How To: DIY Front Splitter

Alright y'all I'm here to show you a guide on how to build a fully functional splitter for around $250.00

Materials you'll need:

(1) 4in. x 8ft 1/4" Thick ABS Plastic Strip - $15.00

(1) 4ft x 8ft 1/2" Thick Birch Plywood Sheet - $40.00

(1) 1ft x 1ft Stainless Steel Sheet - $20.00

(20) 5/16"-1 1/2" Carriage Bolts/Washers/Lock Washers/Nuts - $20.00

(2) 2 1/2" Stanley Hardware Corner Brace - 4 per pack - $8.00

(1) 1 1/2" Stanley Hardware Corner Brace - 4 per pack - $6.00

(1) Minwax 32oz Helmsman Semi-Gloss Spar Urethane - $20.00

(1) Paint Brush - $4.00

(5) 3/8" Thread - 11" Hex Bar Turnbuckles - $32.00

(5) 3/8" Thread LH Male Spherical Rod Ends - $20.00

(5) 3/8" Thread RH Male Spherical Rod Ends - $20.00

(2) 3 Pack of Grade 8 1/4" bolts - $3.00

(6) 1/4" T-Nuts - $6.00

(4) 3 Pack of Grade 8 3/8" Bolts - $8.00

(11) 3/8" T-Nuts - $15

(3) Cans of Black primer - $12.00

(3) Cans of Base coat (color of choice for splitter) - $12.00

(3) Cans of Clear Coat - $12.00

(1) Pack of 200 grit Sand Paper - $4.00

(1) Pack of 600 grit Sand Paper - $4.00

(1) Pack of Tack Cloths - $2.00

Total Cost - $263.00

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The tools you'll need assume that you have access to cutting and drilling tools. If not, this will obviously inflate your costs.

-Basic Hand tools

-Dremel w/ Cutting Wheel

-Circular Saw

-Jigsaw Cutter

-Metal Brake

-Drill w/ Cobalt Drill Bits

-Sanding Block

-C Clamps

-Measuring Tape

-Sharpie

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Instructions:

To start you should cut any part of the underside of the bumper that acts as a flat surface. This will obviously no longer be used since we'll be running the splitter. Now mock up the ABS plastic strip to the bottom of the bumper. From this point I will refer to the plastic strip as the "splitter apron". Determine how low you'd like the splitter apron to sit on the front of the bumper. Keep the thickness of the plywood in mind (1/2") and the fact that you will be using the 2 1/2" corner braces to secure the apron to the splitter itself. The apron should be mounted on the flattest part of the bottom of the bumper. For the Roush, we had to make some clearance cuts because there were some surfaces that would have made it difficult to wrap the apron around without it bulging. You want a perfectly smooth curve for the apron to go around as it will look better and be more efficient.

After you have figured out the best height for the splitter apron, you need to level the apron from corner to corner. luckily the floor in our garage was 100% even so we were able to do this with ease. After you have this done, lock it in place with c-clamps!

Since we have a perfectly level apron now, it would be a good time to start drilling the holes for the splitter apron to mount to the bumper. We used a total of 20 5/16" carriage bolts spaced 4.5" apart. This distance will vary based upon the size of your bumper, but 4.5" should be a pretty good starting point for the distances on all 99-04 mustang bumpers. Drill to the size that will fit the square part of the carriage bolt just barely inside of the drilled hole. I believe this size is 3/8". Once you have drilled out one, be sure to fasten the carriage bolt in place. Do this one at a time going from one side to the other, moving the c-clamp along as you go and stretching the apron on the side not fastened as you go. After you get all the way around to the other edge of the bumper, cut off the excess plastic with a dremel. You may need to cut some excess material off around the air dam if it covers any part of the air dam. If this is the case go in from the rear side of the bumper and mark off with a sharpie where you need to make a cut to open the air dam up, remove the air dam, and make the cuts, then reinstall using the same stretch fashion as before. Now you should be at this point (minus the splitter being already complete...)

