Rear Suspension and Differential

The Hemiceptor features Independent Rear Suspension using a kit produced by Factory Five Racing designed for installation into their Cobra replica kit cars.  Because the Jensen Interceptor as delivered from the factory utilizes a frame with two large main tubes, which are thought to be identical to those supporting the original Shelby Cobra, adaptation of this IRS kit to the Jensen Interceptor was not a major engineering challenge and required no modifications to the kit itself. All replacement parts for this kit are available from Factory Five Racing with the exception of the anti-sway bar and coilover shocks discussed below.

Preparing the Factory Five Racing IRS for initial adaptation
Here we go!
Factory Five IRS suspension in place with Ford 8.8″ differential, Strange coilover shocks, Wilwood brakes and adjustable sway bar

The installation of the IRS allowed for the fitment of wider rear wheels and tires. However, interference between the tires and the inner fender wells mandated minor”tubbing” of the inner wells.

“Tubbing” of the rear wheel well for tire clearance, seen from the outside, looking up into the wheelwell.
Tubbing of the rear fender wells, viewed from the interior back seat area

1.    Sway Bar

The rear anti-sway bar is made by Vintage Performance Motorcars specifically for the Factory Five Racing IRS. The sway bar is completely adjustable by loosening and moving the sliding blocks which attach the Heim-jointed linkage to the sway bar.  As delivered, the Jensen Hemiceptor has a fairly soft adjustment, but as is the case with all the suspension components, road and track testing and final adjustment to the preferences of the ultimate owner is recommended.

Vintage Performance Motorcars adjustable sway bar

2.    Rear coilover shocks

The rear coilover shocks are from Strange Engineering (purchased through Art Morrison Engineering, and, as is the case with the front coilovers, are adjustable both for spring preload (using the included tools) and rebound.  

3.    Spindles

The rear spindles are Ford Performance components, as furnished by Factory Five Racing.

4.    Rear Differntial/Center section.

The differential is a Ford Performance 8.8 Aluminum unit equipped with a Traction-Lok LSD clutch.  The gear ratio is 3:55:1.  This unit is new, not rebuilt. This differential is mounted in the chassis with high-performance polyurethane bushings.

Ford Performance 8.8 Traction-Lok differential in place with polyurethane bushings

a.   Lubricant

Differential lubricant includes the specified Ford Performance Friction Modifier M-19546-A12 additive.

5.    Axles

Axles are 28 spline Ford Performance units as furnished by Factory Five Racing.

6.    Alignment

An initial alignment of the rear suspension has been performed. It is recommended the rear suspension be realigned after initial track testing.  Rear end alignment specifications and techniques for the Factory Five Cobra IRS are detailed in the accompanying attachment.