Puzzled by clutch problem
Thread Starter
Instructor
Joined: Sep 2004
Posts: 212
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From: Bakersfield CA
Puzzled by clutch problem
I know there's been several posts about clutch problems but I have to throw this one out for responses:
I've had two new clutches of the same brand installed with a new master and slave cylinders. I've had the hydraulic fluid thoroughly flushed through from master to slave bleeder. The isue is when I shift at high rpm into 3rd and 4th gear something is delaying the clutch engagement (rpms rising for maybe .5secs after full pedal extension and then engagement). I've heard of the larger soft line leading from the master to slave that has a larger diameter. I haven't tried one because I've never had an issue with engagement before now. The stock line has obviously flowed sufficiently from the stock clutch to the third aftermarket replacement, one being a dual disc and now a triple disc. Is it possible that GM changed the flow rate of their replacement OEM master cylinder or slave? The problem seems obviously to be hydraulic in nature (both new clutches installed have reacted exactly the same). Has anyone experienced this same phenomenon with their C5?
I've had two new clutches of the same brand installed with a new master and slave cylinders. I've had the hydraulic fluid thoroughly flushed through from master to slave bleeder. The isue is when I shift at high rpm into 3rd and 4th gear something is delaying the clutch engagement (rpms rising for maybe .5secs after full pedal extension and then engagement). I've heard of the larger soft line leading from the master to slave that has a larger diameter. I haven't tried one because I've never had an issue with engagement before now. The stock line has obviously flowed sufficiently from the stock clutch to the third aftermarket replacement, one being a dual disc and now a triple disc. Is it possible that GM changed the flow rate of their replacement OEM master cylinder or slave? The problem seems obviously to be hydraulic in nature (both new clutches installed have reacted exactly the same). Has anyone experienced this same phenomenon with their C5?
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
I know there's been several posts about clutch problems but I have to throw this one out for responses:
I've had two new clutches of the same brand installed with a new master and slave cylinders. I've had the hydraulic fluid thoroughly flushed through from master to slave bleeder. The isue is when I shift at high rpm into 3rd and 4th gear something is delaying the clutch engagement (rpms rising for maybe .5secs after full pedal extension and then engagement). I've heard of the larger soft line leading from the master to slave that has a larger diameter. I haven't tried one because I've never had an issue with engagement before now. The stock line has obviously flowed sufficiently from the stock clutch to the third aftermarket replacement, one being a dual disc and now a triple disc. Is it possible that GM changed the flow rate of their replacement OEM master cylinder or slave? The problem seems obviously to be hydraulic in nature (both new clutches installed have reacted exactly the same). Has anyone experienced this same phenomenon with their C5?
I've had two new clutches of the same brand installed with a new master and slave cylinders. I've had the hydraulic fluid thoroughly flushed through from master to slave bleeder. The isue is when I shift at high rpm into 3rd and 4th gear something is delaying the clutch engagement (rpms rising for maybe .5secs after full pedal extension and then engagement). I've heard of the larger soft line leading from the master to slave that has a larger diameter. I haven't tried one because I've never had an issue with engagement before now. The stock line has obviously flowed sufficiently from the stock clutch to the third aftermarket replacement, one being a dual disc and now a triple disc. Is it possible that GM changed the flow rate of their replacement OEM master cylinder or slave? The problem seems obviously to be hydraulic in nature (both new clutches installed have reacted exactly the same). Has anyone experienced this same phenomenon with their C5?
Other member may have better perspective than I do.
I'd suggest not assuming the fluid is OK. First thing to do is bleed the clutch thoroughly to ensure perfect fluid and an absence of air in the hydraulics. Given all that you have invested in the car, I'd do the bleed the traditional way.
If that fails to resolve the issue, I'd to the drill mod, written about extensively on LS1tech.com. Let me know if you need a link.
If that fails, I'd go for the higher capacity hydraulics.
Ranger
Thread Starter
Instructor
Joined: Sep 2004
Posts: 212
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From: Bakersfield CA
The fluid has been completely flushed three times with new fluid to rid any contaminates/particles that could be causing a restriction to the flow (which is what I thought might be the issue). Yes I do have the 3disc clutch and had a dual disc just previously to the the triple. Both were new and broken in before any hard driving and have exhibited the same symptom. You mentioned the higher capacity hydraulics. I'm not aware of any, so suggestions are greatly accepted. I would like that link to the LS1tech thread. I did have a dual disc Exedy for two years of hard running with slightly less power (20rwhp) and the stock master/slave combo with not a single problem.
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
Have you or your installer reported your issue to Exedy tech support?
You have their top-of-the-line clutch. They should be very interested and motivated to help you resolve the issue. They also should have a specification for the hydraulics, particularly the line diameter.
So for now, that's the course I'd suggest rather than improvising a solution.
Finally, you might review your launch technique. My understanding is that clutch hates to be slipped intentionally on launch and unintentionally on shifts. If the clutch release is not fast and a single motion, trouble can follow. That's a subject for discussion with Exedy Tech too.
Ranger
You have their top-of-the-line clutch. They should be very interested and motivated to help you resolve the issue. They also should have a specification for the hydraulics, particularly the line diameter.
So for now, that's the course I'd suggest rather than improvising a solution.
Finally, you might review your launch technique. My understanding is that clutch hates to be slipped intentionally on launch and unintentionally on shifts. If the clutch release is not fast and a single motion, trouble can follow. That's a subject for discussion with Exedy Tech too.
Ranger
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Since your original post doesn't mention Exedy in the title, you might try re-posting with a question specific to Exedy clutch engagement and see if anyone else has run into this. The restriction on the Vette is unfortunately at the slave if you need to drill it out. On the f-body I believe it is at the master so it's easier to do.
Good luck
Good luck
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
I'd suggest that the focus be the "Exedy Triple Carbon Disc" rather than Exedy in gen. Triple Carbon is very unusual and has different characteristic from the others.
Just a thought.
Ranger
Just a thought.
Ranger
Thread Starter
Instructor
Joined: Sep 2004
Posts: 212
Likes: 0
From: Bakersfield CA
Thanks for the responses. Ranger as to your last post, I'll definitely be talking to Exedy on Monday, but the issue is not solely with the triple disc. What I was trying to convey is that I had a new dual disc Exedy installed previous to the triple and had exactly the same issue. That clutch was intalled after two years of faultless performance from a dual disc Exedy and the OEM hydraulics. My pedal has never stuck to the floor or changed it's point of engagement. The only difference (at least of any significance) in pedal action is now with the triple disc the engagement is later in it's throw. Also, I haven't even launched the car with the triple and only had five launches with the new dual disc. I've only ran the car through the gears hard with the triple and have experienced this problem.
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