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New clutch is junk! $1500 more to fix...


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I bought a new Sachs clutch from a local supplier. It came with a Valeo disc that had identical markings to the GM one that came out of the factory. Spent days doing a perfect job. Had a machine shop grind the flywheel. Cleaned every mating surface spotless with Roloc discs and prepped all surfaces with a brake cleaner. Followed the GM manual and torqued everything by spec. Installed a new GM slave cylinder w/TO bearing, a new GM pilot bearing. No shop could do any better - they wouldn't be able to put the 20 hours I did into it.

 

From day one it's chattered :D . Sometimes it's fine and then the next time you take off, it shakes. I've tried to "burn" it in a bit but the chatter eventually comes back :wtf: . So now it's booked into the dealer to let them have a crack at it. I pre-ordered a new flywheel cause I don't want to take any chances (book says replace - no machining). Anybody else have this kind of trouble? :nopity: I almost went out and bought a Toyota!

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From what I've read, clutch chatter is not unusual for the first thousand miles after replacement.

 

Before the shop replaces it, I'd get them to guarantee that their work won't end up acting the same.

 

It's also possible that the trans input shaft is binding (at least a little) with the crank - possibly from a pilot bearing that's slightly too small, slightly crooked trans (maybe a little junk left on the mating surfaces of the bell or block), or bent crank. From the description of the work you did, I'd go with "slightly out of spec pilot bearing" as being the least unlikely of the three.

 

As long as the chatter isn't so great that you think it may be causing damage, I'd suggest putting up with it for a bit longer - it may take care of itself.

 

 

Did you shim the flywheel away from the crank by the same amount that you had it machined down?

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From what I've read, clutch chatter is not unusual for the first thousand miles after replacement.

 

Before the shop replaces it, I'd get them to guarantee that their work won't end up acting the same.

 

It's also possible that the trans input shaft is binding (at least a little) with the crank - possibly from a pilot bearing that's slightly too small, slightly crooked trans (maybe a little junk left on the mating surfaces of the bell or block), or bent crank.  From the description of the work you did, I'd go with "slightly out of spec pilot bearing" as being the least unlikely of the three.

 

As long as the chatter isn't so great that you think it may be causing damage, I'd suggest putting up with it for a bit longer - it may take care of itself.

 

 

Did you shim the flywheel away from the crank by the same amount that you had it machined down?

 

 

 

 

It's been 3 months and probably 2500 miles. Today, it was fine. Tomorrow it might chatter hard on and off during the day. That's the way it's been. The bell hsg to block is clean and tight. Everything still looks clean and dry as a bone from what I can see through the ventilation holes. Never heard of shimming the flywheel.

 

One other odd thing; my original GM clutch didn't hook up as hard as this one. And if I slipped my original GM disc for even a few seconds, say like on a boat ramp or when your in 4WD starting up a steep bank, it would smoke almost immediately. 3 or 4 seconds tops and you could see a little smoke. I can burn this new one for 20 seconds and not a wisp (does stink though).

 

Well, it's booked in Tuesday. Even when it doesn't chatter, I still don't like the feel of it. And even bigger insult is that I could have just changed the slave & TO bearing. I'm sure the orig disc would have gone another 100,000.

 

Thanks for letting me vent.

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Shimming the flywheel by the amount that it's been machined down is about making sure that the throw-out bearing can fully dis-engage the pressure plate from the clutch disc.

 

If the flywheel is thinner and not shimmed, then the flywheel / pressure plate assembly will be farther away (closer to the engine) from the throw-out bearing.

 

I suppose that it shouldn't matter with our self-adjusting slave cylinders. I guess I like the idea of having all the parts exist where the parts that interact with them expect them to be. I doubt that this has anything to do with your chatter situation.

 

 

As far as your chatter problem goes, it sure sounds like you did everything right, indicating an issue with the replacement parts and not the installer. Of course, that opinion and a dollar fifty will get you a cup of coffee....

 

 

I'll be very interested in learning how this works out. Please keep us posted.

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Shimming the flywheel by the amount that it's been machined down is about making sure that the throw-out bearing can fully dis-engage the pressure plate from the clutch disc.

 

If the flywheel is thinner and not shimmed, then the flywheel / pressure plate assembly will be farther away (closer to the engine) from the throw-out bearing.

 

I suppose that it shouldn't matter with our self-adjusting slave cylinders.  I guess I like the idea of having all the parts exist where the parts that interact with them expect them to be.  I doubt that this has anything to do with your chatter situation.

 

 

As far as your chatter problem goes, it sure sounds like you did everything right, indicating an issue with the replacement parts and not the installer.  Of course, that opinion and a dollar fifty will get you a cup of coffee....

 

 

I'll be very interested in learning how this works out.  Please keep us posted.

 

 

 

 

Well, I dropped the truck off today. Now, I'm kinda wondering...

 

I figured that they may as well change my cat-back exhaust while they're doing the clutch. I've had the Borla on almost 9 years and still had the original as-new system in my garage.

 

So, the appointment was for 8:00am. At 11:30, the service girl calls to proudly update me that they had the exhaust system done and that they were going to start the clutch in the afternoon.

 

What the f...?!?!? :(

 

...it's 3 nuts and some rubber hangers. I just had the whole system apart and used copper never-seize on the threads. I also asked for a new 02 sensor so they didn't even have to pull the old one out of the Borla. And why, pray tell, would you install the exhaust system before you tackle the clutch job?

 

Am I missing something here :chevy:

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So, the appointment was for 8:00am. At 11:30, the service girl calls to proudly update me that they had the exhaust system done and that they were going to start the clutch in the afternoon.

 

What the f...?!?!?  :(

 

...it's 3 nuts and some rubber hangers.  I just had the whole system apart and used copper never-seize on the threads. I also asked for a new 02 sensor so they didn't even have to pull the old one out of the Borla. And why, pray tell, would you install the exhaust system before you tackle the clutch job?

 

Am I missing something here  :chevy:

 

 

 

 

Earlier I said:

Before the shop replaces it, I'd get them to guarantee that their work won't end up acting the same.

 

Stay on top of it and let us know how it turns out.

 

Hopefully you got a written estimate prior to dropping it off. At least with that, they shouldn't be able to hold you accountable for charges that exceed the estimate by $50 without contacting you for authorization.

 

 

As far as sequencing the workflow, if you didn't need to drop your exhaust in order to do your clutch work, then the shop wouldn't need to either. I suppose it's possible that they had someone skilled enough to do the exhaust work and either not skilled enough or without enough time in the schedule to crank out the clutch job. Maybe they were just making an effort to get stuff done as soon as they could.

 

(Hey, even if it's not true, it sounds plausible...)

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