Mazdaspeed3 Racing Seat/Harness Install Write Up

The stock seats are great for driving your girlfriend around town, but to maximize the performance on the track, a racing seat/harness is a must. I went through 3 seat rails before I finally found the right setup that allows me to sit in a low position. Hopefully this write-up will help other Mazdaspeed3 owners to do it right the first time.

Parts to buy:

1. Racing Seat: I chose the Sparco Corsa seat for it’s superior lateral holding capability. It’s very comfortable and supportive, I would highly recommended to anyone.
2. Side Mount: Order Sparco Aluminum Side Mount (Part# 00490W)
3. Sparco Hardware Kit: Needed to mount the side mount onto the seat (Part# 50001)
4. Seat Slider: Sparco Flat Slider (Part# 00493), this slider gives you the lowest mounting position.
5. Seat Rail: Call Wendell at Wedge Engineering and order a driver side seat rail for Mazda3, specify you’ll be using it with Sparco Flat Slider, and also tell him your seat width measurement (install side mount on the seat and measure across from the middle of the bottom mounting holes). Since their rails use threaded mounting holes, ask him to include the 4 mounting bolts, they are the perfect size and are very strong.
   

   The Wedge Engineering rail turned out to be a very study piece.

6. Racing Harness: I chose Schroth Profi-II ASM. You can leave it in 4 point configuration for ease of use driving around town, and the ASM technology will prevent you from sub-marining (common with traditional 4pt belts) in an event of crash. For more information see HMS Motorsport. I also highly recommend reading the Schroth Competition Manual to understand proper mounting of racing harnesses.
7. Schroth B24 Bracket and SG11 Bolt: The Profi-II harness came with snap-in ends for use with eye bolts. Unfortunately the right side lap belt mounting point on this rail will not work with an eye-bolt in this configuration. If the eye bolt is installed with the eye on the right side, it will hit the tranmission tunnel. If the eye is on the left side, it blocks the side mount. So it’s necessary to convert the right side lap belt end into a bolt on bracket. It’s important to get the SG11 bolt, so that in a bolt on configuration, the harness end can still rotately freely.
   

   Schroth B24 Bracket. Watch HMS Motorsport's youtube video on how to dissamble the flexi-belt end.

   
   

   SG11 Bolt has a machined shoulder that will allow the B24 bracket to rotate freely.

8. Spacer or washers with ID just big enough to slide over the SG11 bolt but not go over the machined shoulder. This is needed in step 8 to clear the harness of the sharp edge.
9. Sparco Harness Bar for 02+ Subaru WRX (Part# 300175): Thanks for the Cobb Tuning guys who measured the B Pillar distance, it turned out the WRX harness bar from Sparco is a direct fit to Mazdaspeed3 as well ! You’ll also need a longer bolt than the supplied one, take out the stock mounting bolt from B Pillar, go to the hardware store and get 2 Grade 8 or higher bolts that are 1″ longer.
10. Schroth Profi Single Sub Strap: This is optional, I have to use it because NASA requires atleast a 5 point harness. I tried to use a 6 point sub-belt as well, but with the shape of the floorboard, it’s difficult to mount a 2 point sub-strap correctly. Installing this will require driling a hole on the floor board, and cut away the plastic AC vent under the seat.

Install: Now that we have the proper that are tested to work, installation is a breeze.

1. Begin by removing the 4 bolts that hold the factory seat rail down.
2. Reach down and disconnect the air bag sensor. (Push the ribbed tab in a downward direction to disengage the sensor)
3. Carefully remove the seat from the car
   

   Seat Removed

4. Mount side mount on to the seat first (this way the side mount won’t stress the fiberglass after bolted down)
5. Install Sparco flat slider on to the wedge rail
   

   Slider Installed

6. Install Sparco adjuster handle onto the 2 slider adjuster prong (you’ll have to bend the handle alittle bit to the right shape, and then use a rubber mallet to hammer it down, make sure it’s secure)
7. Install the seat onto the Sparco seat rail
   

   Seat Installed

8. At this time you should install the right side lap belt harness onto the rail. Convert the Schroth right side lap belt end into B24 bracket (follow instruction on here). Install the B24 bracket into the seat rail by using the SG11 bolt (the bolt will thread right into seat rail hole). Install the bracket on the outside, and point it away from the sharp edge to prevent damage to the belt when being used. I had to use a spacer to get enough clearance, I found the spacer in my partsbox, you can use washers or find a spacer in the hardware store, just make sure it slips over the the bolt thread, but doesn’t go over the machined shoulder, the shoulder allows the seat belt end to rotate freely.
   

   It should look like this after installed.

9. Go back to the car and install the Sparco Harness Bar, it’s pretty stright forward, follow the instruction here. I did not reinstall the driver side stock seat belt, because it no longer rotates freely. On the passenger side, I angled the upper seatbelt guide forward so that it doesn’t bind when being pulled, a better way to do it is to use the right spacer that’ll allow the seatbelt guide to rotate freely. **Take care to insure the harness bar is nearly horizontal with your shoulder, the harness should be installed at no more than a 20deg downward angle, for more information on this consult Schroth Competition Manual. Torque the top bolt to 57 ft. lbs.
10. Install an eye bolt in the left OEM lap belt bolt hole. This is also were you’ll be mounting the harness bar support. On the passenger side, the hole is there, you just have to cut the carpet to expose it. Torque the passenger side bottom bolt to 57 ft. lbs.
    

