Clutch Delay Valve Removal

This modification is intended to improve the predictability and smoothness of the clutch engagement on the 2003 Hyundai Tiburon.  If you want to skip my writeup and go straight to the modification instructions, just follow the link at the bottom of this page.

If you're a seasoned driver of manual transmissions, you may be finding it difficult to shift smoothly in the 2003 Tiburon.  The reason is very likely Hyundai's use of a delay valve in the clutch slave cylinder.  This delay valve causes the clutch to engage the flywheel at a constant rate regardless of how fast the clutch pedal is released.  Most agree this valve is to prevent inexperienced drivers from rev'ing the engine too high and "dumping" the clutch, resulting in catastrophic damage to the clutch's friction lining.  Instead, the clutch will engage more slowly and slip a little.  However, it also has a tendency to produce an unpredictable clutch engagement point which makes it harder for the driver to coordinate the gas pedal, causing the car to buck or jerk as it fully engages (while simultaneously infuriating the driver).  Logically, I believe it also causes more wear on the clutch lining for more relaxed day-to-day driving since the slowed engagement allows it to slip a little at every shift.  But depending on your driving habits, that may not always be the case.

The problem is most pronounced in the 1st to 2nd shift.  If your passenger's head bobs wildly back and forth when you make this shift, you should definitely perform this simple modification.  Under hard acceleration, it is also very noticeable.  Everything is happening quickly, but you notice the car doesn't begin "pulling" until a fraction of a second after letting out the clutch pedal.  Or if you quickly slam the gas to the floor, the car will jerk due to the load when the clutch finally grabs.

This effect is not to be confused with judder, which some people have reported having with their manual transmission Tiburons.  Judder is generally described as the car shaking when pulling away in first gear and/or having to rev the engine to 1500-2000rpm to get a smooth takeoff.  This modification will not help with judder, though I should point out I've never noticed much of a judder with my car to begin with.

The Tiburon's clutch mechanism is hydraulic as opposed to most "older" vehicles which use a cable-operated mechanism to engage & disengage the clutch.  If you learned how to drive a stick on one of these older clutches, as I imagine most of us did, you'll probably find the Tiburon's clutch frustrating to master.  I did.  I drove it for a year like this before one of the guys* on the NewTiburon forum suggested this delay valve might be the reason.  After removing the delay valve, I'm pleased to say the Tiburon is joy to drive.  Now it behaves like it should (my opinion, of course).  The numb, sloppy feel is gone.  It's now intuitive to match the gas to the tactile feedback from the pedal and the sound of the engine.

The culprit is a little spring-loaded valve that sits just inside the clutch slave cylinder.  It has a small hole in the middle that slows fluid flow in one direction, thus slowing how the clutch engages.  Remove it and the clutch becomes more responsive, almost like a cable-operated one.

Is there a downside to this modification?  No, unless you treat your car foolishly.  Remember why Hyundai installed the delay valve in the first place--to prevent Neanderthal drivers from burning up the clutch.  Drive sensibly and you won't have any problems; just a smoother, more enjoyable ride.

Resources
AdRock2003's DIY article - well-written article that shows you precisely how to do this modification yourself, quickly and easily.  Complete with pictures, details of how to remove the valve, and bleed the hydraulics.
Zeckhausen's BMW writeup - very good description of clutch delay valves on some of BMW's vehicles

* I've searched back for this person to give him credit, but can't find his post.  I'm not positive., but I think it was the person who posted the Zeckhausen link.  It may have been phlash.

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Written by Jason M. Neal
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