RebekahsZ Posted August 28, 2012 Share Posted August 28, 2012 I'm having a problem that, according to LS1tech, is pretty common: great shifting at "normal" rpms, but inability to shift into 3rd and 4th gear when shifting at 6000rpm when rowing thru the gears for max acceleration. I'm lifting off throttle and using the clutch pedal, so I'm not doing (or expecting) anything insane. I've serviced the hydraulics and added venting to the bellhousing and cleaned the inside of the bellhousing well to include the sleeve of the throwout bearing. I've bled like crazy and have a pretty nice pedal. Now that I have a vent hole in the bellhousing, I can see the flywheel, clutch disc and pressure plate. This is kind of hard to describe and a video may be needed: When observing clutch operation from under the car, with my daughter depressing the clutch, I noticed something interesting about my clutch disc. Now, I've never held a clutch disc in my hand, so I'm looking for advice here... When the pressure plate releases the clutch disc, space appears between the two organic clutch material and the metal disc in between them. When the pressure plate comes back down, the space between the components of the clutch disc disappears. With the car in gear on jackstands and the clutch depressed, the rear wheels do not spin. However, when I'm under the car watching the pressure plate, I can't observe any space between the pressure plate and the clutch disc because of the spreading of the clutch disc. Is this normal? Also, does anybody know the thickness of a stock new clutch disc, and the thickness of a clutch disc when it is time for replacment? Is it possible that my symptoms are simply indicative of a worn out clutch disc? What are the symptoms of a clutch disc that needs replacing? My second night at the strip, folks in the stands told me that my clutch was really smelly, but I attributed that to my efforts to slip a little clutch at the line to protect my axles. I have not smelled it any other time. I do not believe the clutch is slipping, except when I'm slipping it on purpose. Otherwise, clutch has 18k miles on it. Please help if you have knowledge or experience to contribute. Quote Link to comment Share on other sites More sharing options...
bejbis Posted August 28, 2012 Share Posted August 28, 2012 It sounds like a problem I had in my 03 zo6. Normal shifting was excellent, but when you went through the gears quickly it was extremely difficult or took a while to get into the next gear. its a common factory flaw and the problem lies with the line from the clutch master to the clutch slave cylinder and it being too small of a diameter to transfer fluid quickly. Basically creating an critical orifice that wont allow the fluid to pass through as quickly as you can press the pedal. Do a Google search for "LS1 drill mod" or "t56 drill mod". you'll get alot of hits and DIY's. Your clutch disk isnt the problem, but with the power of the LS motor, a sure fire way to tell if its too thin is if it slips under load. like getting on the freeway, sticking it in 3rd or 4th, and gassing it, if the RPM goes up without an equal amount of acceleration in the car, then the clutch is slipping. that's usually the main indication of a worn out clutch. What you see under the car when your daughter presses the pedal sounds pretty normal. Lastly, the restriction in the clutch line works both ways, restricting it when pressing the pedal. As well as when releasing the pedal, that could be why the people at the track said they smelled your clutch burning. It probably wasn't fully engaged during acceleration. -Dan Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted August 28, 2012 Author Share Posted August 28, 2012 It sounds like a problem I had in my 03 zo6. Normal shifting was excellent, but when you went through the gears quickly it was extremely difficult or took a while to get into the next gear. its a common factory flaw and the problem lies with the line from the clutch master to the clutch slave cylinder and it being too small of a diameter to transfer fluid quickly. Basically creating an critical orifice that wont allow the fluid to pass through as quickly as you can press the pedal. Do a Google search for "LS1 drill mod" or "t56 drill mod". you'll get alot of hits and DIY's. Your clutch disk isnt the problem, but with the power of the LS motor, a sure fire way to tell if its too thin is if it slips under load. like getting on the freeway, sticking it in 3rd or 4th, and gassing it, if the RPM goes up without an equal amount of acceleration in the car, then the clutch is slipping. that's usually the main indication of a worn out clutch. What you see under the car when your daughter presses the pedal sounds pretty normal. Lastly, the restriction in the clutch line works both ways, restricting it when pressing the pedal. As well as when releasing the pedal, that could be why the people at the track said they smelled your clutch burning. It probably wasn't fully engaged during acceleration. -Dan Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted August 28, 2012 Author Share Posted August 28, 2012 Thanks. Familiar with the drill mod. I have already got an over-size aftermarket braided stainless AN3 clutch hydraulic line... Did the drill mod fix your trouble on your Corvette? I've done every modification to the hydraulic system that is described in LS1tech for this problem without improvement. Time to look inside bellhousing, but I'd like to have the parts on hand before I open things up. Quote Link to comment Share on other sites More sharing options...
bejbis Posted August 28, 2012 Share Posted August 28, 2012 Yep, Drill mod worked for me. But from what I read way back when, getting an aftermarket clutch line remedy's the same problem as the drill mod. Quote Link to comment Share on other sites More sharing options...
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