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NOT A TA
NOT A TA SuperDork
10/10/20 10:16 p.m.

Someone asked about a splitter that could pivot. Here's one I've been working on for my Firebird. The splitter can pivot up on what is essentially a giant piano hinge I made by using PVC tube inside square aluminum tube sections. The part below the engine remains flat. Splitter is 3/8" plywood and strong enough for me to stand on when mounted.

[URL=https://app.photobucket.com/u/NOTATA/a/ac949837-2452-4f6a-b3a7-1455f6a2f0b0/p/140458de-adce-469f-8620-a3b557084114][/URL]

 

Cedricn
Cedricn New Reader
10/13/20 6:09 a.m.
NOT A TA said:

In reply to malibuguy :

Notice in the video he doesn't consider a possible increase in pressure on the top side of the splitter nor does he mention the benefit of much lower pressure on the bottom of the splitter or lever length to the front wheels. Also doesn't take into consideration changes to airflow over/under the vehicle due to adding the splitter. He just uses pressures he measured on a stock Insight and uses math to make up what he believes. No mention of changes in drag, which I'd think he'd be yapping about since he's all about "road" cars not race cars. Seems like the point of his video is "Buy my book" but offers no credibility other than "I write book and do videos". 

He is largely right for a road car, where splitters have a very small area. But for a race car were there are limited ways of creating front DF the splitter can be an important component to get the aero balance right( also taking the leverage into account as you mentioned), adding DF at the rear is a much easier job, finding enough DF at the front to get good balance, not as easy. 

Superslowmonte
Superslowmonte
1/23/21 6:20 p.m.

Before I rush to Lowes and break out the cardboard for templates... does anyone have any empirical data that proves this made their car faster and is worth adding 15 lbs to the nose?

NOT A TA
NOT A TA SuperDork
1/23/21 6:40 p.m.
Superslowmonte said:

Before I rush to Lowes and break out the cardboard for templates... does anyone have any empirical data that proves this made their car faster and is worth adding 15 lbs to the nose?

On what kind of car with what other modifications?

Rick O'Shea
Rick O'Shea New Reader
1/26/21 3:57 p.m.

In reply to Superslowmonte :

My splitter, in combination with a 9lives rear wing, allows me to run lap times on two year old RS-4's that I previously could only run using fresh Toyo RR's. The grip, stability, and confidence through high speed corners is massively improved, despite the added weight. 

Superslowmonte
Superslowmonte New Reader
1/30/21 6:20 p.m.
NOT A TA said:
Superslowmonte said:

Before I rush to Lowes and break out the cardboard for templates... does anyone have any empirical data that proves this made their car faster and is worth adding 15 lbs to the nose?

On what kind of car with what other modifications?

 

A 2013 Mustang on stock struts, boss 302 springs, and roughly 100 lbs reduced. 18x10 wheels, hankook rs4

Superslowmonte
Superslowmonte New Reader
1/31/21 6:36 a.m.
Rick O'Shea said:

In reply to Superslowmonte :

My splitter, in combination with a 9lives rear wing, allows me to run lap times on two year old RS-4's that I previously could only run using fresh Toyo RR's. The grip, stability, and confidence through high speed corners is massively improved, despite the added weight. 

 

 

Are you losing any top end speed on the straights?

collinskl1
collinskl1 Reader
2/1/21 6:30 a.m.

I race a 318ti with a plywood splitter and a fiberglass wing from Wingmen Aerodynamics. At the tracks I've run comparison tests with and without aero (Gingerman, Nelson Ledges, and Pitt Race) I see an average of 2 seconds a lap faster with the aero. My data shows 2.5-4.5 mph faster in each corner, while losing 3.5-5 mph on the straights.

Clock don't lie - Aero (when properly implemented) is faster, even with my underpowered car.

Superslowmonte
Superslowmonte New Reader
2/1/21 7:18 p.m.

