Cuidado del automóvil


Clutch Decisions
To replace at home or not to be?
Por Tom MorrFor the average auto owner, farming out major repairs is usually wise. Sure, saving on labor charges can be enticing, but hidden costs often undermine good intentions. (As a worst-case scenario, one emergency-room trip can make any at-home auto repair extremely non-worthwhile.) Besides, most shops offer some kind of warranty on their work, so the car owner has some recourse should the repair fail within a specified length of time. (Parts-failure warranties can be denied if the manufacturer deems that they were improperly installed by a do-it-yourselfer.)
Circumstances sometimes prompt the hardcore do-it-yourselfer to rise to the challenge of a major car repair. A few of the reasons that saner heads don't always prevail include pending divorces, making a lower-value vehicle saleable, and long winters that offer few other "entertainment" options.
Divorce settlements aside, the intent here is to provide an overview of the tools and tricks necessary to replace a clutch in your garage or driveway. Armed with this insight, you can decide whether or not biting off this job will be more than you can chew.
Historia de casos
Our demonstration vehicle here is a 4WD Isuzu Trooper. It offers a variety of variables not found on all vehicles: two shift levers, the added weight and bulk of a transfer case, a front driveshaft, an exhaust crossover pipe, hydraulic clutch-linkage system, undercarriage skidplates, higher-than-average-cost replacement parts and tight access to many bolts (on account of the aforementioned components). The labor quote on a vehicle of this stature can be as much as twice the cost of the parts (which themselves are surprisingly higher than the typical million-selling car). On the plus side, this body-lifted Trooper has oversized tires that create enough clearance under the vehicle to access the necessary parts without having to raise the truck and put it on jackstands. Instead, we simply blocked the tires.
To reiterate, this isn't a step-by-step how-to on clutch replacement. Instead, it's an overview of some of the challenges to expect if you're considering doing this at home. The clutch job shown here took two weekend mechanics armed with air tools between 9:00 a.m.-6:00 p.m., including a lunch break to get the flywheel resurfaced.
The bottom line: What's your time worth and are you willing to redo/troubleshoot your work should something not function afterward? On the other hand (assuming you haven't mangled it replacing your clutch), you stand to save a few hundred buckswhich could go to the future-ex anywayand you might get some sick satisfaction out of rising to the challenge.
Consejos de instalación
> Park the vehicle on a level surface.
> Disconnect the negative battery cable.
> If necessary, raise the vehicle and secure it on jackstands to allow enough room to work.
> Read the clutch kit's instructions and refer to a service manual before beginning.
> A come-along or hand winch can be helpful when rolling the transmission/crossmember away from the engine on a floorjack.
> Accumulate socket extensions of varying lengths as well as socket "wobble" joints.
> Using two floorjacks provides an extra margin of safety.
> Just as brake rotors and drums should be "turned" when replacing pads and shoes, always resurface the flywheel as part of a clutch job. Replace a too-worn flywheel if necessary. Clean any grease off the flywheel before installing the new clutch.
> Once it's removed, inspect the old clutch for signs of other problems. (Oil on the clutch indicates a seal problem on the engine and/or transmission.)
> Indicators of engine/transmission misalignment: uneven wear on the pilot bushing/throwout bearing, clutch surface itself, or clutch disc splines; broken clutch retainer plate or springs; uneven wear on transmission input-shaft bearing.
> Common causes of engine/trans misalignment: broken engine or transmission mounts, warped bellhousing, loose flywheel, damaged bellhousing dowel pins.

Paso 1
Content of replacement clutch kits varies. The weekend mechanic is best served by using a "complete" kit that includes the clutch, pressure plate and bushings/bearings as well as the necessary lubricants and a pilot/alignment tool.
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Paso 2
This is a driveway job, so the shift levers must be removed so that the transmission can be slid rearward to access the clutch. Center consoles might also need to be removed to get to the levers and their protective boots.
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Paso 3
Disconnect all of the transmission's electrical connections.
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Paso 4
Most likely, the starter motor is one of the auxiliary parts that must be removed as part of a clutch job.
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Paso 5
The driveshaft needs to be unbolted from the transmission so that the gearbox can be backed away from the engine's bellhousing. Because this is a 4x4, the front driveshaft must also be unbolted from the transfer case.
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Paso 6
The transmission's weight is supported on a floorjack. Once separated from the engine, the transmission can be rolled rearward on the jack. For this job, we used two jacks: one under the transfer case (shown) and another under the transmission.
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Paso 7
On this Trooper, the exhaust crossover tube must be unbolted before the trans can be backed away from the engine. Use new exhaust gaskets during the reassembly to avoid creating one problem (an exhaust leak) in the process of solving another.
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Paso 8
After removing all trans-to-engine bolts and unfastening the transmission crossmember from the frame, the gearbox can be moved on the floorjack. This clears a path to the pressure plate and clutch.
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Paso 9
Once the clutch assembly is removed, the flywheel should be unbolted and taken to a machine shop for resurfacing. Assemble the new pressure plate and throwout bearing per the instructions, then check operation/lubrication of the clutch linkage.
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Paso 10
Reinstall the resurfaced flywheel, then insert the clutch and pressure plate, using a pilot tool for proper alignment. Next, lubricate the splines on the transmission's input shaft.
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Paso 11
Torque the pressure plate to spec using a criss-cross pattern. (Use of air tools might void the clutch kit's warranty.) Attach the clutch-release fork to the throwout bearing per the service manual's instructions.
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Paso 12
Reverse the disassembly process. Refer to the service manual for clutch-adjustment procedures and all other applicable details.
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