Now Available — UK & Europe
OS Giken Super Lock LSD
Japanese precision engineering. Progressive locking. Bespoke specification for the Caterham Seven.
A New Partnership — Exclusively for Caterham Owners
Too Fast To Race has agreed terms with OS Giken to supply the Super Lock LSD to Caterham Seven owners across the UK and Europe. This is not a generic parts listing — it is a specialist supply arrangement backed by over 30 years of Caterham development experience.
The OS Giken Super Lock LSD is one of the most technically advanced clutch-type limited-slip differentials available. Developed over four years of intensive research, it achieves something most LSDs cannot: genuinely progressive, controllable lock behaviour without compromising low-speed drivability.
For a Caterham Seven — a car where chassis feel and traction management are inseparable from performance — the difference this makes is not subtle. Every setup we specify will be matched to your car, your application, and how you use it.
Why the LSD Matters on a Caterham
A Caterham Seven's lightness is its defining characteristic. That same lightness creates a specific challenge: with relatively little weight pressing the rear tyres into the road, traction management is critical. On corner exit, an open differential allows the inside wheel to spin freely the moment grip breaks — wasting power, disrupting balance, and demanding constant correction from the driver.
An LSD changes the chassis conversation entirely. Applied correctly, it allows both rear wheels to contribute to forward drive on exit, stabilises the car under power, and gives the driver a more predictable, confidence-inspiring platform to work with.
The key word is correctly. A poorly specified LSD on a lightweight car introduces its own problems — understeer on turn-in, nervous mid-corner behaviour, or an LSD that locks so aggressively it simply creates a different kind of traction problem. Getting the specification right for a Caterham, for a specific application, and for a specific driver is exactly what we do.
"On a Caterham, the LSD isn't just a traction device — it's a fundamental part of how the chassis feels and responds. Specifying it correctly is as important as the spring rates or the damper setup."
— Simon Rogers, Too Fast To Race
OS Giken Super Lock LSD (left) alongside the Dual Core LSD (right) — the difference in side gear profile between the two units is visible. The Super Lock uses parallel-cut gears; the Dual Core uses spiral-cut gears that add rotation-sensitive locking capability.
The OS Giken Super Lock — Technical Overview
Four years of development produced a design that resolves the fundamental conflict in LSD engineering: maximum lock capability without compromising progressive feel.
Lock Timing Control
The LTC system is OS Giken's patented pressure ring design. A miniaturised pressure ring combined with a spline-through-side-gear arrangement allows the OS Giken to house significantly more friction plates than conventional clutch-type LSDs — up to 28 plates in total, and up to twice as many as comparable units.
The result is a unit that can achieve full 100% lock progressively and smoothly, without the abrupt engagement that makes many race-specification LSDs unsuitable for road and fast road use.
Progressive Feel at Low Speed
At low speed — in car parks, slow corners, or everyday road driving — the OS Giken Super Lock behaves like an open differential. There is no clatter, no tight steering feel in slow turns, and no resistance to normal manoeuvring. The cone spring relief cut-out in the LSD case ensures minimal spring degradation over time, maintaining this characteristic.
Under load — on corner exit, accelerating hard, or demanding maximum traction — the LSD engages progressively and completely. The transition is predictable, controllable, and repeatable.
Construction & Durability
All OS Giken components are chemically heat treated and manufactured from high-grade steel alloy. Gears are raw-forged rather than machined from billet, maximising grain structure and fatigue strength. Clutch discs are precision-machined simultaneously on both sides to extremely tight tolerances — a process that minimises warpage and ensures consistent contact across the full friction surface.
The LSD housing itself is machined from a single billet piece. Unlike multi-piece assemblies, this eliminates dimensional variation and ensures complete uniformity under load. No break-in period is required, and the OS Giken is designed to require no scheduled rebuild.
Tunability
The OS Giken Super Lock is not a fixed-specification unit. Multiple tuning dimensions are available, which is central to how we specify it for each application:
- Initial torque bias adjustable via cone spring selection (thicker or thinner springs)
- Lock progression timing adjustable via pressure ring spring stiffness
- Ramp angles customisable by swapping pressure ring and iron cross components
- TCD specification discs available for increased oil cooling and smoother engagement
- Available in 1-way, 1.5-way and 2-way configurations depending on application
For a Caterham used on fast road and occasional track days, the specification will look very different from one built purely for hillclimb or circuit competition. We select the correct configuration for your car and your use case.
OS Giken Super Lock LSD
Specification at a Glance
| Type | Clutch-type Limited-Slip Differential |
| Design | Patented pressure ring — spline-through-side-gear |
| Friction Plates | Up to 28 total — up to 2× competitor capacity |
| Lock Capability | Progressive 100% lock |
| Configuration | 1-way / 1.5-way / 2-way — application dependent |
| Case Construction | Single billet machined housing |
| Break-in Required | None |
| Rebuild Required | None scheduled — designed for long-term durability |
| Tunability | Initial torque · Lock progression · Ramp angles · Disc specification |
| Application | Caterham Seven — all variants — fast road to full race |
| Supply | UK & Europe — Too Fast To Race |
| Price | £1,360 ex VAT · includes UK shipping |
How We Specify It
Specification. Not just supply.
Our role is not simply to ship a unit. It is to identify the correct configuration for your car, your application, and your driving style — and to ensure the LSD works in conjunction with the rest of the chassis rather than in isolation from it.
That means considering your suspension setup, your spring rates, your tyre choices, and the circuits or roads you use most. A Caterham running Nitron R1 on a fast road setup demands a different LSD specification from one running full race dampers at a hillclimb event.
We have the chassis knowledge to make that assessment correctly. That is the value of dealing with a specialist rather than a distributor.
Discuss Your ApplicationConsultation
We discuss your car, your use case, and your chassis setup in detail before specifying anything.
Specification
We select the correct OS Giken unit, configuration, ramp angles, and disc specification for your application.
Supply
Your unit is ordered and supplied directly — sourced correctly for your specific differential housing and spline count.
Support
We remain available to assist with setup questions, tuning adjustments, and further development as your car evolves.
Enquire About the OS Giken LSD
Tell us about your car and how you use it. We'll advise on the correct specification and supply direct to the UK or Europe.
Get in Touch