Now, that the apron is complete you have to determine how far you want the splitter to stick out and how far you want to extend back. The limitations for my racing class is 6" from the bumper and no wider than the widest point of the bumper from a vertical view point and the splitter cannot extend past the front tires. After you've determined these dimensions you want, set the bumper at the very front of the sheet of plywood and with a sharpie trace the shape of the curve that apron follows. This will give you the same curvature back that the bumper follows. After you have the curve, go straight back from the front of the wood to the rearmost part of the bumper, this way it lines up perfectly with the widest part of the bumper itself like so: (imagine a sharpie line where we made cuts)

Now you will do the cutting. **NOTE** Always wear safety goggles when cutting any kind of material!!!. get a straight edge to go from the rear side to side. mark it with a sharpie then fasten the straight edge down with c-clamps. this line will be the line you follow as you make your cuts with a circular saw for the rear of the splitter. Then cut from the front straight back to the rear cut you just made, do a straight cut to make it boxed first. after you make this cut then take your Jig-saw and follow the rounded edges you created towards the front. The smoother you are with this cut the less prep work you will have to do later! Now you have yourself a raw splitter!

At this point you need to line up the bumper to the splitter. we once again used c-clamps to hold the bumper to the splitter. Now you will take the (8) 2 1/2" Corner Braces and the (2) 1 1/2" Corner Braces install them over the 5/16" thread that protrudes through from the splitter apron carriage bolts. Then mark with a sharpie where you will need to drill the through the wood. Do this one hole/brace at a time and install a bolt and t-nut (through the underside) on it as you go. Work from the outer edges toward the front when you do this process. After this reinstall the bumper.

Now we will be mocking up the splitter rods. First thing is first. You will need to use the metal brake to bend some metal. We made a total of 10 support brackets from the 1/4" thick stainless steel sheet. We bent the metal and cut as needed then drilled two 5/16" holes on the bottom side and through the side we drilled 1 3/8" hole. This was the final product:

Now we need to mock up the brackets for the splitter rods. take the bracket and line it up with your grille so that the rods will be able to extend through it. This will take some time and measuring, do not rush this process! you will need to do 5 brackets (3 up front and 2 out back) and 10 drilled holes on the splitter itself and 5 brackets with 10 drilled holes on the bumper support. For the bumper support just mark the spot you want the brackets to be in then take the bumper and bumper support of the car. Now is the fun part. drill the 10 holes into the bumper support. Make sure that you use a VERY sharp drill bit and I highly recommend lubing up the drill bit and surface with wd-40 to help drilling! Next you will need to make a couple access holes in the bumper support so you can thread a nut on the bolt. After you're done it will look something like this:

3 rods for the front and 2 more rods will be added at the end of the bumper support to hold the ends of the splitter up.

Now that you have done the mock up it's time to remove everything from the splitter and prepare it for paint. Break out the paint brush and Helmsman Spar Urethane.

Before you start coating, lightly sand the plywood with 200 grit to remove any splinters, or other damaged areas that may have been caused from your cutting or drilling. At this time you can also use wood putty to fill any holes that are too large for the urethane to fill. I didn't do this because I didn't think about it, but, it's definitely a good idea on the edge of the splitter.

Now it's time to coat the splitter in urethane. do not shake the can of urethane or induce any bubbles, this will negatively effect the adhesion process. You will want to do 4 coats of urethane and sand 200 grit between coats. When you apply the spar urethane apply it in the direction of the wood grain so it can sink into the grooves. Let each coat cure for 24 hours before sanding!!! By the time you are done you should be through the entire can of urethane which is about 1.5lbs worth of urethane.

After your last coat of urethane, sand with 200 grit then in a cross direction sand with 600 grit to prepare for primer. Apply 3 coats of primer and sand as needed after the 3 coats have dried. If you smoothed out the splitter well enough after the urethane, you shouldn't need to sand much. Then apply your base and clear and you're good to go as far paint!

After the paint has cured for 24 hours or so, reattach the bumper to the splitter and mount it to the car and reattach all the mounting points that you created with the splitter rods.

