gt4 style brake ducts

[Theruleslawyer]

So I want to do brake cooling

I'm kinda following along
https://f80.bimmerpost.com/forums/sh....php?t=1837415
and

I ordered a set of GT4 style ducts
https://3amotor.com/products/carbon-...40163706929195

A set of [s]2.5"[/s] 2" hose
https://www.amazon.com/dp/B072LWGB84...roduct_details

A set of stainless hose clamps
https://www.amazon.com/dp/B07Y564X9B...roduct_details

A set of [s]2.5"[/s] 2" aluminum flanges
https://www.aircraftspruce.com/catal...uctflanges.php

With that I can mod my stock brake shields and get air from the front to the brakes. I'm looking a improvement for removal between track days and the rub point I'm worried about on the fender liner that is pretty apparent in the video.
It'll reduce the possibility that you'll rub them turning hard in a parking lot and increase serviceability since the exposed hose will be easy to replace without taking the bumper off. Less obvious 'race car' when you take it in for service too.

2.5" ducting fittings are a PITA to find.

A couple options-

1) This is probably the smoothest solution. If you cut the hole tight and clamp the hose up against it, it will probably be snug. Vibration wear will be on the hard ABS. I could probably epoxy or silicone adhesive it in place too to prevent noises. I don't love that it doesn't have a mounting flange.
https://www.amazon.com/gp/product/B0...GLPNP1IU&psc=1


2) The other thing out there that fits is 2.5-2.25" shop vac connectors. They will slightly restrict the ID and I'd have to see if they vibrate out. If they do, I'd need to figure out a mechanical latch. Bonus is this will look super clean when off.

This would be mounted with the port side out to the wheel well ideally.
https://www.woodcraft.com/products/2...-inlet-fitting

The other side is a hose to port adapter
https://www.woodcraft.com/products/2...ection-fitting


3) I've found a couple bulkhead connectors similar to this that I'd just sandwich the fender liner between and clamp the hose on both sides.
https://www.ebay.ie/itm/272078020199

Any other ideas out there that I'm not thinking of? Opinions on the best solution?

[E92inSG]

i've had extensive experience with this, you will be struggling to get a 2.5 inch hose thru the gaps in the front bumper area. the back of the GT4 ducts actually take a 2" or 51mm hose.

I'm afraid you will need to buy new 2" flanges and hoses instead. a 2" hose will also give you a little more room in the fender liner area during full lock. you will still need to flatten the hose a little bit to ensure completely rub free at full lock.

If you look at realoem, you will see that the GT4 actually specs a 51mm hose for that section of brake duct, but they have an additional larger hose that feeds the discs from the bottom of the GT4 splitter.

[GreenGoblin]

You just need to smash your duct into an oval



You will need 2in ducting, anything bigger will not fit

[Theruleslawyer]

Well that simplifies it a bit. You can actually get really cheap SS flanges in 2" that are designed for closet rods and the like.

Does the hose stretch at bit? How careful do you have to be with OD vs ID measurement on thin wall tubing? A lot of listings aren't very specific. Also how did you clamp on the oval ends of the CF front ducts?

[E92inSG]

Depending on which brand of gt4 ducts u get and the type of hose, I had quite a bit of trouble trying to get the wire hose into the oval gt4 ducts. I just used normal clamps once on though. My gt4 ducts were plastic from burkhart engineering. The hoses really don’t stretch at all because of the wire support.

For the rotor back flanges I got aluminium ones instead of SS. you’re right they’re plenty of those.

[Theruleslawyer]

Update:
Installed the front bits first. Not too hard. Just use the opposite one as a template and cut. There is a second layer of plastic in the bumper but its all easy with a Dremel. Just take it slow opening the hole up and test fit for often.

[Theruleslawyer]

Next up running the ducting. Bumper is a lot of screws. The ductwork is indeed 2”. I lubed the duct and hole with silicone spray and used a broom handle to press it through. You need to be careful about trimming so you can still get the bumper back on. I added a 2” duct outlet to the fenderwell. It always blows in the general direction of the wheel, but also means that i can remove the wall to brake shield hose in the off season. Also if my wheel damages the hose I don’t have to take the bumper off to rerun that PITA install.

[uncle ben]

Where can I get a set of those handy fender liner connectors?

[Theruleslawyer]

Originally Posted by uncle ben

Where can I get a set of those handy fender liner connectors?

https://store.vansaircraft.com/bulkh...nged-duct.html

Kinda expensive for what it is.

[GuyLedouche]

Originally Posted by Theruleslawyer

https://store.vansaircraft.com/bulkh...nged-duct.html

Kinda expensive for what it is.

That's super cheap for anything associated with airplanes.