E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > Tuning & Tech > Motorsports & Track Forum

Motorsports & Track Forum
From Auto-X to Trackday to Racing and Professional Motorsports this is the place to discuss making BMWs fast

Thread Tools Search this Thread Rate Thread Display Modes
Old 05-26-2017, 08:15 AM   #1
Registered User
Join Date: Dec 2011
Location: Westfield, IN
Posts: 877
My Ride: 2001 330ci
Flat floor mounting

Hello all.
I was wondering what people on the forum do to mount underbody panels for a flat floor. I have seen well nuts used, but I don't want to have to drill into the floor as this is still a dual duty car, and those holes would probably begin to rust eventually. How do you guys mount your flat floors? I already have a plan for mounting splitter and diffuser.
I will only be tracking twice a year, so this is mostly a fun project, but I still want to do it right and a splitter/diffuser combo needs a smooth bottom IMO. I also plan to fence off the airflow underneath.


Sent from my XT1080 using E46Fanatics mobile app
Corbeau FX1 Pro & CR1, Ultimo front coils, Rob43 9-click rear shocks, Swift 10k rear springs, Meyle FCA's, AKG 95a FCA, 75d rear subframe, Powerflex 95a RTA, 95a RCA, ECS 88a diff., ECS SS brake lines, LTW FW, M3 engine mounts, UUC 5sp black mounts, BMW Performance SSK, open-loop EU2 tune, CAI, headers, x-pipe, minus ~180lbs.
Weste46 is offline   Reply With Quote
Ads by Google

Guests, get your FREE E46Fanatics.com membership to remove this ad.
Old 06-12-2017, 04:48 PM   #2
Registered User
Join Date: Jul 2007
Location: Dallas, TX
Posts: 102
My Ride: Various BMWs
There are no "hard and fast rules" rules when it comes to mounting flat undertray panels. Adding a flat floor can take a significant amount of fabrication work - not just to cut the panels, but to make the mounting anchors, getting the panels level, additional cooling methods, etc. For only 2 track days a year it might not be worth it... ?

Here are a few pictures of aluminum panels we built for a customer's track car (tube framed car). It was a lot of hours...

There are things you have to keep in mind: the radiators/engine bay mostly vent out of the bottom of the car. Any heat sources above the floor will get hot! And if you have an "off" the under panels are the first things that get destroyed.

You also need to make the panels removable for easy maintenance access. Things like an oil change can take 3 times as long if you have to pull panels off to access the filter, drain plug, etc.

But making a flat floor into a diffuser makes that last part much more effective. Hey, if you have the funds and the skills, go for it. But don't expect major lap time returns for the amount of time/effort spent. This is one of those "small" gains you go look for when the rest of the aero package is already maxed out.

Good luck,
Fair is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON

All times are GMT -5. The time now is 02:54 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
(c) 1999 - 2016 performanceIX Inc - privacy policy - terms of use