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Old 02-07-2020, 01:31 PM   #1
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Location: NY Suburbs
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Clutch Pedal Doesn't Return Smoothly and Completely

The Clutch Pedal Doesn't Return Smoothly and Completely. It gets to about two inches from the top, gets a little stuck and then pops free and comes up all the way.

The clutch itself is performing properly, no slippage at all.

Anyone have an idea what this might be? (Please don't tell me I need a new clutch)

2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
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Old 02-07-2020, 03:31 PM   #2
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It could be you clutch assist spring that's broken and gets jammed inside the housing. If you lie down with you head on the floor and look up at the clutch pedal you will see it close to the pivot point. Its a small cylinder. Try pushing the clutch down with your hand and release it while holding a finger on the spring casing with the other. If you feel it click then you have found the culprit!
2004 Boxster S Silver - FUNTOY
2002 Boxster Base Guardsy Red - FUNBOX
1987 Caterham Super 7 1700 Supersprint
2009 Mercedes Benz CLK 350 convertible
1941 Dodge Luxury Liner Coupe
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Old 02-07-2020, 03:34 PM   #3
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The problem is not in the clutch, the slave or master cylinder, or in the pedal bushings. The problem is in the 'clutch assist spring' device.
This little device consists of a fairly stiff spring about 3 inches long and 1 inch in diameter, which is compressed into a plastic tube with a smaller central tube running along its axis. One end of the spring acts against the plastic to apply force against a metal plunger, which appears vaguely (only vaguely!) like an engine's intake or exhaust valve. This plunger is connected by a beefy clevis pin to the clutch pedal. The plastic tube has two short trunnions on its side, much as the trunnions on the barrels of 18th Century artillery cannon.
The spring is held by a metal bracket whose geometry is cleverly contrived. When the clutch pedal begins its downward movement, the assist spring is compressed, thus increasing the force the driver must apply to the pedal. As the pedal moves further downward, the spring device, pivoting on its side trunnions, 'goes over center' so that as the clutch pedal continues down the spring is now extending, adding force to the pedal and relieving the load the driver must apply. It gives the effect of making the clutch pedal feel lighter and smoother.
The central part of the tube wears, as does the metal pin sliding back and forth, poorly lubricated, within. With age, it begins to stick when it extended most, at the top of the clutch pedal travel.
The solution: Lubricate, or replace, the assist spring device.
I have disassembled, greased, and reinstalled several of these springs. They then work great, smooth as glass, for a few days, then they're right back like they were as soon as the grease has been scraped away. I'd suggest replacing it with a new one.
To do so is simple but somewhat challenging; the device is underneath the dash, above the pedals, and is accessed from below. It is virtually impossible to do without removing the driver's seat.
To remove the seat you'll need a 3/8" drive ratchet, 3-4" extension, an E-40 external -Torx socket, a t-20 Torx screwdriver, a 10mm wrench, a 2" 3/32" cotter pin or nail, and a piece of carpet, cardboard, or foam rubber to lie upon.
First, record the radio security code.
Next, before disconnecting the car's battery (10mm wrench), run the seat forward to expose the rear bolts for removal, then run the seat rearward to expose the front bolts for removal (Torx E-40 heads). Then return the seat to mid-position; it's easier to lift out of the car that way.
Next, lower the top; it's easier to pick up the seat with the top down.
Next, disconnect the battery by removing the negative ('ground' ) lead from the negative terminal.
Tilt the seat back to allow access to the seat's wiring harness; you may have to remove the seat controller from the seat frame (T-20 driver) to disconnect the multipin connectors. When the harnesses are clear of the seat, the seat can be lifted out of the car (~75+ pounds) and set it aside.
Place cardboard or a piece of carpet over the immobilizer box so you can lie down on your back to work underneath the dash.
There is a plastic duct from the heater box to the lateral dash vent; compress it lengthwise to bring its ends off the ducts, and remove it.
The brake light switch impedes access to the clutch assist spring. Twist the switch to free it from the bracket, and move it aside. It is unnecessary to disconnect the wiring.
Now the fun begins.
With the clutch pedal UP, the end of the plunger can be seen to protrude from the closed back end of the plastic tube. Insert the cotter pin, nail, drill bit, etc through the hole in the pin, to retain it when the device is removed.
Next, remove the retaining clip from the clevis pin that secures the plunger to the clutch pedal.
Next, push the clutch pedal down. This action removes the load from the clevis pin so it can be pushed through and removed, disconnecting the clutch assist spring plunger from the clutch pedal. The devise can now be moved forward to disengage its trunnions from the bracket so it can be turned 90 degrees and dropped free.
The car can be driven just fine with the assist spring not installed at all, but I think you will quickly realize what a heavy clutch pressure plate clamping pressure Porsche engineers into these little buggies, and you'll decide you like it better with it in place.
To install the new part, lift it in place inside the bracket, then rotate it so the trunnions engage the felt-covered tracks. Position the clutch pedal so the holes in the pedal line up with the hole in the plunger, and insert the clevis pin and replace its retaining clip. Allow the clutch pedal to return to its upper 'home' position, and remove the cotter pin from the end of the plunger now protruding from the back end of the cup.
Remember to replace the brake light switch and the a/c duct on the way out.
Lift the seat back in to the car, reconnect its electrical, and only after the electricals are connected then reconnect the battery ground lead. The seats can now be moved under their own power to expose the bolt hole in the seat tracks. I suggest fitting all 4 bolt loosely and jiggling the seat before tightening the bolts, so the seat tracks are aligned and the seat can move freely.
Remember to recode your radio, and rezero the window 'up' positions.

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Old 02-07-2020, 04:36 PM   #4
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Location: NY Suburbs
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Thanks Anker and 911.

I'm too old to be laying down doing that job. The local Porsche indy shop will get this one.
2004 Boxster S, 6 spd, Triple Black
1986 944 Turbo (sold in 1988)
Since then, a 300ZX, a few BMW 3 Series, a few VW's
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Old 02-08-2020, 12:08 PM   #5
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OOPS! My bad, E-12 socket, not E-40. Brain backfire...

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