Engineering Information

All RRS products are fully engineered and exceed in both loading and performance OEM products. RRS can supply any data an engineer may require to pass RRS products as compliant to VSB14 and ADR approved.

 

The following is an example of an engineers certificate for vehicle fitted with RRS products:

ENGINEERS REPORT:

The investigation of quality assurance and compliance to the code of practice concerning the RRS Strut and brake conversion kit to suit:

 

XK – XF Falcons, Fairlane, Fairmont’s, LTD 1964 ½  – 1973 Ford Mustang 1967 – 1970 Ford Cougar, Montego and Ranchero’s.

The components as supplied by RRS Pty Limited are as follows:

 

Component Breakdown List

1. TOP MOUNTING PLATE

RRS Manufactured

• 2  x Mounting plate

• 2  x Spherical bush & housing

• 2  x Cir-clip

• 2  x Grease nipple

• 2  x Spacer rings

• Assorted bolts & nuts

 

2. COIL SPRING

2  x springs

• Coil over spring

 

3. ADJUSTABLE STRUT HOUSING

• 2  x shock strut de-carbon gas inserts

• 2  x Gland nuts

• Bump stops

• 2  x Spring seats & threaded sleeves

• 2  x Lock rings

• Bolts etc

• 2 x  RRS Strut housing assemblies

• Locking & adjusting spanner

 

 

4. RRS STEERING KNUCKLE

Fully tested and approved RRS left and right knuckles

• Wheel bearing hub assemblies

• Bolts etc.

• 10 x  Ford wheel studs

 

5. BRAKE SYSTEM

• 2  x slotted disc

• Set of disc pads

• 2  x Flexible brake hoses – ADR approved

• 2  x Brake line bracket

• 2  x PBR caliper assemblies

• 2  x Brake line fitting

• 2  x Tie rod ends if applicable

 

 

3.4 Suspension

This is the data recorded as required to enable the installation of an RRS Strut & high performance brake Conversion Kit.

 

(a) the primary origin of design and subsequent components of the RRS Kit is HSV Commodore and Statesman brake and strut assemblies.

 

(b)the modification and installation to be checked by an authorised RTA recognised engineer is: i) brake line relocation ii) strut tower mounting plate installation  iii) road testing

 

3.5.2 Certification of Suspension modifications:

The Strut conversion as referred herein is a major modification and is designed to replace the original front suspension upper-arm assembly with an RRS McPherson Strut Assembly

 

3.5.3 The only ADR affected by this conversion is ADR 7, which in turn is covered by the usage of a standard 1997 Commodore ADR 7 approved flexible brake line.

 

3.5.4 General Requirements:

 

3.5.4.1 see 3.5.5 for analysis of the RRS Strut assembly

 

3.5.4.2 no cutting, heating, bending or welding is required to install an RRS assembly.

 

3.5.4.3 All fasteners supplied with an RRS assembly are the equavalent or exceed SAE grade 5 or ISO 8.8 according to Australian standards AE111O.

 

A full torque specification according to component manufacturers as used in the RRS strut assembly is supplied with each RRS Strut Kit.

 

3.5.4.4 All tapers are machined in the RRS strut assembly to match OEM            ball joint and tie rod end tapers.

 

3.5.4.6   Operating Clearances

All of the replacement RRS strut assembly components maintain OEM clearance to all other steering linkages, stabilising bar, chassis mounts and OEM reinforcement components.  The RRS Strut assembly gives an additional 32mm tyre clearance over OEM suspension components.

 

3.5.4.8 Suspension bush material has been upgraded at the upper strut mounting location by using a Holden OEM style rotation bearing and Porsche OEM strut articulation bush.  All lower mounting for the RRS Strut assembly are Ford OEM location and design.

 

3.5.4.12 Rubber bump stops with a progressive compression rate are incorporated into the RRS Strut assembly to replicate OEM suspension travel at full bump.  Droop is limited by an average of 12% under OEM droop specification.

 

3.5.5. Design requirements

 

3.5.5.2 Suspension geometry Suspension member and pivot bush angles in both vertical and rolling planes over the range of suspension travel maintain full 10% margin over the full range of movement of the RRS Strut assembly before bind could occur even allowing for extreme caster or camber settings. Full bump, rebound and OEM lock positions maintain a full 10% margin before binding could occur.

 

Roll Centre, the roll centre locus is altered from OEM specification by installing the RRS.

 

 

Strut assembly to being on average 50mm above ground level, the combined result of this change is :

 

(1) track variation reduction over OEM design, track variations is reduced by a minimum of 35mm regardless of wheel alignment tuning variations.

 

(2) improved camber arcs of motion over OEM design, which in turn translates a more predictable tyre to road contact area over the OEM design.

 

(3) decreased amount of weight transfer to the outer wheel.

 

(4) a negative Camber static wheel alignment setting is recommended to maintain a more predictable wheel loading over the OEM design; resulting in minimize  tyre wear and maximize cornering adhesion over the OEM design.

 

Longitudinal geometry: The pitch axis of the RRS Strut is different to OEM suspension layouts primarily because of the RRS increase steering axis inclination which results in a reduction of the dive characteristic of OEM brake and suspension design.  The RRS design gives the extra benefit of a more accurate and tunable track on turns compared to the OEM suspension design.

