Jump to content
SAU Community

Recommended Posts

In the coming weeks I aim to embark on making an undertray for my R33.

Thinking about making it out of 3-ply with a fiberglass overlay.

But what I would like to see is how people have mounted theirs under the car and if you have made any channels in it for super mega downforce.

Cheers

Andrew

Link to comment
https://www.sau.com.au/forums/topic/445884-home-made-splittersundertrays/
Share on other sites

Composite signboard, approx. 4.5mm thick and reasonably flex free. Runs back to the steering rack.

No fancy channels. No splitter section as yet. I consider it is simple design.

Was a bit fiddly to get the whole thing in place. Time permitting I will put some pics up on my R33 build thread.

will it have to meet any CAMS regs? Prod cars, IPRA and Sports Sedans all have very specific rules about allowable sizes

BTW James has what seems to be a good one on his car, seemed to be a bit fiddly to put on but is working well

will it have to meet any CAMS regs? Prod cars, IPRA and Sports Sedans all have very specific rules about allowable sizes

BTW James has what seems to be a good one on his car, seemed to be a bit fiddly to put on but is working well

Nah,

Just track days and the odd hill climb

If it means running SV than I'll run SV

James (GrumbleBee) said he found a noticeable gain in front end grip when he fitted his. I'd say designed properly there are definite gains to be had. Designed poorly, well, you could end up with less downforce!

  • 2 weeks later...

Simple setup I ran for a couple of years.
I like ally as it's easy to work with even though it's not the lightest. Very noticeable gains at PI and EC through long fast sweeping corners even though it was just flat underneath.

post-10715-0-72359600-1406810077_thumb.jpg

post-10715-0-04651600-1406810087_thumb.jpg

post-10715-0-99314600-1406810100_thumb.jpg

  • Like 2

At speed...

1) If front splitter and connecting undertray are flat with negligible air disturbance > negative pressure under front of the car > front 'sticks' to the tarmac.

2) If the rear wing is set up to create downforce > rear 'sticks' to the tarmac.

1) + 2) > all's good

At speed...

1) If front splitter and connecting undertray are flat with negligible air disturbance > negative pressure under front of the car > front 'sticks' to the tarmac.

2) If the rear wing is set up to create downforce > rear 'sticks' to the tarmac.

1) + 2) > all's good

What if one works a lot better than the other?

The sort of front end device we're talking about won't really produce downforce to the extent that aero loading increases the effective vehicle weight above static.

An effective splitter design should protrude a fair bit, and its height above the ground has a big bearing on efficiency/effectiveness.

The outcome I found with my undertray (no splitter) is noticeable reduction in high speed understeer, less tendency to run wide through high speed sweepers. More front grip at speed is good :yes:.

The sort of front end device we're talking about won't really produce downforce to the extent that aero loading increases the effective vehicle weight above static.

An effective splitter design should protrude a fair bit, and its height above the ground has a big bearing on efficiency/effectiveness.

The outcome I found with my undertray (no splitter) is noticeable reduction in high speed understeer, less tendency to run wide through high speed sweepers. More front grip at speed is good :yes:.

That's exactly what I wanted to hear.

I don't even have the factory undertray atm and my car is horrible at taking high speed corners.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Hi, is the HKS  Tower Bar still available ? negotiable ? 🤔
    • From there, it is really just test and assemble. Plug the adapter cables from the unit into the back of the screen, then the other side to the car harness. Don't forget all the other plugs too! Run the cables behind the unit and screw it back into place (4 screws) and you should now have 3 cables to run from the top screen to the android unit. I ran them along the DS of the other AV units in the gap between their backets and the console, and used some corrugated tubing on the sharp edges of the bracket so the wires were safe. Plug the centre console and lower screen in temporarily and turn the car to ACC, the AV should fire up as normal. Hold the back button for 3 sec and Android should appear on the top screen. You need to set the input to Aux for audio (more on that later). I put the unit under the AC duct in the centre console, with the wifi antenna on top of the AC duct near the shifter, the bluetooth antenna on the AC duct under the centre console The GPS unit on top of the DS to AC duct; they all seem to work OK there are are out of the way. Neat cable routing is a pain. For the drive recorder I mounted it near the rear view mirror and run the cable in the headlining, across the a pillar and then down the inside of the a pillar seal to the DS lower dash. From there it goes across and to one USB input for the unit. The second USB input is attached to the ECUtec OBD dongle and the 3rd goes to the USB bulkhead connected I added in the centre console. This is how the centre console looks "tidied" up Note I didn't install the provided speaker, didn't use the 2.5mm IPod in line or the piggyback loom for the Ipod or change any DIP switches; they seem to only be required if you need to use the Ipod input rather than the AUX input. That's it, install done, I'll follow up with a separate post on how the unit works, but in summary it retains all factory functions and inputs (so I still use my phone to the car for calls), reverse still works like factory etc.
    • Place the new daughterboard in the case and mount it using the 3 small black rivets provided, and reconnect the 3 factory ribbon cables to the new board Then, use the 3 piggyback cables from the daughterboard into the factory board on top (there are stand offs in the case to keep them apart. and remember to reconnect the antenna and rear cover fan wires. 1 screw to hold the motherboard in place. Before closing the case, make a hole in the sticker covering a hole in the case and run the cable for the android unit into the plug there. The video forgot this step, so did I, so will you probably. Then redo the 4 screws on back, 2 each top and bottom, 3 each side and put the 2 brackets back on.....all ready to go and not that tricky really.      
    • Onto the android unit. You need to remove the top screen because there is a daughterboard to put inside the case. Each side vent pops out from clips; start at the bottom and carefully remove upwards (use a trim remover tool to avoid breaking anything). Then the lower screen and controls come out, 4 screws, a couple of clips (including 3 flimsy ones at the top) and 3 plugs on the rear. Then the upper screen, 4 screws and a bunch of plugs and she is out. From there, remove the mounting brackets (2 screws each), 4 screws on the rear, 2 screws top and bottom and 3 screws holding in the small plates on each side. When you remove the back cover (tight fit), watch out for the power cable for the fan, I removed it so I could put the back aside. The mainboard is held in by 1 screw in the middle, 1 aerial at the top and 3 ribbon cables. If you've ever done any laptop stuff the ribbon cables are OK to work with, just pop up the retainer and they slide out. If you are not familiar just grab a 12 year old from an iphone factory, they will know how it works The case should now look like this:
    • Switching the console was tricky. First there were 6 screws to remove, and also the little adapter loom and its screws had to come out. Also don't forget to remove the 2 screws holding the central locking receiver. Then there are 4 clips on either side....these were very tight in this case and needed careful persuading with a long flat screw driver....some force required but not enough to break them...this was probably the fiddliest part of the whole job. In my case I needed both the wiring loom and the central locking receiver module to swap across to the new one. That was it for the console, so "assembly is the reverse of disassembly"
×
×
  • Create New...