Can't figure out this clutch hydraulic problem
06-21-2013, 07:40 AM
#1
Can't figure out this clutch hydraulic problem Last weekend I replaced my system with the following:
- New Duralast CMC
- New Duralast Slave - with the "AP" branding and made in Mexico (allegedly, same as a new Delco)
- New LS7 setup - pressure plate, flywheel, clutch
- New Delco pilot bearing
- Tick remote bleeder
So, I basically reused the hydraulic line and the plastic reservoir. I did drill mod the line - 1/8" bit, cleaned out shavings.
I did not bench bleed anything. I also will admit I did not measure for shims. After installation, I used a Motive Powebleeder and ran 32oz (the bigger bottle) of fluid through it. While still on jackstands, the car was very tough to get into gear, and with the clutch depressed, the wheels were turning. Did a "JDM" method of bleeding - cracked the remote bleeder line, put it into the reservoir, and slowly pumped the clutch pedal. A few bubbles came out, and the car functioned normally.
Drove it the next day (Tues) - I put about 100-125 miles on it. For the most part, it felt perfectly fine. Some shifts were like butter, others were a little difficult (not bad though), but overall I thought it was working well. Pedal engagement was right off the floor at first, but within 50 miles it was feeling semi-normal. Really felt good - so much better than my old stock setup. By the end of that night, I had a very rough time getting it into reverse, although it did drop into reverse without grinding.
Wed morning I went to leave for work, and noticed within the first mile that the clutch wasn't fully disengaging - shifts were tough, and at a stoplight, the car was creeping forward with the clutch in. I turned around and took the car home. Couldn't even get it into reverse at this point. Pedal still felt good though.
Wed night I tried the "JDM" method again, thinking a few air bubbles must have worked their way loose or something. After doing this, I basically had no pedal pressure.
Last night, I disconnected the MC from the slave and stood on the clutch pedal - the thing was rock solid, and didn't drop over time even with me really pushing on it. I also pushed the valve in at the end of the line and fluid freely poured out of it - I don't see there being a restriction in the line.
I then tried bleeding different ways - tried the powerbleeder (ran another 32oz through it), tried the JDM, tried bleeding traditionally...I'd get a mixed bag of results. At times, there'd be no pedal pressure whatsoever. Sometimes I'd get pressure, but the car still wouldn't go into gear. A couple of times (literally, out of about 6-8 different bleed sessions, 2 times), I got it into gear flawlessly. I'd turn the car off, get all my stuff cleaned up, shut the hood, start it up, and then it wouldn't go into gear.
I do know that the last time it went into gear smoothly, I had bled via the powerbleeder. I closed the bleeder screw, but left the powerbleeder hooked up with 10-12 PSI. After I saw that it slipped into gear, I disconnected the powerbleeder, put the cap back on, and then it wouldn't go into gear.
I've noticed absolutely no leaks, nor any drop in fluid level.
Any ideas guys? Does this point to a bad CMC? Can a MC be "bad" even though it's maintaining pressure when disconnected from the slave? What's throwing me for a loop is it worked really well for a day. That's making me believe all the mechanics are good - pilot bearing, input shaft isn't hanging up in bearing, no shim needed.
Is there another way to test the master, or the slave, with them in the car? Both are lifetime warranty and have been in the car less than a week. If we're confident that one of them is the culprit, I'll warranty return it for a replacement. I'd obviously prefer not to drop the trans again unless there's really good reason I should.
I'm about to throw in the towel and have it towed somewhere.
- New Duralast CMC
- New Duralast Slave - with the "AP" branding and made in Mexico (allegedly, same as a new Delco)
- New LS7 setup - pressure plate, flywheel, clutch
- New Delco pilot bearing
- Tick remote bleeder
So, I basically reused the hydraulic line and the plastic reservoir. I did drill mod the line - 1/8" bit, cleaned out shavings.
I did not bench bleed anything. I also will admit I did not measure for shims. After installation, I used a Motive Powebleeder and ran 32oz (the bigger bottle) of fluid through it. While still on jackstands, the car was very tough to get into gear, and with the clutch depressed, the wheels were turning. Did a "JDM" method of bleeding - cracked the remote bleeder line, put it into the reservoir, and slowly pumped the clutch pedal. A few bubbles came out, and the car functioned normally.