After you have reattached it to the car, you'll want to adjust the splitter angle up front on the 3 splitter rods. For my car class we have a range of adjustment of +3 degrees to -3 degrees. You'll want to run 0 to -3 degrees generally as this will scoop air and make the splitter more effective at speed. After you have done this and verified everything is solidly attached be sure to test it's strength, you should be able to stand on the splitter no problem. And voila you have yourself a custom, one off splitter!

Finished product:

Behind the bumper attachments:

Brett i feel like those 90's you used are going to bend once you get some serious load on the splitter, would it be more advantageous to go with a straight piece thats bent right at the bolt head instead? that way its not going to bend and basically lengthen out?

Brett i feel like those 90's you used are going to bend once you get some serious load on the splitter, would it be more advantageous to go with a straight piece thats bent right at the bolt head instead? that way its not going to bend and basically lengthen out?

the idea is that you WANT it to bend and have flexibility. if the splitter is too rigid at it's mounting points it will tear off the entire front end of the car. Everything I did was for a reason, the only thing I wanted strong was the front rods. yes the corner braces will flex but I already put them under the most stress they'll ever have, smacking a dip at 80mph on the freeway. everything held up except for the longacre splitter rods which did there job and are supposed to break away under serious stress.

the idea is that you WANT it to bend and have flexibility. if the splitter is too rigid at it's mounting points it will tear off the entire front end of the car. Everything I did was for a reason, the only thing I wanted strong was the front rods. yes the corner braces will flex but I already put them under the most stress they'll ever have, smacking a dip at 80mph on the freeway. everything held up except for the longacre splitter rods which did there job and are supposed to break away under serious stress.

Sounds good to me! That's why you're doing it and not me

Sounds good to me! That's why you're doing it and not me

lol yessir, there's a method to my madness and some madness to my method haha. Learning from my first splitter version the upward loads from hitting the driveway, dips, speed bumps, etc. are much more stressful on the splitter than the loads from downforce. The only part that needed to be reinforced for downforce is the very front where I put the (3) 3/8" rods. This will keep the splitter from dipping under load but at the same time since i used spherical rod ends it does allow a little give in both directions. the L-brackets the way they sit currently do not flex downward with downforce but will flex easily upward with any severe hits, which will prevent any damage to the bumper, bumper support or fenders.This being said, it takes a heavy amount force to bend those braces upward, so realistically unless I'm jumping the car like a rally car I shouldn't have to worry

so the real question is now can you get our of your own driveway to hit the track Can't help but notice that there is JUST enough of a ramp there to make something like this fun?

so the real question is now can you get our of your own driveway to hit the track Can't help but notice that there is JUST enough of a ramp there to make something like this fun?

I scrape a little bit out of the driveway but that's why I went with so many coats of urethane on the underside as well as the t nuts that act as a scrape guard if I bottom out. I make it out of the driveway with no problems and very minimal scraping.

So I have never removed a front bumper from one of these cars, how hard/ quick is it? Pre splitter of course and/or with splitter. Sweet write up btw

bumper isn't too hard.

Obsessed with those rims

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So I have never removed a front bumper from one of these cars, how hard/ quick is it? Pre splitter of course and/or with splitter. Sweet write up btw

bumper is a 5 minute job on my car but I've made a lot of modifications to it. no longer uses tabs on the side, it's held on by two carriage bolts. no more plastic push pins under the bumper or on the top. Also 99-04's are a little bit easier since the headlights are 4 pins that you pull and they slide right out, versus 94-98 which you had to use needle nose pliers to squeeze the headlight pins through the header panel to remove.

Obsessed with those rims

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haha, shoulda told me bud, the rims are going bye bye this month. sold them to [MENTION=19]Solar[/MENTION]

Damn seriously ugh...

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I miss the red edge, other than that it looks great :thumb:

get some more pics up....some from the side. looks nuts lol. surprised how smooth the plywood looks.

A layer of fiberglass matt on the bottom would not only make it stronger but also help water proof it better.

