Chris Isaacs race cars

Unique vision - innovative design - quality fabrication

Alan had been running his all-steel, Pro-charged 540 cu. in. truck in Street Eliminator for a couple of years, beginning to see 9-second success in 2011 with the assistance of Marc Lamude on engine building and CIRC on suspension tuning.  The big decision was taken at the end of 2011 to replace the nearly 60-year-old original frame  with a modern chassis and suspension to complement the potential big power on tap.  CIRC has been entrusted with the job of constructing the new chassis in chrome-moly to SFI 25.3.  CIRC was the first in the UK to build a 25.2 chassis (for Steve Nash's Street Eliminator Cougar), and is now the first to construct a chassis to the 25.3 spec, for cars running under 7.50 secs and weighing up to 3600 lbs.

Drag race cars, like rear wheel drive circuit, sprint or hillclimb racers, like a decent amount of rear weight, something not usually associated with short-cab pickups.  To this end, the existing rear-mounted fuel cell, battery, ice-box and charge-cooler will be joined at the rear of the pickup bed by the radiator and fan assembly, with air ducted to it from under the truck, and exhausting through a slot in the tailgate.

To place more static weight on the rear wheels, it was decided to shorten the pickup bed in front of the rear fenders by 4" and move the whole bed forwards 3" to  meet the cab.  The upper photo here shows the truck in standard-body form as run in 2011, the lower photo shows how it will look with the shortened bed.  This relatively subtle change reduces the wheelbase from 117" to 110" and places a significant extra percentage of the vehicle's weight on the rear tyres.

Up on the jig.  The motor and transmission have been moved back 5.25", as far as we can go whilst retaining some kind of legroom.  The now-ubiquitous Strange GT front struts, first fitted in the UK by CIRC (on Steve 'Splinter' Nash's championship-winning Street Eliminator Mercury Cougar) will be utilized in the new build.

The pickup bed was cut on the edge of the bead-rolled panel, just behind the corner box-section, shortened, and then welded back together and smoothed out.  This preserves the bead-roll detail for an original look.  The front corner box-sections were trimmed down to match the profile of the cab and fitted with a rubber sealing strip, then the bed was slid forward to butt up to the cab corners.  7" of wheelbase gone, and the truck still looks pretty 'factory'.

Initial chassis tubes now going in.  Due to the extreme height of this car, and the requirement for a full exhaust system due to Street Eliminator rules, it was deemed during the design process that the SFI floor tube layout on this chassis would be above the transmission rather than below it, with a double-rail layout running from front to four-link brackets lying below, rather than the conventional position above, the 'floor' tubing.
Also shown here, in the right-hand photo, is one of the body mountings on the new chassis outriggers.

The SFI-mandated floor tubing is now in place, along with the upper mid-plate mounts.

Strut top mounts and additional bracing now in place.

The CIRC-designed 4-link brackets are in place, along with the new axle housing and moly 4-link bars.  The underslung double frame rails, and the uprights joining them to the main floor tubing,  are now in position.

Plenty of tubes in now!  Although there are a lot of tubes in this car due to the somewhat unusual design contstraints of a tall pickup truck, most are quite small diameter and thinwall, making for a surprisingly light structure whilst retaining good torsional rigidity.
Also shown here are the charge-cooler, fuel tank and radiator mounted.  The rad will be fed air from an intake behind the axle, the air passing through the radiator and exiting through a slot in the tailgate.

The driver area getting completed.  The door bars are dropped a little in the centre and the outer forward bar of the funny car cage swept back a little, to increase driver access through what are quite short doors.

Ready for welding.  Fairly obvious in these shots is the fact that there are no rollcage braces from the main hoop down to the rear of the chassis.  These will be added later, as firstly the cab needs to be modified to enable the body to come on and off once these bars are fitted.

The chassis undressed, just prior to welding.  Although there are a lot of tubes in this car, most of those not sized in the SFI spec (which concentrates on the driver safety cell), are comparitively small, resulting in a very lightweight structure.  In fact, the complete frame plus front suspension and brakes weighs in at around 320lbs - compare this to the original truck chassis, where the front 3ft of chassis alone with its suspension weighed over 280lbs!

The main chassis is now fully welded.

Tinwork is now under way, with the bulkhead being the first item to be fabricated.  The kicked-forward sides give just that bit more legroom, and with the Chevy's relatively short cab every inch counts!

Tinwork well under way.  The style of the tin will follow that of an NHRA Pro Stock Truck with the back of the cab being 'open' through into the pickup bed,  and the rear bulkhead being just a small lip above the rear shock area between the chassis and the aluminium tonneau cover.

The charge-cooler pipes being fabricated.  The mounting point for the pipes shown in the centre photo will also double up as the shifter mount.
The right-hand photo shows the running board now shortened 7" to match the shorter pickup bed.  Without parking the truck next to a stocker, the body shortening should be subtle enough to not be noticed by the average observer once everything is smoothed and painted.

The left-hand shot shows the race fuel pump and battery mounts.  A street-only fuel pump will bolt onto the underside of the battery tray.

The centre photo shows the inlet duct for the rear-mounted radiator, whilst the right-hand shot shows the chute mount and the radiator outlet duct which contains the fan.  Once fully welded, the outlet duct will be cut back to suit the tailgate, and the gate slotted to allow the hot air to exhaust from the radiator out the back of the truck.

A Dzus-on panel for the ECU and ignition sits in the passenger footwell, whilst above it lives the fuse and relay panel.  Once the dashboard is in place, this upper panel is hidden behind the dash, but the fuses and relays are still easily accessible via the original glove-box door.

The pedals are fabricated and mounted.  To get another couple of precious inches of legroom with the small cab and set-back engine, the throttle pedal pad is mounted to the side of the pedal arm instead of the more usual place of in front of it.  This allows the pedal pad to go right back to the bulkhead on full throttle whilst still allowing the facility for a proper, adjustable stop.

The LH photo shows the engine and transmission oil coolers mounted, and also the slotted mounts for the front sheetmetal mounting tube which we have fabricated behind the grille.
The centre photo shows the brake master cylinder mount.
The RH photo shows the front mounts - the peg at the top of the original front wing mounting flange slips into a fabricated receiver bolted to the front wing return edge.  Then, the Dzus mounting points at the top (on the strut mount tube in front of the peg) and at the bottom (in front of the running board) holds the front sheetmetal in position with no visible Dzuses on the outside of the body.

The original front bumper has been refitted, then the gap between the bumper and grille has been filled in, and a lower splitter section added.  This will be a buck used to create a fibreglass bumper/splitter unit.

The new aluminium bed cover has been fabricated.

Just before the last welding session, the fully bracketed chassis.