Spitfire Independent Rear Suspension Kit

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Independent Rear Suspension Kit“IRS” KIT

This is truly one of MotoCancelli’s most significant products since opening in Y2K.

No mods or welding required this kit is purely bolt-on taking only about one hour of your time with common tools.

Gone is the troublesome transverse leaf spring that has plagued all Harold chassis cars since their very beginning. No more driver’s side sag or severe negative camber; MotoCancelli’s new “fully independent” rear suspension kit adds adjustability and control at the rear with a whole new level of performance. The cars weren’t test lightly. During development the kit was put through a series of very serious driving stints while installed on to a 130 hp Stage Three prepared Spitfire sporting very sticky 205/40/16 DOT race tires. Every situation was challenged from smoking the rear tires from a launch to power sliding through long sweeping turns at unmentionable speed. The car was even pitched the sideways down a drive way onto a crowned street to put an outrageous side load on the new system while under power and not only did it not phase the kit but it was hardly detectable in the car as it literally glided through the transaction. The car does exactly what you’d expect under any given circumstance. This means greater traction and safety on the street and faster lap times on the track. The car can definitely be driven faster and harder with a much higher level of confidence. The MotoCancelli I.R.S. kit gives the car a higher degree of precise and predictable handling not to mention the super smooth ride it offers. It has been a long time project that didn’t come easily. For this kit to work as well as it does everything had to gel as one unit. The torsional rigidity, travel ratio, spring rate and shock valving took some serious number crunching combined with hundreds of miles of test driving all of which lead to very stunning results. But perhaps the most difficult challenge was to create a simple and affordable solution for a very complex problem, a system that can be easily installed by our customers who aren’t mechanics or fabricators by trade. Like many of MotoCancelli’s products for the Spitfire it is first class in design and materials, we even integrated o.e. products into the kit to keep it true to Triumph tradition.

MotoCancelli I.R.S. kit will also replace 67-72 Spitfire Rotoflex System with greater handling results while aiding in the transfer of more power to the ground. Any future work at the rear will also become much easier and safer after the kit is installed.

MotoCancelli’s  I.R.S. kit is offered in three different stages to suit your experience level.

Please read our purchase policy.

Stage One: $1,485.00 

Includes one pair of handcrafted light weight aircraft aluminum control arms, bushing kits, precision pivot box and one pair of high tech, precisely tuned, adjustable coil over, inverted shock absorbers in the same class as Pensky, Fox and Ohlins.




Stage One IRS “Plus”: $2,565.00

Includes front adjustable coil over shocks.




Stage Two IRS: $2,237.00

Same as Stage One Kit, with upgraded three-way “piggy-back reservoir” shock absorbers that have independently adjustable compression and rebound damping for even deeper tuning for autocross, track or the serious canyon carver.



Stage Two “Plus”: $3,455.00

Includes front adjustable coil over shocks.




Stage Three: $2,445.00

“Remote” reservoir shock absorbers that mount inside car for convenient compression adjustability while driving.



Stage Three “Plus”: $3,830.00

Includes front coil over shocks with “remote” reservoirs for in car adjustability for all four corners.




Heavy Duty Race Axle Set: $2,365.00

Upgrade Option (Add to each of the above kits and save 10%.)