[Guest]

Well, after reading all the documentation on wheel alignment I went to see my friendly mechanic about having an alignment done on my 1996 Impala SS. Some of you may like to read about my experiences.

I showed him the GM specs as in the table below.

Specifications: Chevrolet '93-'96 Caprice/Impala SS (G.M. Factory Specs.)

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">Description Spec (deg) Tolerance (deg)
Front Left Camber 0.00 0.80
Front Right Camber 0.00 0.80
Front Cross Camber N/A 1.00
Front Caster 3.50 1.00
Front Cross Caster N/A 1.00
Front Total Toe 0.00 0.20
Rear Camber 0.00 0.00
Rear Total Toe 0.00 0.00
</pre>[/QUOTE]I also showed him the modified specs that have been posted;

Specifications: Chevrolet '93-'96 Caprice/Impala SS (Modified Specs)

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">
Description Spec(deg) Tolerance (deg)
Front Left Camber -0.25 0.25
Front Right Camber -0.25 0.25
Front Cross Camber N/A 0.25
Front Caster 4.00 0.50
Front Cross Caster N/A 0.50
Front Total Toe 0.00 0.06
Rear Camber 0.00 0.50
Rear Total Toe 0.00 0.12
Thrust Angle 0.00 0.25 </pre>[/QUOTE]He showed me the specs for his alignment machine.These had some resemblance to the original factory specs. He looked through the updates available and got the following data from Mitchell Repair.

Modified GM Specs for the 1996 Impala SS
</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">
LEFT FRONT ANGLE RIGHT FRONT
MIN MAX MIN MAX
-1.0 1.0 CAMBER -1.0 1.0
2.25 4.25 CASTER 2.75 4.75
-0.04 0.36 TOE -0.04 0.36
Note: Preferred value is centre of range.
</pre>[/QUOTE]We talked for a while about the extreme wear that I had on the inside of the tires. We also talked about the type of driving I did. (Mainly express ways at the highest speed the police were allowing )

We agreed that the camber should be close to zero, with a slight negative value. The caster should not be too high and my toe-in should be a little higher.
Anyway to cut a long story short, his shop man set up my alignment as below.

</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;"> Wheel Alignment ----AFTER.
LEFT FRONT ANGLE RIGHT FRONT
ACTUAL ACTUAL
-0.12 CAMBER -0.04
3.11 CASTER 3.48
0.15 TOE 0.19
SET BACK 0.12
9.78 INC. ANGLE 9.99
9.90 SAI 10.04
TOTAL TOE 0.34


LEFT REAR TEST RIGHT REAR
ACTUAL ACTUAL
-1.09 CAMBER -0.27
0.17 TOE 0.20
TOTAL REAR TOE 0.37
0.02 THRUST LINE
</pre>[/QUOTE]It took him over two hours. In part because he took care to remove all rust from the bearing surfaces of the shims and the mounting areas. He also did a proper check of the ride heights and suspension parts.

To my pleasant surprise, there was no charge for the alignment. My mechanic just said "My pleasure". I just said "thank you".
Steering feels a lot better. Haven't had a chance to open it up yet and obviously don't know about the wear.
Obviously a good alignment takes a long time and it's worthwhile having a long talk with the mechanic first.

I also had two new front tires installed. (KDWS. Yes, a subject for another thread. I have read the pros and cons, but I like them for the conditions I drive in and how I drive)

 

[Guest]

Thanks for the documentation of your experience.

I like the KDWS tires for my highway driving, too. They have given me great service driving over 50,000 miles this past year in every kind of weather condition. Except for snow, when the Blizzak's go on.

 

[Guest]

Why didn't he want to go higher on caster? I'm a big fan of 4+ degrees, myself. It will help high speed stability...

 

[Guest]

Increasing caster has the side effect of increasing steering effort.

Personally, I LIKE the increased effort (i.e. I think the B-body has too "light" a steering feel) but others may not.

Oldtimer : as you can see from both the Mitchell specs and GM specs, they are VERY loose (i.e. lets an incompetent alignment tech basically do nothing and still be able to claim it is "in spec" ).

The alignment you had done will have good tire wear, but is basically a "comfort" alignment that gives up some performance (performance, BTW, that could be gotten WITHOUT hurting tire wear) in return for making the car easier to drive (i.e. wanders less).

 

[Guest]

Most of my driving is on the expressways.
The cross-caster was kept lower than 0.5 because they do not have the same crown as other highways.
The actual caster was kept below 4.0 because the trunk was unloaded. Frequently I have the trunk full (luggage etc). This will increase the positive caster somewhat.

 

[Guest]

The alignment you had done will have good tire wear, but is basically a "comfort" alignment that gives up some performance ... in return for making the car easier to drive (i.e. wanders less).

Good, I'm glad to read that, since it was we expecting. Most of my trips are between 3 and 4 hours hours on the expressways. Often, up to 8 hours. For me, comfort and less wandering are more important than performance.

My post was intended to illustrate that </font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: monospace;">the GM specs are extremely loose.
To set up the alignment accurately, takes a long time and probably costs more than the "cheepo" alignment shops advertise.
A good mechanic will try to set the alignment to suit your driving. </pre>[/QUOTE]

 

[Guest]

This is great stuff. I won a 4 wheel alignment at SSHS4 and will be taking it in on Saturday but will have to do some more research so I don't sound like a fool explaining what I want. Thanks