[QR]GARAGE

The Local Hero’s

May 22nd, 2015 by Q

ryanvetteI’ve got my eyes on Ryan (the R part) and his co-driver C. Withell who are in Lincoln this week for the SCCA Solo II Spring Nationals. Both guys have had what I would call decent success in past National Tour and Pro Solo events, and after they cleaned my clock last weekend at a local event, I’m looking for them both to kick butt south of the border.

Both are competing in SSR, in the black C5 Z06 pictured. Live results are being posted here. In addition, the live video feed can be watched at the SCCA Ustream page.

photo credit: Ian Gulinao.

In My House

May 19th, 2015 by Q

HinatacarsWe do cars all the time.  My six year old may not know all her cars, but she knows her Subaru’s. Purple, like Mom’s is her favourite colour.  She does also, seem to know what a splitter is.

My three year old, the other day, was lying on the floor underneath of her tricycle with a kitchen spoon trying to “fix the transmission.”  Probably time to get them both something with a real engine.

Balancing Scales

May 13th, 2015 by Q

idealcornerweightsSupposedly the ultimate step in suspension tuning and set up, it is my belief that corner weighting is often quite misunderstood and the actual act of doing it, very over rated.

Here is why… Corner weighting doesn’t change (or at least not in any meaningful way), front to back weight distribution, or improve left side versus right side balance. You probably already knew that. The only meaningful thing that corner weighting a car can do, is improve side to side balance. I.E. if a car tends more towards understeer when turning one direction, and tends more towards oversteer when turning the other, there is a very good chance that adjusting the corner weights can make the car handle more consistently, no matter which direction is being turned.

Realcar01A new season of racing has begun, and corner weighting has been coming up in conversation quite a bit amongst fellow racers.  Any magazine article that I have ever read, talks about cross-weight (the combined total of the left rear and right front weights), and if you are driving an autox or a road course, they all make a cross-weight of 50% of the total vehicle weight, the final goal of corner weighting.

Circle track set up guys call the cross-weight “wedge”. If a car has a cross-weight of 50% it is said to have zero wedge. With more than 50%, it has positive wedge, less than 50% it has negative wedge. On a circle track, wedge is used to tighten the car up (i.e. it makes the outside front do more work, and the outside rear do less), de-wedging makes the car looser. Guys who turn left however, realize that cross-weights alone, are arbitrary, and the ideal cross-weight for a circle track car (usually much higher than 50%) will depend on a number of different things: stagger, alignment… left to right weight balance and more.

An autox car or road racer is typically as symmetrical as possible… but left to right weight balance is almost never perfect, and that dampens the value of a magical 50% cross-weight.

50pcrossweightAs we already noted, the simple act of corner weighting cannot change front to rear weight distraction, and it cannot change the total weight on either side of the car. That means, it cannot change the total cornering power a car has when turning one direction. The only thing corner weighting can do, is adjust the difference in front to rear weight distribution on either side of the car.

I call it the lateral weight balance.

Adding wedge, increases the forward weight balance on the right side of the car, while simultaneously increases the REAR weight balance on the left side of the car.  Ideally, (1) our right side weight total would equal the left side weight total, and (2) the left side F/R weight distribution would equal the right side F/R weight distribution. If those two things were true, we’d have zero wedge, or a 50% cross-weight.

However, as soon as we have a lop sided car (i.e. with a 7’ tall driver on the left side, or one that was primarily designed to be RHD and thus has major components like the battery, or the gas tank, or the turbocharger on the left side of the vehicle… or ALL OF THE ABOVE) that 50% cross-weight becomes an entirely arbitrary measurement.

extremeweightunbalanceIf the goal of corner weighting is to get the car to handle the same way in left and right turns, then targeting a 50% cross-weight is like measuring strut angle inclination to get camber. The two are related, but not equivalent.