    Driver side installed

11. Install sub strap (optional): I had to install a 5th point sub-strap to fulfill NASA requirement. I had to cut enough carpet to expose the floor board, and cut off the plastic a/c vent piece. I then put the seat in position and marked approximately where the sub-strap should be mounted. On a 5 point harness, it’s recommend that the mounting point is inline with the upper body angle, or further forward. This is to prevent your family jewel from getting squashed in an event of crash. Consult Schroth Competition Manual for more information. I then removed the seat, took out the underbody plastic panel, and drilled a hole using 7/16 drill bit. Schroth sub-belt comes with an eye bolt and a reinforcement plate. Place the reinforcement plate under the car, and thread the eye bolt in from top. Use a screw driver to torque it down. Reinstall underbody plastic panel.
    

    Cut Off the A/C Vent

12. Now we can finally mount the seat into the car. Torque the 4 seat rail mounting bolts to 39 ft. lbs. Clip the left lap belt/sub-belt in place. Wrap the shoulder harness around the rear harness bar. Again refer to Schroth Competition Manual for proper wrapping instruction.
    

    Finished Install ! I'm not trying to make a fashion statement with the seat padding ! It's temporary until I shave off some height off the Sparco padding for a lower seating position.

    

    Note the shoulder harness adjuster are placed as rearward as possible to prevent getting caught in the event of a crash.

    Congratulations ! You’ve got your racing seat and harness installed in a safe maner. You are now ready to rock out on the track !

Willow Springs International Raceway Feb. 7-8, 2009

One thing I’ve learned about building Mazdaspeed3 for racing, on an untried platform, racing parts are few and far and in between.  I ordered the Mazdaspeed coilover from Mazda Motorsport back in November of 2008, as of late January 2009, it was still on back order !  Wayne @ Phase2motortrend.com came through after hearing about my coilover dillema.  He had a source that had a sets in stock, and was able to get it for me in just a week !  Go Phase 2 !  The Mazdaspeed coilover is a very high quality set manufactured by K&W, the damping can be adjusting in both compression and rebound separately.  After looking over the coilover, I realized that my front K-Mac Adjustable Camber/Castor plate will not fit correctly, unless a custom top hat is machined.  I called Jeff @ Tri-Point to custom make an adapter, sure enough a week later, I had the front coilovers back in my hand with the K-Mac Camber plate correctly fitted.  Now with only a week left before the track day at Willow Springs, and a busy schedule at work.  I decided to let Ken @ Performance Autoexpress to handle the install.  They are the only shop in this area that I trust to work on my car.  It also helps that they have an inhouse Hunter laser alignment rack, and corner weight scales.  It makes setting up suspension an easy one stop shop !  Just when I thought this saga is over, Ken calls me to tell me that the stock sway bar end links are alittle too long, and there’s very little clerance between the lower controlarm and the sway bar end.  It’s now Thursday afternoon, crap !  I was determined to get this done before this weekend, I called Tony @ AWR Racing, he had all the components in stock and was able to piece together a set asap, I had him overnight me a set of the shortest off the shelf links he had, it ended up being the Protege link.  Thumbs up to Tony for coming through on such a short notice !

The finished assembly, Mazdaspeed Coilover/KMac Camber-Caster Plate

Friday night, I picked up the MS3 from Performance Auto Express, luckily the sway bar end links got there in time.  Ken maxed out the camber/caster and we set the toe to slight toe out.  I ended up with -2.5 camber and 3.9deg castor (3.0 deg stock), not as much camber as I was hoping for, but it’s not too bad, and the additional castor is a nice surprise.  Rear camber ended up being -2, too much !  A Mazdaspeed or SPC camber arm would fix that, unfortunately that’s not allowed in my NASA TTD class next year.  I get home and measure the ride height, turned out the front ride height was too high compared to Mazdaspeed manual’s reference height, darn it, the camber plate plus the new adapter is thicker than stock, so I lowered it as much as I can, and then I realized the abs sensor bracket is unusually huge and prevents the lower spring perch from going all the way down.  I got the front ride height to be 10mm of the reference setting.  Ohh wellz, close enough.  Next time I’ll have to cut the abs wire bracket and lower the spring perch all the way.  The front ride height will still probably be a few mm too high, I’ll just raise up the rear to compensate.  So with ride height out of the way, I put on the Enkei wheels to see if it clears the coilover, oops the lower spring perch is so low now, it rubs the tire sidewall, f me ! it’s Friday night, I have no place to get a spacer.  I decided to just use the stock Potenza re050 tires for the whole weekend.  Next time I’ll have to use a 5mm spacer.  Maybe the little voice in the back of my head was right, Mazda3 just wasn’t build for racing.

