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Build vs. Buy?

This is the question most people grapple with when thinking about getting involved in the SpecMiata race series. In this article we will outline some of the areas to consider when trying to decide which model year car to purchase and whether to purchase an already completed race car or building your own.

First of all lets identify the eligible cars, there are currently 3 basic versions (see chart below) of Miata available for competition in the Spec Miata series. Early 1.6L cars, early body style 1.8L cars, and the newer body style 1.8L cars up to model year 2005.

Year Weight Restrictor Plate Size Size / Compression Notes
1990-1993 2275 None 1.6L / 9.4 Intake design is free with cone style filter.
1994-1997 2365 47mm 1.8L / 9.0 Must update to the 4.30:1 rear axle ratio
1999-2000 2450 41mm 1.8L / 9.5  
2001-2005 2450 43mm 1.8L / 10.0  
Choosing a car to build or purchase.
Which Car should I get? I would say that depends on several things, your weight being one of them. The early 1.6L cars represent a large portion of the cars in the class due primarily to the low cost of the donor car. If you weigh over 210lbs then you may want to think about the later model cars so that you can get the car down below the race weight so you can add back weight as ballast to help with the overall balance and corner weights of the car.
Some cars will work better at different tracks. The 1.8L cars have better torque numbers, so they can get off the corners a little better, but the 1.6’s have a little better top end. 1.8’s use a Torsen limited slip, and the 1.6’s use a clutch pack style limited slip, or the recently approved 1.8 style Torsen as long as you keep the correct final drive ratio. The 1.6’s have adjustable sway bars front and back, the 1.8 cars do not. 
BuyingBuying is ALWAYS cheaper. If this is your first race car and you are not sure how much you will enjoy the sport then I would suggest buying an existing proven race car. You can get great deals on existing cars and can pretty much hit the track right away. Prior to looking at any used race car make sure you understand the rules (GCR) in depth. Bring a GCR with you and if you are not sure of something the owner is telling you, ask them show you in the GCR where it is legal. This goes not only for the Spec Miata specific ruleset, but also the cage design rules and rules regarding graphic size and placement.
When you are looking at buying a used car remember, there is always a reason why a person is selling their race car, and you should know why the seller is selling theirs. SM is the fastest growing class in SCCA and is one of the most economical classes to run. Are they getting out of racing? Are they changing classes? Are they building themselves a new car?
Generally speaking, you should never buy a race car sight unseen. Buy something within driving distance so that you can go look at the car multiple times if need be. Try to see at least 2 cars so that you have something to compare against. History on an existing race car is very important. The owner should be able to provide you with race results for the previous season or sometimes they can be found online for each region. DNS and DNF’s are very rare in these cars so make sure and investigate the history of the car. Look to the more experienced racers in your region, as they can probably tell you about the car from having raced with it. The vehicles’ log book will also tell you about significant damage, so make sure to look at it along with the vehicle.
When you are buying a used car make sure to look at several of the key components and the maintenance schedule the current owner is on for replacement or rebuilding. Hubs, brake calipers, transmission, differential, and drive shaft are all items that MUST be rebuilt on a timely schedule. They can and will all produce drag and friction and if not properly serviced or replaced, they will cause your car to be slower than ones that are serviced. The current owner should be able to provide you with a maintenance listing of what parts are in the car and when they were last serviced or rebuilt either by the odometer reading, or off of an hour meter.
Utilize your more experienced racers in the region. They are great resources and will be happy to help. There is nothing wrong with buying a used race car as long as you know what you are buying. No matter what level or preparation or quality of car, as long as it is safe you will always have somewhere to run and plenty of people to race with.
Current market value on a used “regional” Spec Miata is anywhere from $10,000 to $18,000.00. Nationally prepared cars with a significant spares package can go much higher.
What tools should I take with me when going to look at buying a used Spec Miata?
1. Helmet. – So you can see how you fit in the car with the cage.
2. Magnifying Glass – To inspect welds.
3. Towel or rubber mat – So you can get down on the ground to get a good look under the car.
4. Jack – So you can jack up the car to look underneath. 5. Flashlight 6. GCR 7. Digital Camera – Take pictures so you can review the car later during your decision making process.
What should I look for when buying a used Spec Miata?
1. Chassis
a. Frame Rails – Get under the car and look at the frame rails. Look for signs of a significant impact, or severe damage. The frame rails should be as straight as possible. Most of these cars that have been turned into race cars will have collapsed frame rails from someone trying to jack up the car on them. Don’t worry too much about this as it doesn’t really hurt the car too much. At some of the rougher tracks around these cars will bottom out off of the FIA curbing and turn exit, so there can be slight damage to the frame rails from this as well.
b. Front Sub Frame – Investigate the front sub frame and look for signs of it being bottomed out. The sub frame is what all your front suspension settings are driven off of, so a sub frame with damage will impact your ability to set up the car appropriately.
c. Camber bolts – Look at the camber bolts and make a mental note of where they are. Are both sides set the same, or are they in out of phase with one another? Typically if the bolts are not in the same place on each side, it is a sign that something is bent. It could just be the
aluminum control arm bolts (very cheap) or it could be the control arms.
