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Transmission

CLUTCH REPLACEMENT PROCEDURES: SERVICE TIPS THWART APPLICATION-SPECIFIC DILEMMAS

Edited from an article by Larry Carley, ImportCar, December 2001

 

Professional technicians who replace clutches for a living usually know the basics of what’s involved but, on some vehicles, the usual procedure may not apply. Or, you may run into a problem that you’ve not encountered before. So this month, we’ve put together some helpful service tips for a variety of import clutch applications.

ACURA INTEGRA
On 1994-’96 Acura Integra models with a 5-speed manual transaxle, a hard shifting problem or failure of the clutch to disengage may be due to a bad clutch disc. The retainers holding the torsion springs in the clutch disc can weaken, allowing the springs to rub against the flywheel or, in some cases, to come completely out. Honda bulletin #96-046 says to replace the disc and also the flywheel if it has been damaged.

BMW
If you encounter a BMW 318i that’s difficult to shift because the clutch is dragging, BMW says any of the following may be a possible cause of the condition:

  • Input shaft taper splines are not lubricated properly or the grease has dried out.
  • Clutch disc is not sliding on transmission input shaft.
  • Clutch disc is bent (wobble).
  • Air is in the hydraulic clutch linkage.
  • Release bearing is defective or is not moving freely on the guide sleeve.
  • Clutch disc or pressure plate is broken or worn out.

BMW says that after removing the transmission, inspect all the clutch components and replace as needed. Because of the labor involved, you probably should replace the disc, cover and release bearing as a complete set to minimize the risk of a comeback.

BMW recommends that the plastic sliding sleeve on which the release bearing rides should never be lubricated. Their reason? They say grease will allow the clutch wear particles and other contaminants to build up on the sleeve, causing an increase in clutch pedal effort. BMW does say, however, to apply a thin coating of its new Esso Unirex 82 grease to the tapered splines and guide section of the transmission input shaft. The new grease was introduced in April 1998 and lasts longer than the previous Microlube G-61 grease used by BMW.

HONDA
On older Hondas with a mechanical cable clutch linkage, clutch play is adjusted by an adjuster nut mounted above the release arm on the transaxle. On a 10-year-old Civic, Honda says 15 to 20 mm (half to three-quarters of an inch) of clutch freeplay at the clutch pedal is acceptable, but recommends adjusting the linkage to set pedal play to the minimum value (15 mm). Minimizing freeplay provides maximum pedal travel and means the pedal doesn’t have to be shoved all the way to the floor to disengage the clutch. Just make sure you leave the minimum recommended freeplay because the linkage needs some freeplay for proper clutch engagement. Adjust the linkage too tight and the clutch will slip and cook the linings!

Pedal height and travel should also be checked. Honda recommends a pedal rest height of 213 mm (8.39 inches) from the floor, with full disengagement at 46 to 70 mm (1.8 to 2.7 inches) above the floor. Overall pedal stroke from rest to fully disengaged should be about 140 to 150 mm (5.5 to 5.9 inches).

Freeplay at the release arm on the transaxle can also be checked, and should be 4 to 5 mm.

On Honda models with a hydraulic clutch linkage, the linkage is self-adjusting. But it can still be adjusted because there is a nut on the pushrod between the clutch pedal lever and the master clutch cylinder.

If you’re replacing the clutch, make sure you get the correct one because Honda uses a variety of different sizes:

  • 1984-’87 Civics and CRXs use a 190 mm clutch disc with a 19 x 13/16 spline size.
  • 1988 Civics and CRXs also use a 190 mm clutch disc, but the spline size is 21 x 7/8.
  • 1989 Civics and CRXs use a 200 mm clutch disc with 20 x 7/8 splines.
  • 1990-’95 Civics, 1990-’91 CRXs and 1992 and newer del Sols and Si models use a 212 mm disc with 20 x 7/8 splines.
  • 1994 and newer del Sol VTEC models use a 220 mm disc with 24 x 1 splines.
  • 1986-’89 Acura Integras use a 200 mm disc with 21 x 7/8 splines.
  • 1990 and newer Integras use a 220 mm disc with 24 x 1 splines.

