944 Clutch — Specifications, Free-Play & Wear
Factory data for the 944's single-plate dry clutch — the pressure-plate and disc specification, the 0.5 mm push-rod free-play that cannot be measured directly, the assist-spring setting distance A by colour code, the drive-disk wear limit, the release-travel nominal value, and the hydraulic-bleeding routine.
Factory data for the 944's clutch. The 944 runs a single-plate dry clutch with diaphragm springs in the pull-release version, mounted on the engine and operated hydraulically. Because the hydraulic linkage adjusts itself automatically, there is no free-play to set at the pedal in the usual sense — the few service figures that matter are the push-rod clearance, the assist-spring setting, the drive-disk wear limit, and the release travel.
For the full overhaul see Clutch Replacement; for the hydraulic side see Clutch Slave Cylinder Replacement and Bleeding and Clutch Master Cylinder Replacement. The transaxle data is on 944 Manual Transmission — Gear Ratios, Final Drive & Oil.
Clutch specification
| Item | Specification |
|---|---|
| Design | Single-plate dry clutch, diaphragm-spring, pull-release version, engine-mounted, hydraulic operation |
| Pressure plate | MFZ 225 — contact pressure 6100 N to 6800 N |
| Clutch disc | 225 GUD (with rubber torsion damper) |
The "225" is the friction-disc diameter in millimetres. The pull-release layout means the release bearing pulls the diaphragm-spring fingers toward the gearbox to disengage, rather than pushing them — relevant when you fit the release mechanism during assembly.
Clutch play (push-rod clearance)
The hydraulic clutch is self-adjusting, so clutch play cannot be checked at the pedal. The clutch will only operate correctly if there is 0.5 mm clearance between the push rod and the master-cylinder piston. This clearance cannot be measured directly: at the pedal pad it amounts to about 3 mm of free movement and must be judged by feel. If it is wrong, correct it by adjusting the piston rod.
Tip: Too little clearance keeps the release system under slight load and can let the clutch slip or fail to fully disengage; too much delays take-up. Set it by feel for that small amount of slack at the top of the pedal travel.
Assist-spring setting — distance A
A spring is fitted to reduce pedal effort by assisting the force applied to the pedal. It has to be preloaded correctly, which is set by distance A measured between the outer edge of the plate and the bearing, with the clutch engaged (pedal at its end stop). Correct distance A by turning the hex nut.
| Assist spring | Distance A, installed (spring removed) |
|---|---|
| Green colour code (no longer available as a spare part) | 60 mm (75 mm) |
| Blue colour code (increased spring rate; in use since February 1986) | 55 mm (68 mm) |
The bracketed figures are distance A measured with the spring removed; the plain figure is the installed setting. When refitting, hold the servo-spring and guide rod together with an assembly wire — a 3 mm-diameter split pin serves.
Drive-disk wear
Drive-disk wear is checked through the inspection cap on the clutch housing, without splitting the transaxle. Remove the cap and measure distance A with a suitable gauge. The figure grows as the friction lining wears, so a larger reading means a more worn disc.
| Distance A | Value |
|---|---|
| New (size when new) | 18 mm |
| Wear limit | 34 mm |
At 34 mm the disc has reached the end of its service life and should be replaced. The hands-on procedure is covered in Checking Clutch Disc Wear.
Release travel
Release travel confirms the hydraulics move the release lever far enough to fully disengage the clutch.
- Remove the inspection cap (as for the drive-disk check above).
- Measure distance B — the travel of the slave-cylinder push rod against the release lever — with a suitable measuring tool.
The nominal release travel B is 15 mm to 18 mm.
Warning: If the release travel is less than 15 mm, there is no guarantee that the clutch disengages fully. Likely causes are air in the hydraulic system, defective cups in the master and/or slave cylinder, no or insufficient clutch play, or limited clutch-pedal travel (for example a bunched-up floor mat).
Bleeding the hydraulic system
A pressure bleeder is recommended.
- Fill the reservoir to the upper edge with brake fluid, remove the restrictor sleeve, and connect the bleeder.
- Switch on the bleeder and open the bleeder screw on the clutch slave cylinder until the escaping fluid runs free of air bubbles. Operate the clutch pedal several times during this step.
- If residual air remains (shown by release travel under 15 mm), unscrew the slave cylinder from the clutch housing, push its push rod against the internal stop, and release it again — with the bleeder switched off and the reservoir not filled to the upper edge. This forces the residual air back up the clutch line into the master cylinder / reservoir.
- Refit the slave cylinder and repeat the bleeding procedure.
Caution: Never operate the clutch pedal while the slave cylinder is removed.
The fluid is shared with the brake system; the slave-cylinder removal and the full bleeding methods are covered in Clutch Slave Cylinder Replacement and Bleeding.