Under normal driving my clutch feels soft but works fine. Under wide open throttle there are many times I can?t get the car to shift at any given gear until the RPMs come down. I have already done the drill mod (or not). What could it be?
The answer to this problem is simple. However, the reason the problem exists is not so simple. This symptom almost always points to air in your hydraulic lines. The reason this causes problems is because, unlike the clutch fluid that is meant to occupy that space and is very incompressible, the air that now resides in the line can be easily compressed. This creates that "squishy" feeling you get in the clutch pedal. Also (and more importantly) the fact that the air compresses means that the fluid is not pushing the pressure plate to its full disengaged state. Under wide open throttle, where the clutch requires even more pressure to fully disengage the pressure plate, the compression of said air is often severe enough to not allow the pressure plate to disengage at all, making it nearly impossible to get into the next gear up. The fix is to bleed down your clutch hydraulics very carefully until all the air bubbles have been removed. There is a write up on how to bleed your clutch hydraulics on www.installuniversity.com
, or you can go to any shop and have it done for a very nominal fee.
Now the bad news: If you never have this problem again (lets say after 3 months), then you are fine and the air probably got there when you performed the drill mod. However, if you have either not done the drill mod, or the symptom returns, then you have a bigger problem. There is most likely a leak in your hydraulic system.
The first culprit to look at is your master / slave line. Inspect it for kinks or pin holes. Next is your slave cylinder. If you have gone through the trouble to remove it go ahead and replace it.