Zennish Autocrossing

The weather debacle and subsequent paper-flying uproar at the Solo Nationals last Friday got me thinking about how Zennish the sport of autocross really is. Usually.

If you haven’t heard, the 5th (and last) heat was stopped due to lightning, but only after 30 or so drivers had a dry first run. No big deal, happens all the time, right?

I left the site just as the rain began traveling sideways at high velocity. On the way to the hotel the windshield wipers were overcome by the deluge, the roads began to flash-flood and intense lightning cracked all around. Poor course workers, I thought!

No, that’s a lie. I was mostly worried about getting struck by lightning in my sheet-molding-compound (plastic) bodied Corvette, which I’m reliably informed provides no protection from 500,000 volt discharges.

Weather happened to our local club the last two events. In one case we called it and all had to stand on runs from the first session. The second case we were able to restart after a delay and get our remaining (wet) runs in, which were obviously slower than the first session. Anyone who coned the first three runs: too bad.

There’s something very Zen about a sport where you spend years in preparation, learning, and practicing, as much mental and emotional practice as physical, all the while banking a store of unconcious knowledge, accessible but perhaps not explainable, so that someday you’ll be able to perform at the highest level for 60 seconds, two days in a row, and win a championship.

Or, maybe instead, you’re the last competitive car to run in your class after 5 reruns from other classes get inserted between you and the next to last and it starts to pour just as the starter says “Go!” (Happened to me at Wilmington one year and, yes, they really should have let me go with my class.)

In Lincoln last week the racing was restarted after a two hour delay. I don’t mean they picked up where they left off, I mean they really restarted, as in, from the beginning. As in, the Steward decided to throw out the prevous dry runs. As in, no precedent for this ever. As in, no rule or authority given to the Steward to support such a decision.

A bunch of people threw paper, i.e., they protested the event. Because Zen violation.

Autocross has always accepted that weather is variable and therefore often unfair. It has always accepted that sometimes you’re the bear and sometimes the bear eats you, even if it means there are National Champions that might have just been extraordinarily lucky. Old Basho would have understood. No car, no course, no driver, no weather, nothing to strive for… the drive just is. The outcome just is.

Last week someone messed with the perfection of the stormy moment and tried to manufacture fairness. In Zen terms, this was an exhibition of the personality over acceptance of the weather-consequence reality. It took an act of ego to exceed given authority in this manner and accept or ignore the explosion of negative human feelings it was sure to generate from the competitors that got screwed (by taking away their luck) in a totally unpredictable and unprecedented manner. Zen teaches that any such act of the personality generates negative consequences, even if done with good intent. This is the Beware of Do-Gooders tenet within classical Zen. (I may have just made up that last.)

Then, bless their hearts, the protest committee upheld the protest and reinstated the dry runs. Thus, the Universe was restored to balance and all sentient beings became enlightened. Right? Not quite.

Unfortunately, in a second act of overwhelming lack of Zen, the Steward gave notice of intent to file an appeal of the decision. The upshot is that the question will be decided by a higher power and the result won’t be known for weeks.

I bet there was someone in that group of early drivers that deserved, by all that is Random and Holy in Autocross, to win their first ever Nationals trophy, after who knows how many years of trying, and walk across the stage at the banquet that night and accept it to the applause of their friends and fellow competitors, but didn’t get to. May never get to.

If you happen to see me in grid, muttering something that sounds like “no car, no course, no driver…” please, please give me the Zen stick by slapping the side of my helmet quite hard.

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Mike’s Cup (at the West Course start, 2016 Solo Nats, ready to go)

Getting it done (in one)

While driving home from Ohio it occurred to me that fighting to not be dead last is exactly the same as fighting for the last trophy (as I found myself doing this weekend) is exactly the same as fighting for the class win. And it doesn’t matter whether it be at a regional, a championship tour or at Nationals. It’s all exactly the same.

More often than not the situation is this: you have one run left and it must save more time, sometimes a lot more time. Thou shalt not hit a cone, but thou shall be close. Thou shalt not slide or spin, but thou shall be at the limit. Thou shalt not make a mistake of any consequence.

So, we might as well figure out how to get it done in the one chance remaining while we’re still at the bottom of the time-sheet. Why wait?

