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Author Topic:   mod spoiler help
Dirt Freak

Total posts: 334
posted April 13, 2005 09:51 AM  
Our track is allowing spoilers this year so I need to build one. Rule reads: May have spoiler, 5 in. total material.

Most that I looked at around the track are just aluminum. Some are the same angle the whole way, while others start at an angle, then after 3 inches or so, have another bend that almost puts it straight up and down.

Any ideas on the angle I will want?

I just plan to make 4 braces…one on each quarter and one on each side of the fuel filler panel. I’ll just slide the spoiler under the rear decking to pop rivet it on.

Any hints / tips, as this will be my first spoiler.


Dirt Forum Champ
Total posts: 2007
posted April 13, 2005 10:04 AM  
Id make it so that the last 1" or so was bent forward a little to stiffen it. Then Id start with it about 60* or so from horizontal so like you were saying thelast 1" or so might end up about straight up and down.

The other thing you can do instead of the braces in the middle is run a 1X1 aluminum angle along the top edge on the back of it to stiffen it. Then you dont have the braces in the middle of the deck.

Dirt Forum Champ
Total posts: 505
posted April 13, 2005 10:27 AM  
I usually build them similar to db. If you have 5 inches to work with I would do 4 inches @ 60-70* from vertical then a 1" wicker bent forward 90* to the rest of the spoiler. I also like to split the spoiler ~12" from the right edge and put a brace there so if you hit the wall with the rr corner it only takes off that 12" piece and not the whole spoiler.

[This message has been edited by wfoondirt (edited April 13, 2005).]

Dirt Freak

Total posts: 334
posted April 14, 2005 07:51 AM  
What change in handling can I expect by adding a 5” spoiler?

More rear down force down the straights, resulting in less rear percent needed, resulting in a lighter car…what about in the and around the turns though?

First night out, had a guy run all down the left side of my car going into turn 1 at the start of the feature. Somehow, he managed to hit me again last week…so we had to have a “nice conversation” I like to call it. He said the first time was because it was his first time running a spoiler…so either a spoiler takes away ALL sidebite on entry, or just makes you not let off going in so you can use the other cars as a wall.


Dirt Full Roller

Total posts: 46
posted April 14, 2005 01:54 PM  
We added a spoiler this year. We took out some rear% thinking we wouldn't need as much. We have added it all back. Really can't tell much diff. on our 3/8 mile semi banked track, but the car sure looks faster with a spoiler on it. LOL.

Dirt Forum Champ
Total posts: 2007
posted April 14, 2005 02:16 PM  
While I am sure the spoiler helps some, I dont think it really makes a huge difference. In order to really get good downforce you need to have smooth airflow to the spoiler. With a mod you have the driver ruining the air on 1 side which prob screws up most of the spoilers effect there and what little you get out of the other side is prob hardly noticeable. Now if you could run a 10" spoiler that might be different.

We used to say that the best part about a spoiler was it kept people from sitting on the back of the

[This message has been edited by dirtbuster (edited April 14, 2005).]

Dirt Forum Champ
Total posts: 755
posted April 15, 2005 07:08 AM  
Honestly when our track started allowing a 5" spoiler a few years ago some people ran them and some didnt. Some won with them and some won without them. I dont think a 5" spoiler is tall enough to do any real difference.

In my latemodel I got my spoiler (8") knocked off one night and after that I couldnt touch the throttle without buzzing the tires, but with the modified I could never tell a difference with or without it.

About the only thing I think it DOES do is make the cars look cooler

Dirt Full Roller

Total posts: 49
posted April 15, 2005 07:17 AM  
I've run with a spoiler and without and honestly cannot tell any diference. If you want to run one though, DO NOT PUT A 1", 90 lip at the top. There hve been wind tunnel tests on Late Models that show the extra little bend actually takes downforce off the spoiler! Build the thing straight from bottom to top and put a piece of flat strap aluminum on the backside to stiffen it up.

Other than making the car look cooler there doesn't feel like any benefit to adding one.

JMO from what we've run.

Dirt Forum Racer

Total posts: 86
posted April 15, 2005 07:47 AM  
I studied aerodynamics for a private pilots ground school. Any spoiler or flap that becomes too steep to the wind starts to stall out and the big turbulence it creates behind takes away the lift in front. A 45 degree angle is the all around best for down force versus drag.

Dirt Forum Champ
Total posts: 2007
posted April 15, 2005 09:07 AM  
I agree that 45* is prob better for 'aero' downforce but there is also a school of thought that just the braking effect of the spoiler has more to do with traction than actual aerodyanmics. The idea is that the more vertical the spoiler is the more it drags which creates leverage over the rear axle that transfers more weight from the front. I have seen this with some latemodels that have big 10" spoiler almost straight up and down.

Dirt Forum Champ
Total posts: 1875
posted April 15, 2005 10:08 AM  
a thought as far as mod aero/ late model aero, a latemodel has air flow over it much better than a modified does. the front tires of the mod throw alot of air off the car.
personally i run a spoiler for looks only, i have ran spoiler, no spoiler, and drag the spoiler behind the car, i cannot tell the difference in any of them. i think the car looks better with one.

Dirt Freak

Total posts: 334
posted April 15, 2005 12:05 PM  
Sounds like the consensus is that it helps looks only. I’ll spend more time on the scales this weekend instead of making the spoiler.

Forgot to mention. The track also allows a 2” spoiler on the front nose on each side as well. Any thoughts on effectiveness?

[This message has been edited by dluna (edited April 15, 2005).]

Dirt Maniac

Total posts: 169
posted April 15, 2005 02:52 PM  
I think the look cool,I was gonna make some for the front,like your talking about.

Dirt Maniac

Total posts: 168
posted April 15, 2005 08:24 PM  
One of the things to think about is drivers vision is restricted when solid panal spoiler are used. by not being able to see thru other cars as easly. I think if I made the rules they should at least start out as something transparent like the one wfoondirt has pictured. One never knows if or when a accident could have been avoided.

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