clutch pedal returns 3/4 of the way

[jkb157]

The clutch pedal on my 99 996 intermittantly returns 3/4 of the way after being fully depressed.Sometimes I need to use my foot to bring it all the way up and other times it comes back up on its' own. This only occurs when the car is being driven. When the pedal is fully depresssed gear changes can be done without issue.The onset of this problem started after a hard stop requiring hard braking and clutch fully depressed. Any thoughts?

[JFP in PA]

Could be a couple of things; when was the last time the clutch was flushed and bled? How many miles on the clutch (lowering and/or stiffening pedal are common observations on an old clutch on its way out)? There is a "boost spring" assembly attached to the pedal under the dash; it may of come loose or is failing.

[987_RDC]

I thought the boost spring had to do with assiting pressing the clutch down? I had this symtom and did a bleeding of the clutch slave to resolve.

Brief How-to: Hold clutch down w/ broom handle and using power seat. Use Motive bleeder on brake fluid reservoir to pressurize. Loosen bleed valve on top of transmission for slave cylinder to bleed old fluid and then close. Manually lift clutch pedal slowly. Top up brake fluid with proper DOT4.

Edited March 20, 2013 by 987_RDC

[JFP in PA]

It does make the clutch pedal feel softer to depress, however the way the boost spring mounts ahead of the pedal (towards the driver) and above the pedal pivot point, if it comes loose from the pedal assembly, or breaks internally, you can get both a stiffer pedal and sometimes one that stays a bit lower to the floor. It should be easy enough to confirm it is connected and working, but you need to look up under the dash to see it:

I fully agree that the clutch hydraulics should be suspect, which is why I inquired when they were last serviced.

[Fatbloater]

I had the same problem, it was the boost spring that had snapped and the pieces had become entangled preventing the unit from fully disengaging the clutch somehow.

I have replaced the spring within the clutch assist unit to resolve the issue. To do this I measured the spring gauge and visited a spring manufacturer who fabricated an identical spring which was a straight swap.

Quite a simple fix and only cost me £40 for 10 springs. Cheaper than a new clutch boost module and I've sold most of the spares onto others with the same issue.

This also fixes heavy clutch issues and crunching / clicking clutch. Essentially the majority of issues you see with having a busted clutch boost spring.