Hydraulic Throwout Bearing — B48 Transverse | Clutchmasters × Esse Werks

A first of its kind — the only adjustable hydraulic throwout bearing built for the factory Getrag GS6-17BG transverse 6-speed. For twin-plate clutches only, and natively designed around the Clutchmasters CM 850 Strapped DLX twin-plate.

Developed by Clutchmasters and Esse Werks on the shop F56 race car, it replaces the entire OEM mechanical linkage — throwout bearing, slave cylinder, clutch fork, pivot ball, and the hard lines feeding all of it. The OEM stack is fine for stock-power street duty; under sustained track load on a Stage 2 or Stage 3 calibration, the system-level flex shows up as inconsistent pedal feel, late engagement, and eventual fork or pivot failure.

Twin-plate clutches only

This conversion is engineered for twin-plate (twin-disc) clutches — not single-plate. It was natively designed to work with the Clutchmasters CM 850 Strapped DLX twin-plate, and configures for other twin-plate clutches via the matched bearing face below.

Which clutch are you running?

Pick your twin-plate clutch above — we ship the bearing with the contact face matched to it, so you don't have to know face shapes. It's a required choice with nothing pre-selected, so identify the clutch you intend to run; the wrong face won't release properly. (Shape noted in italics for those who track it.)

Switching clutches later? You don't rebuy the assembly — just order the matching Esse Werks HTOB Bearing & Face ($195) and fit it to your HTOB. It's quick.

• Clutchmasters — peaked face — a rounded peak machined into the center, built for the CM 850 Strapped DLX twin-plate. A matched pair, not adapted to fit.
• Tilton — flat or radius, matched to your Tilton twin-plate.
• SPEC — matched to your clutch at intake.
• Other / not sure — we confirm the correct face before it ships.

What this fits — transmission, not chassis

The qualifier is the gearbox, not the car. This unit fits the Getrag GS6-17BG 6-speed transverse manual transmission as fitted from the factory to MINI F-series Cooper S and JCW manuals — we've personally fit both the Cooper S and JCW boxes. If your VIN shows that transmission, this part fits. The chassis list below identifies where the Getrag GS6-17BG came from the factory:

• F56 Cooper S and JCW 3-door hatch — B46/B48 with the GS6-17BG manual
• F55 Cooper S 5-door hatch — B46/B48 with the GS6-17BG manual
• F57 Cooper S / JCW Cabrio — B46/B48 with the GS6-17BG manual
• F54 Clubman Cooper S — B46/B48 with the GS6-17BG manual

Does NOT fit: the Aisin or ZF automatic transmissions, DCT transmissions, or longitudinal BMW Getrag boxes (different family entirely — GS6-37BZ, GS6-53BZ). Confirm transmission type at checkout — your VIN tells the story.

Pivot-arm throwout bearing vs hydraulic throwout bearing

The OEM transverse clutch actuates through a chain of mechanical components: master cylinder → hard line → slave cylinder → clutch fork pivoting on a ball → throwout bearing → clutch fingers. Every component in that chain contributes flex, lash, and wear. The pivot ball wears. The fork flexes. The slave seal weeps. By lap 30 the pedal engages in a different place than it did at lap 1.

The hydraulic conversion eliminates the mechanical chain entirely. The slave cylinder is integrated into the throwout bearing itself, mounted concentrically around the transmission input shaft. Fluid pressure pushes the bearing directly against the clutch fingers — no fork, no pivot, no fork-to-bearing contact point, no cumulative wear chain. Pedal feel at the end of a session matches pedal feel at the start.

What Ford already figured out

This isn't a novel architecture. Ford fitted a factory Concentric Slave Cylinder — the OEM term for a hydraulic throwout bearing — to the Mk3 Focus ST and the Mk3 Focus RS, both of which use a different Getrag 6-speed (the MMT6, not the GS6-17BG). Ford engineers reached the conclusion we did: mechanical fork actuation isn't durable under sustained high-clamp load. They picked the hydraulic path from the factory. BMW and MINI picked a different cost/durability trade-off and shipped the GS6-17BG with the mechanical pivot system. We chose Ford's answer for the cars that didn't get it from the factory.

Why adjustability matters

A fixed-position throwout bearing has one engagement point. Any change in clutch finger height — from a new disc, from disc wear, from a different pressure-plate spec — moves engagement away from where the driver expects it. Clutchmasters built this unit with an adjustable air gap, set with the included shims, so the bearing-to-finger preload can be dialed in for the twin-plate clutch you run and re-dialed as the disc wears.

F56 race car development

This wasn't engineered off a CAD model and shipped to test. Clutchmasters and Esse Werks developed the assembly on the shop's F56 race car — same factory Getrag GS6-17BG every customer car runs, real heat cycles, real lap data. Iterations validated under load on the Getrag bell housing, not on a bench fixture.

What's in the box

• The Clutchmasters × Esse Werks hydraulic throwout bearing, with your selected (matched) face
• Stainless-steel braided line and fittings
• Shims (to set the air gap)

Clutch compatibility

Twin-plate clutches only. The native pairing is the CM 850 Strapped DLX twin-plate (our peaked face was built for it); Tilton, SPEC, or another twin-plate brand are matched too — choose Other and we'll match the face. Actuation force is matched to OEM clamping pressure; very high-clamp competition clutches may want a master-cylinder upgrade, which we can recommend at intake.

When you need it

Track-day cars on Stage 2+ calibration. Cars driven hard in stop-and-go with frequent clutch use. Builds where the original fork or pivot has already failed and you're replacing parts anyway — the labor to drop the transmission is the same either way, and the system-level upgrade saves a second tear-down later.

Install

Transmission removal required. Coordinate with a shop comfortable with MINI transverse drivetrain. Esse Werks installs in-house at the Boca Raton shop on appointment.

Made in the USA by Clutchmasters (Rialto, California).

Warranty: Manufacturer warranty on the Clutchmasters hydraulic assembly. Esse Werks supports installation troubleshooting through sales@essewerks.com.