One key is being able to remember and think back over the previous run to identify mistakes plus identify what changes will allow you to save more time. If you can’t remember the run vividly enough to identify mistakes, and if you can’t think of any way to at least possibly save more time, then you have little chance of achieving your goal.

Trying to drive harder usually won’t cut it. You’ve got to force yourself to think, man!

Like anything else, it takes practice. In this case, mental practice.

 

Falsely Accused of Driving Smoothly!

On a recent weekend I ran two different autocross events, one in Huntsville on Saturday and another in Chattanooga on Sunday. Both days, someone (not the same person) commented that I looked very smooth. How outrageous! Don’t they know that I once authored a blog post entitled Smooth Is Slow?

I guess the car looked smooth from their exterior vantage point. Both persons had been working on course during my run group. I can’t be certain, but I don’t think they were trying to slyly tell me I was slow. I was driving faster than ever. Too fast on Saturday, in fact, to stay off the cones.

Both courses were tight and busy. Inside the car I was working furiously, making a huge number of small, quick corrections at both steering wheel and throttle, moving the weight around, finding each scrap of grip available right at the edge of traction and on the precipice of loss of control. I was very busy and I felt nothing smooth about it! I guess since I didn’t spin, didn’t have any big slides and the tires were howling more or less at a consistent pitch and volume it seemed smooth to the observers.

I discussed this observer-versus-driver disconnect phenomenon in Smooth Is Slow. I re-read it just now. Still happy with what I said back then in one of my very first posts. This has made me ponder a slightly different subject, however, which has a connection to smoothness.

Most autocrossers have run into the following complaint about autocross from track-day junkies, usually when asked why they have no interest in autocross: Autocross is dumb because you spend all day to get 6 runs of 60 seconds each. Just not enough seat-time. On a track day I  get 5 sessions of 20 minutes each… that’s 100 minutes of seat-time versus 6 for autocross!

I’ve always thought there was something a little screwy with this position. If you don’t find autocross fun, OK. If you don’t care for the competition and can’t enjoy it while losing, well OK to that also. The seat-time argument, if intended to imply that you become a better driver faster, seems wrong to me.

I’ve found that many of the people who say things like this, despite many hours of time on the track dwarfing the time I’ve spent on the autocross course, are painfully slow when I get out there on track with them. (I’ve done  17 track-days. I like doing them. I’m sure I’ll do more.) Typically, they exhibit car control skills that I think of as mediocre at best, which causes them to drive what seems like a very slow pace in the corners, necessarily leaving a large margin for error. I’ve been thinking about why this might be the case, after all those hours they have on track, and have come to an idea about it.

The idea is this: it seems to me if you want to develop high-level car control skills there’s a fast way and a slow way. The fast way is most accurately measured by how much time you’ve spent at the limit of tire adhesion.

During a day of autocross you get, if properly aggressive, 6 minutes at the limit, more or less. It doesn’t matter what car you are in, how much horsepower you have, or what tires are mounted. Spending time at the limit is what counts when it comes to developing car control.

In that 100 minutes of track driving, the typical, sane person gets how much time at the limit? Zero.

None. Zilch. Not any a’tall, which is infinitely less time at the limit than an autocross gives.

Why is this? Very simple. To get to the limit you must go over the limit. Otherwise, you can’t tell, especially before you are an expert, that you got to the limit. Right? So, what happens if you go over the limit during an autocross? Worse case, you tank-slap spin and that run is toast. Guess what, though? You get to start up again, rejoin the course, and drive the rest of the run at the limit. You’re not out anything except a little tire rubber. Maybe you don’t win your class that day. Maybe you don’t beat anybody that day. You can’t worry about that. This is just practice. All runs are just practice. Some of them, eventually, might win you a trophy, maybe even a National event trophy, but it’s all just practice until you’re running for that National Championship jacket. Maybe even after you’ve won one of those, too.

What happens if you go over the limit on a race track? Worst case, you die. Bummer. Best case, you have an off and return to the pits for an inspection and maybe a time-out. You don’t even get to drive hard the rest of the lap. Rats!

