the_vetman

As many of you know, our brakes can run incredibly hot at the track. At minimum, we should be running GT3 front brake ducts to help dissipate the heat. GT2 front ducts are better but $$.

Unfortunately there are no good stock options for rear brake cooling ducts (Interseries run NACA ducts from the front radiator area to rear brakes). There have previously been threads on modifying 996 turbo ducts to cool 987 rear brakes (P-9 and CR). I installed them over the past winter.

A couple of issues with 996 turbo ducts are A) a decent amount of modification is needed and B) the directed air doesn't really hit our smaller rear rotors though this is not a problem for those running the larger Girodiscs.

Then I became aware of 997 turbo rear ducts that can be modified to fit 987s (thank you, jabo!). I recently installed them and took some pics. Note that I still have 996 turbo ducts so they're both on the car. First pics are of 996 turbo ducts. Later pics show 997 turbo ducts with 996 version in the background. Apologies for bad pics in advance.

997 turbo ducts also need to be modified but not as much as 996 ones. And they should, in theory, direct air better toward 987 rear rotors. Please note that the top front portion of 997 turbo ducts need to be trimmed a decent amount so they don't rub on tires.... ask me how I know!! I had to make emergency repairs in the hospital parking lot at 11:30pm while driving overnight to Mid-Ohio!

the_vetman

996 turbo rear ducts modified to fit 987:

the_vetman

997 turbo rear ducts modified to fit 987. Note the 996 version in the background. I'd also like to point out that you don't need as many zip ties... I just happened to go a little crazy with them. And there are more zip ties on them now (pics were pre-Mid-Ohio)...

its about time...

this is great stuff! are these OEM 997 turbo parts? any difference from 997.1 to 997.2?
Thanks,
Jim

orthojoe

Thanks, vet! Do you basically trim the ducts until they fit and then ziptie the ducts on?

the_vetman

Thanks, guys.

They're OEM 997 turbo parts. I believe part number is 99733148702KT. Don't know if there's a difference between 997.1 and 997.2. I got them from ECS Tuning (no affiliation) for $34 here:

http://www.ecstuning.com/Search/9973...2KT/ES2581880/

Depending on the source, 996 turbo parts are $160-200.

You have to cut out a section on the front & top portion of the duct. The more tricky part is getting around the brake line that's in the way.

jabo posted pics on P-9 about how he cut out a section and had the brake line go above the duct (see post #29 on http://www.planet-9.com/987-cayman-b...-r-setups.html). This is probably the better option. I, on the other hand, got nervous about pushing the brake line out of the way (so they're not subjected to unintended stress.. probably not a big deal) and instead cut the duct at the top portion, fed the brake line through, then taped up the cut edges.

Taping it up doesn't work well because the tape and duct edges come apart under the force of wind. It's already a fairly soft material to start. Like I said, jabo's set-up above may be the better option as long as pushing the brake line out of the way is not a concern.

Should've mentioned above: 997 rear ducts kind of fit on the suspension arm in the pics but it's not a tight, perfect fit like GT3 front brake ducts. So you kind of put it on, position it where you want it, then zip tie tightly into place. Cutting for brake line will have to have occurred before you can seat it on the arm. Cutting the front top portion can be done before or after installation (before is easier).

TroyN

Any ideas whether these will fit on a 981? Or if 991 parts are compatible?

the_vetman

I suspect that they can be modified to make them fit, but 981s already have rear brake ducts stock.

Dr.Bill

Looks like that should work! Most of the rear brake heat comes from the PSM (or some other alphabet nanny) trying to 'help'.

Another option - drill small holes in the duct to pass the zip ties through, instead of wrapping them around the duct. I've got one or two in each front GT3 duct. Hopefully will keep me from losing them should I scrape on something.

the_vetman

Great idea.

What I did was zip tie the clip-on parts to the suspension arm so that the ducts can't fall off unless duct clip-on parts break off. Zip ties going around the whole duct are there to prevent the soft plastic from bending backward and letting air escape to the top and bottom. What you suggest is a great idea and something I considered, then I got lazy and remembered the mild difficulty I had when trying to drill through the stock front brake ducts (I had previously tried to modify them for use in the rear). Could've just been that my broken drill bits were dull though.

gman3280

Reviving an old thread. Anyone have a DIY to making the rear ducts fit?

I bought 997 331 488 / 487 and can't for the life of me figure out how to put these on my 987.2.

Track event next weekend. Help appreciated.

the_vetman

Sorry for the late response. It goes on the trailing (?) arm. You have to cut it at the top so it can wrap around the brake line. Do what you can to reconnect the cut ends. Unfortunately I do not have any pictures currently.

gman3280

No worries. Thank you. I butchered them but figured it out. I'll probably buy another set since they're pretty cheap at ECS tuning and try it again...

gman3280

Does anyone have some old trailing arms that would be willing to part with them? I've found someone that has a 3d printer that would be willing to prototype some 997 turbo like ducts that fit better and are lower in the airflow similar to front gt3 ducts. He's out of state to me so him having the arms would be best. Thanks

olegd

What do they look like? Can you post a pic? I have some suspension parts from 987.2