Complete Clutch Repair

Overview

Before You Start 

When a customer brings in their vehicle for a clutch related problem, it is important to understand fully what their concern is. It is possible that the perceived problem is a normal characteristic of the vehicle.

Talk with your customer to understand their concern and determine when the problem first started. You may have to take a test drive with the customer to verify the problem.

It is important to verify the cause of the concern or failure. Once the problem has been identified, talk with the customer about the repair procedure and how the clutch system operates.

Make sure the customer understands and feels comfortable with the repair being performed on their vehicle.
 
Complete Repair

Complete clutch repair is diagnosing the cause, fixing the problem and examining and replacing all worn and damaged components.

Component parts incur wear. Some adjust their operating points to compensate for normal wear in disc friction material. The service life of clutch components is not infinite. “As-new” performance can be expected when LuK RepSet® components are installed.

Examination and replacement of all worn clutch system components is critical to ensure the full service life of the clutch and disc.

When the vehicle is pulled into the shop for repair, the first thing that should be done is to check for Technical Service Bulletins (TSBs). Sometimes there may be a bulletin that has information regarding clutch system issues and may have updated information and parts to fix the problem.

If no TSB’s are found, start by checking all the external parts related to the clutch system before removing components for further diagnosis of the clutch related problem.
 

Step 1

Inspection of External Components

Clutch Pedal

When checking over the external parts, examine the clutch pedal linkage under the dash. Additionally, check all bushings and connections related to the clutch pedal. Insure all linkages move freely and do not have excess play in them.

Clutch Release Cable

If the vehicle has a clutch release cable, verify that the cable is routed in the correct location. Verify the clutch cable is free from binding. Check to make sure the cable has not stretched.

Hydraulic Release System 

If the vehicle is equipped with a hydraulic release system, verify the fluid is clean and filled to the proper level. Next, check for any signs of fluid leakage from the clutch master cylinder, clutch fluid line, and clutch slave cylinder.

Bell Housing 
 
  • Some vehicles use a concentric slave cylinder (internal slave cylinder), which is located inside the bell housing. Look for any signs of leakage coming from inside the bell housing.
  • Check the bell housing for any signs of fluid contamination due to a leaking engine or transmission. Leaking fluid can be the cause of the clutch issue the customer is experiencing. Fluid leaking into the bell housing can contaminate the clutch disc.

Engine and Transmission Mounts 

Loose engine and transmission mounts can simulate a clutch problem.
 
  • Check u-joints / half-shafts and drive line angle. Verify that u-joints / half-shafts are not binding or loose.
  • Check carrier bearings and mounts. Verify the carrier bearing and mounts are tight and not walking around inside the mount.
  • Look for any aftermarket parts that may change drive line angle. 

After all external components have been checked, remove the transmission.
 
Teardown

Organize teardown procedures to keep track of parts and speed installation. Many of the procedures you use during removal of the old clutch can prevent errors. As you remove the old clutch, note all bolt locations. Bell housing bolts may have different lengths, diameters and thread pitches. If any of the bell housing bolts are used to attach a ground cable to the transmission, mark the bolt and its location. Clean and check all bolts for thread damage.

If the crankshaft flange bolt pattern is symmetrical, mark the relationship of the flywheel to the crankshaft mounting flange to eliminate a balance problem. If the pattern is asymmetrical, the flywheel will only go on one way. 

Removing the Transmission

During transmission removal pay careful attention to detail. When the transmission is being removed verify the dowel pins between the engine and transmission are not missing and are in good condition.

Inside the Bell Housing
  • Check for leaks and fluid contamination
  • Examine the input shaft for wear and free play
  • Verify the condition of the following components:
    • Throw-out bearing 
    • Bearing retainer
    • Release fork and pivot ball
  • Inspect the concentric slave cylinder for leaks.
After all of this has been thoroughly examined, it is time to diagnose the clutch.
 

Step 2

Clutch Diagnosis

Clutch Fingers
  • Look for signs of heavy wear, melted fingers, uneven fingers, and contamination.
  • Next, look for signs of over heating.

Pressure Plate
 
  • Determine if the pressure plate has hot spots or bluing on the outside.
  • Unbolt the clutch pressure plate evenly and in a star pattern. Unbolting the clutch pressure plate incorrectly may cause damage and warp the pressure plate. While removing the pressure plate be careful the clutch disc does not fall out.
  • When removing the pressure plate, remove the disc at the same time.
  • Place both clutch and disc on a work bench. 
  • Carefully examine the pressure plate and disc. 
  • Inspect the pressure plate for bluing and hot spots on the friction surface. 
  • Check the pivot ring to insure it is not broken or missing. Make sure the drive straps are not bent or broken.
Disc
 
  • Check for stop pins that have show wear.
  • While looking at the stop pins also examine the damper springs to verify they are not loose or missing.
  • Examine the disc center hub for splines that are worn or stripped out.
  • Look for excessive grease.
  • Check the friction surface of the disc for contamination.
  • Measure the disc thickness per manufacturer specs.
  • Determine whether the friction surface is burnt or missing.
  • Look for evidence of the damper package interfering with the clutch pressure plate or flywheel.
Flywheel 
 
  • With the flywheel still bolted to the crankshaft, examine the friction surface.
  • Determine if the flywheel shows signs of over heating, hot spots, or cracks.
  • If the flywheel is stepped, measure the step and compare it to OE specs.