Driving over the limit is really stupid at a track day. Nobody is going to kiss you at the end and hand you a trophy. Therefore, the fast way, trying to drive every moment at 100%, is not available to track junkies. They have to do it differently. They have to do it the slow way. The slow way takes a looooong time (as measured in track minutes) and lot$$$$$ of money, as measured in entry fees, travel costs, brake pads and discs, tire wear, extra brake fluid and engine oil changes, etc. And the kicker is that if you don’t do the slow way right you won’t ever get fast.

How can you drive hundreds of hours at the track and never get fast? I’m not totally sure, but from what I’ve observed you do it by driving consistently well inside your comfort zone. I suspect these folks steadfastly refuse the instructor’s pleading that you are now ready so please try going just a little bit faster. Probably, as soon as they can, they ditch the instructor and just circulate. Having fun. Some of them are really smooth, too.

Which brings up my next point: it’s pretty easy to be smooth at 90%.

What is the track junkie to do to get fast and develop top-notch car-handling skills? Other than doing 50 non-fun autocross events with such paltry seat-time and having to accept losing over and over again. Losing to teenagers in smoking, clapped-out Miatas with mismatched body panels and 300 HP less than you have. Losing to grandmothers. Losing to 85-year olds. Lots of losing in autocross!

You do what all the instructors say: gradually ramp up the speed while working on, wait  for it, Smoothness!

Why work on smoothness on the track and not the autocross course? Because what you really need to do is get sensitive. Trying to be smooth helps you do that, in the right circumstance, which is driving just a little bit out of your comfort zone. Not much out, just a little. Do that consistently and you improve.

If you drive on the track, you must drive below 100% if you want to own an operable vehicle at the end of the day, not to mention operable legs. But, if you drive at, say, an average of 95% you will actually vary around that by some percentage…let’s pick 3%, because nobody is perfectly consistent, certainly not the novice or intermediate tracker. That means you’ll wander around in the 92% to 98% range.

So, sometimes, for a brief moment, you actually are very near to the limit. If you are sensitive, driving for extended durations  at an average of 95% is close enough to get the feel for what the tires are doing and how weight shifts with every input you make and how that affects the level of traction front to back and left to right and how it affects what the car will do next and how it affects how you can execute the technique your instructor has given you, or the drill/practice/cornering method you have set for yourself. You will develop mad skillz, Bro.

On the autocross course you can use the fast way. Immediately push yourself to the limit and learn to handle it. What will you actually be doing? You’re understanding of the car’s dynamics will expand, you’ll anticipate events earlier, your sensitivity to what the car is doing will naturally increase, you will make corrections better, earlier and faster. You get instant feedback from all angles, including the time on the clock. Looking at data will show how much time each little mistake costs. If you want to win you stop making them. You will develop mad skills, Bro.

You might even get to the point where someone will accuse you of being smooth.

One last thing. Is one way really faster than the other? Let’s say you do 25 autocross events per year for 5 years. That’s 125 days of your life. I think most people can develop quite good skills with that amount of autocross running, if they do it right.

Let’s say you do 25 track days per year for 5 years. That’s 125 days of your life. I think most people can develop quite good skills with that amount of track running. If they do it right.

Interesting: the two methods are not different in total time expended, but very different in seat-time.

Put in the time, either method, and you’ll get there. But, whatever you do, don’t drive the track at 100% (or you won’t last long) and don’t drive autocross at 95% (unless you’re OK with staying slow or you think of your tires like pets and can’t bear to torture them.)

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At TAC/TVR #3                        Photo by Scott Budisalich

 

 

 

 

 

Data Analysis of Sharp Turn At Wilmington Pro-Solo

Just back from Wilmington, Ohio where I ran the Spring Pro-Solo. Great event with the usual close competition and great competitors in B-Street. This was my 3rd Pro-Solo, spread out over a 4-year period, and first Pro-Solo trophy, 3rd place.

B-street at Wilmington

Fig 1- B-Street Class at 2016 Wilmington Spring Pro-Solo

 

If you don’t know about Pro-Solo, it starts with a short drag-race between two cars lined up side by side. After 150 feet or so of full-throttle acceleration the cars peel off in opposite directions into mirror-image autocross courses. After the finish, the two cars cross over to the other lane and run the other side, again with a drag-race start. Then you swap sides two more times. Very, very intense.

