Parts Catalog Accessories Catalog Tech Info Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
Bookmark and Share

Pelican Technical Article:

Clutch Replacing

Nick Czerula

Time:

9 hours9 hrs

Tab:

$1000

Talent:

*****

Tools:

Socket set, transmission jack, Inverted Torx sockets, E10, E12, E14,

Applicable Models:

BMW E46 M3 Coupe/Conv (2001-06)
BMW Z4 Coupe/Conv (2006-08)

Parts Required:

Clutch kit, exhaust gaskets

Hot Tip:

Set aside a day and read procedure through before beginning

Performance Gain:

New clutch

Complementary Modification:

Replace driveshaft flex-disc

Clutch components

The traditional automotive clutch is a device that is used in a vehicle drivetrain with manual (standard) transmission. The driver uses the clutch to disengage engine power from the transmission so that a different gear can be engaged without transmission teeth gnashing or damage. Engaging the clutch smoothly then allows engine torque to reach the transmission and the driving wheels, thus driving the vehicle forward or backward.

The clutch resides in a flared housing (the bellhousing) that forms the seam between engine and transmission. The clutch pressure plate is bolted to the engine flywheel. The clutch disc is securely sandwiched between the flywheel and the pressure plate. With the clutch engaged, all three components rotate at engine speed. The transmission's splined input shaft fits in a similarly splined coupling at the center of the clutch disk. With the clutch engaged, the transmission input shaft also rotates at the same speed as the engine.

The clutch pressure plate consists of a set of springs which ordinarily press against the clutch disc and lock it to the flywheel. There are spring release levers attached to a release disc on the pressure plate. Pressing on the release disc lifts spring pressure off the clutch disc so that it can spin freely.

To allow transmission gears to slide so that a different gear ratio can be used, the driver presses on the clutch pedal. Through the use of a cable or hydraulics, clutch pedal movement translates to pressure on the release bearing which presses on the pressure plate release disc. The pressure plate disengages from the clutch disc, allowing the disc and transmission input shaft to spin free of the engine. Once the driver has changed gears, releasing the clutch pedal allows the pressure plate to reengage the clutch disc and once again transmit engine torque to the transmission.

The springs and levers in a traditional clutch pressure plate are generally designed so that the point that the driver feels engagement or disengagement of the clutch is roughly half-way through the movement range of the clutch pedal. However, as the clutch disc, usually made of a fibrous friction material such as asbestos, wears and becomes thinner, the point of clutch engagement moves up (toward the driver) in the range of clutch pedal movement. Eventually, of course, if the clutch disc becomes so thin as to no longer contact the pressure plate, there is no engagement and the clutch slips completely.

Self Adjusting Clutch (SAC) components

In order to keep the feel of clutch engagement relatively constant through the life of the clutch disc, BMW designed the self-adjusting clutch (SAC), installed in most of their vehicles since about 2000. The SAC uses a specially designed pressure plate with a set of self-adjusting shims. As the clutch disc wears out, the shims compensate by moving the fulcrum point of the pressure plate spring release levers. The feel of the clutch pedal is, in theory, kept constant in this way.

Here are relevant recommendations to keep in mind:

The feel of the SAC does not change appreciably, but the clutch does wear out. A worn or slipping clutch manifests itself by allowing the engine to rev up without the vehicle appearing to pick up speed (feels like an automatic transmission). The easiest way to test it is to place the transmission in a high gear while moving slowly or stopped and attempt to race the engine. If the engine does not stall but instead speeds up, the clutch is slipping.

As with any clutch replacement, SAC replacement procedure requires that the transmission be removed from the vehicle. In addition, special BMW tools are required for removal and installation of the SAC pressure plate.

The SAC is generally mated to a dual-mass flywheel. This type of flywheel cannot be machined. In the typical clutch replacement job, replace flywheel, pressure plate, clutch disc, release bearing and pilot bearing.

Clutch hydraulics

The BMW clutch is activated using hydraulics. The clutch hydraulic components consist of a master cylinder at the clutch pedal and a slave cylinder at the transmission bellhousing. Fluid from the brake fluid reservoir is shared with the clutch system. Depressing the clutch pedal forces fluid in the clutch master cylinder to travel through the fluid line to the clutch slave cylinder. This activates the clutch release lever, forcing the clutch release bearing against the clutch pressure plate to disengage the clutch.

Keep in mind the following:

If brake fluid is lost for any reason and the level in the brake fluid reservoir drops below the level of the clutch master cylinder shunt hose, clutch hydraulic failure may follow.

