Splitter / Undertray recommendations?

[Mick]

Interesting about the brake temps. Which pad are you running?

I had considered closing off my ducts too but thought it might affect the longevity of the wheel bearings.

[1990m3]

Interesting about the brake temps. Which pad are you running?

I had considered closing off my ducts too but thought it might affect the longevity of the wheel bearings.

forgot to include. Currently using Wilwood HD discs (like $60 each) and Hawk DTC-70 in front and DTC-60 in rear (cause they need a little less heat)

[jimmy p.]

I'll post what I do, its not perfect and I do have a evolution in mind to make it better, but what I have been doing for the past 5 or so years is I retained the stock plastic engine screening (aka undertray, aka the plastic that is between the frame rails).
I dont duct right to the backing plate, I just duct cool air into the inner wheel well like the factory E2 ducts.

I cut 3" holes in a similar in location to where the factory E2 duct holes would be.
The brake ducts I use have the outlet offset to one side
I positioned my brake ducts so they are aiming as close to those holes as possible.
I use a stiffer black flex hose clamped to the back of the brake ducts and bend it so that its aimed at those holes.
The ducting is cut "just" longer than where it extends "just" through the holes I cut in the plastic undertray.
This ducting has a wire spiral in it.
When I slide the bumper on the car the ducting basically lines right up with the holes, I shove the bumper all the way on, then I reach into the wheel well and pop the ducting through the hole.
Basically one round of the spiral wire protrudes through the plastic.
The spiral wire core holds it in place on the plastic.
If the 5 years I have been running them like this they have never moved out of the holes.

I startred out I used to zip ties them into the holes in the plastic but I forgot to do it one day and they were perfectly in place when I realized it.
I've been racing it like that ever since.

My update that I want to do is I need to find some appropriate piece of ducting with a 3" stub as a receiver on the plastic side so I dont have to reach in and make sure they are aligned and through the hole. I just have not done that yet.

EDIT: My brake setup is similar to what Lee sold as his Rally setup. 11.75 x 1.25" curved vane rotors in front with 6 piston Wilwood in front, 11.75 x .810 straight vane rotors with 4 piston Wilwood Superlights in the rear. Using Wilwood's rebranded Raybestos pads F&R (Equiv of ST43 fr / ST44 rear)
On the hottest days I have never even come close to getting a soft brake pedal.

Forgive the hammered bumper, and splitter. This one has been through many wars.
Its about time to retire it to become a spare, get a new bumper from Mario and build anew. This one has been repaired SO many times.

[Mick]

That's one happy bumper!

Do you recall which Willwood compound that is? B front E rear?

Not sure if you're looking for a 3" coupler, or something more like a 4" to 3" funnel for your ducts. If you need 3" couplers I have a pile of these. I bought them from a NASCAR team many years ago when I was looking for a ducting solution but the flanges were just too short to get a hose clamp on. If you think they might work for you let me know and I'll drop some in the mail.

[jimmy p.]

That's one happy bumper!

Do you recall which Willwood compound that is? B front E rear?

LOL yeah its been through some shit. I just had to repair the Right Front corner of the splitter again from punting a cone at Pocono.
What I use in Wilwood is H front and J rear.
The Js are no longer in the Wilwood catalog so when my back stock runs out I need to buy them from Raybestos. I LOVE that J pad. I used to use them all around and my buddy at Wilwood talked me into trying the H in front with the J in rear and I have to admit, I like it alot.
In Raybestos they transpose to ST43 & ST44 (I think the 44 = the J pad, its either 42 or 44 but I think its 44)

Not sure if you're looking for a 3" coupler, or something more like a 4" to 3" funnel for your ducts. If you need 3" couplers I have a pile of these. I bought them from a NASCAR team many years ago when I was looking for a ducting solution but the flanges were just too short to get a hose clamp on. If you think they might work for you let me know and I'll drop some in the mail.

Wow those look like kind of exactly what I was picturing for the job. Can you measure the actual OD? I'll measure the actual ID of this ducting I have and see if it will slip over.
In my master plan all it would need to do is slip over a stub like that and hold it from moving.
Sliding it through the hole in the plastic works like a champ its just not very "elegant" by any stretch.
Having some sort of a receiver for it to slide over would be much slicker.
Let me know what they measure and if they fit I'd gladly buy a few from you.

[1990m3]

I used the Wilwood H in the past and liked that pad too, they worked really well.

Nice bumper Jimmy!

[Mick]

Wow those look like kind of exactly what I was picturing for the job. Can you measure the actual OD?

They're just under 76mm.

[anaphe]

I was always told that if you can't stand on it, it is not strong enough. I have been through EVO3 splitters, Alumalite (they always slice a tire on impact) and now onto baltic birch. Also I have now de-coupled the splitter from the bumper.

[jimmy p.]

I was always told that if you can't stand on it, it is not strong enough. I have been through EVO3 splitters, Alumalite (they always slice a tire on impact) and now onto baltic birch. Also I have now de-coupled the splitter from the bumper.

Thats the real way forward is to make an understructure the support the splitter and let the bumper cover just be a cover.
There is no bumper cover supported splitter that will ever withstand being stood upon.
Fabricating a separate splitter support is "the way".

I'd love to see pictures of what you did and the structure you are using.
There were some pictures I had of a perfect splitter support structure on an E30 that I found and saved but I cannot find them.

[Ironhead]

I was always told that if you can't stand on it, it is not strong enough. I have been through EVO3 splitters, Alumalite (they always slice a tire on impact) and now onto baltic birch. Also I have now de-coupled the splitter from the bumper.

I've read that also, but I think it's kind of bullshit. Your typical splitter on a track car might generate something like 100# of downforce at speed, but that 100# would be completely, perfectly distributed over every square inch of the splitter. Even if you only weigh 100#, and have size 15 feet, standing on it would still be vastly more concentrated stress than the air would ever provide.

And if you're a fat f&%$ like me? Different story entirely.

I think a splitter needs to be sturdy, but the need to "stand on it" is a major exaggeration IMHO.