Lots of things are a pain
Have lots of different assembly sub-projects in the works at the moment. About 40 items on the to-do list left. Try to see them through, but often times they reach a frustrating point, and instead of getting aggravated and potentially causing a mess-up I’d regret later, the approach is to move to another project. That gives the subconscious time to work on the problem, maybe order a new tool or part that would help, and re-address it later when fresh.
Unfortunately after a while, you run out of stuff to switch to, and have to pick back up a frustrating aspect of the project. Here’s a brief rundown of some things causing frustration at the moment.
Power steering pump catastrophic leakage.
Spent a lot of time getting the power steering lines all cinched up, with the basic routing done. Poured in a couple ounces of the new Redline PS fluid, turned the wheel a bit (car in the air), all seemed fine. Added about half a quart. What’s that I hear? The PS fluid is streaming directly onto the floor! It’s not leaking from any of the fittings or orifices, it’s leaking from between the main pump body and the outer reservoir housing. No way to stop the leak, so I put the half full bottle of PS fluid back underneath and let it pour right back in. Used the above little lab bottle to collect the drips that continued for the next couple weeks, haven’t had the heart yet to get in there and undo all the painstakingly attached hoses. Need to get a new pump too.
Not hard to see how Donohue gave up on PS after only one or two races! It’s a lot of weight (20+ lbs.) and complexity, all up at the nose of the car, that also robs power. Just don’t think I can autocross this beast with a lot of caster without it though. Not and provide very precise driving inputs anyway.
Brake line fittings
This project has made me realize how easy most of my earlier car projects have been. Something as simple as brake lines, has been a big pain. The OE-style replacement hard lines don’t thread into the regular Wilwood calipers. Have to get a special adapter. Then there’s stuff like this one-
Have to figure out if it’s a bad fitting, mismatched threads, bad flex line, or something else, now after the system has some brake fluid in it. At least it’s a neat blue (ATE Superblue). Speaking of blue, took this photo of some oil. The LAT engine oil now in the car is a really fantastic blue color. Tried to capture it here by pouring a little in another bottle-
If you’ve ever seen the movie the Fifth Element, it looks just like blood from the Diva Plavalaguna after she gets shot. I’m sure that’s just what the oil engineers had in mind when they were blending it… 😉 Fortunately the engine oiling system is currently all set (though the pan install was not without its challenges), and doesn’t leak, now that an oil temp sender has been installed in the pan. Even have a dipstick now!
Leaf Springs
As noted back here, ride heights are all wrong at the moment. Front is relatively easy to adjust, with some turns of the Afco adjuster. Rear, not so much…variable height spacer blocks are available, but you don’t want to run any more spacer block than you have to.
The Hypercoil springs I first bought way back when are the only composite leafs they offer, and come with a 4.5″ “true arch”, whatever that mens. Of the many mistakes I’ve made in the progress of this project, one was assuming this would be a reasonable ride height. Turns out it is way way off, even with a 1″ spacer block. Car needed to be about 3″ lower from where it was with the Hypercoils, so the only real option was another set of springs. Liteflex LLC, who makes the springs for Hypercoil, didn’t return my message (their unit is a very high quality piece, despite the poor fitment for my application), so I called Flex-A-Form. With one call they were able to take my order. I wanted to replicate the Hypercoil specifications (spring rate and size), but be 3″ lower.
To their credit, they did get the springs to me relatively quickly, considering they had to be custom made. To their discredit, they weren’t going to offer anywhere near 3″ lower height than the Hypercoils. But again to their credit, they have an offset eye design in the spring end, which helps mitigate this – by disassembling the spring end and mounting it upside-down on the leaf, you can lower the effective mounting point by 1″ at one or both ends.
Looks easier than it is, they use a pretty aggressive glue to hold it on, making it some careful prying and chisel work to get the end off without hosing the fiberglass leaf. And the contours aren’t quite the same when upside-down so a bit of file work is required for it to fit right.
