced to show how to check all mechanical components and ride height quickly and accurately, so there Is no need to go Into that here. But, If you don't know how to read all the angles accurately, and consistently correct (and that goes for S.A.I. (Steering Axis Inclination) and turning radius). touch base with your alignment equipment service training representative because that's their job. And if they say: "Don't worry about S.A.I. and turning radius because they are both non-adjustable angles and you can't adjust them anyway." It's because they either don't know how to get consistent accurate reading, or simply don't know how to read them. Either way, get someone who can, because both readings are critical to proper diagnosis and solving the type of tire wear we are talking about.

Once you've read and recorded all the alignment angles and the riding height, then check all the steering and suspension parts for wear and damage. Also inspect the frame cross members and body for signs of damage, both present or repaired. Incorrectly repaired damage Is a common cause of various handling and tire wear problems on today's cars because even though the adjustable angles may be okay statically, they may not operate at the proper angle dynamically and this Is where S.A.I. and turning radius come In to the picture. If these two angles are not correct, there Is almost always a bent component
involved.
For example: control arms, spindle and support, ball joint stud, MacPherson Strut shock rod, strut tower and mounting supports, frame or cross member, steering arm, pitman arm and steering box support. Idler arm and frame support, rack and pinion housing support. You've really got to take a close look at these components when checking for damage. Often, the only way is to compare from side to side and/or make measurements from the component to the floor, to the wheel, to the mainframe. The main clue to a problem here Is that physical damage will usually result In unequal S.A.I. and turning radius from side to side. Even though you may not have the specs (and unfortunately some leading manufacturers do not give us
this Information), check them anyway because they should normally be within one degree of each other side to side. And since It's unlikely both sides of the vehicle will suffer equal and similar damage, a difference means a problem If the readings are equal, there is not likely a problem!

Wed Nov 29, 2006 5:43 pm

That out to go up in the "technical information I would suggest.

Wed Nov 29, 2006 5:46 pm

You may be right however there are a few guys here looking for this info. Change it if you must but let everyone know where it is.
Later
Dan

Wed Nov 29, 2006 7:38 pm

I'll put it in the index sticky

Wed Nov 29, 2006 7:44 pm

Thanks Glenn
If anyone wants a bigger, clearer scan, email me at [email protected] subject ALIGNMENT SPECS

Wed Nov 29, 2006 7:53 pm

dan macmillan wrote: Thanks Glenn
If anyone wants a bigger, clearer scan, email me at [email protected] subject ALIGNMENT SPECS

Rescan them larger and put them in the gallery.

Thu Jul 19, 2007 10:05 pm

Or better yet, scan it in an put it in a .pdf format so it will print correctly.

Fri Jul 20, 2007 3:23 am

Yes I could have put it in pdf but one could also just write down the specs for their model and bring it with them to the alignment shop. If you want a bigger image that prints properly, email me.

Wed Mar 05, 2008 11:03 am

this info is awesome!!! thank you SO much

Fri Jun 13, 2008 12:02 pm

Im I glad to come across this!
Where I live there is nothing but Detroit iron!!!!!

Fri Jun 13, 2008 12:24 pm

Great information, but rather as a Sticky, should be in the Samba's Technical Archives.

Mon Jun 23, 2008 1:29 pm

so if i print out this sheet and take it to a shop theyll know the right specs to align my bug?

Thu Jun 26, 2008 2:55 pm

stuntpogoer wrote: so if i print out this sheet and take it to a shop theyll know the right specs to align my bug?

Yes.

Thu Jun 26, 2008 3:46 pm

Any good shop should already have this spec. It was in the Hunter machines I trained on...

Fri Sep 11, 2009 4:39 pm

dan macmillan wrote: Thanks Glenn
If anyone wants a bigger, clearer scan, email me at [email protected] subject ALIGNMENT SPECS

New email address
[email protected]

Sat Sep 12, 2009 8:55 am

You rock dan :D

Sat Sep 12, 2009 5:14 pm

vintageorbust wrote: You rock dan :D
Thanks

Wed Jun 09, 2010 3:57 pm

How can you figure out alignment specs for a lowered car?

For example a '72 SB lowered 2"... :wink:

Wed Jun 09, 2010 7:16 pm

Luftgekült wrote: How can you figure out alignment specs for a lowered car?

For example a '72 SB lowered 2"... :wink:

Same specs should be used. Caster increase when running wide front tires.

Tue Jun 15, 2010 1:33 pm

Dan, I was told that I needed a stobe alignment on my 73 super. Is this correct?