Clutch hydraulic failure causes a softness in the clutch pedal. The lack of resistance means that the clutch is not becoming fully disengaged when the pedal is depressed to the floor. As a result, gear shifting becomes difficult; the transmission gears clash and grind during shifts. Damage to transmission synchronizers and gears will result.

If experiencing grinding gears and difficult shifting:

Check brake fluid reservoir level. Top off if necessary.

Check clutch fluid lines for leakage. Repair as necessary.

Check clutch master cylinder for leakage. Replace if necessary.

Check clutch slave cylinder for leakage. Replace if necessary.

Bleed clutch system.

Failure Summary

Faulty transmission of power to the wheel is caused by a worn out clutch. If the engine revs up without a corresponding increase in vehicle speed, clutch mechanical components are at fault.

Grinding gears when shifting, or difficult shifting up or down the gears, is caused by a failure in clutch hydraulics.

Clutch Replacing

Have a new clutch kit and new exhaust gaskets and bolts on hand before beginning. Read through procedure to be sure you have all the tools required and the job is not beyond your skill set.

This article will show steps from a Z4M and a Z4 model, noting steps needed for SAC models.

Jack up your vehicle and support using jack stands. See our tech article on jacking up your vehicle.

Disconnect the negative battery cable. See our tech article on battery replacing.

Remove the exhaust system. See our tech article on exhaust system removing.

Remove the driveshaft. See our tech article on driveshaft replacing.

First we have to remove the starter.
Figure 1

First we have to remove the starter. It is located under the intake plenum on the left side of the engine compartment (red arrow). Remove the intake manifold plenum. See our tech article on intake manifold plenum replacing.

Working from above, remove the starter (green arrow) bolts (red arrows).
Figure 2

Working from above, remove the starter (green arrow) bolts (red arrows). The bolt heads are E12 external Torx (inset). This photo shows the bolts, looking down from firewall area (intake manifold plenum removed). If removing the starter from below, you can access the bolts easier by unbolting the transmission mount and lowering the transmission, if needed. Using a 24" extension, universal joint and an E12 socket, reach up from below left side of transmission and remove starter fasteners. Remove starter from engine by rotating counterclockwise and in a downward direction.

Removing from above, use a ratchet and an E12 socket (red arrow) to loosen bolt bolts.
Figure 3

Removing from above, use a ratchet and an E12 socket (red arrow) to loosen bolt bolts.

Then remove using a smaller ratchet (red arrow).
Figure 4

Then remove using a smaller ratchet (red arrow).

Slide the starter out of the bell housing toward the radiator (red arrow).
Figure 5

Slide the starter out of the bell housing toward the radiator (red arrow). Leave the cables attached, just move it enough to free it up.

Disconnect the reverse light switch.
Figure 6

Disconnect the reverse light switch. It is located on the right side of the transmission. Press electrical connector wire retainer and pull connector straight off switch (blue arrow). Once disconnected, unclip harness (red arrows) from mounting clip toward top of transmission.

Working in the transmission tunnel, remove the shift rod clip (inset).
Figure 7

Working in the transmission tunnel, remove the shift rod clip (inset). You can unlock using your fingers and slide clip off (red arrow).

Remove the shift rod linkage from the shifter.
Figure 8

Remove the shift rod linkage from the shifter.

Working at the transmission, remove the mounting clips for the shift support (red arrows).
Figure 9

Working at the transmission, remove the mounting clips for the shift support (red arrows). Flip the clips up, then slide out toward the sides of the vehicle (purple arrow). Store the clips in a safe place, replace if detent tabs are damaged.

Working at the right side of the transmission, remove the two 13mm slave cylinder fasteners (red arrows).
Figure 10

Working at the right side of the transmission, remove the two 13mm slave cylinder fasteners (red arrows). Then pull the slave cylinder out of the transmission. Tie it aside and out of the way. Remember, do not press the clutch pedal with the slave cylinder removed, it will be damaged.

Working at the left side of the transmission, remove E10 (blue arrows) and E14 fasteners (red arrows).
Figure 11

Working at the left side of the transmission, remove E10 (blue arrows) and E14 fasteners (red arrows).

Working at bottom of transmission, remove two E10 fasteners (red arrows).
Figure 12

Working at bottom of transmission, remove two E10 fasteners (red arrows). Then remove the E14 fastener (blue arrow).

Support the transmission with a jack (red arrow) and a solid hardwood block.
Figure 13

Support the transmission with a jack (red arrow) and a solid hardwood block. Attach the jack to the transmission using a chain or strong strap.