Once that’s done, I take a closer look at the Flex-A-Form leaf next to the Hypercoil, and realize that it is at least 2″ longer in the rear section. Ugg! So what do I do now, send them back? Will they take them back now that I’ve flipped the eyes? The more important question that came to mind was, what are the chances they even get it right the second time around, and what will continued messing about mean to the timeline? Instead, decided to modify them myself-
Marked and cut off the extra length; re-contoured the fiberglass to receive the spring eye; positioned eye (in the lowering upside-down orientation) and drilled holes for the mount bolts; cleaned it up, applied sealer/adhesive, and bolted it back together.
Then there’s the issue of bushings and bolt sleeves and washers and fasteners. John Coffey did a good job getting the Hypercoils mounted up way back when but had to custom-make a few pieces on his lathe to get it to go together. I don’t have a lathe or the raw materials, and thus had to improvise, cutting down and hogging out bushings to fit the larger sleeves John had made. *Nothing* about the springs just fit as delivered. Oh, and the subframe connectors have to be mostly removed to get the forward spring pockets out, which requires pulling apart a bunch of the interior.
What should have been a couple hours (swapping out rear springs for lower units) ended up taking at least 8, and only the first one is done! Other side should go faster but geez what a pain. Good news is, I should have all the info needed to get the next pair of Flex-A-Forms built right (I don’t expect the 250# spring rate I’m starting with, to be the one I stick with forever) so the work on the bushings and hardware should be re-usable on the next pair, making this swap only a couple hours, the sort of thing you might try between days at a multi-day race, with normal tools.
Road Draft Tube
Most people don’t even know what this is, and admittedly I didn’t either until recently.
In the old old days – like, before the Camaro – automakers had this thing called a “road draft tube”. They recognized that engines built up positive pressure in the crankcase, especially while the engine was working hard, and they had to figure out what to do with it. Without anywhere else to go, the pressure would cause oil to leak out past the seals, and make a mess of the car. So what they did, was run a tube from a port on the engine, down and back a ways, so liquid and mist oil escaping from the engine, would drip “harmlessly” on the road beneath the car. This was a significant contributor to the black stripe in the middle of our highway lanes; an intentional, built-in oil leak.
By the early 60’s people had begun realizing 1, this was bad for the environment, and 2, engines actually like a little bit of vacuum on this port – so what the heck, why don’t we just ingest this misty oily air and burn it in the combustion chamber? Thus the modern PCV system was born.
In the case of a ’67 Camaro V8, the road draft tube and PCV system are fairly basic. In the picture below (not my engine) you can see the “tomato can” – a very basic attempt at an air/oil separator – it is plumbed to the port on the block you see at the very top left.
From that port, a tube runs up and into the underside of the air cleaner lid. This provides a slight vacuum and causes oily badness to get sucked into the engine. This is actually not a good thing for combustion in a performance scenario, as it affects mixture in a negative way. Thus the benefit of catch cans, which are allowed in STX (even Stock) so long as the “original PCV function is retained”. Current plan is to run the road draft tube outlet to a catch can-slash-air/oil separator, which will then be plumbed back into the original place in the air cleaner. This should meet the rules while helping preserve healthy combustion.
So all of this ancient emission history is great, but what’s the problem? The problem is, the tube has this dome thing on it where it covers the port, where a single long bolt runs down through it, into female threads in the block. Since this probably makes for a common oil leak spot, somebody in the history of this block, must have overtightened the bolt, and it is now snapped off in that port, without enough meat protruding to get a tool on. The broken-off bolt has a nice dome shape to its top, making it tough to keep a drill bit centered, and it is recessed so far down there, normal bolt extractor bolts and tools can’t reach. Yay! As an added bonus, this is at the extreme rear of the block, so to even look at it, requires climbing into the engine bay and contorting one’s self, being careful not to mess up all the shiny, new, and sometimes delicate, engine parts.
I plan to give it a go with a traditional drill bit, and maybe see about extending the bolt extracting bit in some way, to get it down into the hole drilled. On a day when I’m feeling very patient and well rested… 🙂
Coolant Temp Sensor Port
The pristine intake manifold I bought from Jerry MacNeish two years ago now-
came with a plug in the port next to the thermostat housing mount, there on the right side. That port is used in ’67 Camaros for the coolant temperature sensor. In later years it was moved directly to the cylinder head.
