SCCA Super Touring U Build
 

Since Fall 2009 I have been in the process of converting my 83 Improved Touring 7 RX7 to one of the SCCA's newest classes. I'm not done yet but have reached a point where the light at the end of the tunnel is a little brighter. So, I thought I would share the experience with you.

The Super Touring category is relatively new to the SCCA. It was originally introduced in 2006 as a set of National classes that would allow ex-SCCA Pro Racing World Challenge cars a place to compete in SCCA Club Racing. In the beginning two classes were called B Prepared and D Prepared. The BP class for Vettes, Vipers, etc and DP for the small bore sedans. In 2008 the classes were renamed Super Touring Over (over 3.0L) and Super Touring Under (under 3.0L). In addtion to the rename the SCCA decided to allow 1989 and later SCCAvImproved Touring cars to compete in STU as a way to boost the class and let more drivers experience SCCA National Racing. In 2009 the age rule changed to 1985 which made my car eligible because it was series produced through calendar year 1985.

The make up of the Super Touring class also changed from being a haven for ex-pro cars to being a builder's class. As a result the rules have been written, rewritten and then changed again. This has posed a number of challenges over the years and I suspect dealing with this rule set will continue to be "fun" for years to come. At least the SCCA has been responsive to some of my rules requests.

At it's heart Super Touring is an engine swap class. Eligible cars are allowed to use any engine as long as it was available in the US, from 1985 to present, and is available from the maker of the car. So this means my RX7 can use any Mazda engine that was sold in the US since 1985. This would include rotory and pistion engines both normally aspirated and turbocharged. In STU the engine displacement limit for my car is a 3.2L V6.

The cars in the class are balanced by a wieght x engine displacement formula of 1.1lbs per CC. Turbocharged cars use a weight scale that factors in a Single Inlet Restriictor (SIR). Currently normally aspirated rotaries are allowed at favorable wieghts - 2200 for a Street Port 12A and 2300 for a Street Port 13B. Renesis engines are allowed at 2300 (unported) and jsut this month a Bridge Ported 13B was classed at 2600lbs. Induciton is limited to stock EFI or a 2bbl Weber with specific chokes.

You can read more at www.SCCA.com - Club Racing - Cars and Rules.

Here is the starting point - built in 1995 as an ITA racecar. I am the car's 4th owner and I bought it in 2003. Over the next 7 seasons I won 16 clubraces, 1 SCCA Pro Race, set 3 track records and shared a Division points championship in 2007:

From an October race at Gateway International 2008
http://inlinethumb13.webshots.com/44...600x600Q85.jpghttp://i1273.photobucket.com/albums/...pszkojadz5.jpg

The interior
http://inlinethumb61.webshots.com/48...600x600Q85.jpghttp://i1273.photobucket.com/albums/...psqubr4sia.jpg
Attachment 718401

The engine - 12A Stock Port with an ISC Niki and ISC Header
Attachment 718402
http://inlinethumb44.webshots.com/45...600x600Q85.jpg

Frist steps - stripping the car.

Interior getting stripped as well. Factory steering column mounts cut out of the car and the brake/clutch pedal assembly has been removed.
Attachment 718403

Another shot of the interior - the steering shaft can be seen
Attachment 718404

The 12A engine shortly before removal
Attachment 718405

Scott, its funny that you posted this. I was JUST looking for a build thread just like this one for inspiration on my build.

Keep the updates coming :nod:

I wish i still lived in KC, it always made my day going to your shop and Charlie's shop :icon_tup:

Roll Cage and Chassis work

The STO/STU rule sets allow for inner fender modificatons. Since fender flares are not allowed and an 8" wide wheel is i decided to do some cutting in the engine compartment. This will allow the car to be lowered drastically without tire rub issues. Before cutting out the inner fenders I made a temporary brace so that the shock towers would not move. You can see this in some of the photos

Left front inner fender removed - this includes cutting into the box structure that runs across the top on both sides.
Attachment 718406

Right Wheel Well
Attachment 718407

The openning in the boxed section was sealed with 16ga-14ga steel to maintain strength. This work was done on both sides
Attachment 718408

New inner fenders were made out of basement window covers from Lowes. There is some additional cage work in some of these phots that I will detail later
Attachment 718409

Will do. Yeah Charlie's shop is super educational!

More Cage work

Mounting the forward tubes in the rollcage. These tubes are required for SCCA Production and GT cars. They are also allowed in Super Touring. Connecting the front of an RX7 to the roll cage makes a HUGE difference in how these cars handle. The front of this car will be triangulated and connected to the rest of the car through the cage.

