Mating a Flywheel onto an S6 4.2 V8 Going into a 987 Cayman S

[rkmann]

Hi, new here. I've looked through the existing threads and can't find any answering this question, so here goes.

I am fitting a 2002 BBD/ANK 4.2 liter into a 2007 Cayman S with a 6-speed manual. Overall, it is going amazingly well, with most of the bellhousing bolts lining up, the starter, etc. (evidently Porsche used an Audi transmission here, which shifts awesome by the way).

The thing I'm not sure about is putting the flywheel on the crank. I ordered the European single-mass Audi part I found listed for the S6 (part # 077105269LX). It bolts up, but the bolts that came off the flex plate don't tighten all the way (they are supposed to be the same per the diagram I found), and if I push the flywheel against the crank flange, it hits the mounting surface on the engine block.

I'm taking this to mean there should be a spacer between the flywheel and crank, but I want to make sure of this before I get too far. It seems odd that they would put one there, since it could hurt piloting. I found a diagram on this page:

http://www.jimellisaudiparts.com/sho...ssembly=753405

I think it may say that the spacer (part # 6) is used for both flex plates and flywheels, but it isn't too clear.

What sounds right?

[G0to60]

I'm sorry that I can't really help with your question but I would love to see some pictures of your swap. It sounds pretty awesome!

[rollerton]

I'm not entirely sure which flywheel that is, but I'm nearly 100% sure you need shorter flywheel bolts no matter what.
And typically Single Mass flywheels bolt on with no spacer, but again..that V8 only came to us in the U.S with only an auto so we're used to needing the thin 'shim' behind the flywheel when using a dual-mass flywheel from the V6 2.7.
The part# for the shim is 035-105-303A it is roughly 3-4mm thick and should be what you need for clearance. Pretty cool project- I've read about people bolting the Audi V8 into a variety of cars, a Boxter is a great application for it, it sounds like.. but we'd love to see how it turns out.
You have any clearance issues on top of the engine? Seems like that's where people ran into some trouble.

[rkmann]

I'm sorry that I can't really help with your question but I would love to see some pictures of your swap. It sounds pretty awesome!

I have a build thread going on Planet-9.com, at http://www.planet-9.com/987-cayman-a...cayman+audi+v8

It has quite a few pictures. I'm trying to document it pretty well, because there are a few people who have had engine failures and don't want to pay for a Porsche engine.

[rkmann]

I'm not entirely sure which flywheel that is, but I'm nearly 100% sure you need shorter flywheel bolts no matter what.
And typically Single Mass flywheels bolt on with no spacer, but again..that V8 only came to us in the U.S with only an auto so we're used to needing the thin 'shim' behind the flywheel when using a dual-mass flywheel from the V6 2.7.
The part# for the shim is 035-105-303A it is roughly 3-4mm thick and should be what you need for clearance. Pretty cool project- I've read about people bolting the Audi V8 into a variety of cars, a Boxter is a great application for it, it sounds like.. but we'd love to see how it turns out.
You have any clearance issues on top of the engine? Seems like that's where people ran into some trouble.

Sorry for the slow response. I didn't realize I had to click "subscribe" to get notified of replies!

Since my post, I got the 3 mm spacer, which is actually P/N 54105301, and found it was too thick, moving the flywheel out to the point it didn't engage the piloting ridge. But, based on the fitting, the part number 035-105-303A you mentioned (1.25 mm) should be just right. And you're right, I do need shorter bolts. I've found a few different lengths in the Audi parts list (as short as 17 mm). That can wait until I need to order a few more Audi parts.

The top of the engine definitely causes a clearance problem, if you keep the powertrain level (based on Boxster conversion pictures I've seen, I swear they have their oil pans hanging low). I'm going to have to do some "trimming" soon on the sheet metal, and build a new engine cover. I think that in a Cayman a modification in this area is less of an issue than for a Boxster, since there's no top to stow. There are a couple of inches of foam rubber over the engine for noise, so I might be able to use some of that room. Maybe it could end up at stock height.

Lots of open questions yet, but taking them as they come.

[rkmann]

Another big issue here is getting the right clutch and pressure plate. I ordered a LuK replacement set that I thought would work, but the pins that center the pressure plate don't fit through it. I think what I need is Audi P/N 077141117PX, a Europe-only part as far as I know. I found a picture on a website:

Pressure Plate 077141117PX.jpg

Here you can see where the two bolts in each sector fit, and between them is a large hole for the centering pin. This clutch looks like it will fit on the pins on my flywheel (of course it should, because the flywheel and clutch are both for a European S8).

I also find that the clutch disc should be P/N 077141031L, but there are 4 variants of this part number (077141031L, 077141031H, 077141031LX, and 077141031HX). I have no idea what is different between these part numbers. They are priced differently.

Before I spend the big bucks on the OEM parts, does anyone have any advice on the best part numbers, or is there a good aftermarket (like LuK) that offers a kit?

Thanks!

[G0to60]

Thanks for the link! Looks like you're making good progress.