I’ve tried penetrating fluid, tried heat, and even tried extreme force (ended up breaking the 1/2″ -> 3/8″ adapter), and nothing has been able to make that plug move. At this point it likely needs divine intervention, but in the meantime, have emailed Jerry asking for advice. Might try drilling it out, though I’m not enamored by the idea of the inevitable loose aluminum shavings floating around the cooling system.
On a related note, recently bought a complete tap and die kit. Not sure how I ever got along without it before, it’s been tremendously valuable.
Vent Windows
1967 was the only year the Camaro came with vent windows and as such, this is one area where replacement parts are hard to come by. And there are a whole lot of parts to replace! While I’m a big fan of the vent windows and like their classical elegance, from a technical standpoint, they are probably the least elegant things on the car. It takes an atrocious number of oddly shaped metal parts, contorted gaskets, and strange hardware, to make one of these vent windows work. Since some of the key stuff isn’t remanufactured, you have to make the best of what you can find. When it’s all said and done, it is heavy and makes you wonder why they even tried doing these things in the first place.
It’s not all cleaned up here, and the gasket still needs some trimming, but the driver’s side vent window is IN!
Headers back, couple minor things
Headers made it back from Swaintech with their White Lightning coating.
Again a very high quality result, and now that I see how close the headers run to critical components like the starter and power steering, am even more glad I went with it.
The coating itself should last a long long time, and help the neighboring components last longer too.
Thought I’d let the pimpy valve covers make their entry now. They’re the same off-white used everywhere else on the car, though they do look a little different here in the light.
Still have a few little things to take care of on the underside of the car before the exhaust can go in, not the least of which is the remaining bends to make on the shifter linkage so it doesn’t bind itself up when in reverse.
Out back, made a couple modifications to the rear swaybar, even though it hasn’t been used yet. One, was shortening the endlinks on both sides by about an inch. The second, was shortening the driver-side arm, so it’s the same length as the non-adjustable passenger side. These two changes should provide a lot more bump travel – with this arm length, the bar arm ends will contact the floor (if nothing else hits first) at its highest point, allowing for maximum travel. You can see it somewhat here:
A couple weeks ago I put together a to-do list of things I could think of off the top of my head. Presently it has 57 items, of which 7 have been done. 4 will require outside help – mount tires to wheels (which themselves haven’t even been made yet), add a slight bend to front swaybar arms (purchased a narrower front center section for the swaybar to allow for more tire clearance, but it requires modification to the arm shape), welding the alternator bracket to the header (found a bracket but should have it welded for better stability/reliability), and the headliner install. I could *try* the headliner install myself but everything I’ve seen says you need at least 2 people, if not 3. It’s not like newer stuff where it snaps in, it’s a real fabric thing with adhesive and these wacky metal rods. Looks like awful work.
Each of the tasks on the list are 4-8 hours, so still a long way to go. Will try to take more pictures along the way. Here’s an artsy one in the meantime…
STX thrust comparison 2012-2013?
A recent thread on the new Toyota Scion FRS & Subaru BRZ on roadrace-autox.com took an interesting turn around post #3680, when someone opined on where the car should go in the Street Touring category.
Now that Street Touring has moved from seats-and-displacement based classing, to one relying on subjective assessment of vehicle performance, there are many places where a given car could land. As a normally aspirated and lightweight 2+2, the FRS/BRZ could fit in many of the classes, and every single one – STC, STS, STX, STR, and STU, have been mentioned.
A good bit of the discussion was on how the car would fit in STX, given how similar it is to the RX8. Some dynos were shared and thoughts on acceleration given.
Since I’d already collected the data for some other STX cars, it was not too much work to provide an STX-centric thrust spreadsheet, which I’ve linked to below here.
There’s still a lot unknown about the FRS/BRZ, including what size tires it can fit. Feel free to download this spreadsheet and make adjustments as you see fit.
