Budget Transmission Part 2: How I Chose a Road Racing Final Drive

Introduction

In my last post, I discussed the first upgrade for my budget transmission-- moving from a helical limited slip differential to a clutch-type differential.  If you didn't read that yet, I suggest you go back and take a look.

A pic from my Instagram of Damien and I at New Jersey Motorsports Park (Photo by Windshadow)

The second of two transmission modifications allowed in the National Auto Sport Association's (NASA) Honda Challenge H4 class is a final drive gear with a different gear ratio from stock.  

So, what does a final drive do?  In this post, we'll delve a little into that and we'll discuss how you should choose one for the road course.

What is a Final Drive?

The final drive is basically the last gear between the transmission and the drive axles.  By altering the final drive gear ratio, you alter the amount of wheel rotations per rotation of the selected gear.

So, a 4.2:1 final drive will rotate the driven wheels 4.2 times for each rotation from the transmission and a 4.7:1 final drive will rotate the driven wheels 4.7 times for each rotation from the transmission.

Understanding a Final Drive

If we select a "shorter" final drive, we are saying we want a final drive with more rotations at the wheels per rotation at the gear.  This gives us more torque at the wheels and more acceleration, which we gain in return for a loss in top speed.  We call this a "shorter" final drive because the amount of time between gear shifts is now not as long as it once was.


2 Fast...

On the flip side, if we choose a "longer" final drive, we are trading straight line torque and acceleration for top speed and a potential gain in fuel economy.  The longer final drive gives less rotations at the wheel per rotation in the selected gear.  It takes more time between shifts, so we call it "long."

Why Should I Change My Final Drive?

In a drag racing car, we can go faster by turbocharging our cars or modifying the engines to generate more torque and horsepower.

However, if the stock final drive is too short, one disadvantage is a loss of top speed.

If the stock final drive is too long, one disadvantage is a loss of torque at the wheels.

So, drag racers must find the proper balance between torque to the wheels and top speed by selecting the correct final drive.  Many other factors play a role in this phenomenon, but they're beyond the scope of this article.


A Camaro at the strip

In road racing cars, the sessions are typically longer, the tracks have corners and elevation changes, and horsepower isn't as important as cornering speed in most amateur classes.

So, to go faster we can't rely on adding power at the cost of reliability, choose a final drive that will give us the best straight line speed, or choose the final drive with the best acceleration.  We must consider other factors.


Ken, Kallie, and Brian at New Jersey (Photo by Windshadow)

How to Choose a Final Drive

There are five steps outlined in this article for choosing a final drive.

Step 1: Find the Powerband

Step 2: Find your Corner Speeds

Step 3: Compare Final Drives for Each Corner for Each Track

Step 4: Repeat Step 3

Step 5: Test

Step 1: Find the Powerband

Let's take a look at the stock, 94-01 Acura Integra LS/RS/GS-- a popular Honda for road racing due to its suspension geometry and operating costs.

The stock Integra that loaned its motor to my race car

The powerband for a car is a colloquial term which refers to the engine's RPM range at which it operates most efficiently.  If you're low on money and have a relatively stock motor and no dyno sheet, a great way to find your car's powerband is through the internet.

Wikipedia states that the stock 1998 Acura Integra generates peak torque at 5,200 RPM and peak power at 6,300 RPM.  So, we will conservatively assume that the powerband is from ~5,000 to ~6,500 RPM, allowing for shifting inaccuracy and any changes in engine efficiency due to age and use.

Pulling a stock Integra motor from #TrashTeg

So, we know where the car's RPMs need to be to remain happy, but how do we apply this to the track?  You may be racing Summit Motorsports Park Main with a 0.55-mile-long straight or Lime Rock Park which is a Miata track.  You may be racing somewhere with anywhere from ten to twenty-five corners, all with different average speeds and elevations.

Some corners are extremely important and can lose races if the car and driver are not fast through them and out of them-- like Turn 1 at Watkins Glen.  Some corners are not important at all and are referred to as "throw-away corners,"

So what do we do?

Turn 1 at Watkins Glen International Raceway

Step 2: Find Your Corner Speed

Disclaimer:  This is where we must analyze our cornering speeds-- it is an art and our conclusions may not always be the same.  However, i'm going to do my best to break it down so you can make your own decisions in the end.  The most important thing is that you trust your gut and supplement that with real-world data.

