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Rail Draggin’ the Square BodyHAMMERING A ’79 C-10 WITH PORTERBUILT AND KP COMPONENTS

CERTAIN TRUCKS REQUIRE A CERTAIN LOOK TO MAXIMIZE THEIRNATURAL LINES AND ACCENT THEIR FACTORY SHAPE. The ’73-87 GMpickups are undoubtedly boxy and are referred to many in the scene as“square bodies.” These trucks survived the production line at GM for 14years, and as a result, many are still doing duty on the road today, makingthem perfect candidates for full-throttle customizing. Investigating the chis-eled lines and squared off corners these trucks feature makes us want to

plant one on the ground and go cruising. Like all pickup trucksthere are definite hurdles to cross when it comes to seriouslymodifying the chassis and suspension. For the square body GMsit is the pesky factory cross member that puts the lower controlarms in the dirt even with a moderate static lowering job. Whenyou ‘bag one you better plan on buying the city a few reflectorsbecause you will definitely be clipping some off the highway.

The folks at Porterbuilt Street Rods have designed a crossmember system called the “Dropmember,” which is a bolt-incross member section specifically designed to substantially lowerthe truck, while eliminating cross-member-to-ground-clearanceissues. The frame rails become the lowest point on the chassis —the part you want to drag! The steering system is converted torack-and-pinion for a more controlled feel and the system can beused with either factory control arms or Air Ride TechnologiesStrong Arms. This cross member unit from Porterbuilt also nar-rows the track width by just over an inch per side and locates thewheel center forward from its factory position, which centers thewheel and tire in the fender well upon full deflate of the air sus-pension and allows for more firewall clearance when running bigwheels and tires.

To lay out the rear of this truck, we partnered up with KPComponents and installed one of their 6-link rear systems paired

with Slam Specialties airbags. The KP 6-link is a bolt-on 4-link and cantileverunit requires no fabrication. The system produces 12 inches of travel, will laythe truck out using an 18- to 22-inch wheel and tire combination, and fea-tures a bolt-on Watts link system to eliminate axle shift.

With a truck waiting to hit the tarmac and endless miles of Arizona high-way ahead of this low-down cruiser, we rolled the truck into the bay atPorterbuilt and got to work. Follow along and watch this C-10 transform. ■

Our victim is a ’79 Chevy C-10 short bed thatis currently in nosebleed country with an oldschool static lowering job. The PorterbuiltDropmember, KP Components 6-link and SlamSpecialties airbags will take care of that.

In the rearwe chosethe KPComponents6-link sys-tem, whichis a bolt-on,cantilever

system producing 12 inches of travel. The system accommodates up to a 22-inch wheel,features a bolt-on Watts link to eliminate axle shift, and is designed for ‘63-87 GM trucks.The Porterbuilt Dropmember comes with the main X-member section, inner frame supportplates, upper control arm/’bag mount plate, transmission cross member, shock mounts,billet tie-rod ends and heavy duty Heim joints with hardware, aluminum shock mountbushings, C-notch for rack-and-pinion tie rod clearance, motor mounts, and all of thehardware and instructions.

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Up front, the factory inner fenders and A/C box will need to be removed for clearance.

Here is a glimpse of the factory front suspension and cross member. Note how low thecontrol arms hang down. This is a common problem on these trucks.

After the truck was secured on the lift, or jack stands for those of you working in thehome garage, the factory cross member and front suspension were removed to make wayfor the Porterbuilt cross member, tubular Air Ride Technologies arms and Slam Specialties‘bags. Porterbuilt recommends pulling the drive train out of the truck before removing thefactory cross member and installing the Porterbuilt unit. Fuel lines need to be properlycapped to avoid sparks from the welder or cutting tools.

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RAIL DRAGGIN’ THE SQUARE BODY

The necessarytie rod notch

was located onthe frame rails.

The center ofthe rack notch is4.25 inches for-

ward of theDropmember’smost forward

mounting hole.The top of the

rack notch willbe located at

2.25 inchesbelow the top of

the frame rail.Nathan marked

the notch, cutout the marked

frame sectionand trimmed to fit. It was

then welded inplace.

Nathan installsthe supplied

motor mounts.

An inner framesupport plate isincluded in thePorterbuilt kit

and is installedfor strength.

TheDropmembermain piece isinstalled andwill soon be

ready to ham-mer this C-10 on

the asphalt!

In this picture youcan see how muchthe engine will beraised up. Thedrive train willhead north approx-imately 1.5 inches.

The supplied trans-mission crossmember is installed.After it was slid intoplace and the motormounts wereinstalled, Nathan setthe pinion angle onthe transmissionoutput shaft, boltedup the transmissioncross member tothe transmissionmount, squared upthe transmission,marked the holes,drilled the holes,and bolted thecross memberdown.

The holes used tomount the uppercontrol arm and‘bag mount platewere drilled out to1/2-inch.