Saturday morning, I get to willow springs, and the track is cold and wet.  My favorite !  This is the only place where the 3 feels somewhat tail happy, haha….  So I set off to learn the track that they call “The Fastest Road in the West”.  Being in big willow feels like a step back in time, they still have the original paintings for the Indy car garages.  The track itself is fairly straight forward, until you get to turn 8,  it’s darn scary, it’s a right hander bend taking at close to 110mph, I take it in top of 5^th gear with a slight lift…  I can feel the load being forced into the outside Potenza RE50 tires in a manner that I’ve never experienced at any other track, needless to say, it kept me on my toes the whole day, one small mishap here can lead to disaster !   Turn 9 is even worse, you are slowing down in top gear, while turning into a highspeed decreasing radius corner while keeping up speed, it’s very tricky to get it right.  In fact, I went off in Session 2, because I used alittle too much track on the outside.  LoL, the images of the Mullerized EVO crash flashed through my eyes !  Turn 1 and 2 were abit problematic in MS3 compare to other cars, as the front end is too heavy, and the tire washes out quickly.  It was difficult to carry speed in those corners.  Hopefully the RA1 will have enough grip to offset the weight.  Later in the day I met Sheng the ex-Asia Formula Renault driver, he’s a instructor at Speed Venture and was driving around in his wifes stock E46 M3.  He hopped in my car for a few laps and gave me some excellent pointers on the track.  Fastest lap of the day was a 1 min. 40 seconds.  That’s pretty good on stock tires, as the TTD class record at NASA for this class is 1 min. 35 seconds.  This should be no problem with Toyo RA1s.

Clint's Turbo Focus, possibly the Fastest Focus in the country !

This Ford GT looks incredible ! However the axle bolt somehow backed out... They had a near catastrophe !

A Noble M12 on slick tires with upgraded suspension. There's always some tuner out there to make your car go faster, if you can swing the price tag !

Insane Bimmer with slicks and force induction !

Mazda owner's hang out spot

Sunday morning I get to the track and it’s dry !  Hooray if only I brought r-compound tires.  By now my stock front tires were gone.  The outside front was severely chunked all the way to the cord, probably from the load it took in turn 2 and turn 8.  I decided to swap it to the inside rear, it will see the least load there.  By 2^nd session, I did a 1min 39sec !  yay !  My joy didn’t last long as the car developed a clunk on the right front corner.  This track is no place to risk mechanic problems, I jacked up the right front and looked around.  Turned out the top nut on the strut was loose, WTF !  the shock coulda came off on track !  I borrowed a impact wrench from Tony the crazy mazda6 showroom stock racer, and tightened it back up.  Good to go again !  My right front tire continues to chunk at an alarming rate now that the track is dry, I swap my last good tire on the outside front.  Over the weekend, I eventually chunked all 4 stock tires, lol……  As I tightend up the lugnut, I stripped yet another wheel stud !  WTF…  This time I’m 100% sure it’s not my fault, Mazda just uses seriously cheap material on the studs (or is it FORD?)  I jam the lug nut in, and hoped it will hold for the last few sessions.  I’ll use less torque on the lugnut next time, and if it happens again, I’ll replace them with ARP studs !

Tony the crazy racer drives a mazda6 at the SCCA showroom stock C class, his car has a full cage, it’s his daily driver, and he drives it to the track to race wheel to wheel ! Nuts ! Humm, what if I put in a cage, and ….

Brian showed up in a stock MS3 with Neova AD08 tires. He's building a MS3 for time attack and had camera crew documenting their progress.

I also met Ricardo, who used to work with Mazda rally/road race programs in the 70s/80s, he brought out his friend’s 1st gen RX7 with a Corvette LS1 motors ! the car is a total sleeper, it looks like a completely stock 1st gen rx7, until you start the engine !

It was interesting to talk to him about the rotary engine, he prefers NA rotarys with bridge/peripheral ports rather than turbocharging them. He says rotaries are simply not reliable when turbocharged at high boost level. I told him about my FD at home, and it was good to know that even Mazda gurus hates the FD sequential turbo vacuumlines, haha…

After Speed Venture, I headed over the to streets of willow to meet up with Sam and his Subaru crew.  Race flias got them pretty good, as everyone was having mechanical problems.  Sam somehow hits a cone on the track and it destroyed his undertray !  I met the tuners at Yami sport, who were respected ecu tuners in the Subaru community, they were interested in developing ecu tunes for Mazdaspeed3.  They explained to me that the newer cars are very complicated to tune due to the ecus having additional compensation fuel/igniton maps.  And it turns out the Mazdaspeed ecu has 16 ignition maps?  Wtf????  No wonder people were having so much problem with ecu flashes on the Mazdaspeed3.

Overall the weekend was very positive, I was able to get to grip with Willow Springs quickly and the new coilover is performing well.  Once I optimized the suspension setting, the car should be even closer to neutral.  Stuff to do before 1^st race March 7^th: cut abs sensor bracket and lower front ride height, loctite upper strut nut, dyno the car and submit to NASA for class approval.  Mount new RA1 tires in the front.  Order H&R 5mm spacers.  Replace wheel stud.  Corner balance the car.