Then remove four 13mm transmission mount fasteners (red arrows).
Figure 14

Then remove four 13mm transmission mount fasteners (red arrows). Most times I leave the driveshaft attached to the rear differential (blue arrow). If you do this, be sure to tie the driveshaft up at this point, it will fall once the mount is loosened. Lower the transmission jack enough to access the top bolts on the transmission.

Working at the top of the transmission, remove the two E12 Torx bolts (red arrows).
Figure 15

Working at the top of the transmission, remove the two E12 Torx bolts (red arrows). These are the final fasteners and the transmission should be free now, be prepared to support it.

Once all the transmission bell housing bolts are removed, separate the transmission from the engine by wiggling it back and forth.
Figure 16

Once all the transmission bell housing bolts are removed, separate the transmission from the engine by wiggling it back and forth. Then lower the jack and remove the transmission from the vehicle (blue arrow). To remove the clutch, remove six 6mm Allen bolts from pressure plate (red arrows). Loosen bolts in alternating pattern. Support pressure plate so it does not fall when removing. To remove the flywheel, remove six bolts from the flywheel. Loosen bolts in alternating pattern. Support flywheel so it does not fall when removing. If surface of flywheel is in good shape, you can leave it installed. Dual-mass flywheels cannot be machined, so if the surface is in bad shape, you have to replace it.

To replace the pilot bearing, remove the bearing using a small slide hammer.
Figure 17

To replace the pilot bearing, remove the bearing using a small slide hammer. Note the depth of the bearing before removing. Then install the bearing using a bearing driver.

Now it's time to install the new clutch kit.
Figure 18

Now it's time to install the new clutch kit. You will need a clutch disc alignment tool. Your clutch kit should come with one. The green arrow points to the tool that came with my clutch kit. The yellow arrow points to the BMW tool equivalent. Each one does the same job. I will be using the BMW tool in this procedure.

Install and center clutch disc using alignment tool (green arrow).
Figure 19

Install and center clutch disc using alignment tool (green arrow). Then remove center bolt from alignment tool. If you want, you can remove this bolt before aligning clutch disc.

Install pressure plate on alignment dowels, then install six new Allen fasteners (green arrows).
Figure 20

Install pressure plate on alignment dowels, then install six new Allen fasteners (green arrows). Tighten Allen fasteners until pressure plate is flush with flywheel.

Check that the pressure plate is flush with the flywheel.
Figure 21

Check that the pressure plate is flush with the flywheel. Then remove the SAC lock. Mine came out by rotating counter clockwise using a 14mm Allen. Once this lock is removed, the self-adjusting clutch (SAC) will move if not against clutch disc. If it does move and ratchet, you will need additional special tools to reset the SAC feature of the pressure plate. This step applies to SAC equipped vehicle only.

Then tighten six new Allen fasteners.
Figure 22

Then tighten six new Allen fasteners. Check the torque specification for your vehicle to confirm. Once torqued, remove the clutch disc alignment tool from the clutch disc. Now you can service the items on the transmission bell housing.

Remove the throwout bearing by sliding it off the transmission output shaft.
Figure 23

Remove the throwout bearing by sliding it off the transmission output shaft. Note orientation when removing.

Then remove the clutch fork (yellow arrow) by releasing the spring retaining clip (green arrow).
Figure 24

Then remove the clutch fork (yellow arrow) by releasing the spring retaining clip (green arrow). Then remove clutch fork from bell housing.

To replace the throwout guide bushing, remove four 10mm fasteners, then remove guide bushing from transmission.
Figure 25

To replace the throwout guide bushing, remove four 10mm fasteners, then remove guide bushing from transmission. Install new guide bushing, then install and tighten the fasteners. Install the new clutch fork if you are replacing it, or reinstall the old one. Then slide the new throwout bearing over the guide bushing and align it with the clutch fork. Now it is time to reinstall the transmission. Apply spine grease to the spines on the transmission output shaft. Your clutch kit should come with the correct grease. Jack transmission into place, then line up properly and slide transmission shaft into clutch. You will have to wiggle the transmission to engage the shaft. Once engaged, slide the transmission forward until the bell housing is flush with the engine. Install the bell housing fasteners and tighten. Be sure to replace all the aluminum bolts. Once transmission bolts are tightened. Install transmission mount and secure transmission in place. Now install remaining items, reverse the removal procedure when installing. Be sure to tighten all fasteners correctly and properly route all wiring harnesses.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Privacy Statement]
 [Contact Us] [About Us] [Shipping] [Map to our Location] [Careers]

Copyright © Pelican Parts Inc.

Page last updated: Sat 12/3/2016 03:08:39 AM