DIY Network

Clutch Replacement: Inspection and Diagnosis From "Weekend Mechanic" episode WKM-306

	Bruce Bonebrake does a full clutch replacement on this Ford F-250 pickup.
	Figure A

In this episode, Weekend Mechanic host Bruce Bonebrake does a full clutch replacement on a Ford F-250 pickup. The procedure involves removal of the truck's transmission to access the clutch, removal and replacement of the clutch and related parts and, after the installation is complete, bleeding the air from the clutch hydraulics.

Materials:

In addition to standard auto-mechanic's tools (wrenches, ratchets, extenders, screwdrivers, nut-drivers, etc.), some of the specialty tools (figure A) that will be needed for this project include a transmission jack, torque wrench, clutch-alignment tool, vehicle jack, jack-stands and hydraulic bleed tool. An air-compressor and set of pneumatic tools will be very helpful for this project.

DIY Difficulty Rating for Repair: This job is a fairly advanced job and does require some special tools. We gave it a difficulty rating of 4 on a 5-point intermediate-level scale. It took us about 8 hours to finish this job. Depending on the nature of the problem, your work time could vary. If you decide to undertake a clutch replacement yourself, allow yourself the full weekend to complete this project properly.

Safety Alert: Always wear eye protection, and follow proper safety precautions, when working with power tools or when working beneath a vehicle.

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The problem: Our project vehicle, a Ford F-250, won't go into gear properly. The clutch pedal can be depressed all the way to the floor with no resistance (figure B). The clutch master-cylinder is empty of fluid, and the clutch slave-cylinder is badly damaged. In fact, after pressing the clutch pedal and hearing a loud "pop," the owner of the vehicle found a piece of the slave-cylinder (figure C) laying beneath the truck in his driveway. (The slave-cylinder is the part that disengages the clutch so that the gears can be shifted.) In short, this truck needs a clutch overhaul in the worst way.

Figure B

Figure C

Clutch Inspection and Diagnosis

With the truck safely on a jack and supported by jack-stands, we conducted an inspection to pinpoint some of the problems. Other problems and degree of clutch wear would only become evident once the transmission was removed and the old clutch was disassembled.

• Behind the brake master-cylinder (figure D) is the separate clutch master-cylinder (figure E). Both the brake and clutch systems are hydraulic systems and use DOT-3 or DOT-4 brake fluid.

• The clutch master-cylinder connects to the clutch pedal. When the pedal is depressed, fluid and pressure is transferred to the clutch slave-cylinder which functions to disengage the clutch to allow gear-shifting. Our master-cylinder was empty of brake fluid, so it was clearly non-functional.

  Figure D

  Figure E

  
  

• Checking from underneath the vehicle, we were able to inspect the slave cylinder and discover that, not only had it broken loose from its mount and was hanging loose (figure F), but it was actually coming apart (figure G). Clearly the slave-cylinder was in need of replacement, but the fact that it had broken free might be an indicator of further problems with the clutch assembly.

  Figure F

  Figure G

  
  

  	Figure H
  	Figure I
  	Figure J

• The next step is to remove the clutch-inspection plate to get a closer look at the clutch assembly. The plate is directly beneath the fly-wheel and is held on by two bolts. Loosen and remove the bolts, and carefully lower the plate out of the way (figure H).

• With the plate removed, the edges of the fly-wheel and clutch-disc are visible (figure I). From this inspection angle, it can be seen that the clutch is worn thin and in need of replacement.

• The clutch fork is evidently either disconnected from the clutch throw-out bearing or is badly damaged (figure J). During operation, the clutch fork presses against the slave cylinder. The damage in this area may explain why the cylinder part dropped off the vehicle.

Important: Included in this segment are the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of repair-kit you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and precautions that come with your kit or replacement parts.

Safety Alert: As a standard safety precaution, always disconnect the vehicle's negative battery cable before you begin work on any electrical or mechanical components.

RESOURCES :

The Complete Idiot's Guide to Trouble-Free Car Care
Author: Dan Ramsey
ISBN: 0028635833
Alpha Books

Auto Repair for Dummies
Author: Deanna Sclar
ISBN: 0764550896

Wings West Corp.
Known as "America's largest aftermarket automotive aerodynamic manufacturer," Wings West makes a wide variety of autmotive body-modification kits and products.
Website: www.wingswest.com