Clutches Basic purpose Used to disengage engine from input shaft Flywheel –Bolted to crankshaft –Provides surface for clutch disc to work on Clutch disc.

Clutches

Basic purpose

• Used to disengage engine from input shaft

• Flywheel– Bolted to crankshaft– Provides surface for clutch disc to work on

• Clutch disc– Splined to transmission input shaft– Fits between flywheel and pressure plate

Basic purpose

• Pressure plate– Bolted to flywheel– Applies squeezing pressure to disc– Acted on by throw out bearing

Flywheel

Flywheel

• Acts as engine balancer– Works with crank balancer to smooth out firing

pulses– Some will be balanced to engine

• Adds inertia to engine rotation• Works as heat sink for clutch• Ring gear for starter engagement• Some vehicles have dual mass flywheel

Flywheel service• Visually inspect for hot spots, grooves,

scoring and cracks

• Check with dial indicator for runout and crank end play

• Most flywheels can (should) be resurfaced– Must remove dowel pins

• Inspect ring gear

Flywheel service• Flywheel should be marked before

removing to maintain balance

• On Front wheel drive cars a lot of Flywheels are used for Ignition timing marks. They should be marked before removing. Some will only bolt on one way don’t take the chance MARK IT

Clutch disc

Clutch disc

• Friction material disc splined to input shaft

• Friction material may contain ASBESTOS

• Friction material can be bonded or riveted

• Friction is attached to wave springs

• Most have torsional dampener springs

• Normal wearing component

• Normally a worn out disc will cause slipping

Clutch disc service

• Inspect for wear similar to brake pads

• Common to have loose or broken springs

• Common failure due to oil contamination– Must find cause BEFORE repair

• Normally purchased in kit containing pressure plate, disc, throw out bearing

Clutch disc service• Clutch disc will normally have a flywheel

side

• Disc must be centered with clutch alignment tool before pressure plate bolted down

• Make sure new disc fits on input shaft of the transmission before you install it

Pressure plate

Pressure plate

• Provides clamping pressure to disc– Works like spring loaded clamp

• Bolted to _________________

• Can use Belleville spring acted on by Throw Out bearing

• Can use coil springs and levers acted on by Throw Out bearing

Pressure plate service

• Mark relation to flywheel if reused

• Remove bolts slowly in criss-cross pattern

• Inspect fingers for parallelism, cracking or uneven wear

• Inspect friction surface for hot spots, cracks etc and with straight edge for warpage

• Must be torqued to specs and in sequence

• Uses hard bolts

Release/ throw out bearing

Release/ throw out bearing

• Acted on by clutch fork - acting on pressure plate

• Moves toward flywheel when pedal pushed

• Slides on front portion of transmission called bearing retainer

• Normally not in contact with pressure plate until pedal pushed

Release bearing service• Very common failure - isolated by lightly

applying clutch and listening

• Inspect for looseness or roughness

• Most are sealed but some were lubeable

• Clutch fork must be lubed at pivot point and bearing contact points

• Bearing retainer and input shaft should be lubed

• Clutch fork must be secured at the pivot point

Pilot bearing / bushing

• Used on some cars

• Supports front of transmission input shaft

• Can be needle bearing or bronze bushing

• May be part of clutch kit

Pilot servicing

• Should always be changed with clutch

• Can be isolated by applying clutch in gear

• Special pullers may be used for removal– Can be removed with grease

• Should be lightly lubed on installation

Clutch linkage

• Can be operated by cable, rods or hydraulics

• May be automatic or manually adjusted

• Hydraulic will have a master and slave cylinder– Will use brake fluid for hydraulic action– Will need bleeding with repairs

The End