Using an AiM Solo or an equivalent lap timer, take a look at all of the tracks you race in a typical season in your area.  For each track there will be several key corners where exit speed is critical because momentum is lost.  For example, below you'll find a trace of one of my fast laps at NJMP Thunderbolt last year with a 4.2 final drive:

Data from an AiM Solo

There are three graphs drawn versus track distance in the above figure.  In order from top to bottom they are: lateral G's, longitudinal G's, and speed.  We use the longitudinal G and lateral G graph as a reference point and the speed trace to see what our corner speeds are.

In this figure, I have highlighted several corners where a lot of momentum is lost due to braking which is required to make the tight-radius corners.  Those corners are 1, 2, 5, 7, and the exit of the octopus.  Below you'll find a track map and video for reference:

NJMP Track Map

A lap of Thunderbolt in my old single cam HPDE setup

Looking at the AiM data, we can see the following corner exit speeds for a 4.2:1 stock final drive in an H4 Acura Integra:

Approximate minimum speed per corner at NJMP Thunderbolt

Watching video and using common sense, I can look at these speeds and remember what gear I'm in while on track, which is third gear for every. single. corner!  Why is this useful again?

Step 3: Compare Final Drives

The internet doesn't just have the powerband for a stock B18B1, it also has calculators that allow you to look at the RPM vs Speed trace for a stock Integra transmission.  The calculator I like to use for Hondas is from Zeal Autoworks.  It's been around since forums were hot and it's still in use-- so you know it's good.

You can choose the Honda transmission you're interested in and alter gear ratios as well, comparing two at a time.  Tools for other cars are likely to exist on the internet as well.

Zeal Autoworks Transmission Speed Calculator...Stock 4.266:1 Final Drive in an Integra

The screenshot above shows the max MPH for each gear using a stock 4.266 final drive in an Acura Integra.  Using this calculator, we can also get the values for a transmission with a different final drive.  For our example, we'll look at a comparison between a stock 4.2:1 and an aftermarket 4.7:1 final drive.  Trans 1 uses a 4.2:1 final drive and Trans 2 uses a 4.7:1 final drive:

We can see that the RPM increases much quicker for a given change in speed with the 4.7:1 when compared to the 4.2:1.  However, you'll also note that the top speed in 5th gear is much lower with a 4.7:1 final drive than it is with a 4.2:1.  This reinforces what we stated above, that a longer final drive has less acceleration ability, but a higher top speed, and vise-versa.

Now, we know the corners we want to optimize our car's final drive for, we know the minimum speed through the corners, and we know the power band for our car.  All that's left is to compare graphs of RPM vs. speed for different final drive ratios to find the most optimal for your car.  For the sake of simplicity, we'll analyze the comparison between a 4.2:1 and 4.7:1 transmission further.

Dame and I going at it at Lime Rock Park

Below you'll see the graph we looked at previously, but this time I've overlaid two y-axis lines and several x-axis lines.  The y-axis lines are in red and they represent the powerband and the x-axis lines are the minimum speeds for the corners we deemed most important at NJMP Thunderbolt.

Overlaying pertinent powerband and track corner speed data on the RPM vs speed trace for different transmission gearing

Corner by corner, let's look at what the data tells us...

Step 3a: Compare Final Drives-- Corner by Corner Analysis

In this next sub-step, we will go through each of the corners we deemed most important and select the final drive ratio that benefits us most.

Turns 1 and 2:

Below is a graph of RPM vs speed for a transmission with a 4.2 final drive and a 4.7 final drive.  We can see that when proceeding through Turns 1 and 2 in a 4.7:1 final drive transmission, we have two options for gear choice:

We can stay in fourth gear through turn 1 and keep our feet to the floor as we progress through turn 2, minimizing brake input.  Or, we can keep the car in 3rd, turn into corner #1, and shift into 4th out of turn 2.  Either way, we need to row through the gears to optimize mid-corner to corner exit speed with the 4.7:1 final drive.

Graph of RPM vs. speed for a transmission with a 4.2:1 final and a 4.7:1 final

Yet if you look at the green line in the above graph, you'll see that through turn 1, you can maintain 3rd gear, through turn 2 you can maintain 3rd gear, and once through turn 2, onto the back straight, you can shift into 4th all while staying in the powerband.

This implies that a 4.2:1 final drive is most advantageous for turns 1 and 2.

