Toyota Hydraulic Clutch Assembly Maintenance
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By: Mike Nevitt - April 2004
Is your clutch moaning, clicking or otherwise sounding unhealthy when you depress the pedal? If you have ruled out the clutch assembly itself, you likely need to replace the clutch master cylinder and / or the clutch slave cylinder. For a small investment in a remanufactured unit, new replacement unit or a rebuild kit, well show you how easy it is to swap out the offending hydraulic assembly for better actuation of your clutch and assure longer life of the disk assembly.
First the proper tools:
This job should take approximately one to one and a half hours.
Remove the lower portion of the dash (four 10MM bolts on a third generation 4Runner) and the associated wiring plugs, cables, etc. Take care to list or photograph the assemblies in the assembled condition if you feel that you cant keep track of what goes where. Removing the panel is necessary unless you have the hands of a three year old and the arms of Manute Bol.
Remove the cotter pin holding the cross pin through the clutch pedal and push the cross pin through the pedal assembly. You may need to depress the pedal slightly to release the tension off of the cross pin. Retain the cotter pin and the cross pin, these will be re-used in the replacement process.
Under the hood, remove the necessary items to gain access to the clutch master cylinder. When removing vacuum hoses, again be careful to label or photograph the location of each hose removed to avoid confusion during re-assembly. Once you have gained access to the master cylinder, start by removing the hydraulic line fitting (flare nut) with the 10MM flare nut wrench. Save yourself a great deal of time, effort and possible additional expense, use a flare nut wrench ONLY on hydraulic fittings. With a drain pan under the assembly, loosen the fitting until you can remove the flare nut and gently pull the tube from the master cylinder. Now, using the 12MM deep wall socket and the necessary extensions, remove the nuts holding the master cylinder to the firewall. Use caution removing the nuts when at the end of the mounting stud so as not to drop the nuts into the recesses of the frame / body.
When replacing the master cylinder with a new unit, align the two on a bench and roughly adjust the free play length to approximately equal length. This will make the final adjustment easier.
Replace the old master cylinder with the new or newly overhauled master cylinder in reverse order of the disassembly with the exception of the cotter pin that retains the cross pin. Torque values are unnecessary in this assembly, the common rule of tighten until snug and one sixteenth / eighth turn applies well here, however, the proper torque values are:
|Lower Dash Assembly removed for access||View of Engine compartment access required||Cotter Pin and Cross Pin from Clutch Pedal Assembly|
The area in which the slave cylinder is placed is very close fit, but common hand tools will work. A special tool (a crows foot flare nut adapter) is recommended by the service manual, but I have found that a regular combo flare nut wrench will work in the area affected.
Placing the drain pan under the assembly, remove the flare nut fitting using the flare nut wrench. Some contortionist moves are required here, but 40 year old fat hands can get to it. Allow the fluid to drain in the pan. Using a 12MM socket and different extensions, remove the two retaining bolts from the transmission housing. The slave cylinder simply pulls away from the housing.
Replace the old slave cylinder with the new or newly overhauled slave cylinder in reverse order of the disassembly.
|Slave Cylinder view - Tight, Tight, Tight!|
As in the case of the master cylinder, torque values are not necessary but the specification is as follows:
|Bleeding the System|
Fill the master cylinder reservoir to the limit indicator with SAE J1703 or FMVSS No. 116 DOT 3 Fluid. Connect the flush (hose) line of the one-Man bleeder system to the bleeder screw on the slave cylinder. Loosen the bleeder screw to a slightly open position.
Depress the clutch pedal. The pedal assembly will likely sink to the floor; this is the start of the bleeding process. Continue to cycle the pedal (approx. 10 stokes) and check for resistance in the pedal feel and fluid level in the master cylinder. Do not let the master cylinder cycle without fluid. When the pedal returns to its normal position and the fluid level in the master cylinder is normal, turn the bleeder screw on the slave cylinder to the wide open position and allow the system to gravity bleed (assuring fluid is free of air bubbles.) Tighten bleeder screw when fluid is clear of air, fill the master cylinder to the mid-point (nominal) level as indicated by the min. / max. lines on the reservoir then replace the float and cap.
|Adjusting Pedal Free Play|
Using hand pressure, push the clutch pedal assembly in (actuation) and note the amount of movement until you feel resistance. This is Pedal Free Play.
Using a tape measure or a combination square, find a spot on the floor or firewall that you can locate repetitively with the end of the rule. Measure the free play from the floor to the top of the clutch pedal. The specification is .197 to .591 inches (roughly 1/4 to 1/2 inch). If the assembly is within the range, replace the cotter pin through the cross pin and proceed to the Final Assembly / Test.
If the free play is not to specification, you will need to adjust the pushrod on the master cylinder. Loosen the nut on the adjustment screw (located on the master cylinder pushrod) slightly. Remove the cross pin from the clutch pedal and rotate the pushrod to the approximate length needed to meet the free play measurement. Re-install the cross pin and measure the free play. Adjust until specified measurement is met then install the cotter pin to the cross pin and tighten the retaining nut on the pushrod.
|Final Assembly / Test|
Move the clutch pedal through its range several times while checking the hydraulic line fittings for leakage, tighten as necessary to seal any leaks.
Re-assemble the lower dash panel, check all electrical / mechanical connections prior to bolting the dash panel in place.
Assuring that the truck is in an area that is free of any buildings, danger of a collision, etc. put the transmission out of gear, depress the clutch and start the engine. Release the clutch while the transmission is out of gear to assure proper engagement / disengagement. Depress the clutch again and shift the transmission in gear and release the clutch. Move at idle speed to assure that the clutch is fully engaged. Drive around the block using all the forward gears while noting the engagement of the shifting. Stop and engage reverse. When assured that all is well, park and inspect the system one more time for leaks and proper fluid level.
If the clutch does not engage normally throughout its operation, the free pedal adjustment is not correct, the system has not been bled properly (i.e. air remains in the hydraulic system), the components were not installed properly or the wrong components were installed. Go through each step of the installation, checking and adjusting as necessary until the clutch engages smoothly.
Once everything is completed satisfactorily, park your truck in its proper spot and open can of favorite beverage, you are finished and have successfully repaired the hydraulic clutch system on your Toyota!