The “amateur” or “old” drag race light-tree is used: a white light indicates the car is properly staged, then three yellow lights illuminate in sequence leading to the green go-light. The idea is to get in sync with the lights, learning when and how to launch, so that everyone leaves more or less at the same time, but no earlier than 0.500s after the green light. (0.500s is theoretically about the typical human reaction time to any signal.) Otherwise, people would simply guess the green light, most runs would be early and red-lighted (disqualified) and the winner would be the lucky one who managed to go right on the green without being early.

With the light-tree skill and experience are required to match your start time and technique with the car to get an on-time start (low, but not too low, reaction time) and best acceleration. Too much wheelspin and you’ll be slow, even if you started at the right time. Bog the motor and you’ll also be slow. Reaction time and time to cover the first 60 feet is recorded so you can analyze how good you’re doing. Any reaction time less than 0.500s (called a 500 light) results in a red-light and disqualification of that run. A good 60 foot time might be in the range of 1.9s for a car like mine when the start area has rubbered-in… I got one of those. A more normal 60 foot time for me was in the range 2.1s to 2.2s, so significant room for improvement exists. Too much wheel-spin at launch is my typical issue.

Each heat consists of four runs, two on each side of the course. Your final time is the best run on each side added together over three rounds, two rounds on Saturday and the third on Sunday. Three rounds times four runs per round equals 12 runs total, six on each side to determine the class winner.

Pro-Solo courses are typically shorter and faster than standard Solo courses, sometimes even less than 30 seconds if the area is small. These courses were 36+ seconds for B-Street and a bit unusual in that each side contained two very sharp, slow corners. These sharp corners were clear examples of age-discrimination. Both were more than 90 degrees, the second being a turn of an estimated 130 degrees. Many of the over-60 crowd (like me) can’t turn their head that far! I smell class-action lawsuit. (Just kidding, Mr. Herbst, course designer!) The options for taking that sharp corner are the main subject of this post.

A path plot from my data is shown in the figure below. This is only the left side course and the green start dot is placed near the end of the drag-race section, just before turning left into the autocross course. At that point the car is moving 30+ mph.

wilm course numbered

Fig. 2- 2016 Wilmington Spring Pro-Solo Left Side Data Paths

The plot shows three paths, one from each of the three rounds. There may be a little bit of GPS drift evident, but not enough to ruin the comparison. Light green is the best run from the 1st round, purple is from the 2nd round and red is the best run from the 3rd round.

I’ve marked the key turns as 1, 2, 3 and 4. Turns 2 and 3 were the sharp, slow corners I mentioned earlier. Turn 4 continued into the finish lights, so if you did it right, you never did get back straight until after the lights. Lots of fun testing your resolve and ability to control the car as you exited the 50+ mph, 7-cone slalom and negotiated this turn. After walking the course my plan was to stay tight, tight and tight on turns 1, 2 and 3. Sometimes I pushed out by mistake (entering too fast), but the plan was to stay very tight. In fact, the wide green path in corner 2 is a push-out caused by entering too fast. Later runs I fixed that.

After analysing data Saturday night, I changed the plan to: flow-thru 1, maintaining more speed and not trying to be close to the second cone that defined this sweeper, stay tight on 2, and not quite as tight as before on 3. My idea was that the entrance to the slalom after turn 3 is slow and short and therefore, 1) wouldn’t be much affected by more turning to get into it, and 2) didn’t afford enough of an acceleration zone to be worthwhile, especially starting from such slow car and engine speeds.

Not over-braking and flowing thru 1 to maintain more speed and engine rpms saved time down to turn 2 as compared to a tighter and shorter path… about 0.2 seconds. This should have saved time on both sides Sunday, but I red-lighted an otherwise mistake-free run on the right side, so I lost that improvement.

Staying tight and short around 2 was clearly correct. I had several different paths, due to mistakes, to compare one to another. I kept doing it as tight as I could on Sunday.

How tight was right around turn 3? That’s the question we are going to explore with the data. Turns out my first plan was best, but not by much. Though it certainly felt better to go faster around that corner, and was not any further distance, it didn’t quite pay off like I thought it would.

The figure below is a closeup of turn 3. It shows tight (green), not quite so tight (purple) which was a failed attempt to stay tight, and significantly wider and faster (red), which was done on purpose…

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Fig. 3- Wilmington Sharp Turn 3

… and here is what that corner looked like in reality:

wilm corner 3 annotated

Fig. 4- Approaching Turn 3

You approach at full throttle, figure out where to brake and what speed to brake down to, turn about 130 degrees and then accelerate while curving back to the right into the entrance to a long slalom.