If it's not too big of a deal could you post up a link here when you make progress? It would be great to see this thing come to life.

[rollerton]

As far as you flywheel / clutch comb problem goes if I was you I would take those parts all back and go here:
http://ttvracing.com/
They have a few flywheels that bolt right onto the V8 and accept an OEM Rs4 clutch and pressure plate- which is good for about 600hp reliably from what we know.
And since those TTV flywheels are spec'd for the Rs4 kit, they will also work for a variety of BIGGER power/ aftermarket clutch sets also.

What ECU/ engine management will you use? Custom / standalone..? Seems like it'd be tricky to keep that legal in Europe with no OEM ECU.
Looks awesome:

[rkmann]

As far as you flywheel / clutch comb problem goes if I was you I would take those parts all back and go here:
http://ttvracing.com/
They have a few flywheels that bolt right onto the V8 and accept an OEM Rs4 clutch and pressure plate- which is good for about 600hp reliably from what we know.
And since those TTV flywheels are spec'd for the Rs4 kit, they will also work for a variety of BIGGER power/ aftermarket clutch sets also.

What ECU/ engine management will you use? Custom / standalone..? Seems like it'd be tricky to keep that legal in Europe with no OEM ECU.

Thanks for the info. I'm probably a little different than most, because I'm already looking at a good HP increase, at 335 HP for the BBD 4.2 vs. the Cayman S 3.4 (295), and it's a 3000 pound car. Also, because of poor airflow into the (mid-) engine compartment, I'm actually using the stock clam shell exhaust manifolds to cut down heat. I don't plan on adding much power, and I'll daily drive it, so a standard-weight flywheel and production tuned clutch material and springs should make it more livable. Anyway, I'm really easy on clutches - I never launch hard. My fun is in 3rd and 4th gears on the track.

I live in Michigan, and we don't have very strict rules on engine controls. I plan to run the Audi ECU and interface it to the Porsche system. I've got someone helping with that, who's pretty comfortable with it. I'm going to leave the cat's and the AIR system functional.

[rkmann]

Thanks for the link! Looks like you're making good progress.

If it's not too big of a deal could you post up a link here when you make progress? It would be great to see this thing come to life.

I'll try to remember, but there should be a lot of posts in January and February about the engine cradle, etc. Thanks for the interest!

[rollerton]

I live in Michigan, and we don't have very strict rules on engine controls. I plan to run the Audi ECU and interface it to the Porsche system. I've got someone helping with that, who's pretty comfortable with it. I'm going to leave the cat's and the AIR system functional.

Are you sure you're not in Europe?! My brain told me you were..so, one of us is confused.
Well then..you bought an OEM single mass flywheel for an S8 from Europe!? That wasn't CHEAP. You sort of have to use that. But there are way easier ways to achieve the same thing.
Those TTV flywheels are works of art and for a one-time purchase might be worth considering. As far as the pressure plate mounting; if you're sure the specs are right (stack height, clutch surface depth vs. pressure plate, etc..) then you can easily have those dowel pin holes opened up on the pressure plate. They're not exactly "precision" parts beyond matching dimensionally to make the clutch work.
And you're right about the shim from earlier- the 'thin' one is 1.5mm vs. the 4mm + I misquoted..I've been there too.

[rkmann]

Are you sure you're not in Europe?! My brain told me you were..so, one of us is confused.
Well then..you bought an OEM single mass flywheel for an S8 from Europe!? That wasn't CHEAP. You sort of have to use that. But there are way easier ways to achieve the same thing.
Those TTV flywheels are works of art and for a one-time purchase might be worth considering. As far as the pressure plate mounting; if you're sure the specs are right (stack height, clutch surface depth vs. pressure plate, etc..) then you can easily have those dowel pin holes opened up on the pressure plate. They're not exactly "precision" parts beyond matching dimensionally to make the clutch work.
And you're right about the shim from earlier- the 'thin' one is 1.5mm vs. the 4mm + I misquoted..I've been there too.

Let me check... Yup, pretty sure I'm in Michigan! Maybe my vocabulary is wrong?

No, the flywheel wasn't cheap, but I'm trying to do this build with OEM or large aftermarket parts, so that 5 years from now they'll be the same. I think part of the reason is that I work for a large OEM, in noise and vibration (largely driveline and engines), and if my car gets too loud EVERYTHING at work sounds good! I also see all the work that goes into making things reliable and driveable. I will use specialty aftermarket in some cases. I got a Wavetrak diff, for example, because it doesn't produce ground up clutch material in the transaxle like a limited slip.

I looked at machining out the dowel pin holes, but there's too little material around them (optimized design, right?). I probably should just use dowel pins that step down to the smaller diameter. I do want to make sure that pressure plate is precisely centered, because of its heavy mass - doesn't take much eccentricity for imbalance. The clutch disc in my kit is the right diameter and slides onto the trans input shaft, but I'm going to check the springs in it to makes sure they're not too stiff for street use (gear rattle, you know).

Thanks again for your help.