Should i be worried about aero overwhelming my stock-ish suspension? Like the 100 mph t12 road atlanta in already out of travel.... but places like the esses at vir, i think i have some travel left. 

Superslowmonte
Superslowmonte New Reader
2/1/21 7:58 p.m.

Should i be worried about aero overwhelming my stock-ish suspension? Like the 100 mph t12 road atlanta in already out of travel.... but places like the esses at vir, i think i have some travel left. 

collinskl1
collinskl1 Reader
2/2/21 6:58 a.m.

"It depends."

If the aerodynamic devices are effective, they are adding load to the suspension - which will use additional travel based on the springrate. How much is the next question to answer.

Rick O'Shea
Rick O'Shea New Reader
2/2/21 1:17 p.m.
Superslowmonte said:
Rick O'Shea said:

In reply to Superslowmonte :

My splitter, in combination with a 9lives rear wing, allows me to run lap times on two year old RS-4's that I previously could only run using fresh Toyo RR's. The grip, stability, and confidence through high speed corners is massively improved, despite the added weight. 

 

 

Are you losing any top end speed on the straights?

I see a 3-5mph loss on my E46 330 doing 115-120mph on the main straights. I make up for the lost time in the corners and braking. That works for me doing TT but decreased Vmax may become an issue in W2W racing.

So, i went with 1/4 instead of 1/2 with my new splitter. The 1/2 one was destroyed by a deer carcass. 

Its WAY more floppy and flexible than I expected. However,  for autocross i think it will be fine, and the weight savings is substantial. 

Am i underestimating the loads on it? Its limited to csp rules.

stafford1500
stafford1500 Dork
2/8/21 10:08 a.m.

In reply to Dusterbd13-michael (Forum Supporter) :

For highway speeds or lower, with less than a few inches of extension, 1/4" will be fine.

Once you start getting more speed and/or more extension, the bending/deflection will get severe, possibly to the point that it can actually break from the loads.

Robbie (Forum Supporter)
Robbie (Forum Supporter) MegaDork
2/8/21 10:11 a.m.
Dusterbd13-michael (Forum Supporter) said:

So, i went with 1/4 instead of 1/2 with my new splitter. The 1/2 one was destroyed by a deer carcass. 

Its WAY more floppy and flexible than I expected. However,  for autocross i think it will be fine, and the weight savings is substantial. 

Am i underestimating the loads on it? Its limited to csp rules.

Can you wrap it in epoxy fiberglass? That could up the stiffness quite a bit. 

Dusterbd13-michael (Forum Supporter)
Dusterbd13-michael (Forum Supporter) MegaDork
2/8/21 10:50 a.m.

Oof. 

The thing is supported at four points by eye bolts,  fender washers,  and steel cable. Firmly bracked on the topside by the air dam, and protrudes about four inches on the front. Acts as a belly pan to the crossmember. 

Pictures if they help.

Should I be nervous? remove and remake? Send it and see what happens?

stafford1500
stafford1500 Dork
2/8/21 10:55 a.m.

In reply to Dusterbd13-michael (Forum Supporter) :

The epoxy would help with stiffness, but I would go with paint and a well sealed leading edge and send it.

Make sure you have the template, in case you find another deer.

Dusterbd13-michael (Forum Supporter)
Dusterbd13-michael (Forum Supporter) MegaDork
2/8/21 11:45 a.m.

In reply to stafford1500 :

Has a thick coat of leftover valspar rilust tough on all surfaces. 

 

And i kept the "fixed" 1/2 splitter for a template. Cause i know ill need it again. 

triumph7
triumph7 Reader
5/16/21 10:03 p.m.

With current plywood prices some of these splitters would now be more expensive than the rest of the car!

 

wvumtnbkr
wvumtnbkr PowerDork
5/16/21 10:30 p.m.

Lolz....

 

For those of you who are thinking of trying it...

Don't use the 1/2 inch pvc board.  It's tempting because it is weather proof and seems strong enough.

