Thanks to all the previous posters on this forum and others that explained the benefits of removing the flow-limiting diaphragm from the OEM bleeder block. And explained how to do it. Big, big thanks!!
Following is a quick explanation of why and how I modified my OEM bleeder, and the difference felt in driving afterwards:
Driving the Gti at first left me wondering: I often fumbled shifts, regardless of whether I was on it or not. Shifting casually, I couldn't avoid an occasional jerking of the drivetrain, as though I had misstimed clutch release... Though I am no pro, I have 30 years' experience with manual gearboxes. My other cars include a synchro-less 1967 SIIA Land-Rover which requires double-clutching & rev-matching, a 1971 Citroën SM with a peculiar gearbox/clutch... I know how to use a gearbox. Yet this Gti threw me curve-balls I couldn't manage!
Very fast shifts brought out another strange behaviour: when very quickly shifting and releasing the clutch, the pedal would stay down for a split second then pop up. Not good.
Thanks to other posters, I learned that VAG designed & implemented a flow-restricting diaphragm in the hydraulic line between the master cylinder (clutch pedal) and the slave cylinder (transmission). Its purpose is to delay the action of the clutch with respect to the position of the clutch pedal.
Removing it means that the clutch engages & disengages in direct relation to the pedal position. Without the diaphragm, poor pedal use is no longer hidden by the delay in hydraulic fluid flow. And without it, the above strange behaviors completely disappear: no more strange clutch actuation. No more clutch popping in very fast shifts. Wonderful, and I wish I had done it sooner.
Two ways to do it: buy and install the ECS bleeder valve or remove the diaphragm from the OEM piece. The ECS valve is reported to flow more than the modded OEM piece and also incorporates a one-way bleeder valve. I'll pick one up next time I order stuff from the US!
I simply modded my OEM piece, and here's how:
- remove airbox and you'll see the bleeder block: it's the black plastic piece that has a rubber hydraulic line going into it, and it's attached to the transmission just ahead of the gear selector shaft,
- using a thin screwdriver, lift up the two clips (they don't need to come all the way off,
- the block can be removed from the transmission, and the line can be pulled from the block (brake fluid will escape from both ends so prepare with lots of rags/paper towels),
- looking inside, you will see the yellow diaphragm:
- it's blocked on one side by a ridge and on the other by the base of the bleeder valve which protrudes into the block. A 9mm wrench will let you unscrew the valve, and a narrow screwdriver will let you simply push the diaphragm out:
Installation is straightforward, but air that got into the line now has to be bled out. To do so, a helper makes things easier. If you are alone here's how I did mine: cut down an old broom stick the correct length to keep the pedal all the way down. Push & pump pedal by hand a few times, wedge stick between pedal and seat base hardpoint. Open brake fluid réservoir cap. Go to bleeder block with lots of rags, remove nipple from bleeder valve, open valve slowly, hear & see bubbles coming out, close valve. Release pedal. Top up brake fluid réservoir *don't let it go below minimum level*. Repeat a few times. Five rounds did it for me.
And voilà!! The clutch now just follows your left foot. Swapping gears is now devoid of strange, obtrusive behavior, and fast gearchanges are hangup-free!!
An absolute must imho!!!
Hope this helps,
Ben.
Following is a quick explanation of why and how I modified my OEM bleeder, and the difference felt in driving afterwards:
Driving the Gti at first left me wondering: I often fumbled shifts, regardless of whether I was on it or not. Shifting casually, I couldn't avoid an occasional jerking of the drivetrain, as though I had misstimed clutch release... Though I am no pro, I have 30 years' experience with manual gearboxes. My other cars include a synchro-less 1967 SIIA Land-Rover which requires double-clutching & rev-matching, a 1971 Citroën SM with a peculiar gearbox/clutch... I know how to use a gearbox. Yet this Gti threw me curve-balls I couldn't manage!
Very fast shifts brought out another strange behaviour: when very quickly shifting and releasing the clutch, the pedal would stay down for a split second then pop up. Not good.
Thanks to other posters, I learned that VAG designed & implemented a flow-restricting diaphragm in the hydraulic line between the master cylinder (clutch pedal) and the slave cylinder (transmission). Its purpose is to delay the action of the clutch with respect to the position of the clutch pedal.
Removing it means that the clutch engages & disengages in direct relation to the pedal position. Without the diaphragm, poor pedal use is no longer hidden by the delay in hydraulic fluid flow. And without it, the above strange behaviors completely disappear: no more strange clutch actuation. No more clutch popping in very fast shifts. Wonderful, and I wish I had done it sooner.
Two ways to do it: buy and install the ECS bleeder valve or remove the diaphragm from the OEM piece. The ECS valve is reported to flow more than the modded OEM piece and also incorporates a one-way bleeder valve. I'll pick one up next time I order stuff from the US!
I simply modded my OEM piece, and here's how:
- remove airbox and you'll see the bleeder block: it's the black plastic piece that has a rubber hydraulic line going into it, and it's attached to the transmission just ahead of the gear selector shaft,
- using a thin screwdriver, lift up the two clips (they don't need to come all the way off,
- the block can be removed from the transmission, and the line can be pulled from the block (brake fluid will escape from both ends so prepare with lots of rags/paper towels),
- looking inside, you will see the yellow diaphragm:
- it's blocked on one side by a ridge and on the other by the base of the bleeder valve which protrudes into the block. A 9mm wrench will let you unscrew the valve, and a narrow screwdriver will let you simply push the diaphragm out:
Installation is straightforward, but air that got into the line now has to be bled out. To do so, a helper makes things easier. If you are alone here's how I did mine: cut down an old broom stick the correct length to keep the pedal all the way down. Push & pump pedal by hand a few times, wedge stick between pedal and seat base hardpoint. Open brake fluid réservoir cap. Go to bleeder block with lots of rags, remove nipple from bleeder valve, open valve slowly, hear & see bubbles coming out, close valve. Release pedal. Top up brake fluid réservoir *don't let it go below minimum level*. Repeat a few times. Five rounds did it for me.
And voilà!! The clutch now just follows your left foot. Swapping gears is now devoid of strange, obtrusive behavior, and fast gearchanges are hangup-free!!
An absolute must imho!!!
Hope this helps,
Ben.
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