An accurate method of determining the alignment of the underbody uses a measuring tram gage. The tram gage set used to perform the recommended measuring checks must include a vertical pointer able to reach 457 mm (18 in).
Two types of measurements can be made with a tram gage, direct point-to-point measurements and measurements calculated on a horizontal plane, datum line, parallel to the underbody. Point-to-point measurements are generally taken on steering and suspension engine compartment parts and simply require the vertical pointers to be set equally.
For horizontal plane measurements, the vertical pointers must be set as specified for each point to be measured.
Dimensions-to-gage holes are measured to the center of the holes and flush to the adjacent surface metal unless otherwise specified. It is recommended that the diagonal dimensions to the cross-body be checked on both sides in order to verify the dimensional accuracy of the vehicle underbody.
Floor Pan Insulators
The floor pan insulators have been designed for the higher floor pan temperatures that result from the use of the catalytic converter in the exhaust system. Therefore, when servicing a vehicle, it is essential that any insulators that may have been disturbed or removed be reinstalled in the original sequence and location. Also, if an insulator needs to be replaced, use only the insulation specified for that location on the floor pan.
When servicing or replacing interior insulators, observe the following instructions:
| • | Install the insulators in the original position and sequence. Join the pieces together in order to avoid gapping or overlapping. |
| • | If it is necessary to replace an insulator, use only the specified insulation. |
| • | Use the original part to determine the amount of replacement material required and as a template for cutting and fitting the new piece to the floor pan. |
| • | When installing the insulator, do not enlarge any cutouts or holes that are used for the attachment of interior parts such as the instrument panel or the floor console. |
| • | Route the cross-body harness for interior parts over the floor pan insulators. Clip it in the original location. |
| • | Do not apply spray-on deadeners or trim adhesives to the top of the floor pan at the area directly over the catalytic converter or the muffler. |
Any insulator service repair or replacement should be the same thickness, size, and location as the original installation in the vehicle.