 

1 trip down the straight at Roebling Road and it broke in half and exploded....

 

Back to plywood for me!

malibuguy
malibuguy HalfDork
7/25/22 8:21 a.m.

Is the consensus that for a 99% autoX car 1/4" birch shall be sufficient with adequate bracing/reinforcement ?

apexanimal
apexanimal New Reader
7/30/22 9:09 p.m.

1/2" birch is what you'll want.

gsettle
gsettle
9/7/22 9:41 a.m.
Rick O'Shea said:

BMW E46 Splitter and Air Dam, Part 2

 

I want to be able to install and remove the splitter without taking the bumper off. This way I can load the car into my trailer easier with the splitter off and then take a couple minutes at the track to pop it back on. Plus I don’t have to give up any street driving ground clearance like I would with a permanently mounted splitter. With this in mind, a while ago I removed the front fog lights and filled the openings where the lights were with a thin sheet of plastic. The fog light bezels are made to remove from the outside very easily, and they happen to be big enough for me to fit my arm into when removed. This is how I install and remove the pins that hold the splitter in place.

 

 

 

 

 

With the splitter mounted and level I then traced the outline of the bumper directly to the wood surface using the same 4” square.

 

 

 

My splitter came out to 3.25” off the ground, which should be a good height for balancing performance potential and prevent bottoming out too much.

 

 

 

To fill the gap between the splitter and the bumper I am making and airdam out of .070” HDPE sheet. The airdam is mounted to the splitter surface with a length of .75” x .062” aluminum angle. I cut numerous slits into the angle so it could be shaped to follow the contour of the bumper outline. It is attached with #8 wide head wood screws. The part is made as two pieces so I formed and joined them in the middle with a rivet.

 

 

 

 

 

With the airdam mount in place I marked the splitter at 4” projection and trimmed the splitter to final shape.

 

 

 

The airdam material is soft and easy to cut but also very durable and lightweight. I carefully measured, cut, and riveted the HDPE sheet to the aluminum angle forming a perfect gap filling piece that stays permanently attached to the splitter.

 

 

 

 

 

I know this is an older thread but, does anyone know where to buy this HDPE sheet material to fill the gap?

thanks

With the fabrication finished I took everything apart and scrubbed the aluminum pieces with a red Scotch Brite pad and painted the splitter wood with truck bed liner to seal and protect it. You can also see the finished rear mounts and braces in these pictures. I am using two pieces of 3/16” aluminum that protrude from the back of the splitter. These slot into the U-channel bolted to the undertray providing a sturdy metal to metal junction. Braces were also added to connect the front mount angle brackets to the rear mounts. These braces added a lot of strength for their half pound weight penalty. Final weight of the splitter assembly is 15.5lb. If I change to ¼” Alumalite I should be able to drop another 3-4lb.

 

 

 

 

 

 

 

Before I reassembled the parts I traced the splitter outline onto the rest of my 4x8 sheet so I can cut and prepare a spare to keep in the trailer.

 

 

 

The underside of the splitter is perfectly flat other than a 1/16” lip and button head fasteners at the back edge. I used ¼” ribbed elevator bolts to attach the wood to the aluminum mounts. These have a very wide head that sucks up into the soft wood when you tighten the nuts down.

 

 

 

 

One last thing to show is the leading edge of the splitter. It is important to put a nice radius on this edge to reduce aero pitch sensitivity and help prevent catching on things in the paddock and on the track. Plus it just looks more finished.

 

 

 

Lastly, here are pictures of the finished product on the car. Looking mean! I am hoping for a 1-1.5 second improvement at High Plains Raceway due to the aero improvements.

 

 

 

 

gsettle
gsettle New Reader
9/7/22 9:43 a.m.

Looks great! Does anyone have a source to buy the HDPE material to fill the gap?

 

Ajax2029
Ajax2029 New Reader
9/7/22 2:30 p.m.

In reply to gsettle :

Speedway Motors HPDE

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