Based on what I’ve seen so far, the accelerative capability (which by no means dictates in-class performance!) looks to be on par with the RWD class leaders in STX. The BMW 328 appears to have a slight edge over 55mph, and the Scionaru would appear to have an edge at very low speeds (~25) which could possibly be an edge up to 35mph if there were a way to tune out the torque dip. These all pale in comparison to the nearly-forgotten WRX, which dominated the class for so long but has been out of favor in recent years.
The sample data I’ve provided here for the Camaro includes a very optimistic curb weight, and dyno numbers from a magazine engine build, that are possibly somewhat representative, but certainly not identical, to a stock-legal engine build for the same motor.
Header test fit
Small-block Chevys with headers is the automotive equivalent of a peanut-butter sandwich with jelly – once you have the first thing, you have to try having it with the second. I’d bet anyone, that more headers have been designed, built, and sold for the ubiquitous SBC, than any other engine in history, and likely, for any engine that ever will be made. So choosing headers for the car should be a slam dunk right? 😉
Given the popularity and huge run of the SBC, there are a staggering number of choices out there. And amongst those choices, pretty much all are available to fit in a Camaro – which, for the most part, has plenty of room for headers of any design.
The most common design is a 4-1 long-tube style, usually with primaries about 30″ in length. Among the best of this breed are Stahl headers – these:
are built off the same jig used to make the headers used on the Penske/Donohue road race cars from ’68 and ’69. Great ground clearance, with a race-proven design. Fits the theme too…so a good choice?
Since the primary use of cars like Camaros from 1970 until recently has been drag racing, most of the brand names you think of (Hooker, Hedman, etc.) designed their headers with drag racers in mind. Drag racers don’t tend to run their cars as low as road racers, so they’re less concerned about ground clearance, and low weight. Most headers you find for this crowd are a heavy-ish gauge steel, with a crummy high-temp coating, and hang down 2″ or more below the frame of the car.
One trait drag racers and road racers have in common, is a focus on the top end of the powerband. As a vast generalization, the common 4-1 design SBC header promotes maximum peak horsepower, and the primary tube diameter (1 3/4″) and collector size (3″) most often offered, is really bigger than needed for a typical SBC in most uses. In my case with a 302 (at the small end of SBC displacement) and a focus on midrange (this is an autocross car after all!) – the vast majority of the headers out there just weren’t the right fit for the application, at least not as I see it today – including Stahl’s headers above.
My priorities:
- Good ground clearance, not hanging below the frame if possible. The car will be on and off trailers often. Super low cars with long wheelsbase (108″ remember!) are a nightmare to load and unload from trailers. Plus sometimes we have bumps or dips while racing.
- Good low-end and midrange. While even in the worst case I should have more acceleration at low engine speeds than the competition (especially now that unfortunately, Terry Fair has wussed out and gone to ESP with his crazy-powerful 5.0 Mustang), the 3000-4500rpm engine speed range (equating roughly to 30-45mph with initial gearing choices) are what matters, and a lot of people will say the 302 doesn’t even “wake up” until 4500. I’m hoping “those people” are those used to big blocks, who would say that something like an RX8 never wakes up… 🙂
- Low weight. This weight is up on the nose, and not all that low. Thin-wall stainless like 18ga would be lightest, but also the most fragile in a header-impacting event.
Based on this, I took a plunge on an off-the shelf header that *should* meet these requirements. As with the shifter in the previous post, things aren’t quite right out of the box – the passenger side header needs to be bent downward a bit at the rear, to keep from hitting the floorboard. Might just cut off the triangle flange and go with a v-band, haven’t decided yet. Driver side fits perfectly.
Instead of a 4-1, it’s a “tri-y” design, also known as 4-2-1. It’s not stainless, but is a thin-wall mild steel, the units are quite light. Primaries are 1 5/8″, and collectors are 2.5″. Those are good conservative starting values, similar to what was used on the engine dyno, though the dyno headers were 4-1. The purpose of the test fitting was to make sure they’d fit the car and its components, before being sent off to Swaintech for their White Lightning coating to be coated inside and out. This stuff is extremely effective at keeping the heat in, I had used it years ago for the turbo components when I took my 240sx to Street Modified:
This should really help keep the interior heat levels under control. A lot of the restomod/Pro-Touring guys add a hundred pounds of sound and thermal insulation to their cars…definitely not a fan of that approach for a car with heavily sporting intent. Will probably be doing Swain on the rest of the exhaust system (which itself is still somewhat TBD) to help keep the floor cooler.