HYUNDAI
Some 1996-’97 Elantra and 1997 Tiburon models may experience clutch drag if grease has formed an obstruction in the hydraulic clutch line. The grease was used during assembly of the clutch master cylinder. The cure, says Hyundai, is to remove, disassemble and clean the master clutch cylinder. Bulletin #97-40-020 says to remove the spring, spring seat and black valve from the master cylinder piston assembly, and to carefully wash in brake fluid or brake cleaner. Air dry the parts, then reassemble, add fresh fluid (DOT 3 brake fluid) and bleed the clutch line.

On 1996 Elantra models, removing the clutch release bearing when servicing the clutch can be difficult - unless you use this procedure:

1. After removing the transaxle, leave the clutch cover bolted to the flywheel.

2. Rotate the release bearing by rotating the crankshaft and locate the opening for the snap ring.

3. Insert the snap ring pliers to expand the snap ring.

4. Press firmly on the bearing to fully seat it against the clutch cover.

5. While the snap ring is in the expanded position, pry the clutch release bearing away from the clutch cover. You may have to use a small pry bar if the bearing cannot be removed by hand.

According to LuK, another problem to watch out for on Hyundai Excels is clutch release problems caused by broken roll pins. The roll pins secure the release bearing fork to the cross shaft. These hollow spring pins tend to fatigue and break from repeated cycling of the clutch. LuK recommends replacing these pins with every clutch change, as well as a careful examination of the holes in the shaft and fork. Any deformation of these holes will allow movement between the shaft, fork and pins, and accelerate the pins’ failure.

MAZDA TRUCK
If you encounter a clutch that’s hard to disengage on a 1993-’94 Mazda Navajo or 1994-’97 B-Series truck, the problem may be due to a worn slave cylinder in the hydraulic clutch linkage. Mazda bulletin #001/98 says to replace the slave cylinder with a modified slave cylinder ZZP0-16-222 that includes a new dust shield and upgraded lip seal.

NISSAN PICKUP
Some 1990-’91 Nissan 4-cylinder pickups may have clutch release problems due to the disc binding on the transmission input shaft. Bulletin NTB92-010 says you should isolate the problem by checking the slave cylinder travel to make sure it is 12-14 mm (.470-.550 inch). If not, bleed and recheck the travel - or replace the hydraulic components as needed to obtain normal travel.

If the no-release problem persists, replace the clutch cover, disc, release bearing and pilot bearing. Be sure to carefully inspect the input shaft for spline wear, galling or scoring.

SUZUKI SIDEKICK
Increased clutch pedal effort on 1992 and newer Suzuki Sidekick trucks may be caused by galling or wear on the clutch cross-shaft or bushings. Suzuki bulletin 3-20 08312 outlines the parts, tools and procedure for changing the cross- shaft bushings to cure the hard-pedal problem. The new cross-shaft is chrome-plated and uses either metal or resin bushings depending on the application. The VIN codes affected are JS3TA01CN4140538, JS3TE01VN4100586 and JS3TD02VN4110704.

If there is evidence of galling on the old shaft or bushings, be sure to replace the clutch cable, too. The added release load may have stretched it enough to affect release travel.

TOYOTA PICKUP
Clutch noise or squeal upon a cold startup in some 1990 Toyota 3.0L pickups may be due to a combination of insufficient preload on the release bearing (should be 18-22 lbs.) and a "stiff" bearing (grease viscosity is too thick). The noise occurs because the bearing contact surface is sliding over the diaphragm spring fingers instead of rotating with the fingers.

The solution, according to Toyota bulletin 032, is to change the slave cylinder if the noise stops after the vehicle has been running for approximately five minutes. If the noise continues after the vehicle is warm, the release bearing or pilot bearing may have to be replaced.

VOLKSWAGEN GOLF, GTI AND JETTA
On older (1985-’89) VW Golf, GTI and Jetta models, clutch engagement and release problems can be caused by an improperly adjusted clutch linkage. One of two different types of clutch cables (which are not interchangeable) may be used on these applications. One is a manually adjusted cable that requires periodic adjustment to compensate for clutch wear. The other is a self-adjusting cable that can be identified by a rubber boot atop the clutch cable sleeve on the transaxle end of the cable.

On the adjustable variety, clutch freeplay should be measured at the large plastic disc that butts up against the rubber cable grommet on the transaxle, not at the sleeve. Volkswagen issued a technical service bulletin on this item (TSB 88-01) because technicians were breaking the sleeve by trying to check the adjustment at the sleeve instead of the disc.