Drove it the next day (Tues) - I put about 100-125 miles on it. For the most part, it felt perfectly fine. Some shifts were like butter, others were a little difficult (not bad though), but overall I thought it was working well. Pedal engagement was right off the floor at first, but within 50 miles it was feeling semi-normal. Really felt good - so much better than my old stock setup. By the end of that night, I had a very rough time getting it into reverse, although it did drop into reverse without grinding.
Wed morning I went to leave for work, and noticed within the first mile that the clutch wasn't fully disengaging - shifts were tough, and at a stoplight, the car was creeping forward with the clutch in. I turned around and took the car home. Couldn't even get it into reverse at this point. Pedal still felt good though.
Wed night I tried the "JDM" method again, thinking a few air bubbles must have worked their way loose or something. After doing this, I basically had no pedal pressure.
Last night, I disconnected the MC from the slave and stood on the clutch pedal - the thing was rock solid, and didn't drop over time even with me really pushing on it. I also pushed the valve in at the end of the line and fluid freely poured out of it - I don't see there being a restriction in the line.
I then tried bleeding different ways - tried the powerbleeder (ran another 32oz through it), tried the JDM, tried bleeding traditionally...I'd get a mixed bag of results. At times, there'd be no pedal pressure whatsoever. Sometimes I'd get pressure, but the car still wouldn't go into gear. A couple of times (literally, out of about 6-8 different bleed sessions, 2 times), I got it into gear flawlessly. I'd turn the car off, get all my stuff cleaned up, shut the hood, start it up, and then it wouldn't go into gear.
I do know that the last time it went into gear smoothly, I had bled via the powerbleeder. I closed the bleeder screw, but left the powerbleeder hooked up with 10-12 PSI. After I saw that it slipped into gear, I disconnected the powerbleeder, put the cap back on, and then it wouldn't go into gear.
I've noticed absolutely no leaks, nor any drop in fluid level.
Any ideas guys? Does this point to a bad CMC? Can a MC be "bad" even though it's maintaining pressure when disconnected from the slave? What's throwing me for a loop is it worked really well for a day. That's making me believe all the mechanics are good - pilot bearing, input shaft isn't hanging up in bearing, no shim needed.
Is there another way to test the master, or the slave, with them in the car? Both are lifetime warranty and have been in the car less than a week. If we're confident that one of them is the culprit, I'll warranty return it for a replacement. I'd obviously prefer not to drop the trans again unless there's really good reason I should.
I'm about to throw in the towel and have it towed somewhere.
06-23-2013, 09:11 PM
#2
FYI, for future searches....
I had originally installed a Duralast CMC and powerbled the system - I did NOT bench bleed.
I tried to do a "traditional" bleed, but when I depressed the pedal and cracked the bleeder, I couldn't get any fluid to refill in the CMC. I got no pedal, couldn't get it to bleed.
I yanked it and got it replaced under warranty. I bench bled the new one, and then did a traditional bleed when I got it installed. Thus far, the car is shifting smoother than it ever has (I only got it 4k miles ago though) - really, it's silky smooth, no hangups like it has been doing for a while.
Whether the other CMC was bad, or whether I ruined it with a powerbleed, I will never know. It's working great now.
Knock on wood, but I think I am good to go. Hopefully no other issues pop up!
I had originally installed a Duralast CMC and powerbled the system - I did NOT bench bleed.
I tried to do a "traditional" bleed, but when I depressed the pedal and cracked the bleeder, I couldn't get any fluid to refill in the CMC. I got no pedal, couldn't get it to bleed.
I yanked it and got it replaced under warranty. I bench bled the new one, and then did a traditional bleed when I got it installed. Thus far, the car is shifting smoother than it ever has (I only got it 4k miles ago though) - really, it's silky smooth, no hangups like it has been doing for a while.
Whether the other CMC was bad, or whether I ruined it with a powerbleed, I will never know. It's working great now.
Knock on wood, but I think I am good to go. Hopefully no other issues pop up!
06-24-2013, 06:20 PM
#3
Staging Lane
Join Date: May 2011
Location: JAX Florida
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Glad to hear you got it figured out, from my understanding, the cmc and slave from most parts stores are the same ones gm put in out cars, as long as it says AP on them, but for fraction of the price. When you say "powerbled", what are your referring to? Just wanna now so I don't bleed like that lol
06-25-2013, 07:38 AM
#5
That being said, I am really liking the clutch. Not sure if that's because my old one was worn and the hydraulics were obviously bad, but it's a much smoother clutch and engages much better.
