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are different from side-to-side. Therefore, these

dimensions are asymmetrical. In this case, both length

or diagonal measurements will be shown, reflecting

the difference between each side.

Underhood View

On underhood view drawings, all dimensions are point-

to-point, closest distance between the two points of

measurement.

Bottom View

On bottom view drawings, all dimension are point-to-point, closest distance between the two points of

measurement.

Side View

On side view drawings, all dimensions are measured

parallel or perpendicular to the datum line.

Measurements and not point-to-point.

Centreline

All unibody drawings include a centreline in the

dimensional drawing. The centreline represents the true

centre of the vehicle and runs the length of t he chassis.

To check total width at any measurement point, add

the two dimensions from centreline together.

Datum Line

The datum line is an imaginary line or plane established

at a fixed distance below the vehicle. It is used to

provide a fixed reference point for all vertical underbody

measurements. The datum line is established using

holes, bolts or other obvious

underbody points.

VEHICLE CENTRE LINE

UNDERHOOD VIEW

BOTTOM VIEW

DATUM LINE, DATUM HEIGHT, DATUM DISTANCE & SIDE VIEW

PROCEDURE EXPLANATION

2009 Boyce's Automotive Data

POINT-TO-POINT MEASUREMENT

UNIBODY AND FRAME DIMENSIONS DATABASE

Before starting to use the manual please note the

model carefully to make sure the illustration sheet is

the model to be prepared. E.g. The case of 2 or 4

door model each will be presented on a separate

sheet.

Measurement Point

Bolts, nuts and non-removable plugs are always

measured from the centre of the unit. Holes, whether

round, oval, square or rectangular are measured from

their closest edge to the other point of measurement

reference. The symbol next to a hole indicates thatthe measurement is taken from the centre of that hole.

Pinchwelds are measured out edge-to-outer edge of

pinchweld area. Any exceptions to the above will be

clearly noted on the drawing. Bolts, nuts and non-

removable plugs are always shown on the illustration

as a solid object. Holes are shown as outlines only.

Solid dot always indicates a centre measurement; an

outline, unless marked otherwise, indicates an edge

measurement.

Hole Diameters

All unibody drawings include measuring point hole

diameters. As previously mentioned, most of the

bottom view measurements are from the closest edge

of a hole. If a width measurement from the centre of a

hole to the centreline is required, add one-half of the

hole diameter to the dimension. This is a centreline-

to-centre of hole measurement. If a centre of hole-to-

centre of hole measurement is required for a point-to-

point length or diagonal dimension, one-half of both

hole diameters must be added to the overall

dimension.

Symmetrical Measurements

Most bottom view length and diagonal measurements

are the same from side-to-side. Therefore, these

measurements are symmetrical. In some cases, the

drawing may show a length measurement on only one

side of the vehicle or show only one diagonal

measurement. When this is done, the measurement

also applies to the other side of the vehicle or to the

opposite diagonal measurement.

Asymmetrical Measurements

Some bottom view length and diagonal measurements

Datum Distance

Datum distance is the distance along the datum line

between the centre of each of the datum height

measurement points. It is important to remember that

this is not a point-to-point measurement. Datum

distances are valid only when the datum line is

established . The measurement between any two

points must always be made parallel to the datum line.

In cases where the datum distance is different from

side-to-side, two sets of datum dimensions are

provided, one labelled Driver Side and the other

labelled Passenger Side. The driver side dimensionsgiven distances between measurement points on the

left side of the vehicle; the passenger side dimensions

give distances for the right side.

Datum Height

Datum height is the distance from a measurement point

on the vehicle to the datum line.

ILLUSTRATIONS

Underhood View

This is a view of the engine compartment as seen from

above the vehicle. On unibody drawings, it includes a

centreline which establishes the true centre of the

underhood area. All important bolts, holes, braces and

other components are included in the underhood view.

Bottom View

This is a drawing of the underbody of the vehicle as

seen from underneath looking upward. It includes side

rails, cross-members, holes, bolts and other important

components. The drawing is positioned on the page

with the front of the vehicle facing left. Therefore, the

DRIVER side is always at the top of the illustration.

Side View

This is a drawing of the side view of the vehicle

underbody. It includes side rails, spring mounts,

brackets and any other components necessary to

illustrate measurement points. This view is positioned

to align exactly with the bottom view illustration.

MEASUREMENT TOOLS

Boyces Unibody and Chassis Dimensions can be used

with any type of measuring system, from a steel tape

to the most sophisticated laser beam set-up.

Steel Tape

Although it is the least accurate vehicle measuring tool,

many measurements can be made with a steel tape.

In most cases, vehicle drive train, exhaust or

suspension components and other obstructions mustbe removed to obtain a direct st eel tape measurement.

Datum Gauges

Datum gauges can be used to establish an imaginary

line or plane at a fixed distance below the vehicle. See

Datum Line. The gauges hang from reference points

on the vehicle underbody. Datum gauges assist in

detecting kick-up, kick-down and twist.

Tram Gauge

Most of the dimensions can be measured using a tram

gauge with the pointers set at equal length.

Measurements can be read directly from the tram

gauge bar scale or by measuring the distance from

pointer tip-to-pointer tip with a steel tape.

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BODY DIMENSIONS AND MEASUREMENTMETHODS

PROJECTED DIMENSIONS, ACTUAL DIMENSIONS,

AND MEASUREMENT METHODS

(1) Type A (projected dimensions)

Indicates the dimension when a measurementlocation is projected onto a plane. The differencein height of the measurement points should betaken into consideration when measuring.

(2) Type B (actual measurement dimensions)indicates the actual distance between themeasurement points. Measure using a trackinggauge or a measuring tape, etc.

NOTE(1) Make the lengths of the tracking gauge probes

the same (A =A).(2) Do not bend or twist the measuring tape.

(3) Insert the tracking gauge probes securely into themeasurement holes.

Diagram showing orientation of drawings in relation to vehicle

Actually-measureddimension

TYPE B

TYPE B

Projected dimension

Probe

Height

PROCEDURE EXPLANATION

DIAGRAM ORIENTATIONThis book has been prepared for the Collision Repair Industry. The car

dimensions are presented so that there is no confusion as to where eachmeasurement point lies. The diagram shows how the projection of the

drawing has been chosen.When the car is raised and you stand facing the front, the drivers side is on

the left (for R.H.D. vehicles), as it is shown in the book. The bottom viewshows the body frame as if you are standing in the front of the vehicle

viewing upwards.

2009 Boyce's Automotive Data UNIBODY AND FRAME DIMENSIONS DATABASE