It is recommended to replace the flywheel anytime the clutch is changed. Many of today’s vehicles do not have adjustable clutch release systems. Machining as little as .010 of and inch can cause release issues.
 
  • Remove the flywheel.
  • This is a good time to examine and replace the engine rear main seal if needed.

Pilot Bearing/ Bushing

If the vehicle is equipped with a pilot bearing/bushing inspect the condition of the bearing/bushing. Many times this step is overlooked or the pilot is not replaced. The pilot bearing is the cause of many clutch related problems. Most pilot bearings fit in the end of the crankshaft, some fit into the flywheel. If the pilot fits in the end of the crankshaft, use the special tool designed to remove these bearings.

Bell Housing
 
  • Now is a good time to clean inside the bell housing!
  • Remove as much grease, oil, and clutch material as possible. The cleaner the job the better the clutch will work.

Step 3

Reinstallation of Components and Transmission
  • Install the new pilot bearing/bushing if installed in the end of the crankshaft.
  • Install the flywheel following the manufacturers torque specs. It is critical to follow the proper torque specs! If the flywheel is torqued incorrectly the end of the crankshaft can be distorted and cause the rear main seal to leak.
  • Once the flywheel is properly installed use a good cleaner and thoroughly clean the friction surface of the flywheel.
  • Once complete, insert the clutch alignment tool into the clutch disc and connect to flywheel.
  • Attach the clutch pressure plate onto the flywheel.
  • Torque the bolts following a star pattern, to manufacturer’s specs. Failing to follow proper torque specs will result is a warped pressure plate and will cause clutch related problems. Most clutch kits come with spline grease. It’s very important to put a very light coat on the input shaft. Remember less is more when it comes to grease on the input shaft. If too much is applied it will sling grease all over the new clutch disc and cause problems..
  • Install the throw out bearing or concentric slave cylinder. If the vehicle has a concentric slave follow proper torque procedures.
  • Lift the transmission into place using proper equipment.
  • If the vehicle has a concentric slave cylinder follow the procedure for proper bleeding.
  • Always use the proper fluid specified in the owner’s manual. Failure to flush the fluid will result in release problems and leaks in the hydraulic system.
  • Attach the transmission and engine together. Do not force the transmission into the clutch. Forcing the transmission into the clutch will damage the clutch disc hub. Do not allow the transmission to hang from the input shaft.

Finishing the Repair 

Once the transmission is reinstalled in the vehicle, test drive the vehicle to let the clutch break in. Do not drive the vehicle aggressively. 

Talk with the customer and explain not to drive the vehicle aggressively for about 250 miles.
 

Do’s and Dont's

Do’s 
 
  • The dual-mass flywheel is a wear item and should be replaced at EVERY clutch change
  • Solid flywheels should be replaced or surfaced at EVERY clutch change
  • Verify all contents and inspect them BEFORE installation
  • Flush hydraulic release systems and replace fluid with fresh new fluid recommended by the manufacturer
  • Crankshaft end play will cause release problems. Always inspect and diagnose adjacent systems for possible problems
  • Inspect for oil leaks coming from the front of the transmission and the rear of the engine. If leaks are present, oil contamination will incur on the clutch system and a slipping condition and premature failure will result.
Dont’s
 
  • As little as a fingerprint can contaminate a disc
  • NEVER grease a bronze pilot bushing
  • Product/ compound used to prevent seizing is NOT spline lubricant
  • Self-Adjusting Clutches (SAC) are preset by the factory and require no modification
  • Do not machine a dual-mass flywheel

Summary

Solutions That Work

When it comes to a job as complex and labor intensive as a clutch replacement, you can’t afford a comeback. Cheap, inferior parts can cost you hundreds of dollars in unreimbursed labor. For over thirty years, smart technicians have staked their reputation – and their customers’ satisfaction – on genuine LuK RepSet clutch and clutch system components. 

Every LuK RepSet is 100% functionally tested and guaranteed to meet OEM performance specifications. Each LuK RepSet contains everything you need to get the job done right: new clutch, disc, release bearing, pilot bearing, spline tool and lubricant. LuK offers a complete line of clutch system components, including flywheels, hydraulic release system components and cables.