ONLINE INTERCHANGE MANUAL: CHASSIS SECTION
This section goes in depth about the chassis components
that are commonly interchanged, and most of the information will be detailed
in which what fits and what does not. Most of the components that are commonly
interchanged are A-frames, trailing arms, and rearends. I have included
the steering components, in which some other vehicles from other years
and chassis lines, will retrofit and function like the original.
The information, like the Chevelle
Online Interchange Manual, has been abstracted
from outside sources, and through my field experience. Some of the data
might be incomplete, but send me an e-mail
if there are pertinent data that would concern interchangeable parts. Note:
some components and dimensions are shared by other GM vehicle production
lines, like the Camaro/Firebird, X-car (Chevy II/Nova), and full size (Impala,
Caprice, Bel Air, Biscayne)
Additions to the chassis page have been abstracted from "Inside '64
-- '72 A-Bodies", Car Craft, March 1998.
REAR END HOUSINGS
The rear end housings are based on dimensions that
have been gathered from magazine articles, and some of the data that have
been published by magazines like Hot Rod may be inaccurate. The figures
are correct, and each dimension has been referenced with certain components,
like axles and the GM part numbers that specify the exact part used. This
might be a reference in which swapping non-GM rearends into GM chassis
will provide the required data for a factory-like swap.
*From 1964-67, Chevelle rearends that
were used have been manufactured by the Chevrolet Gear and Axle Division,
and the housing dimensions measure 56.5 inches, from flange to flange.
Total measurements with the drums in place is 60.5 inches. The dimensions
are similar to the 1967-69 Camaro/Firebird, and 1968-74 X-cars and clones,
except leaf springs were used.
*1968-72 rearend housings measure 58.5
inches from flange to flange, and with the brake drums in place, the total
dimensions measure 62.5 inches. The dimensions
are similar to the 1970-81 Camaro/Firebird, and 1975-79 X-cars and clones,
except leaf springs were used.
Note: internal components have a characteristic that is common to the housing
used: 10 bolt pieces fit other 8.125" 10-bolt housings (the rearend used
in Chevrolets), and 12-bolt pieces interchange with other 12-bolt housings
(not the one from the Chevrolet pickup or Oldsmobile, which has a 12 bolt
cover and a 10 bolt gear, which measures 8.3"). This means that a posi
carrier will retrofit in place of a standard differential.
Axle shafts are common to the housing used, and due to the usual characteristics
like overall length and spline count, the shafts only interchange with
the housing that is used. (e.g. 12 bolt shafts fit other 12-bolts, and
10 bolt shafts fit other 10-bolts.)
*Addenum from "Inside '64 -- '72
Rear spring mounting pads differed,
in which 1964-66 rearends used a flat pad with a hole drilled in the center.
1968-72 rearends have circular spring mounting pads, which are 3/4" higher
that the early flat pad.
1967 was a transition year, in which
A-cars might have a 1964-66 style rearend, a 1968-72 rearend (which is
wider, and commonly available), or a "hybrid" rearend, which will have
the 58.5" width, but with the early spring mounting pad and trailing arm
Rear upper control bushing eyes
differ, and the positioning of the bushing eyes will differ. 1968-72 rearend
housings will have a 3/8" forward positioning, which is farther that 1964-67
1964 was the only year that the
rearend bushing are small, and any upper trailing arm (from any GM division)
will fit 1964 rearend housings.
REAR TRAILING ARMS
The rear trailing arms (or control arms) consist
of four arms that connect the rearend to the frame, and the setup consists
of two long and two short arms. The lower trailing arms for use with a
sway bar is unique, and the usual characteristics is that the arm is boxed
and gussetted. The upper arms vary, and there are two part numbers in the
Chevrolet Parts Interchange Manual that separate 1964-67 and 1968-72 Chevelles
and BOP A-Bodies.The lower arms are interchangeable (all years), and a
car that did not have a sway bar can be modified to fit.
1973-77 lower rear trailing arms
will bolt in, if using either 1973-77 rear anti-sway bars, or 1977-96 B-car
sway bars, common on vehicles like Cadillac limos and police-optioned Caprice
There are 201 1965 Chevelle SS 396s
(RPO Z-16) had unique lower arms, which is a one-year item.
Upper trailing arms of 1964-67 vintage
interchange, and they are 1" shorter, which will not fit into 1968-72 A-cars.
1968-72 A-cars have longer upper arms, and when switching upper arms, be
careful here, in which the pinion nose angle might be affected. According
to Inside '64 -- '72 A-Bodies, there are 10 different rear upper
control arms offered. Other characteristics include clearance bulges, common
with 12-bolt differentials in A-cars, and adjustable upper arms, optioned
on Oldsmobile A-cars (F-85, Cutlass). 442s had boxed upper arms, and this
is a sought-after item in a restoration.
On 1968-72 A-cars, like high-performance,
4-speed, and Monte Carlos/Grand Prixes, there is a triangulation brace
bracket that is standard. This stiffens the chassis, and tubular versions
are available from Edelbrock and
Note: the trailing arms fit either side, and this means that the left upper
arm will fit on the right, and vice versa.
CONTROL ARMS (FRONT)
Most of the control arms for the 1964-72 Chevelle
interchange, and the lower control arm used for the front suspension had
these distinct features.
*One version was produced from 1964-66,
and utilised 1.90" (1 5/16") diameter bushings. There are two arms used
from 1967-72, and the category includes the LCAs with round bushings (1.625"
diameter), commonly found on 1968 (all models) or 1969-72 vehicles like
Chevelle SS, Pontiac GTO, Oldsmobile 442, and the Buick GSX. Most of the
lower control arms used on the other A-cars had oval bushings.
