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Testarossa / 512TR
As our gallery at the bottom of the page highlights, shafts, gears and differentials were all weak points on these platforms. Even at relatively low mileage, the lower-grade 16NiCr11 alloy used to make the original gears exhibits severe pitting. Rather than replace an old, failure-prone component with a new, failure-prone component we offer the option of properly engineered replacements that won't fail - shafts designed to twist that won't snap, gears made of modern alloys and treated that won't break or pit and differential housings that won't crack and don't require reusing 30+ year old internals.
After commissioning a complete replacement of his 512TR's internals with our components, one 40-year Ferrari owner commented: "I have never driven another Ferrari that manually shifts as well, is as quiet or as smooth... absolutely no excuse that a quarter million-dollar super car, that was also Ferrari's flag ship back in its day, should shift so poorly or have the history of gearbox problems the Testarossa and 512TR do. Now mine doesn't and it's a joy to drive again."
Gearbox Solutions
Ring & Pinion
Propeller Shafts
Propeller Shafts
HCF's Ring & Pinion replacements are the finest quality available. They are superior in every way to the original fitments parts - made of modern, high quality aerospace steel, cut by the superior Klingelnberg Palloid method of gear hobbing and isotropically finished. Available in both 512TR and Testarossa ratios.
(Ferrari P/N's 168969, 110016, 159069)
Propeller Shafts
Propeller Shafts
Propeller Shafts
The propeller shaft transmits engine power to the transaxle. In response to many early failures, Ferrari made a stronger shaft which commonly broke the, now weaker, transmission main shaft. The unique steel alloy of this improved shaft is designed to provide a high degree of torsional flex to insulate components like the main shaft from destructive shock loads.
(Ferrari P/N's 151651, 162909)
Main shafts / Gears
Limited Slip Differentials
Limited Slip Differentials
Main shaft and gears manufactured from a aerospace-derived steel alloy. The combination of higher quality materials and processing techniques eliminates common issues with the OEM components - broken gears and snapped input shafts. See gallery below for detail on failed OEM gears and shafts.
(Ferrari P/N's 109716, 156925, 183964)
Limited Slip Differentials
Limited Slip Differentials
Limited Slip Differentials
Limited Slip Differentials feature a one-piece machined housing rather than the welded unit many came equipped with. They have all new and improved-quality side gears, spider gears and positraction components. See gallery below for detail on failed OEM limited slip differentials.
(Ferrari P/N's 106769, 101626, 147258, 190005, 199782, 183932, 238598, 103262, 146769, 148253, 155099)
Ring & Pinion in Process
Blanks rough milled, ready for teeth
Teeth cut, grinding tooth faces
Completed ring gear, ready for pattern test with pinion gear
Splines cut on pinion shaft
Completed pinions, awaiting isotropic finishing
Pattern testing
Kevlar Composite Clutch Solution
Kevlar disc clutch assemblies and flywheels - in stock
Upgrading to HCF's Kelvar composite clutch assembly has two primary benefits over the OEM assembly. First, there is a noticeable improvement in pedal effort that customers report makes the car more enjoyable to drive. Secondly, the wear characteristics of this particular kevlar composite are 1/2 to 1/5 that of traditional OEM facings. Lightweight flywheel available on request.
Fits: 512TR, F512M, 456, 550, 575, 612
Complete assembly with pressure plate
Pressure plates rebuilt and customized to work with kevlar material. For proper results, the kevlar disc must be paired with one of our customized pressure plates.
Kevlar composite disc
Made in the USA of a patented textile kevlar composite material, these kevlar discs outperforms other kevlar facings in terms of disc wear, engagement, chatter and flywheel abrasiveness.
Kevlar Disc Real World Example
512TR / 550 Maranello Kevlar Composite Clutch Disc
Rebuilt OEM disc with segmented facings. As installed during engine-out service in 2011.
1 year later - disc condition
A little over a year later the gearbox was damaged and developed an oil leak, necessitating a tear down. Clutch disc showed virtually no wear and, as this particular Kevlar fiber composite material is designed to work wet or dry, it did not need to be replaced due to oil contamination.
6 years later - disc condition
In 2017 the gearbox main shaft broke, giving the opportunity to inspect the clutch components. No more than 0.5mm of measured wear.