Turn 5:

The next corner we'll analyze is the slow left-hander out of the high-speed, sweeping right-hander at NJMP Thundebrolt-- also known as Turn 5.

Photo of Condor Speed Shop's Bimmer through what looks like Turn 5

The graph shown below is similar to those above, but the x-axis line in this graph is for Turn 5.

Turn 5 min speed, stock Integra powerband RPM range, and RPM vs speed plots on one graph

Driving a 4.2:1 transmission, we have two options for gear choice-- 2nd or 3rd.  In either gear, we're significantly far from the powerband while close to the minimum speed for this corner.  4.2:1 is far from optimal for this corner.

However, a 4.7:1 final drive puts us at the intersection of the powerband for our motor and the minimum speed for Turn 5 when in 3rd gear.

From this, we can conclude a 4.7:1 final drive is better for Turn 5.

Turn 7:

The second-to-last corner we'll analyze is Turn 7 at NJMP Thunderbolt.  This corner is a lot of fun because it requires a lot of braking, but if you choose the proper line and throttle/brake inputs through here, passing can be completed against a fierce competitor.

Looking at the graph below, it appears that a 4.2:1 final drive would be the best from the middle to the end of turn 7 as it requires less shifting and starts at the bottom of the powerband.

Keep in mind, however, that exiting turn 7 is not a straight, but a decreasing radius right-hander that requires grip.  Not all speed through this section is due to final drive selection.  It could be due to other factors not covered in the scope of this article, such as driving style or differential setup.

With situations like this, it's best to rely on your experience driving the track.  Feel the corner and use your intuition to gauge what would be most advantageous in the big picture.  I may think this is an important corner for final drive selection, but maybe it's not!  Remember what I said in the beginning disclaimer-- this is an art.

Take a look at the graph and map below:

Graph of turn 7's min speed on an RPM vs speed graph for a stock Integra with different final drives

Diagram of T7 at Thunderbolt

The Exit of the Octopus

 If we zoom out on Turn 7 and The Octopus together we can better put things into perspective.

The "back half" of NJMP Thunderbolt

From the exit of The Octopus, it's easy to see that the 4.7 final drive is better positioned to exit the corner than the 4.2 final drive is.  The 4.7 AND the 4.2 final drive are both in 3rd gear which means they still have a 4th gear to shift through before they reach the abysmal, long fifth gear in these cars.

Engine speed vs car speed chart for the exit of The Octopus

However, a car must be tuned within the context of the track and therefore it is an art as mentioned above.  Keep in mind that after the exit of The Octopus, racers in a low-powered car will never lift until they get all the way back to Turn 1 at NJMP Thunderbolt.

This reinforces the point that tuning a car cannot focus on only one aspect-- road racing or for the drag strip...

Photo by Viken Photography

Step 4: Repeat 3A

Using different ratios, now it's time to experiment with which one works best for your driving style for a given track.  Additionally, remember to consider corner speeds for other tracks you regularly drive.  Lime Rock Park and Watkins Glen may deserve two totally different final drives for example.

Step 5: Test

Lastly, get your car on the track and see if it works.  Compare data using your on-track lap timer.  This is an essential tool.

Conclusion

As stated above, a final drive can have a large influence in corner exit speed for a track car.  While it also factors into the top speed of a track car, there are other factors to consider such as gear ratios for each individual gear and overall horsepower/torque for the car.  Additionally, there are factors that will make the car corner faster, thus potentially affecting final drive choice.

Photo by Viken Photography

I'm glad you guys had a chance to stop by.  Please recommend my blog and share my posts if they help you at all.  See you guys next time!

A Method to the Madness: Setting Tire Pressures for the Race Track

Introduction

It was about two to three years ago when a friend at the track asked me the question, “what tire pressures do you run” when I first dove into the world of car setup.  The conversation went something like:

Me: I run whatever, I just like to drive FAST

My friend: Okay, but have you ever considered that you could be faster?

Me: What do you mean?  I am fast. I drive flat out.  I don’t care about my tire pressures.  Did you see that FWD drift in turn 3? I’m fast.  I don’t need to set tire pressures.

Drifting at New Jersey Motorsports Park Lightning Course

My friend: …Okay, Go out this next session and when you come into hot pits stop up at the wall and I’ll take your hot pressures for you.