On the left side. This is a 14ga plate that replaced the OE firewall on that side. The tube that passes through it will be welded to the plate as well as to the shock tower and the cage inside the car. Attaching the tube to the firewall adds to its effectivness.

Attachment 718410

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Two more tubes are added to create the triangle. These tubes do not pass through the firewall. Instead they weld to the 11ga plates that have separate tubes on the inside of the car that attach to the cage.

Attachment 718412

Inside the car - the two center tubes can be seen

Attachment 718413

Left side detail

http://inlinethumb23.webshots.com/49...600x600Q85.jpg

http://i1273.photobucket.com/albums/...psyfzxoagc.jpg

WOW great job good use of the rule book. The last pic reminds me of a 3rd gen rx7 they are the same with out inner wheel wells.

Nice work
 

Love the way you raised the strut towers. I'm going to look at that on mine so I can get some suspension travel back.

The rest of the cage upgrades

At the back of the car I triangulated the area between the spring mounts and the center of the main hoop. This car has to use the OE rear spring location so I extended the cage to the factory reinforcement structures.

Attachment 718414

In the center I used an "X" brace to connect the front and rear of the car. An alternate option would have been a single straight tube from the front to the back but this places a tube close to the driver. The "X" brace moves the tubing away from me and distributes loads to multiple locations in the cage.

Rear
http://i1273.photobucket.com/albums/...pspefnktn1.jpg

Front
Attachment 718415

On the driver's side I added another tube to the door bars and then attached the door bars to the rocker sill. The bace to the rocker sill sets on top of a jack post the goes through the rocker panel. I did the same thing on the passenger side.
Attachment 718416

Thanks, here is how I did it'

I started by making tops out of 11ga steel. The strut hole was cut with a 3" hole saw on a Mill/Drill. The strut mount holes were copied from the oe mounting holes. So that the new strut tops would be in correct place I bolted the new tops to the OE strut tops. I used some double ended lug nuts for spacers so that the new top is about an inch higher. I also angled the new strut tops by spacing the forward holes more than the rear holes to help the upper spherical strut bearing align better in its race.

New strut tops bolted into place with the front and back side tacked in place
Attachment 718417

The sides were formed out of 11ga steel and welded/hammered into shape
Attachment 718418

The OE strut tops were cut out with a plasma cutter at a later date.

Right side finished
[Attachment 718419

rear
 

I did similar on the rear. I'm definitely going to copy what you did for the front. Mine won't sit quite as low as yours for everyday use. I'm looking for a little more suspension travel for the street but I do want to be able to set it pretty low for autocross. Here is what I did on the rear. This should give me enough shock travel.

Looks good, really like the welding.

To get shock travel on my car I lowered the shock mounts on the rear axle. Either way you do it, this is a good mod because allot of shock travel is lost when you lower these cars.

Suspension
 

Long before I started updating the roll cage for this project, I started working on the rear suspension. This was not completely planned as I had originally intended to do the cage first but the cage allowances for Super Touring were not clear in the fall of 2009. So I worked on what I could. The joys of building a car to a half baked rule set, I guess.

I investigated several designs before settling on a three link. One of the first considerations was a modified 4 link like the one used successfully in E Production. I decided against this design because it used up too much rear wheel well room. In hind sight this design could have been used because inner wheel wells were eventually opened up for modification in the Super Touring rule set.

Here is a modified 4 link from my friends E Production car. By the way this car won the 2011 E Production SCCA National Championship.

Attachment 718420
Attachment 718421

The upper arm mounts to a bracket that is part of the cage. This setup works but drivers report some bind related issues.

Here is what I decided to go with - 3 Link with a Pan Hard bar. The third link has 7 adjustment holes to accommodate a number of ride height and geometry changes.

Attachment 718422

Here is the 3rd link covered. The top and sides was constructed our of one piece of 18ga steel. The front was 16 ga steel with 14-11ga reinforcements. This piece took a real long time to make and attach to the car. I sealed it with automotive seam sealer. This needs to provide a fire barrier

Attachment 718423

Later I braced the the third link mount to the cage. This mount will apply allot of force to the car and if it can flex it will eventually fail. Been there - seen that.
Attachment 718424

Attachment 718425
Here is the view of the suspension from under the car

http://inlinethumb57.webshots.com/47...600x600Q85.jpg

Rear axle housing. Panhard mount, third link mount and lower control arm mounts

http://i1273.photobucket.com/albums/...ps1791b6e5.jpg
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It's coming together nicely, looks like it is going to be a blast to drive.


