Didn't get any response in the Drivetrain section.. Soo i'll try here..

Ok, this is on my friends 99. Here is his problem. After acouple quarter mile pass's when shifting out to 3rd into 4th the clutch pedal goes soft. There's less then half pedal left.. Then once you pump it acouple times full pedal comes back..
Soo i figured there was air in the line. So i bleed it for about 30 mins just to make sure i got all the air. Pedal felt good. But again after couple WOT runs it did it again..

You guys have any ideas?? I'm drawing a blank.. The hydro'a are fairly new. I put them in with his new LS7 clutch. There's only 30k on them now and i did put the updated 01-02 hydros in..
Could the master or slave gone south already?? I sure it could happen, just hoping thats not the case..

 

If you have to pump the pedal, I'd say a master problem..

The mods are gonna get on you for posting the same Q in two rooms, tho. Try a different title next time, that seems to help... Or BUMP it back up.

 

Yeah...do a little search on Yahoo for the "LS1 drill mod" that's done on the master cylinder. There might be something over at www.installuniversity.com in one of the clutch install documents.

 

Yeah the drill mod should make it better. And it's not done to the master. It's done to the hydraulic hose.

 

I already did this when i put them in with his new clutch..

I'm thinkin its the master as well.. Anyone else have an opinion?

 

Your right, i'll delete the one in Drivetrain..

 

Does the car have headers?? If so is the clutch line close to a header tube? If so the fluid could be overheating and boiling. It would probably do the same thing sitting in extended traffic.

Re'

 

Umm didn't even thing about that.. Yes the car does have headers.. I'll look and see if the lines close, and I'll try moving the line and wraping it with some type of heat shield..

 

Huh, mine's doing the exact same thing . It was like that last summer after I did the M6 swap, but I figured I just didn't bleed the clutch properly (since it was my first experience dealing with the T56, clutch, etc.). Well, I just finished getting the tranny re-installed this past weekend (it had to come out to replace 2nd gear synchro) and when I hooked up the clutch, I opened the bleeder to let it do a "gravity bleed" for a good few minutes (yes, I kept the reservoir topped up ) but now it almost seems like it's even worse than before?!

However, I have also installed headers this winter! So maybe that's a contributing factor?? But I have the braided line tucked in behind the heat shield that's right there ... I don't know what more is necessary? (or is there really just a problem with the master cylinder itself, and it has nothing to do with the extra heat? )

... it's not very confidence inspiring having the clutch pedal almost on the floor!?!!