(The “Ricky Bobby Effect” is slightly exaggerated here)

Note: Hot pressure = tire pressure after a full-pace session on track
Cold pressure = tire pressure in paddock or while cold, before on track

I was having issues with lockup going into turn 1 at New Jersey Motorsports Park (NJMP) Thunderbolt.  I felt as though I had more brake in the car, but the tires didn’t want to stop.  The tires felt sluggish and unresponsive to my inputs.

Turn 1: NJMP Thunderbolt

After my friend took my hot pressures once I came back into pit lane, we looked up the optimal hot pressure for the Nitto NT-01s I was running on some forums.  Based on our research, we decided to add one PSI to the tire while hot.  Miraculously, my braking ability increased, my lockups deceased, and my times decreased.

A man checking cold pressures at New York Safety Track

As outlined above, knowing one's hot and cold tire pressures can make a seasoned driver faster given different ambient conditions, but it can also improve safety for a novice track driver.

Cold pressures are typically set with a target hot pressure in mind. Because air expands when hot, we set our cold pressures low and the air will expand after a hot session, at which point we can record our hot pressure.

The hot pressure is the pressure the tire works best at. While knowing your cold pressure is important, it's your HOT pressure that will tell you if you're extracting the most grip out of your tire's contact patch.

As an instructor with the National Auto Sport Association (NASA) it's common to encounter first-time students that don't know whether they torqued their wheels, let alone set their tire pressures correctly. I have heard stories of students going on track with 60 PSI cold or 10 PSI cold and coming back with horrified, but safe, instructors.

A scared instructor

However with the right approach, you can be both fast and safe. For both approaches covered below, the assumed tools at disposal are:

1.) Car

2.) Race track

3.) A pen and paper

4.) Tire data (Google)

5.) A REPEATABLE tire pressure gauge

6.) A friend to help (optional)

Alex, TJ, and I going over tire temperature data at Watkins Glen

The First Approach (Easy but Less Optimal):

Anecdotally, tire pressure gauges are most accurate in the middle of their range. So for track days in a regular car, a 0-60 PSI gauge should do fine. This statement applies because for a street car, your hot pressures should be between 30 and 40 PSI on average.

You can purchase a tire pressure gauge from Joe's Racing, a reputable brand, on Amazon for a little over $20.

Joe's Racing tire pressure gauge

After obtaining your tire pressure gauge and going to the track, write down the ambient conditions on your paper with your pen. This should be done before each session. You should ask:

1.) Is it cloudy?

2.) Is it raining? How heavy if so? If heavy, a lot of this article isn't applicable, so stop reading now.

3.) What is the humidity level?

4.) What is the ambient temperature?

5.) What are your cold tire pressures?

Next, go to Google and search the interwebs for what people with your tires on similar cars like to set their hot pressures at for the track. It's important to get multiple opinions to get rid of the incorrect data, or noise, from your observations. Forums, Facebook, hobbyist websites, and manufacturer websites are some sources you can mull through.

Note: You can also just TALK TO PEOPLE at the track!

A review of the NT01 from Race & Track Driving

Once you know a base for your starting hot pressure, write that down, set your tire pressures at a reasonable cold pressure, and head on track. For most Civics, Integras, Miatas, and E30s with 15-inch tires, at most ambient conditions, I find 30 PSI cold to be a reasonable starting pressure.

Note: Your cold pressure must be lower than your target hot pressure. Air EXPANDS when hot!

Next, drive the car. Go out for a full session on the tires. If the car feels funny at all, try to drive around the car's character. If the car feels unsafe, bring it in. Not only will driving around your car's imperfections improve car control and driving skill, but it will allow us to reach our final goals which are:

1.) Observe what your tires feel like (very important)

2.) Get enough heat in your tires to get an accurate hot pressure (also very important)

Lawnmower life

If you've observed what your tires feel like, you should know to a certain degree what your car feels like under braking and turning. We will now use the following table to determine whether your car's tires are under-inflated, over-inflated, or just right:

Figure showing car "feel" relative to tire pressure

If, per the table, your car's tires feel under-inflated or over-inflated, adjust the pressures as necessary.  Repeat the steps of adjusting tire pressure and driving the car as necessary until you find a happy spot.

For a front-wheel drive car, when a hot pressure works well for the front of the car, I've found that the same hot pressure should be set at the rear of the car.  However, I'm close to certain that this is the right approached based on feel, but also based on data, which we will now cover in...