d. Log Book – Look at the logbook as it should have notations from an SCCA steward about any significant damage that occurred during a race weekend. Its important to note that damage can occur on test days and other non SCCA sanctioned race weekends.
2. Body
a. Engine Bay – Look at all the sheet metal in the front of the car. Look around under the headlight assembly to see signs of impact. Also look at the where the upper chassis meets the firewall. If the car had significant front end damage, it is hard to hide it at the firewall area especially under the brake master cylinder. Most of these cars by now have had some contact either as a street car or in their racing life. Minor damage in the front is ok, you just need to know that the repairs were done properly and what you are actually buying.
b. Trunk – Look in the trunk for signs of a big impact. If the car has had a substantial rear impact, the rear bumper support will show signs of the impact.
3. Motor/Running Gear
a. Differential – What diff is in it? Now that 1.6’s can use the 1.8 Torsen, you need to correctly identify which diff is in the car. If the car has an open diff, then you will be looking at roughly $1,000.00 to convert to the Mazda Comp differential.
b. Compression test – A Compression test will give you a good idea of the general condition of the engine. You want to look for compression numbers with a minimum of roughly 180 with a consistent reading across the board. Compression lower than 180 is probably ok if it is consistent from cylinder to cylinder, but you may be down on horsepower compared to the front running cars. Front running cars will be around 200 as a reference point (but compression gauges don’t all read the same). The key here is a consistent reading and using the gauge correctly.  When performing the compression test you will want to first bring the motor up to operating temperature. Once up to operating temperature you will want to disconnect the coil pack remove all 4 spark plugs. Then crank over the motor until the gauge stops raising with throttle wide open.
c. Leak Down – The leak down test is a little more accurate assessment of the condition of the motor that will require special tools. What you should be looking for is a number that is ideally 5% or less. A high mileage street car may come in around 10% which isn’t necessarily something to be afraid of, it just isn’t at its peak performance. Any leak down issues with these motors are easily fixable in the rebuilding process.
d. Transmission – Make sure the transmission shifts easily into each gear. You can jack the car up and shift through the gears with the motor running to test it. These transmissions are rock solid and usually last a long time. Replacement or spare transmissions can be found at junk yards across the country for not much money.
4. Roll Cage
a. Design - Look at the roll cage design. Take your helmet with you when you go to look at a used race car. Is it updated to the latest (Dual Nascar Bars) rules? Do you comfortably fit in the car? Is your elbow away from the upper Nascar bar? Is your head far enough below the main hoop? Where does the forward down tube land? Can you use the stock dead pedal, and how will that tube play a part in an accident?
b. Welds – Investigate the welds with a magnifying glass to look for cracks. Painted roll cages make it easy to identify cracks if the car has been in a big accident. Also make sure that the welds are 360 degrees around the tubes. Run your finger around those tight weld joints and use a flashlight to look at all weld joints to ensure they go all the way around the tube.
c. Legality/Material construction - Make sure that there are inspection holes in each one of the primary tubes in the car so you can check for appropriate wall thickness and material. Refer to section 9.4.2 in your GCR, or go online and you can view the roll cage requirements @ There are some builders using obscure sized tubing and some of the early cars are using .120 wall cages which can weigh as much as 25lbs more than the allowed 1 1⁄2 x .095 DOM. Keep resale in mind here as well. How will your cage help or hurt your cars resale value? What if a tall or big person wants to buy your car, will the design and weight be an issue for them?
Building a car
If you have race experience and are moving into the class, or are particular about your car then building a car has a lot of benefit. Primarily you know what is in the car and will more than likely avoid repair/replacement work at the track on race weekends.  Roll cages are part of our business and I can not stress enough the importance of a good safe cage made out of the appropriate size and material that fits you and gives you the maximum amount of room in the car.
By building a car you can ensure that the proper cage for your car and body type will happen. This will not only make you safer in the car, but will also help the resale value should you ever to decide to sell the car.  The beauty of building a car is that there are no surprises. You know what is in the vehicle and have a blank slate to start your maintenance and replacement schedule. In most regions the championship is a tightly contested battle that will come down to the last race of the year. Missing one race and having a DNF from a “surprise” is enough to cost you a championship.
You can expect at least $18,000.00 to build a new 1.6L car and $20.000.00 to build a new 1.8L car, if you are doing a lot of the work. A very nicely built “regional” 1.6L car can be done for under $20,000.00 and a 1.8L car can be done for under 30,000.00.
Whether you build of buy, preparation plays a large part in how fast you will go. These cars are low horsepower cars and every little bit helps. 3 Horsepower in the class is huge! Rebuilt hubs, brakes new drive shaft, all of these things can add friction and rolling resistance to the car and add up, so be realistic with your goals based on the car you buy or build.
Some guys align their car every race, and some do it once a year. Ask around and watch, and by the end of the season with the right tools you
can be doing your own alignments and preparation.
The best part about this class is the people that make it up. Go to one of the races in your region and you will find very knowledgeable friendly people who are willing to help and welcome you into the sport. No matter what level of car you buy or build and no matter how fast or slow you may be, you will always have a fun and safe environment and other like minded people to race with.