ASE A3 cheat sheet

Pedal free play is the distance the pedal moves before the release bearing contacts the pressure plate fingers; typical spec is 1/2 to 1 in (13-25 mm). Zero free play keeps the bearing loaded and causes slip.

Slip symptom: engine rpm rises without a matching rise in road speed under load. Causes include oil-fouled facings, a weak diaphragm spring, a glazed flywheel, or no pedal free play.

Chatter on engagement: oil or grease on the facings, warped flywheel or pressure plate, worn pilot bushing, broken engine or transmission mounts, or loose bellhousing bolts.

Pilot bearing noise is heard with the pedal depressed and a gear selected, when the input shaft is stationary and the crankshaft turns. Throwout bearing noise also appears with the pedal depressed but changes with pedal pressure.

Replace the disc when the facing is worn to within 0.015 in (0.4 mm) of the rivet heads, or when facings are cracked, rivets are loose, or a torsional damper spring is broken.

Hydraulic release systems: a soft or sinking pedal that will not fully release usually has air in the system or a leaking master or slave cylinder; bleed at the slave bleeder, the lowest point.

Diaphragm spring fingers must be even and unworn; bent fingers or a broken strap drive require pressure plate replacement, not adjustment.

Flywheel service: check flatness with a straightedge and feeler gauge and runout with a dial indicator; resurface only within the manufacturer's minimum thickness and step specification.

Output torque equals input torque multiplied by the gear ratio; at the wheels, torque is multiplied again by the final drive ratio.

Vehicle speed formula: MPH = (RPM x tire diameter in inches) / (gear ratio x final drive ratio x 336).

A worn synchronizer blocking ring, identified by a ring-to-gear gap below specification, causes gear clash; measure the gap with a feeler gauge before reuse.

Bearing noise heard in every gear except direct drive (1:1) points to the input shaft or countershaft bearings, because the countershaft is unloaded in direct drive.

Popping out of gear: worn synchronizer sleeves or engagement teeth, bent shift forks, weak detent springs, or excessive shaft end play from worn bearings.

Hard shifting with cable or rod linkage: check for binding cables, worn bushings, misadjustment, and correct lubricant level and type before internal diagnosis.

In a transaxle the differential shares the transmission case; the output shaft drives the final drive ring gear, which drives the differential pinion gears and side gears.

Common leak points are the input shaft seal, output or axle seals, shift shaft seal, and case seams; verify the vent is clear before condemning a seal.

A single Cardan universal joint produces two speed fluctuations per revolution; two joints cancel them only when their operating angles are equal and opposite, within about 1 degree.

Two-joint drive shafts must be phased with both yokes in the same plane; an out-of-phase shaft causes a cyclic vibration that varies with road speed.

Universal joint checks: looseness, binding through the arc, missing needle bearings, and red-brown rust dust all indicate replacement.

A missing balance weight, a dent, or heavy undercoating on a shaft causes vibration at one specific road speed; confirm with a dial indicator runout check, typically under 0.010 in.

Center support (carrier) bearing: a cracked rubber insulator or a rough bearing causes clunking and low-frequency vibration on two-piece drive shafts.

Outboard fixed CV joints (Rzeppa) click or pop in turns under power when worn; a torn boot with grease loss and dirt entry is the usual cause.

Inboard plunge joints (tripod or double offset) shudder or vibrate during straight-line acceleration when worn or when their boot is torn.

Install CV boots with the specified moly-type grease and non-twisted clamps; never pry on a half-shaft to separate a joint, and support the shaft during removal.

Final drive ratio equals ring gear tooth count divided by pinion tooth count; for example, 41 ring teeth and 11 pinion teeth give 3.73:1.

An open differential divides torque equally, so total usable traction is twice the traction at the wheel with less grip; one spinning wheel can stop the vehicle.

Clutch-type limited slip: chatter or shudder in tight turns is corrected by adding the specified friction modifier; worn clutch packs cause one-wheel spin.

Pinion bearing preload is set with a crush sleeve or shims and verified by measuring turning torque at the pinion flange; excessive preload destroys bearings.

Ring gear backlash is measured with a dial indicator perpendicular to a tooth at the ring gear; set it to specification, then re-check the contact pattern.

Contact pattern with marking compound reveals pinion depth errors (pattern toward heel or toe) and backlash errors (pattern toward face or flank).

Noise diagnosis: whine that changes between acceleration and coast points to ring and pinion setup; steady noise that follows vehicle speed points to bearings.

Check fluid at the fill plug (level with the hole) and use the specified lubricant; helical or Torsen gear differentials require no friction modifier.

Semi-floating axle: the shaft carries both drive torque and vehicle weight. Full-floating axle: the hub rides on bearings on the housing and the shaft carries torque only.

C-clip axles retain the shaft in the differential; in-and-out shaft movement, a leaking seal, or a grooved shaft surface usually means a worn C-clip or side gear.

Part-time 4WD has no center differential, so use on dry pavement causes driveline windup, binding in turns, and tire scrub; engage it only on loose or slippery surfaces.

All four tires must match in size and wear; different rolling diameters make the transfer case fight and produce windup, vibration, and component damage.

Front and rear axle ratios must match exactly; a mismatch binds the driveline as soon as 4WD is engaged.

Center axle disconnect uses a vacuum or electric collar to engage one front half-shaft; no 4WD with a functional transfer case often means a failed actuator, vacuum line, or collar.

Automatic locking hubs engage with driveline torque, while manual hubs must be locked before 4WD is needed; a failed hub leaves that wheel undriven.

Transfer case lubricant varies by design (ATF versus dedicated fluid); wrong lubricant or overfilling causes foaming, seal leaks, and shift concerns.