*The bushings described in the lower
arm are located in the rear pivot area (the TRW or MOOG manual calls this
the rear control arm bushing) on both sides of the car.
*All oval bushing arms, 1.90", and
1.625" round bushing arms (1 5/8") manufactured used a 1 3/8" (1.375")
diameter front bushing.
*The lower arms interchange as an assembly,
regardless of the spring diameter that distinguishes 1964-67 and 1968-72
front springs. You can use a later arm on early models (1964-67), but I
have not heard of a 1.90" lower arm used on a later A-body.
Note: the lower arms may differ, in case a replacement or factory mismatch
are common when locating the correct lower arm for a restoration. The only
problem with oval bushings is that the existing bushing cans will have
to be reused, and aftermarket companies that use solid or Del-A-Lum (a
Global West product) bushings as replacements might require locating a
set of round bushing lower arms, either a 1.90" or 1.625".
*Upper control arms for Chevrolet Chevelles
and El Caminos use crossshafts that used bolts to secure the cup washer
to the bushing. BOP A-Bodies used crossshafts with threaded ends with locknuts.
Due to the possibility of frame spread, MOOG or TRW manufactures an offset
control arm shaft that allows the camber angles to be corrected via OEM
The springs vary with application and chassis packages, but
there is one thing that is important: 1968-72 A-cars have a different front
spring diameter when compared to 1964-67 front springs ("Knuckle Sandwich",
Hot Rod, 6/87). 1969-present springs are based on computerized data concerning
chassis package and bodystyles, but the rates vary, in which a softer or
stiffer ride is preferred.
Note: 1964-67 front springs can be found on 1967-69 Camaros and 1968-74
Novas, but the spring rates will differ. 1968-72 A-body front springs are
used on 1968-70 BOP full size cars, but the spring rates vary.
The data that is true for front springs is the same for rear
springs, and 1964-67 rearends have provisions for bolting on the spring
to the pad.
Another difference is that 1964-67 springs are pigtailed
on one end only. 1968-72 rearends use a cup, and is flanged to hold the
spring in place.
The A-body frame,
unique to the Chevelle and their BOP counterparts, is a unique design that
has been incorporated by the other auto manufacturers, and there is a deep
history about this. Since the late 50s, GM used an X-frame design, that
had little concern for side impacts. This frame design was used on full
size cars like the Impala, and this design utilised a three-link rear suspension
that had two long lower control arms and a third link.
Company had a frame design that was far more superior to the GM design,
and the side frame rails are positioned outward. The entire frame, if looking
underneath a 1960-64 Galaxie 500, is a modified ladder frame, and leaf
springs were used at the rear. This design was the basis for what is to
come: the perimeter frame.
frame, an improvement of the ladder frame, which utilized an independent
front suspension, was one major design of the A-car. A full, rectangular
perimeter incorporated the emphasis on safety, like side impact collisions.
Another design was the use of four trailing arms and coil springs, which
resulted in a softer ride than a leaf springed car or truck. Imagine a
Chevelle with the body off, and this is what the frame would look like.
The year following the introduction of the GM A-body, other manufacturers
like Ford incorporated this design, and the full size GM except the Buick
Riviera used the "new" design.
Note: the rear trailing arms are
different on the upper links, and they are bolted to the axleshaft. This
is common with 1965-70 GM full size vehicles, and 1965-79 FoMoCo full size/1972-79
The four-link trailing arm suspension (from the
GM A-car) was also incorporated on 1978-present Ford FOX-platform vehicles,
and the 1985-97 Ford Aerostar minivan. Also, 1979-present Ford full-size
vehicles (LTD, Crown Vic, Grand Marquis, and Town Car) had the GM-patented
4-link incorporated in their production vehicles.
Since the A-car line of General
Motors was to be aimed at a different audience for car buyers not desiring
a full size car or a compact, this is where the senior compact (a Buick
term) or midsize came into play.
*1964-67 A-bodies used the same
frame design, but different models and bodystyles utilized various body
mounting, while all frames had a 115 inch wheelbase, which is similar to
the 1955-57 Chevrolet.
*1968-72 frames had two different
wheelbases, a 116 and 112 inch wheelbase. Sedans , station wagons, and
utilities like the El Camino used a 116 inch frame, and the frame is interchangeable,
except that the sedan had non-boxed rails.
The hardtop and convertible used
a 112 inch wheelbase version, and all models except for Pontiac 455 powered
hardtops and convertibles interchange. The convertible utilised a boxed
design, for added strength.
1969-72 Grand Prixs and 1970 Monte
Carlos used a modified hardtop frame, and the only design difference is
the movement of the front wheels four inches forward of the traditional
front wheel position on the hardtop and convertible. The engine and tranny
position remained at the same place, but the mass of the components resulted
in the engine and tranny combo behind the front wheels. The frame's wheelbase
dimensions measure 116 inches, and this frame design is exclusive to the
Grand Prix or Monte Carlo.
The 1969-72 Grand Prix was designated as a "G" body by
the Fisher Body division, but A-car suspension components are used. The
Monte Carlo was designated as the "A-Special" series, and the official
use of the G-car designation was in 1982.
Today, only Ford Motor Company still manufactures full perimeter framed
cars, and GM has phased out production in 1996 of the traditional, full
perimeter, rear wheel drive family sedans, hearses, and limosuines. It
seems that everyone is drawn to the sport utility and front wheel drives,
since this was a corporate decision that GM has done to boost sales.
Copyright 1997, 1998,
1999, 2000 LSC Publications/LSCSETX (c/o
SERIBUTRA). All Rights Reserved. This page will continue to evolve
if any pertinent information is detrimental to the restoration of the GM