Nathan installedthe upper controlarm/’bag mountplate keeping inmind there will beone hole on the‘73-87 chassis thatwill need to bedrilled into the topof the frame rail.

Next, the rack-and-pinion, which is a’79-93 Mustangrack with 15.5inches center onmounting points, ismounted up withthe supplied alu-minum bushings.Porterbuilt notes toinstall the rackbefore the lowercontrol arms.

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RAIL DRAGGIN’ THE SQUARE BODY

Prior toinstalling thelower control

arm, the arm’slocating pin is

installed toensure every-

thing is squaredup properly.

The lower control arm is

bolted up utiliz-ing the billet

mounting capsand supplied

hardware.

The upper con-trol arm was

installed into theupper control

arm/’bag mountplate. We used a

set of Air RideTechnologiesStrong Arms

here. The factoryupper arms may

be employed ifneed be.

If you choose toutilize the facto-ry upper control

arms it is neces-sary to trim therear portion of

the control armat the bushing

for frame clearance.

The spindle’ssteering armhole must bedrilled out to

5/8-inch to becompatible with

the new rack-and-pinion com-

ponents.

Next, Nathanreinstalls thespindle and weare one step closer to puttingthis baby on theground — literally!

Supplied in thePorterbuiltDropmember kitare heavy-dutyHeim joints,spacers and bil-let tie rodadapters, whichare installed onthe topside ofthe spindle’ssteering arm.

For correctgeometry it wasimperative thatwe trim 1.25inches from therack-and-piniontie rod ends.Using a cut-offwheel, Natewent to work.

The airbagmounting loca-tion on thelower controlarm will need tobe moved out1.25 inches onthe lower A-arm.We scope thingsout with thetape.

With the truckstill on the rack,we used thefloor jack andjacked the frontwheel up in thefender to get theviewpoint oncethe truck wasaired out andlaying frame.Muy bueno!

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RAIL DRAGGIN’ THE SQUARE BODY

To get started on therear KP components

suspension the bed hadto be removed from the

truck. We employed adolly for the bed to rest

on while we got busy onthe chassis tail section.

Here are the rear framerails in their stock and

untouched state. Thefabrication pros at

Porterbuilt were about tochange all that!

Nate starts by cutting offthe factory exhaust.

A custom system will be built later to route

around all the wild chassis and

suspension work.

The factory leaf springsand assorted brackets

and hardware areremoved from the frame.

Nathan ditched the factory spring hangers.

With the KP 6-link these will no longer

be needed.

The factory spring hanger holes were

drilled out to 1/2-inch toaccommodate the new

KP Components forward4-link mount.

Next, the front 4-linkmount was installedonto the frame so wecould mount the restof the bracketry andset up the link bars.

The factory shockmount tabs wereremoved from the axlehousing using a cut-offwheel.

Porterbuilt installed theurethane bushings andinserts into the 4-linkends to prep them forinstallation.

A view of the 4-linkand axle bracketsinstalled according tothe KP Componentsinstructions.

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Here is the rear cantileverbracket/airbag mount

being installed.

A custom step notchwas built by Porterbuilt

to allow full travel of therearend when the truckis laid out. It was boxed

and welded solid forstrength.

The supplied Watts linkbracket from KP

Components is installedonto the rearend.

Here is a view of the KPComponents Watts linkinstalled and fit withadjustable brackets fab-ricated by PorterbuiltStreet Rods.

The Slam SpecialtiesRE7 ‘bags were fit withthe supplied hardwareand fittings and installedin position.

Next, the supplied steer-ing linkage from thesteering column to therack was installed bylosing the steering boxand dropping the steer-ing down to the rack-and-pinion, this is a nec-essary step.

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RAIL DRAGGIN’ THE SQUARE BODY

The center of thebed and factory

inner fender hous-ings were cut out

to provide roomfor the frame

notch and wheeland tire combo.

Eventually,Porterbuilt willfabricate some

custom tubs andbuild a notch

cover for the bed.

A peek inside theengine bay

reveals the miss-ing inner fendersand A/C system.A Vintage Air or

Hot Rod Air system would

most likely be thebest option in this

truck with all the new

modifications.

With the truckaired all the way

out the tire tobattery tray

clearance is a lit-tle tight. We

might move thebattery into the

bed later. We gotthe clearance

where we reallyneeded it

between the tireand the firewall.

A rear view of theKP 6-link systemand step notched

and air-baggedchassis; all wehad to do now

was reinstall thebed and go

cruising.

After a fewdays atPorterbuiltthis formernosebleeder’79 C-10 wassuccessfullyin the weedsand looking10 times bet-ter than it didwhen it rolledin. The bestpart is thesmooth rideand groundclearancegained by theDropmember.

Now that’slow.

An undercar-riage shotshows theframe firmlyplanted onthe asphalt,proving thissetup hasstreet credit.

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