From inside the engine compartment, passenger side-
Not much going on over there, especially with no heater. The Swain will help keep the starter from getting cooked, and not working on a hot engine on a hot day.
Driver’s side is a lot more cramped, but they fit well, with at least ~3/8″ clearance to the other hard parts. Again, counting on the Swain coating to help keep the PS fluid from boiling, or other things from melting.
Ground clearance – not perfect, but close to it, for this car. The larger diameter things have a harder time staying tucked up like this.
If I end up with the nice-to-have problem of too much low-end and midrange torque, such that throttle modulation is impossible and the 265 street tires are constantly being blown away… then I might consider going to a more top-end-centric header design, as an archaic sort of traction control. Or, if the power feels lacking somewhere, having someone like Burns Stainless design and build a custom super-thin stainless set of headers based on all the engine parameters, with a focus on beefing up the spot of the powerband that feels lacking.
I’m hoping the SBC have been around long enough, the unit I have is an effective design, taking into consideration its apparent goal of being a good “street” header. I had Burns do a full workup years ago for my 240sx when it was in STS (stock engine, normally aspirated) and the tubing diameters and lengths their software spit out, were pretty much exactly what DC Sports had put together in their cheap off-the-shelf unit.
Now that I’m confident these things are going to fit, placed an order for the rest of what needs to go under the hood. Hope to get the flow of updates coming more regularly soon.
Stay tuned!
Site running in an upgraded home
Spent a little time over the last few days, moving the site to a host in Amazon’s EC2 “cloud” infrastructure. The dusty laptop in my closet serving rhoadescamaro.com was 5 years old at the beginning of this project and is now over 7, long past its due date.
Got WordPress up to latest version and did some other general cleanup. This should all be transparent to the site’s followers.
I anticipate providing a lot more high-definition content in the coming months. Amazon will be able to deliver the site’s big photos and video faster than my pro-sumer home connection could.
Don’t worry fans, this is me gearing the site up for the car’s exciting final build steps!
Taking a little break
I know some of my more ardent blog followers will find this disappointing, but I’m going to be taking a break from the Camaro for a while.
As for progress from the last update – the rear quarter windows have been installed (much harder than it sounds to get it right), and I’ve put the rear seats in. Windshield washer system is put together. Flywheel/clutch/pp, bellhousing, and transmission are all together and in. Fuel tank is fully in and buttoned up. Original driveshaft fits perfectly though it will need to get cleaned up and receive fresh U-joints.
Left on the to-do list:
- Fuel system
- Cooling system
- Power steering system
- Electrical system (alternator and gauges)
- Vent windows and door glass
- Front seats
- Exhaust system (headers and header-back system)
- Wheels and tires
- Odds and ends
Planning to get back to this late in the Spring or sometime in Summer. In the meantime, have a planned investment in infrastructure – an enclosed trailer, which I’ve never myself owned before, always borrowed. The timing should work out well, I can use San Diego’s great autumn and winter to fine tune the car, so it is all ready to go for next year, instead of a big event like the SD Tour being its first outing.
If you’ve been following along some of the SCCA forums threads, you may have an idea what I’ll be driving in 2012 instead of this. Some opportunities are too good to pass up!
When I’m back to work on the car, I’ll put some notes up on Facebook and the forums I visit, so don’t worry about visiting here every day for updates.
CVD Series – Chapter 3 started
Made a couple updates to the CVD series, chapter 2 and 3a. If you mouse-over the 
box at top, it should provide a drop-down to all chapters.
Chapter 2 is a boring yet somewhat gruesome dissection of a classic autocross lap.
Chapter 3a is the longest yet, explaining the process for evaluating and comparing the rolling acceleration capability of two cars. This should be a good resource if you ever find yourself embroiled in a “horsepower vs. torque” debate.