Isaac

Love the work your doing. Thanks for documenting it!!

Love seeing fab work like this, definitely subscribing to this one. Do you have any more close up shots of the panhard mount on the body?

3 link
 

I was looking at the 3 link setup. Question, is there a reason you ditched the watts linkage? Would it be in the way? I was thinking about using it with a 3 link setup.

Really digging the work! To me the fab work is the best part of doing a car.

Here is a close up of the chassis mount. This is a 5/8" UB Machine Serrated plate and matching serrated block. It allows the chassis end to be adjusted and the serration help lock the mount into place. I personally don't like slotted mounts on a racecar because they get loose. This should be fine as long as I can keep the bolt tight. I bought all of the this from pitstopusa.com It is circle track stuff
[Attachment 718429

Thanks

The OE watts link is mounted too high in the car and yes, the arms would interfere with the third link. If you want to use a watts link it would need to mount to the back of the rear end housing.

An alternative would be to build a watts link that pivots on the chassis with arms that attach to the rear axle. To see this design go to http://fays2.net and check out the watts link they make for Mustangs.

I went with a panhard bar for several reasons. First it is cheaper - there are only 2 heims. It is lighter because it is simple. Finally, it is possible to get a lower roll center with a panhard rod.

A watts link is a better design because it imparts no handling vices as the car goes through roll. That said, a panhard bar works and is butt simple.

3 link
 

Thanks for the reply. I like the link you gave me. The pivot for the watts is on the frame, not the axle housing. Still works the same but out of the way. Thats pretty cool.

I like their design but allot of it is based around the adjustability of the axle clamps. These work great on a rear axle that is built with round axle tubes like a Ford 8.8.

The problem that I see with the Mazda rear axle housing is that axle clamps won't work because the axle tubes have an irregular shape. This means that brackets would have to be welded to the tubes which presents some challenges. The other issue would be exhaust clearance.

That said, the Fays2 system is something I may put on my Fox Mustang at some point in the future.

Bump Steer Correction
 

I decided to build in the ability to correct bumpsteer in the front suspension. I have been racing the car for 7 years with a 1" strut spacer and the car lowered probably 2" below stock and I really haven't noticed in bumpsteer. That said it is probably an issue.

Bumpsteer will be corrected at the spindle by using a rod end to replace the outer tie rod end. Typically a 14MM female rod end is used but I decided to use a 5/8 rod end because it will allow me to use spacers that are left over from the bumpsteer kit I put on my Mustang. This meant that I have to build an adjusting stud that has 14mm Right Hand thread on one end and 5/8 Left hand thread on the other. Here is how I did it.

Starting with a new adjusting stud I cut off the RH end and turned it down to 1/2 on a lathe. For the 5/8 side I purchased a 12" hardened steel threaded rod from McMaster-Car and cut it to length. I also turned one end to 1/2 on the lathe. To join the two haves I cut 1" length of 1/2 inside diameter tubing. Everthing was TIG welded together by my friend David Long

Pictures

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More Bumpsteer
 

One of the issues with using a rod end in place of a standard tie rod end is that a rod end will not allow as much misalignment. This particularly an issue when the suspension is in droop. What happens is that the ball in the rod end binds against its race. Eventually this can damage the rod end. To help resolve this I heated and twisted the steering knuckle a few degrees.

Here is the difference between an OE tie rod end and the 5/8" rod ends I am using
Attachment 718433

Right Hand Knuckle - Before
Attachment 718434

Right Hand Knuckle - After
Attachment 718435

Note, this is the second set of steering knuckles I did this too. The first set were bent the wrong way!

Before putting a twist in the steering knuckle, I drilled steering arm to 5/8". I also drilled the strut mounts out to 1/2"

Installed!

http://i1273.photobucket.com/albums/...ps9fbb5007.jpg

bumpsteer
 

Cool solution to the problem. Can't wait to see how it does on the track. Looks like you are about there on the suspension.

As somebody else already commented -- thanks for documenting and sharinig. I'm doing the same sort of thing (Toyota 8 in FB), and I'm glad I found your thread.

Regarding lateral axle location -- have you considered a horizontally mounted watts link attached to the bottom of the pumpkin? It seems to provide a low roll center, and it moves the mechanism away from the back of the axle, where I'm lacking in real estate.

Yeah I have seen this setup. A friend of mine had an SCCA GTL Nissan Sentra with a 3 link and a bottom mount watts link. It seemed to work just fine.

The only negative is that roll center isn't very adjustable and can be pretty low depending on the diameter of the rear tires.