The Second Approach (Hard but Betterer)

For the second approach, we need one additional tool, which is:

1.) A tire pyrometer

A tire pyrometer uses a probe, inserted into the tire's tread, to measure the temperature of the tire's rubber.

Taking a reading of tire temperature (photo from Turnology)

The temperature of your tire's rubber is probably the most important measurement you can have for your tire, after your hot pressure.  This is because not only does tire temperature tell us about whether our pressures are set right, but it also tells us things like:

1.) Where the majority of the weight lies (front or rear of the car)

2.) How the spring rates or sway bars we've chosen affect tire loading

3.) Are our camber settings correct for this track?

A tire pyrometer

Some will use infrared (IR) temperature guns to read tire temperature when the car has pulled into pit lane, but this is not as accurate.

IR Temperature gun reading engine bay temperature

Part of why infrared guns are not useful for measuring tire temperature once the car has stopped and is in hot pit lane is because they only measure the temperature of the surface of the tire.  Tires cool extremely fast after a hot lap.  As a result, the surface temperature will not be representative of the tire's actual temperature at pace.

Additionally, user and machine error (distance from measuring target and surrounding brightness) can also affect the measurement.

Tire pyrometers can be found used on eBay for ~$50 if you wait for a good deal to pop up.  Mine was purchased two years ago (2017) for $50 in used condition.  It sits in the glove box of my Civic during practice sessions.  My friend Alex's was purchased this year (2019) for $60 with a carrying case.  He will be using this at upcoming events.

Alex (owner of TrashTeg) and Brian going head to head in their Honda Challenge H4 cars.

In the second approach, we do most of the same as the first, initially.

1.) Record ambient conditions

2.) Find optimal hot pressure for tire and car

3.) Set cold pressures as described above

4.) Finally, go drive the car-- observing how the car feels

Where the second approach differs starts with when we pull the car off track.  In the first approach, we may wait until the checkered flag is thrown.  After this, we may have a cooldown lap and bring the car in to record our tire pressures.  However, remember that I said that tires cool extremely fast.

So, we pull the car in a lap or two early after running it at full pace.  We come to a full stop in hot pits, and we have a friend immediately record tire temperatures-- or we do this ourselves.  If you're going to do this yourself, put your pyrometer and tire pressure gauge in your glovebox.

Recording tire pressure at Watkins Glen in a racing suit

There are three tire temperature measurements to record for each tire-- a total of 12 measurements.  We want:

1.) Inner tire temperature

2.) Middle tire temperature

3.) Outer tire temperature

I typically record my tire temperatures first, in order of driver front tire, passenger front, driver rear, and passenger rear for a clockwise rotation track.  Then, since tire pressure decreases less rapidly with time, I record tire pressures second.

There are printouts available online that make the recording process easier.  Or, you can make your own printout.  Digesting the data from a printout is much easier than a bunch of scribbles in a beat up book (which is what I do).

Photo taken from Quickcar Racing Products

As mentioned above, tire temperatures can tell you a lot about the car beyond what your pressures should be.  This is why I prefer this method.  I'll briefly go over what temperature can tell us for camber and chassis loading and get back to specifics about hot tire pressures.

Every tire has an optimal average temperature.

Average temperature should be close to that optimal temperature and is mainly driven by weight-to-tire-width ratio, spring rate, and other variables.

Camber and other alignment/chassis setup factors can affect tire temperature distribution from the outside to the inside.  Generally we want a 10-15 deg. F. distribution from inside to outside with the inside hotter than the outside.  This tells us that the camber is adequately negative for a given track and chassis setup condition.

Setting camber with a plumb bob, a stick, and some stuff and things.  Pic from LexiLaron.

However, for the sake of this article, we're looking for two things:

1.) The middle of the tire is not hotter than the outside and inside

2.) The middle of the tire is not colder than the outside and inside

Insert Civic picture here

We want to set the hot tire pressure so that the middle lies in between the outer and inner temperature.  The procedure for adjusting hot tire pressure based on a pyrometer reading is as follows:

1.) If the middle temperature is higher than inner and outer temps, the hot pressure is too high-- lower it by 1 PSI

2.) If the middle temperature is lower than inner and outer temps, the hot pressure is too low-- raise it by 1 PSI

Continue adjusting tire pressure per the procedure above until the middle temperature is in between the outer and inner tire temperatures.