The choice was this: whether to maintain the corner super-tight, which is almost always best, plus it gave a better entry to the slalom, or maintain more speed with a bigger arc, which takes a more direct path to the first slalom cone, but then sacrifice the slalom entry angle and acceleration to some extent. Because of the rather unique geometry of this corner as it led into the slalom, the various paths were all about the same total distance, so we can neglect distance effects. What does the data say? Here it is:

Wilm data 1

Figure 5- Turn 3 Data

The 340 position index is about the braking point. The LongAcc curves are all very negative by 350, indicating heavy braking. Looking at the top Speed trace you can see (if there were more gradation marks) that the minimum speed for the tight, green path is 22 mph, the next slowest is the purple path at 24.5 mph and the faster red path slowed only to 28.4 mph. So, we have three instances with different speeds around this corner and quite different paths.

Right of the vertical cursor line (set at 440 Position Index) on the Speed graph we see that the green path is higher (faster) than the others. The cursor is located where the green LongAcc trace turns positive, indicating acceleration. That’s one advantage of the tighter green path: it gets back on the gas earlier. In this case, that was made possible by starting from a lower speed.

Of course, what we really want to know is the time saved. This is shown in the DELTA-T traces on the bottom. The red path has been chosen as the baseline, so it stays flat while the other two fluctuate around it. We see that both the green and purple traces lose significant time during the corner, as much as .37 seconds. The time saved by the red path is 0.3s or more compared to the other two all the way out to the where the cursor is located, which is about where I begin to turn around the first slalom cone in each case. If we stopped our investigation at this point it would appear that the wider, red path saved significant time. The issue becomes clouded with what happens next, however.

Both wider paths have to continue turning longer in order to get around the first of the 7 slalom cones. The purple path almost, but not quite, makes up all the time lost to the red path by the time the car is half-way to the 2nd slalom cone. In fact, it might have made up all the time except for a drop-out in acceleration that’s evident in the LongAcc trace at about 465 Index. Probably the rear tires slipped out a bit.

By the end of the data trace the green path has saved almost 0.1s as compared to the red path. This isn’t a lot, but there are some other facts we must consider:

1) the grip was the least during the first round (green trace) and best during the 3rd round (red trace). So, if I’d continued to always take the tight path the time saved by the tight path probably would have been a little more because the cornering speed would have been higher at the same tight radius.

2) a significant slow down is evident in the red Speed trace at the 450 position index. The car slows back down to 28.5 mph a second time in order to negotiate the first slalom cone turn, which is sharper due to being “out of position.”  This is what really hurt the wider, faster red path.

Conclusions: for my car, with its particular grip and acceleration characteristics, it didn’t much matter how I took this turn! There’s hardly any difference in the Delta-T once you take the first part of the slalom into account. What appeared at the time to be better, namely a wider, faster turn with a more direct path to the slalom did not actually save any time. On the other hand, it appears to have cost only a very small amount.

What about for other classes and cars? Well, a faster accelerating car would gain more accelerating into the slalom. So, tighter would have definitely been better. A weakly accelerating car might very well have saved time by not staying super tight and maintaining more speed, more like the red path.

$2 C5 Seat-back Flop Fix!

One of the most annoying and inexcusably dangerous aspects of the fifth generation Corvette are the seats. Specifically, I mean the tendency of the seat-back to flop to the fully reclined position when loaded. Such as during an emergency maneuver, at the worst possible time during an autocross run, or when pulling out onto a busy highway. Each has happened to me, starting from when I bought the car in pristine condition with 13,800 miles on it.

My seats got progressively worse over the next 40K miles. First, they occasionally let loose at any intermediate position. They gradually worsened until they would not hold any position at all other than fully upright, which is not at all comfortable. At any angle more reclined, one side would slip backwards under normal sitting pressure. Either side could let loose with more load, sometimes both sides at once. Yesterday the seat-back flopped from the fully upright position. I’d had enough.