 

3.5.5.3 Vertical Wheel Travel

The compression rate of the RRS Strut assembly with a typical 275 pounds per inch of travel spring is more compliant to small road corrugations while being more firm with large corrugations which is an improvement over anything OEM design could produce.  This in part is a result of the Strut, spring and shock absorber operating at 1:1 of wheel travel; while OEM spring and shock absorbers operate at less than 1:2 wheel travel therefore OEM shock absorbers cannot cope with dampening large suspension movement and also allow compliance to small corrugations.  Furthermore the RRS Strut assembly uses far more advanced spring wire technology than OEM springs, which in turn generates a closer and smaller oscillation rate (CPM) than OEM springs.  The shock absorber is either de-carbon gas design or rebound adjustable oil design to suit a vehicle that weighs between 1250kgs and 1850kgs with a 55% to 58% front weight bias. Vertical wheel travel from standard ride height is the same on RRS strut and OEM suspension.

 

3.5.5.4 Component Stress Levels

All of the components listed in RRS strut assembly component lists can handle stress levels far higher than the OEM suspension components

 

The RRS component design is based upon the component design and parts used on HSV Statesman Commodores

 

1. Wheel Rim Offset

The stress levels created by HSV rim width, diameter and offset more than embrace the rim choice allowed to be fitted to a Ford using an RRS strut assembly.

2. The RRS Strut assembly, uses the same steering stop location and are of motion to OEM suspension design.

3. The track on turns is more accurate and tunable than the OEM suspension design combined with less pivoting points of deflection than OEM suspension parts, therefore; the RRS strut assembly will give more accurate steering response and tyre adhesion in extreme driving conditions.

4. The steering system whether modified or not attaches to the RRS strut assembly in an almost identical position and manner duplicating OEM or modified steering loads (NB modified here means the usage of a conversion rack and pinion or a left to right conversion)

 

The RRS strut upper mounting bracket duplicates or reduces the load placed on the chassis of the Ford vehicle by comparison to the OEM spring and shock absorber attaching point.

 

The key load bearing components that have been redesigned from the GM application to be used by RRS in modified Fords are as follows:

Bearing hubs

Strut legs

Steering knuckles

 

Component Stress Level Checks:

1. The articulation bush used in the RRS Strut Kit is 50% larger than that used in a Porsche.

 

2. The rotation bearing used in the RRS Strut Kit has a 20% increased load bearing capacity over  Commodore rotation bearings.

 

3. The Strut leg is a remanufactured  Commodore with no increase or decrease in structural integrity of strength.

 

4. The RRS bearing hub, manufactured by SKF or NSK bearings companies has the following load capacity:

45,000 kgf Dynamic load

54,000 kgf static load

over the largest OEM bearing capacity which is:

35,700 kgf Dynamic load

48,500 kgf static load

 

5. RRS Steering knuckle summary specifications and design evaluation:

 

Knuckles are manufactured to exceed strength, durability and accuracy of the standard OEM steering knuckles fitted to GM Commodore Statesman production years (similar design to RRS knuckles).

RRS knuckle used .73kg of extra reinforcing material over GM steering knuckles.  Increasing load-bearing capacity by 12.25%.

GM knuckle sand cast steel

RRS knuckle investment cast malt – XK 1340 steel annealed and heat treated to 30 HRC

RRS knuckles evaluated to ensure quality by ETRS according to quality management system certified by NCS International Pty Ltd. That complies with the requirements of Aus/NZ’s ISO 9001: 1994, also NATA accredited laboratories.

RRS steering knuckles CNC machined to plus or minus 0.020mm

 

3.5.5 Road testing The RRS Strut assembly has been road tested in a variety of conditions, which include controlled testing at Wakefield raceway and a variety of street conditions eg traffic navigation, highway usage and dirt roads.

Track Testing:  The RRS Strut assembly has been evaluated at Wakefield Raceway by an RRS designated test driver in a 1966 Mustang Coupe

which yielded the following results:

1. reduced lap times over OEM suspension

2. reduced dive under braking over OEM suspension

3. improved steering response time over OEM suspension.

 

The RRS Strut assembly has been evaluated during regular (30,000 kms) of road use by an RRS nominated test driver in a 1966 Mustang Convertible with the primary objective of replicating the “Road Feel” of a grand tourer G.T., whilst maintaining driver comfort and road holding improvements over OEM style suspension options.  The road testing yielded the following results:

1. reduced braking distance in emergency situations over OEM suspension performance

2. vastly improved road manners during traffic navigation

3. improved grip on corrugated bitumen surfaces

4. improved grip on gravel surfaces

5. improved steering response time over OEM suspension design.

 

In conclusion, brake testing and geometry checks, were performed by an authorised RTA Roadworthy Inspection Station - Brian Blake Auto’s. Who in turn confirmed RRS Strut and high performance brake conversion kit is of a higher standard both in accuracy and performance than OEM design and complies with all necessary roadworthy requirements as specified by the RTA.

 

3.3 Brakes

 

3.3.3 ADR 7 approved hydraulic brake hoses supplied with each RRS Strut Kit

 

3.3.4 General Requirements

RRS Strut and high performance Conversion Kits are supplied with VT Commodore or Statesman discs or better and twin spot sliding callipers or better with high grade pads.

 

3.3.6 Road Test

The RRS Strut Kit extends braking performance over OEM brake options with a similar pedal feel (effort) and progressiveness.

No imbalance between front and rear brakes occurs by using the RRS Strut Kit.  The RRS Strut Conversion Kit is less likely to produce brake fade or the lock-up characteristics of OEM equipment and is therefore safer in extreme and emergency braking circumstances.

 

 

 

"Road" "Race" "Science"

(61) 02 9907 3755

US Toll Free 866 597 4662