To adjust the linkage:

1. Work the clutch pedal several times. Then raise the clutch release lever by hand until resistance is felt.

2. Check the freeplay adjustment by measuring the distance between the transaxle housing and the large plastic disc on the cable. Volkswagen calls for a clearance of 12.0 mm (15/32 inch). VW has a special tool gauge (US 5043) that can be slipped between the disc and transaxle to check clutch freeplay.

3. If the cable needs to be adjusted, loosen the locknut under the adjusting sleeve and turn the sleeve as needed until the specified clearance is obtained. Then hold the sleeve and tighten the locknut to 4-6 Nm (36-48 in. lb.).

If a cable is broken, binding or corroded and has to be replaced, a manually adjustable cable can be removed by loosening the adjusting sleeve and backing off the sleeve until the cable’s tension is relieved. The clips that attach the cable to the release lever can now be removed and the cable disconnected.

To remove a self-adjusting cable, the spring under the rubber boot must be compressed before the clips that hold the cable to the release arm can be removed and the cable disconnected from the arm. Do not open the automatic adjuster mechanism. VW says if the adjustment mechanism is opened, the cable assembly has to be replaced.

The clutch assembly in VW Golf, GTI and Jetta models is unusual in that the clutch bolts to the crankshaft and the flywheel bolts to the clutch. It also does not have a conventional release bearing. The release arm works a small lever in the release housing on the transaxle that pushes a small bearing against the end of a long pushrod. The pushrod runs through the middle of the transaxle mainshaft and pushes against a "release plate" over the clutch. When the pushrod moves toward the engine, the release plate presses against the clutch diaphragm to release the clutch.

If dirt gets in between the pushrod and transaxle mainshaft, it may cause the pushrod to bind in the released position, causing the clutch to slip. If the pushrod wears through the release plate or the lever arm in the transaxle release mechanism is broken, the clutch may fail to release when the clutch pedal is depressed. In either case, the pushrod and release mechanism should be inspected to determine the cause.

When servicing the clutch, the release rod bearing, located at the rear of the transmission under the round, sheet-metal cover, should always be replaced along with the other clutch components. The sheet-metal cover can be easily bent during removal and may also have to be replaced. Other items that should be replaced are the seal and bushing that prevent transmission oil from leaking into the transaxle and contaminating the clutch. Also, inspect the release rod for wear or distortion, and replace it if either condition is found.

VW uses a stepped flywheel on these cars, so that when the flywheel is resurfaced, equal amounts of metal must be removed from both surfaces to maintain the proper clutch height and pressure. If only the inner face is resurfaced, the clutch will not exert enough pressure against the disc, which may allow it to slip, overheat and wear.

If you’re installing a new flywheel because the old one is cracked, damaged or too badly worn to be resurfaced, you should know that some replacement flywheels may not have an ignition timing mark. If there is no mark, you’ll have to make one by filing a notch 12 mm (0.472 inches) to the left of the Top Dead Center mark.

Position the clutch pressure plate on the crankshaft. Apply threadlocking compound to new bolts, and install and tighten the bolts without shoulders to 75 Nm (55 ft. lbs.) or bolts with shoulders to 100 Nm (72 ft. lbs.). VW released a bulletin (92-02) that revises the bolt torque specs on 1987 and up Golf, and 1989 and up Jetta (and Passat). The bulletin says to tighten the bolts to 60 Nm (44 ft. lbs.), then turn them an additional 1/4 turn (90 degrees).

Next comes the release plate. The center contact for the pushrod should be lightly lubricated with lithium grease. The retaining ring should be aligned so the open ends are over one of the holes in the plate.

The clutch disc can then be placed inside the flywheel, and the flywheel bolted onto the pressure plate. You’ll need a special centering tool because an ordinary pilot tool won’t work on this application. VW’s clutch centering tool for 1.8L SOHC engine applications is VW 547, while the one for the 1.8L DOHC 16-valve engine applications is P/N 3178. Use the tool to hold the disc in place while the flywheel bolts are tightened evenly in a star pattern to 20 Nm (15 ft. lbs.).

On 1995 and newer Golf, GTI and Jetta models with the 02A transmission, failure of the clutch pedal to fully return or failure of the cruise control to operate may be due to the clutch pedal over center spring dropping out of position. The cure here is to check the clutch pedal assembly for a missing or broken spring. VW says the spring support should also be replaced with a new part number (1HM 419 555D) and pedal stop (861 805 461) installed into the support (VW bulletin 98-01).

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