UrScubed

Got most of the parts today and went to the shop to test fit everything. Main area of concern is the stack depth of the 7A vs. the stock dual mass. It may or may not be obvious from the pics below, but the mounting surface (flywheel to crank) on the 7A is inset compared to the OE flywheel and we weren't sure what impact this would have on installed depths. If the installed position of the PP is significantly different, it could cause problems with the slave and/or engagement.

<img src="http://www.motorgeek.com/phpBB2/gallery2/d/79737-2/P1010006.JPG">

So, we set the flywheels on a spacer so they'd start out even, and then used a straight edge to measure PP shell depth and then PP release finger depth on both setups. 7A is on the left with the new PP, and the OE setup we pulled out of the car on the right.

<img src="http://www.motorgeek.com/phpBB2/gallery2/d/80051-4/p1010004.JPG">

One of the reasons we wanted to try test fitting and measuring everything is because I was one of the early victims of Luk's 02-026 clutch kit, which has the wrong PP for US-spec C4 cars- it's significantly deeper and has a different profile than the stock AAN PP (you can see the difference in profile in the picture above). I was lucky enough to not damage my transmission like others have, but the company that sold it to me refused to take it back since we'd already installed it, and it's been lying about ever since.

BTW, I'm pretty sure this is the same PP the RS2 and 4.2 V8 C4 S-cars used. To make the extra room to fit the deeper PP, they used a spacer between the block and bell housing, and I was planning to source one if the measurements showed the two flywheel were dimensionally identical.

As luck would have it, the deeper 02-026 kit PP compensated just about exactly for the differences in the flywheels- the measured depths of the housings were less than 1/32 of an inch off, and the release fingers were within 1/16th. This means I'll finally get to use most of this kit after having it sitting on a shelf for a couple years. You can't imagine how many points that scored with the wife ;-)

The only thing I can't use from the 02-026 kit is the clutch disk- the stock AAN disk isn't sprung (the dual mass flywheel is designed to smooth out engagement, so the disk doesn't have to) and so tends to chatter with a solid flywheel. I looked at a couple different options, but ended up sourcing a new RS4-spec (V6TT, not V8) clutch disk. Pics of the original solid (still a lot of wear left at ~150K miles) and brand new sprung RS4-spec below. BTW, the standard S4TT clutch disk should also work, but I decided to go with the RS4 because it should add a few HP ;-)

Old crustiness:
<img src="http://www.motorgeek.com/phpBB2/gallery2/d/80069-2/P1010015.JPG">

Shiny newness:
<img src="http://www.motorgeek.com/phpBB2/gallery2/d/80075-2/P1010013.JPG">

I'm not completely out of the woods yet- it's possible the difference in profile is still enough to make the deeper 02-026 kit PP bind on the 01E transmission housing, but we're going to reinstall just the trans very gingerly, hand-crank everything, and then run the car to make sure there's no binding or scary noises before we button everything back up.

We were hoping to get that done today, but I wasn't able to get a clutch slave, so the suspense will have to drag out until some time this week. More news and driving impressions once everything's back together.

germantoy

all the lightweight alum ones are direct copy of the 7a. hell a b5 s4 clutch even bolts up its quite odd.

UrScubed

Also, while I and the shop I'm working with have been researching this, we've found multiple reports of clutch slave failures when going to the 7A, for no readily apparent reason. A couple cars have gone through multiple slave cylinders in a relatively short period of time.

Based on the measurements we did Saturday, it appears that the 7A flywheel moves the friction surface on the flywheel in by a significant amount (I need to go back and measure exactly how much) which might explain the premature failures.