A layer of fiberglass matt on the bottom would not only make it stronger but also help water proof it better.

that's what the urethane was for. Urethane is more flexible than fiberglass which has a tendency to crack when bent. it also weatherproofs it and the splitter took a full 1.5lbs of the urethane. Don't think I'll have an issue with it between the urethane and all the coats of paint.

get some more pics up....some from the side. looks nuts lol. surprised how smooth the plywood looks.

what kind of pics lol. I'll probably do a photoshoot this weekend, next month I'm removing and hacking off body panels for its new look next year so I might as well do a "before".

plus the lack of water it will see simply cause of no rain havin' sunny cali :tsk:

plus the lack of water it will see simply cause of no rain havin' sunny cali :tsk:

lol still has to survive being washed... I'm crossing my fingers for a rain auto-x soon honestly. I'd love to get my dorifto on lol

what kind of pics lol. I'll probably do a photoshoot this weekend, next month I'm removing and hacking off body panels for its new look next year so I might as well do a "before".

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lol still has to survive being washed... I'm crossing my fingers for a rain auto-x soon honestly. I'd love to get my dorifto on lol

yea...just do a shoot. i wanna see side shots. also if you can some from up kinda high. bet that would be a sick shot. climb a tree or something :look:

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you wash your racecar? aaawwwwwwww....i'm telliiiiiinnnn

lol I don't need to climb a tree I'm tall enough lmao

damn right I wash it. the paint is what makes the car look as sick as it does. You know this foo! lol

My wheels! Getting them in the next two weeks btw [MENTION=6]iRoush[/MENTION]

[MENTION=19]Solar[/MENTION] super jelly

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Thanks for the write up man! I've been gradually working on a splitter similar to this, great pics.

Just wondering [MENTION=6]iRoush[/MENTION] why do you use wood. Trust me not familiar with any of this style of modifying so just wondering.

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Just wondering [MENTION=6]iRoush[/MENTION] why do you use wood. Trust me not familiar with any of this style of modifying so just wondering.

originally I was planning on only using it as a template but found out the 2013 Street Modified National Champion runs a wood splitter as well. Birch Plywood is a very lightweight a strong wood so it was a viable product to use. Obviously just needed the weather proofing attention and that's its really. This being said, I do still have a sheet of Tegris that I will eventually use when I want to go to a more permanent solution. This splitter will remain a very good template for future designs though.

How has this worked out for you so far Brett?

How has this worked out for you so far Brett?

Still holding up. I'll take some pics tomorrow. some of the paint on the lip has chipped a little bit but overall it's doing very well. This being said, the plywood is being replaced for Tegris next year for Version 3 of the splitter!

Holding together! you can see on the edges where the most abuse occurs... That's only due to my driveway otherwise there'd be minimal scraping lol.

Still holding up. I'll take some pics tomorrow. some of the paint on the lip has chipped a little bit but overall it's doing very well. This being said, the plywood is being replaced for Tegris next year for Version 3 of the splitter!

I would look into a lighter material as well, is a plate of carbon fiber too expensive?

I would look into a lighter material as well, is a plate of carbon fiber too expensive?

Tegris is lighter than carbon fiber and stronger. I already have a 4x8 sheet, cost me $550 for it lol

Tegris is lighter than carbon fiber and stronger. I already have a 4x8 sheet, cost me $550 for it lol

Well then make it happen' captain'

Well then make it happen' captain'

on the to do list, I have a couple of other projects that are more important right now.

Tegris is lighter than carbon fiber and stronger. I already have a 4x8 sheet, cost me $550 for it lol

Interesting material, just looked it up. 

We're did you purchase the abs plastic from? Thanks

We're did you purchase the abs plastic from? Thanks

a local plastic fabrication shop. ATI Plastics

a local plastic fabrication shop. ATI Plastics

I read that you also have carriage bolts holding the bumper do you have spacers in between?

Cool thanks

I read that you also have carriage bolts holding the bumper do you have spacers in between?

yes on the sides I used a 3/4" spacer so the sides don't get sucked in weird.

yes on the sides I used a 3/4" spacer so the sides don't get sucked in weird.

Thanks sorry for all the questions I just love how your front end looks. Keep up the good work

Thanks sorry for all the questions I just love how your front end looks. Keep up the good work

no problem! that's the whole point of this thread!