5 lug to 4 lugs how to
 

I am using the RE Speed big brake kit on my car. This alows me to use FC 11" Turbo brakes. These brakes came from the factory with a 5x4.5 lug pattern. However, I decided to run a 4 lug pattern on my car because it is easier to get 15x7 and 15X8 wheels in the right offset. To do this, I had to redrill the lug pattern on the brake rotors. Here is how I did it.

Tools:

1 4 lug base model FC brake rotor to be used as a drill pattern - I used a front rotor but it would have been better to use both front and rear rotors as patterns - buy the cheapest ones you can find.

2 1/2x2.5" fine thread bolts
2 1/2" 20 tappered lug nuts
1 1/2" drill bit
1 big clamp
1/2" Drill Press

Attachment 718436

Here is the rear rotor that I am going to drill

Attachment 718437

Because the 4 lug and 5 lug patterns share the same bolt circle (4.5") one of the lug holes on the 5 lub rotor will be reused. To begin the process, bolt the 4 lug rotor to the 5 lug rotor. Make sure that the rotors are centered and the bolt/nut is tight. Note that the tappered end on the lug nut will help to center the holes in each rotor.

Make sure you clamp the rotor to the drill press and drill the first hole. Once you have the first hole drilled, insert the second bolt/nut and tighten it. Now the rotors are held together using two bolts. Drill the remaining 2 holes.

Attachment 718438

Here is the finished product

http://i1273.photobucket.com/albums/...ps6cztn3ym.jpg

Note that two of the new 4 lug holes are close to 2 of the original 5 lug holes. This isn't an issue.

If you are going to use the OE 12mm lug studs, the 1/2 holes drilled in the rotor will provide plenty of clearance. If you are using 1/2 studs like I am you will need drill the holes out to 9/16.

I'm really enjoying the custom work you're doing. I will definitely be copying your front strut tower mod later this year.

Thanks, it keeps me off the streets and out of trouble!:)

Good points.

Roll Center: Do you have a feel for what's optimal on an FB? My G-Force panhard had the nominal roll center set about 4 inches below axle centerline (adjustable up or down about an inch). A horizontal watts link would put it about 7 inches below centerline.

Ground Clearance: This definitely concerns me so I'll make some drawings to check it. I'm running 15" wheels with 225/50 tires, but I'll lose some clearance with my larger Toyota 8 pumpkin.

Also, it looks like you must be using springs with flat ends top and bottom. Where did you find them in the correct rate? I need 8" long ones at approx. 200 lb rate. Most of the ones I find at that length have rates that are too high.

We always set the panhard bar even with the lower shock mount.

These are 2.5" coil over springs. The springs I have under the car at the moment are 275lb 7" springs. I will probably need 6" springs on the rear of the car to get the ride height I want. For rates I am planning on running 225lb to 300lb springs for the rear depending on the track and conditions.

Basically you can source these from a Circle Track supplier. www.pitstopusa.com is pretty good to deal with. Colemanmachine is another great company to deal with. There are allot of circle track vendors out there maybe even a brick and motar busines near you.

Ahh - that's the difference. I'm running 5" dia springs. The selection isn't as broad. Maybe I should convert. With these larger dia springs, the only company I've found that makes what I'm looking for is "Suspension Spring Specialists" --> http://pitstopusa.com/i-5056307-susp...ng-200-lb.html . I'm not familiar with them, and don't know anything about the quality of their product. The alternative is to get springs with a flat seat on one end and a pigtail on the other. Re-Speed sells these, and they make them by buying a slightly lower rate racing spring and cutting it to the correct length. This doesn't seem like a bad way to go, but I'll have to come up with a pair of OEM-style spring seats to fit my Toyota 8 axle. If I use flat bottom springs, I can easily make some seats.

Elwood,

You're probably not going to find a 5" spring that is short enough with two flat ends. You'll need a pig tail mount on the rear axle. You could always cut them off of a stock rear axle housing.

With a pigtail mount on the axle you could buy some tall - 13" - low rate springs and cut them down. We had the best luck using Eibach 100-125lb 13" springs and then cutting them in half. This nets a 225-250 spring that is the right free height.

Before figuring this out we were using 8" 175lb springs and shortening them. This worked but they were prone to coil bind. The taller springs the Eibach sells have fewer active coils so coil bind isn't an issue.

I have used Suspension Springs for years and they are a good spring for the money. They don't offer the light weight springs that Swift and Eibach make but for coil overs they are a good choice.