Once the tire temperature distribution is satisfactory per the above requirements, we employ the feel technique which we covered in the first method.  Based off of experience with a car of the following specs, I find a range of ~5-6 PSI where I can adjust hot pressures to influence car feel:

2500 lbs Civic

B18B1 Engine (stock)

Integra brakes

Toyo RR 15/50 R205 tires

Once the car feels good, feel free to rip.  Take the data from your notes home, read up on suspension setup, make tweaks, and be faster than before (hopefully).

Peace

Thanks for reading all!  Have fun racing and driving.

#TrashTeg, The Chronicles; Part 3-- DIY Racecar Seat Back Brace

When we last left off regarding #TrashTeg, we discussed safety upgrades before an HPDE event.  In this blog post, we're going to narrow the scope a bit and talk about some specifics-- specifically regarding the seats.

Recall that the seats we used in this budget, to-be, Honda Challenge H4 race car, were found on Craigslist for an extremely cheap price due to their condition and age.  We paid ~$150 picked up ~30 minutes from home.

While the condition of the seats won't win any car shows, we don't care because we're racing the car.  However because the seats are old, their FIA certification has expired.

When doing HPDE or track days with the National Auto Sport Association (NASA) or other clubs, this may be okay as long as the car passes other safety rules.  However, wheel-to-wheel racing is a different story.  If the FIA certification is expired, the seat must be reinforced to ensure the seat back doesn't snap on impact.  To solve this problem, enter the back brace.

A seat back brace is intended to prevent excess movement of the seat forward or backward in a crash.  This ensures that the driver stays in the same spot, the harnesses do their job, and the driver is unharmed due to whiplash or other injury caused by sudden, harsh movement.  To read more about seat back braces and why they're useful, see this article by IO Port Racing.

Since our Integra was being converted from an HPDE car with a roll bar to a race car, one thing (among many) we needed to add was this seat back brace.  

The IO Port back brace is what we used, not because we're sponsored by them (I wish), but just because it's what we happened to order from them.  The kit comes with everything you'll need.  The picture below shows the contents of the kit and what purpose the components serve:

To begin installing our new brace, we first stripped the pristine fabric off of our God-knows-how-old years-old seats.

Lifting back the foam, it was easy to see where we could drill into for our new brace.

Next we began bolting things together.  In the labeled picture of the seat back brace above, you'll notice that the tube that transfers load from the seat to the cage in the event of a crash is secured to the cage with a two-piece, machined block of metal.  The top half of this block bolts to the cage and the bottom half bolts to the tube that transfers load.

We loosely bolted this onto the cage first.

Next, we grabbed our load transfer tube shown below:

And we inserted it into the bottom part of the machined block which we had loosely attached to the cage.  After doing this, we tried our best to center the bracket on the middle of the seat.

You'll notice that seat-back bracket was flat but the seat was curved.

To remedy this we needed to intervene, bending the soft aluminum with a vise and a hammer.  While in the vise, we also drilled the holes for the seat-to-bracket mounting hardware.  

Note that in the NASA Club Codes and Regulations (CCR), the mounting hardware facing the back of the car's driver must be flush with the seat, not protruding.  IO Port includes allen bolts which preclude any potential conflict with this rule and also provide for additional safety.

With the bracket bent to the profile of the seat, we centered the bracket with a whiteout marker and marked where the seat needed to be drilled.

Then, we secured the bracket to the seat using the provided hardware from IO Port.  On the side of the seat facing the racer's back, we used allen bolts with rounded heads as previously mentioned.  On the side opposite the racer's back, IO Port provided us locking nuts to use.

With the seat back brace secured to the seat and all other components loose, we finally began securing all other components which would bring us near completion.

The diagram below shows the order of final installation.  First, tighten the back brace-to-load transfer tube bolts.  Second, tighten the allen bolts securing the main block to the cage.  Third, drill a hole in the load transfer tube and insert your cotter pin:

With the back brace fully installed, we finally put the fabric back on our seat and concluded our install.  The fabric is easy to install back onto the old Corbeaus.  It has an elastic band that allows the fabric to stretch around the contours of the seat and tighten once past the edges.

Detailed photos of the installation are shown below:

On May 3rd, my friend Alex is going to New Jersey Motorsports Park with NASA Northeast to participate in Competition School for his provisional license and hopefully begin racing with the Honda Challenge H4 crew.

If you wish to attend one of our events, reach out to me in the comments section and I can get back to you ASAP!

Thanks for reading! --Track Rat