The closer the two side weight totals of the car are to each other, the closer a 50% cross-weight will be to getting you to an equivalent lateral weight balance. If the car has very different total weights side to side, and a 50% cross-weight, then it’s going to handle very differently when turning left vs right.  We can always adjust the corner weights for a 50% cross-weight, and we can always adjust the corner weights for an equivalent lateral weight balance, but since the cross-weight doesn’t ALWAYS give us the result we are looking for, why not look instead at lateral weight balance?

asmuchbalanceaspossibleBut wait… it’s not that simple… lets think of some other things that affect the way our car handles: alignment, roll couple, total weight transfer, driver inputs, differential set up and on… and on. All of these things can effect what corner weights give the best feel/performance. Maybe as a driver you always turn in harder to the left and thus feel like the car understeers when going left. Is it worth removing some cross-weight? You could. What if the car has an open diff and always blows up the drivers rear tire on corner exit? Is it worth adding some cross-weight to help put the power down? Maybe. And there is more we can think about than even that (i.e. tire physics and the decrease in tires operating coefficient of friction as the weight on it increases, or the rate at which lateral load transfer takes place) but things start to get quite complicated. Ultimately, I’ve always been happy adjusting corner weights at the track, without a scale based on what I want the car to do. I suppose that would require having some sense of feel for the car, which is 93% of the fun here anyways. If you are missing that, then I guess you should just copy the fastest guys set up and hope for the best.

DISCLAIMER: my opinion, my methods, my failure or success. Discussion welcome.

Real Break In

April 29th, 2015 by Q

firstautoxOne auto-x down… kind of. The event was actually a practice event with the SASC at Ft. MacLeod last Saturday. The actual competition was on Sunday, but other obligations forced me to miss that.

So how was the car? My first runs were about as uncomfortable as any runs I have ever taken. I chalk that up largely to a lack of familiarity, and an irrational fear of doing damage. The performance seemed quite underwhelming. In recent years everything that I’ve driven hard has had at least 300lbft. 120lbft seems quite inadequate. Balance wise, the 1″ Hotchkis front bar I’ve installed works very well. The car tends heavily towards understeer, and I like the stability that creates. Typically, an aggressive rear differential would allow me some ability to work around that understeer. The stock torsen completely fails in that regard though. That diff, which can’t make up it’s mind ever about where it wants to send power (left, left, left right left) is easily the feature I hate most about the car (120lbft included!), and it makes smoothly creating and eliminating angle a nuisance.

toppaxAll this aside though… the times I was setting were good enough for top PAX. Keep in mind this was a practice event with smaller attendance and lots of guys running on old rubber, but more than a 1second lead is a good sign for future events.

undertrayAs for the real break in… I hit two cones all day… a small number really, that indicates I was driving conservatively. These two cones however, made their mark. The first, left a huge 2′ long orange smear in my 3M that doesn’t buff out. (I despise 3M more every day that passes and am very close to removing it altogether.) The second popped my front grill out (breaking tabs in the process) as well as totally smashed the front under tray and cracked my fender liner. These were both middle of 3rd gear hits (120 plus kph), and hopefully not that indicative of future cone hits… I did though, order multiple copies of the replacement parts.

You Already Know This

April 19th, 2015 by Q

wingbracesolid188 Strength versus weight…. the common belief is that you can drill holes in practically anything to make it lighter, without compromising strength. We drill holes in everything, and seldom worry about the strength of what is left behind. A lot of the time it doesn’t matter.

Sometimes strength and stiffness is critical however. In that case, is it true that drilling holes is the best way to add lightness? I recently made some simple bolt together bracing for a car with a very flimsy body being asked to hold up a wing with the potential to make a lot of downforce. The braces consisted of some frame and body side mounting brackets and with aluminum bar connecting them. Simple.

And keeping it simple, what is the best way to keep things light while maintaining enough stiffness to prevent the area surrounding the trunk from caving in on itself at speed?