If you want to switch over to 2.5" coil overs you have to cut out the factory spring mount that is on the body. I used a plasma cutter to remove mine and replaced them with these;

Attachment 718439

The 2.5 coil overs are lighter than the 5 inch springs but on the downside you can't cut them down to change their rate. So you have to buy the specific rates that you want.

Another option would be to go to coil over shocks. I can't do this beacause of the rule set that I am building to. That said, I would consider it if rules/budget allow.

Thanks for the wealth of info! I'm leaning towards putting pigtail spring seats on my axle. Do you have any suggestions on where to find a pair? I don't want to destroy a good axle housing just to cannibalize the spring seats.

Well, you could cut the spring pockets out of a 79-2004 mustang front control arms. Those cars used a 5" spring with a pig tail on the bottom. With some trimming that would be a very effective mount.

Good suggestion; thanks again.

Paint
 

I painted the interior, engine compartment and rear of the car. I used Rustoleum brush and rattle can Smoke Gray. I also repainted the door jams. Really makes the car look cleaner.

Attachment 718440

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Looks nice and clean. Nice shop btw

Looks good
 

Looks like you are ready for assy. Like I said, I'm jealous of anyone ready for, or painting their cars!

a brush! so simple! i tried spraying the inside of mine, and it really is awful....

Thanks guys!

Yeah a brush on the lower surfaces and a rattle can on the upper surfaces so they would be smoother. I ended up spraying most of the insides like the roof and it was a pain in the ass. The brush painted sections seem to be holding up a little better than the sprayed sections. Took about a month start to finish.

The shop is the Santa Fe Garage. I rent a stall from them - have for a long time. Santa Fe Garage started as a hobby shop for racers and slowly it has turned into a serious repair shop specializing in alignments and high end tire work. The do allot of Viper work. It would not be possible for me to do this work at home. www.santafegarage.com

Struts
 

Here are some shots of the struts I am using on the car.

These started life as big bearing spindles from an 84-85 model car. I have been using them on this car since 2006 or so. The OE tubes were cut and machined out of the spindles on a lathe. New 2"diameter tubes sources from ground control were welded in so that Koni racing struts can be used.

Here is a comparison between the finished strut and an original one
Attachment 718445

Before being repainted, I sand blasted them and had them checked for cracks

Attachment 718446

Here is a shot after paint and the installation of the RE-Speed big brake spacers. I have also added reinforcments between the spindle and the tube as well as a sway bar mount on the back of the tube. A 1" spacer is welded to the bottom of the strut tube. These do not add additional ackerman.

Attachment 718447

Koni inserts - Single Adjustables
Attachment 718448

Another 1" drop
 

I have been using a 1" strut spacer on my car for a long time. When I bought the car is had G-Force Ackerman spacers installed but they didn't fit my driving style. So I installed non-ackerman spacers and welded them in place. By the way, the stock RX7 suspension already has Ackerman steering so the "Ackerman" style spacers just add more. Great for Solo.....not some much for club racing in my opinion.

For the STU conversion I made a few more mods to the struts. The 12mm bolt holes were drilled out to 1/2" and the area around the bolt holes were spot faced so that bolts and nuts can be used to hold the struts to the steering knuckles.

Next, because STU allows for a lower ride height I decided to use a second 1" spacer on each strut. This sounds like a simple enough change but it added allot more complexity to the car. For example, I had to raise the strut tops to accomodate the lower ride height.

These are the spacers - these are from G-Force
[Attachment 718449

Here are the bolts I am using to hold the struts to the steering knuckles - they are AN 8 MIL spec bolts. AN bolts are listed in increments of 1/16" so an AN 8 is a 1/2" bolt. Note the long shoulders on the bolts. This means there are no threads in shear.
Attachment 718450

Here is a comparison between standard Grade 8 bolts and AN bolts of the same length
Attachment 718451

Here are some shots of the struts installed.

Attachment 718452

Attachment 718453

Attachment 718454

suspension
 

So what spring rates you going to run?

Nice looking welds on those strut tubes. I've toyed with the idea of bracing the tube to the spindle like that, looking good.

i like those struts! you're right about the second spacer adding complexity...

The current spring rates are 400lbs. Probably going to add 450 and 500lb springs to my inventory.

A friend of mine does the TIG work - he is really good. The braces are a good idea as we have had struts fail in that area before.

Yeah and more than just the strut tops. I have fitted an FC 4 lug hub to one of the spindles and.....drum roll.....the 11" turbo rotors hit the end of the control arms. I will be making some spacers to fix this....film at 11:00 as they say.