PSA: 7A and AAN flywheels aren't dimensionally identical (edit to add crappy pics)
12-17-2008, 05:15 PM
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PSA: 7A and AAN flywheels aren't dimensionally identical (edit to add crappy pics)
I'll post more details tomorrow after we get everything bolted together, but I spent some more time today doing careful measurements of the 7A vs. AAN flywheels. The net is that the 7A is effectively 3/8" thinner, meaning that the friction surface is 3/8" closer to the motor. That's a lot for even a hydraulic clutch to make up.
Fortunately for me, the pressure plate from the Luk 02-026 clutch kit I've had lying around because it doesn't work with the stock flywheel just happens to be 3/8" thicker than the stock AAN PP, so everything works out, but the extra work the slave would have to do with a stock PP could explain the premature slave failures we heard about from a few shop owners.
I took a bunch of pictures, but unfortunately, you can't read the scale on the quick square because of the reflection from the flash. The ones below are good enough so you can get the idea, though- look at the top surface relative to the cutout in the square. The 2 flywheels aren't particularly close.
I'll try to get better ones tomorrow before we put everything back together. In a odd coincidence, a local S6 just had it's clutch fail- it's being put back together with all stock parts (including a brand new $700 dual mass flywheel) so we should be able to do back-to-back drives of both setups.
Stock AAN flywheel:
<img src="http://www.motorgeek.com/phpBB2/gallery2/d/81409-2/P1010007_001.JPG">
7A flywheel:
<img src="http://www.motorgeek.com/phpBB2/gallery2/d/81415-2/P1010008.JPG">
Fortunately for me, the pressure plate from the Luk 02-026 clutch kit I've had lying around because it doesn't work with the stock flywheel just happens to be 3/8" thicker than the stock AAN PP, so everything works out, but the extra work the slave would have to do with a stock PP could explain the premature slave failures we heard about from a few shop owners.
I took a bunch of pictures, but unfortunately, you can't read the scale on the quick square because of the reflection from the flash. The ones below are good enough so you can get the idea, though- look at the top surface relative to the cutout in the square. The 2 flywheels aren't particularly close.
I'll try to get better ones tomorrow before we put everything back together. In a odd coincidence, a local S6 just had it's clutch fail- it's being put back together with all stock parts (including a brand new $700 dual mass flywheel) so we should be able to do back-to-back drives of both setups.
Stock AAN flywheel:
<img src="http://www.motorgeek.com/phpBB2/gallery2/d/81409-2/P1010007_001.JPG">
7A flywheel:
<img src="http://www.motorgeek.com/phpBB2/gallery2/d/81415-2/P1010008.JPG">
12-17-2008, 10:18 PM
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no surprises here
the difference is made up by the pressure plate.
The 7a flywheel mod works on //s cars because the 7a style clutch kit everyone winds up with has a 3/8" thicker pressure plate (like the one you wound up using).
The 7a flywheel mod works on //s cars because the 7a style clutch kit everyone winds up with has a 3/8" thicker pressure plate (like the one you wound up using).
12-18-2008, 03:37 AM
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If the need to use a 7A-style PP is so well known, why didn't anyone mention it when I asked?
See my original thread below- I proposed using a stock AAN PP, and nobody said boo.
Not trying to pick a fight, just a bit aggravated- I'm trying to fully document the process and parts required because I couldn't find a good write up when I started down this road, and first the only comments I get are saying "it just bolts up" (without any detail as to exactly WHAT combination of parts should just bolt up) and now you're saying the need for a different PP is common knowledge? WTF?<ul><li><a href="https://forums.audiworld.com/s4s6/msgs/245744.phtml">https://forums.audiworld.com/s4s6/msgs/245744.phtml</a</li></ul>
Not trying to pick a fight, just a bit aggravated- I'm trying to fully document the process and parts required because I couldn't find a good write up when I started down this road, and first the only comments I get are saying "it just bolts up" (without any detail as to exactly WHAT combination of parts should just bolt up) and now you're saying the need for a different PP is common knowledge? WTF?<ul><li><a href="https://forums.audiworld.com/s4s6/msgs/245744.phtml">https://forums.audiworld.com/s4s6/msgs/245744.phtml</a</li></ul>
12-18-2008, 04:37 AM
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Fair enough, and again not trying to pick a fight. I had to take one all the way back apart before..
during the Luk 02-026 fiasco, so I'm more than a bit gun shy about the process. I was lucky in that we didn't damage the transmission, but it still sucked having to tear everything back down.
What flywheel/clutch setup are you running in your Avant? I didn't see any mention of it in your MG project thread.
What flywheel/clutch setup are you running in your Avant? I didn't see any mention of it in your MG project thread.
12-18-2008, 05:21 AM
#7
Personally, I advocate the dual mass and no one out here (BC) has swapped flywheels. The CO and CT
folks are the one who tend to have swapped flywheels (mostly to aluminum/steel single mass hybrids).
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12-18-2008, 06:09 AM
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Actually, we don't know exactly what the 02-026 PP is, besides dimensionally identical to the 7A...
As far as I've been able to determine, the 7A, RS2, C4 S-car V8, S4TT, and RS4 (V6TT) pressure plates are all very close if not identical dimensionally, but I'd be surprised if they're also identical in terms of clamping force.
I couldn't find a part number on the PP in the kit, so I contacted Luk and asked exactly what the 02-026 kit PP is- I'll post whatever information they're willing to cough up.
I couldn't find a part number on the PP in the kit, so I contacted Luk and asked exactly what the 02-026 kit PP is- I'll post whatever information they're willing to cough up.