The easiest thing to do is to cut the bars out of solid 3/16″ aluminum. Pulling out my nameless auto cad program and doing some testing, we approximate about 1mm of displacement under full load, and a weight of 195grams, which came in a little bit lighter than the actual piece I constructed for test fitment on the car.

wingbrace6x1.25The obvious thing to do is drill some holes. Note that my testing showed that hole size has a pretty big impact on the result. A single column of larger holes does a better job of shedding weight while maintaining strength, than does multiple columns of smaller holes. Of course, making the holes too large seriously compromises structure. The best balance I found was 1.25″ diameter holes through the 2″ bar.  The weight savings were 33%.  Stiffness and strength drop 27% and 8% relative to our solid bar.

wingbracesolid125That seems like a reasonable step forward, but if weight savings are important, what about starting with thinner bar? Shaving 1/16″ off the solid bar lends very similar weight savings (35%), but a much larger 34% drop in stiffness and 32% drop in strength.  As you might expect, considering “strength versus weight” there are negligible gains.  But if the structural requirements allow, it’s a much simpler way to save weight than starting with something big and cutting holes in it.  Obviously.

wingbracetrianglesIf this was a race car that was professionally built and engineered 20 years ago, you might see something like this. Weight savings are 46%. Strength falls only 20%, but stiffness is a disappointing 48% that of the solid 3/16″ bar. Stiffness is what is critical to this application, making this design an obvious dump. However, it is also not nearly as easy for a hack in his garage to create. Possible… but, not as simple as just drilling a few holes.

graphI played with a number of different designs, and was somewhat disappointed (although not surprised) that none of them provided better results than a single line of holes. That’s not to say its the ultimate: 3D structures can easily provide superior stiffness versus weight. When we have limited machining tools/skills however… and hole saws are cheap… making swiss cheese of everything gets really tempting.

Back in grey

April 8th, 2015 by Q

debut2015My new shoes are boring and grey, but somehow I like them. If no one ever noticed my car that would make me happy. Any attention is bad attention.

If you think my car looks hotter than ever though, despite the boring wheels, you’d be right. It is. As a result of a recent revision to SCCA regulations, the FRS community was alerted to the legality of TRD optional springs and sway bars for street class. Always looking for a reason to modify my car, I immediately ordered said parts. They come with a mild rise in spring rate, and a 1″ drop. The stock suspension on these cars is already really quite good and I can’t say I notice any difference in performance on the street. Having not yet had my car to the track, I’ll never be able to compare to the stock parts, but at the very least, it looks better.

The disappointing part, is that the car woke up with an oil leak. The smoke rises from the rear passenger side of the engine where there is reportedly a cam seal that fails often. Looking quickly, I saw no residue of oil anywhere and was too annoyed to look further. The car has 3300km on it at this point, and none of those km have been hard by any even my grandmothers definition.

Subaru. Fail.

Shatter Proof

April 6th, 2015 by A

FLAPROAD

Flaps aren’t just for mud, but they aren’t just for winter either. And they certainly aren’t just for the look. Even an STI that remains gridlocked on Calgary pavement for it’s entire life will still throw slush/gravel/salt up onto the body for about 9 months a year…

The first generation Legacy came with mudflaps from the factory. But the seam where flap ended and fender began was a notorious spot for rust to brew.

I trust that Subaru has better paint/metal/finishing methods now than they did then, but I wonder if they would still have the same rust issues if factory-flaps held grime against the fender for 20 years.

So what then.. We can’t live with them, and we can’t live without them?

Countless chips in the rocker paint say I can’t live without them.

And an already flawed wheel well makes me fear that the fender can’t live with them.

I suppose the answer is obvious -> Maintenance.

A “set it and forget it” approach might be OK with flaps that are installed very carefully when the paint/undercarriage is flawless.

But in my situation, the approach will likely need to be:
Install for winter -> Clean thouroughly often -> remove for spring cleaning -> address and treat with Por15, rocker guard, and curses accordingly -> reinstall for summer -> cross fingers firmly

In any case it is always satisfying to make flaps from scratch.

We learned our lesson about trusting in names a long time ago.

And the Popular Armor that is out there just seems too dainty (and expensive) for my needs.

fullprogress

I started with an online template of the best selling stuff. But before cutting the rubber I played shadow puppets with cardboard and realized bigger is better since I am trying to protect both the inside and outside of that area. I just hope I’m not trapping a lot of junk that high jumps over the flap and gets caught at the mounting points.

I guess I should add ‘full flap flush’ to my bi-weekly service schedule….

FlapShine