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I'd like to build on Satch's post a little bit, and create a single thread that should really help a lot of folks diagnose these issues.

Not all clutch creep or clutch drag issues on 02M are caused by the excess axial play of the input shaft.

In cases where Aftermarket clutches (stage 2+) are used, the 02M slave cylinder may not generate enough hydraulic force to fully disengage the pressure plate from the friction disk. Enter the NLS shim kit. That kit essentially shortens the amount of extension required to fully disengage the pressure plate.

Obviously not all clutch kits are built the same, and not all slave cylinders are the same, so it is impossible to say that all of them will suffer from this deficiency, but it is a good recommendation when upgrading or replacing, to go ahead and add the NLS (Nothing Leaves Stock) shim kit to your purchase.

(I am not associated with NLS, they are just the only vendor I know of that sells this kit)
 

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The Issue, with some detail:

It amounts to the bore of the piston in the slave and master, and the materials used in construction. You understand the basics, so when you press the pedal, it pushed a cylinder, which forces fluid in the lines forward, which eventually pushed on the piston in the slave, that piston activates the clutch.

It can only exert as much force is put into it, and it's asked to exert quite a bit as that one little piston is asked to compress the entire PP. So there is a finite amount of pressure (force) available from the system. Go over that, and you start to have issues.

The farther a hydraulic piston is extended the less force it has at point of contact. So if it starts out at 100psi it may end up with only 40psi at the end of its stroke (those are completely random numbers, but you get the point). Also, hoses flex, reducing the forward potential as fluid starts to expand outward instead of forward. hydraulic fluid is compressible as well, not nearly as much as water, but it is, so that factors in as well as you approach limits. Colder weather means stiffer fluid, stiffer fluid offers less compression. Again this is rather small and only factors in near limits.

Now we get to the crux. The system was engineered to handle the stock clutch system, and not much more. That means stock PP clamp force and friction disk thickness. If you put a PP with 1.5x clamping force and a friction disk that's 0.1mm thicker, you need that much more force and stroke to fully actuate the clutch.

If you try to push the pedal in that scenario, the PP will depress to a yield point, at which either the fluid is maxxed out, the hoses are flexing and allowing too much outward pressure, or the piston has just extended too far and no longer has enough force behind it to continue pushing the PP.

Rubber hoses flex, plastic housings on the slave/master are pretty rigid, and any flex you get from them is negligible.

How to fix:
1. SS clutch lines take a significant amount of flex out of the clutch lines, allowing more force to be applied to the slave.

2. Shim kit. This basically shortens the amount of extension needed to actuate the PP, which means there is more force available at the point of full PP extension (compression).

3. The root problem is the bore and/or stroke of the master cylinder is too small. increase either of those and the potential force dramatically increases. To my knowledge no one has done this yet, as the shim kit is much cheaper and, is equally as effective.


Way longer post than I normally like, but there it is, my take on hydraulic clutch
 

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I've had the same thought, but I haven't seen any reports of failure I would link to the shim. I would say the only failure you'd likely see is internal seal failure of the master or slave. And there is little you can do about that. There is also no way to really link a failed seal to a shim kit.

Those cylinders just fail, whether metal, OEM, or Aftermarket; it's a relatively common fail point on any car with a hydraulic clutch. That's one reason why they aren't terribly expensive to replace... except on the 02M, where you have to drop the trans, but even then, the part itself isnt so bad.

SS lines and the shim are about the best solutions. even if someone came out with a bigger bore/longer stroke master, I might still suggest the shim first.
 

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The older versions of the 02M did not have the shims, which resulted in the shaft essentially slowly boring itself a biggerhole to sit in. that larger hole is where the play comes from. Newer versions had this corrected and came stock with said shims to alleviate the issue.

I do not know when specifically that change happened.

But it stands to reason that a trnas with heavy use would have more than a lightly used one.
 

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it gets tricky when talking trans models and car models, and I'm not confident enough in my knowledge of the 02M to comment accurately.

I will say this though:
The first year for a GQV may be be from 2002, where the first year for a DRP may be 2003. So even though YOUR GQV came from a '04 model car, that trans model may be an older version than the DRP. Confusing enough for you?

To find out for sure you'd have to track the release of each 02M trans model, independent of what model and model year car it was used with.
 

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oh no offense taken at all, the more this stuff gets talked about, the more I get to learn.

If we can identify exactly which trans models have the issue, we can start to map which other versions are likely to see the same issue, and which ones are not.

My only point was that you can't base it solely on the model year of the car. :thumbup:
 
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