For 1990-2009 cars

# Adm Msg - Alignment Questionnaire

Subject: | Alignment Questionnaire

Models: |

Attention: | Service Managers

I would like to thank all of you for filling out the questionnaires and faxing them in. We are getting some great data to help us improve the alignment of our vehicles prior to shipping them to you.

On the questionnaires being done for Trucks, some important information is being left off: Z-height or trim height and the Frame Angle.

Trim height or Z-height is a measurement of the front suspension lower control arms relative to ground. An example of this can be found in SI Document ID# 745583 and 1270403. Frame angle is a measurement of the frame rails relative to ground. According to engineering, if the frame angle is not comprehended in the caster measurement, the caster setting can be incorrectly set relative to specifications. SI Document ID# 647752 is an example that explains caster relative to the frame; the caster values must be compensated for the measured frame angle by using a digital protractor or equivalent on a flat portion of the frame in front of the rear tire.

Before faxing the questionnaire, if you would, please record these measurements when doing a truck alignment (all Silverado/Sierra versions, all Tahoe/Suburban versions, all Yukon versions, all Escalade versions, all Avalanche versions, all Express/Savana); we would appreciate it very much. Engineering needs to know the specific trim height and frame angle to properly evaluate some of the issues that you have reported.

Your continued cooperation is greatly appreciated!