I’ve searched the internet in vain for anyone who knew how the seat-back locks worked and how to fix them. No luck. Lots of people searching for a solution, but no one finding one. I found various people who had taken their new Corvette to the dealer, supposedly had it fixed with new parts (no longer available) only to have the problem reoccur. Today, I had a little time so I pulled out the seat determined to understand and fix the issue, even if I had to weld it into one spot. Turns out welding wasn’t necessary. Two $1 hose clamps did the trick.

Here’s what you see after removing the seat bottom cushion: two cylindrical mechanisms, one for each side of the seat-back. I call them angle locks. Since they are independent in operation (but actuated together) one can slip and the other hold, creating the common situation where one side falls back and not the other. (The fiberglass construction of the back is very flexible in torsion, so it has no problem twisting until one side falls waaaay back there.

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Figure 1- Seat Mechanisms with Bottom Cushion Removed

 

The green springs you see in the figure above are what bring the seat-back up to touch you when you actuate the lever. This way, you don’t have to pull the seat up and you then just lean back to the preferred angle and drop the lever. The angle locks are supposed to hold it at your preferred angle. Now, let’s look a little closer at one angle lock device.

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Figure 2- Angle Lock Device

The main body of the lock is a steel cylinder that is pinned at the forward end. (It has to rotate a little bit during the seat-back movement.) The cylinder is holding together two split sleeves that are inserted into it. Inside the sleeves is some sort of cam-lock device. I don’t know exactly what it is, but this is the bad-boy that slips. The cam-lock is locking the axial position of a shaft that runs from inside the cylinder all the way back to where it is pinned to the lever arm of the seat-back. (You can’t see it… it’s inside the green spring.) With the shaft locked into position, the seatback is prevented from rotating about the seat-back pivot which is fixed to the lower frame.

To release the cam-lock a cable pulls tangent to the lower edge, causing it to rotate inside the split sleeves. (Two cables are pulled at the same time, actuating both devices simultaneously, more or less.) It takes very little rotational motion, at least on both of mine, to release the shaft and allow it to move in or out.

Some have thought that the weight of the driver pressing down through the foam can deflect the pull cable and release one side. Nice theory, but I don’t think so. The cables do get pinched between the seat cushion support wires and the silver metal shaft you see in the picture above, but the cables have a good amount of slack in them. I tried, but, in spite of how little motion it takes to release the shaft, I could not create any cam-lock rotation and thus seat-back release by deflecting the cables unless I pulled them totally outside the volume of the seat.

I think there’s some sort of spring inside the cylinder that serves to pre-load the cam and thus lock the shaft at all times unless pulled by the cable. It’s theoretically possible that the green springs are doing this job, doing double duty. Maybe the spring(s) get weak? Maybe, but my buddy Glenn and I came to a different conclusion.

We noticed that the gap between the split sleeves wasn’t uniform. The gap was bigger in the middle where the pull cable comes in and smaller at the end where the shaft protrudes and smaller at the other end where the sleeves disappear into the cylinder. It looks like the split sleeves have dimples at the shaft end to lock them to a ferrule of some sort that carries the shaft and holds the split sleeves together.

Our theory is that the cam locks the shaft by squeezing on it. An equal and opposite reaction (expansion) within the split sleeves is therefore required. That expansion may spread the sleeves apart over time, such as during the delivery trip from the factory to the dealership. And they probably weren’t particularly close-toleranced to begin with. So, Glenn suggested that we squeeze the two halves together better. We put hose clamps around them as close to the pull cables as we could and tightened until they cried for their Mamas.

It worked!

The seat-back now locks firmly in any intermediate position, which it would not before. I slam back into it and Holy Toledo Pro-Solo! it holds. Driving the car is so much more comfortable, not to mention much safer.

We’ll have to see if this procedure is permanent, but I can dig deep and afford to put two $1 clamps on each side if I really have to. (Glenn thinks I should market a machined and anodized aerospace-grade aluminum two-piece clamp with thread-lockable screws. What do you think…$25? Hey, maybe titanium. Yeah, that’s it. Titanium! $99.95) If anyone wants to protest me, go ahead and try. I’m not removing those hose clamps! I hereby proclaim this to be the industry-standard repair for a safety issue that’s been vexing Corvette owners for nearly 20 years.

P.S. If anyone has ever cut up or otherwise disassembled one of these angle locks I’d love to see a picture.