Started work on 3b, then on to cornering! Car got back-burnered for a couple weeks while John works a little magic on an A-Mod autocross car.
Staying sharp in the off-season – sim racing
The “sunshine tax” we Southern Californians pay affords us year-round opportunities for autocross and track days. Still, since I won’t have a car for a while, and there’s some free time while the car is out, decided to do a little more sim racing this winter.
There are several sims out there, the two I’m most familiar with are the SimBin GTR series of games (GTR2, GTR Evolution, Race07), and iracing.com.
The SimBin games are fun and a tremendous value – for $20-30, you’ve got unlimited access to 100+ awesome cars and dozens of neat tracks. Within a few minutes of installing, I was driving a Team Oreca Viper around the Nurburgring. Their Porsche 935 is by far the most fun sim car I’ve driven. You can download even more cars and tracks from sites like nogripracing.com. They also have a “Hot Laps” section, where people can post up their fastest laps, so you can see essentially the world record laps to compare to.
iracing.com is a little more hardcore. When you sign up you only get access to a small handful of cars, on an even smaller handful of tracks. The only real car you get when you start is a crappy Pontiac Solstice. You’ve got to keep paying a monthly fee, and you have to pay more every time you want to try a new car or a new track. Still, the simulation aspect of iracing is even better than the GTR games, which makes the subscription-based iracing a worthwhile endeavor for a few months in the off season. From within the iracing website, you can look up the world record laptimes for a given car on a given track, to compare to. No excuses here – with an average PC and wheel/pedal combo, you should be able to run with the very fastest guys in the world, once you’ve had some practice.
The sims always feel a bit cartoony and obviously the sensations are missing, but anecdotally it seems helpful. It helps you remember how to stay focused, how to stay smooth on your inputs, and if you race against other people, it even feels like a bit of exciting pressure at times. Some of my best driving in 2010 was the year’s first event – the San Diego Tour, when I hadn’t driven the Viper for 5 months, but had played a bunch of iracing after Santa brought a Logitech G27 wheel for Christmas.
Also, I look at a guy like Bryan Heitkotter. Bryan was already a really good autocrosser, then he got into iracing and rose to be one of the gods amongst its ranks. Meanwhile out in the real world, the guy is now just plain unstoppable, winning every race he enters, in a tough class against some really great drivers.
This isn’t an advertisement for any sim racer (though if you sign up for iracing, I wouldn’t mind if you told them I referred you 😉 ), just an observation that these programs have come far enough along now, to be valid training tools for use in the off season.
More fabrication work complete
Despite having to simultaneously deal with a cold and waves of “Camaro groupies” coming by the shop to check things out, John has made a bit more progress on the car.
Unitrax completed the rear end with the ring & pinion and diff all installed right. The passenger-side leaf spring mount was bent, rusty, crooked, and had been re-welded or something by a caveman with a blowtorch; it needed some fixin’-
The sawzall, saws all:
Removed, and readied for the new perch:
This is one place the Camaro’s popularity helps. Replacement spring perch from Summit was just a few bucks, they had it in stock, etc. Probably not many cars where replacement welded-on pieces like this are so easy to come by-
All prettied up and rust protected:
I’d been thinking about buying a lathe and making some of my own bushings, but there are really only a few this car needs, and I don’t have a ton of spare workbench space…so I’m having John make the custom bushings the car needs also. He completed the first couple pairs, for the rear leaf spring shackles-
These Hydlar bushings should offer much improved response over the worn-out stock bushings, which in an informal durometer test, measured just above “marshmallow”
Why are old Camaros always so slow?
Them be fightin’ words in some circles but since this is my blog, it’s a fair question to ask. The context of the question today, is around why they’re slow in autocross, when seen from the eyes of a typical die-hard SCCA competitor.
One of the more interesting aspects of this project, has been the speculation and conjecture on why the car is going to be slow in STX. As a car builder, one ought to understand their platform, and in leveraging available allowances, do everything possible to minimize the impact of any deficiencies, while accentuating the strengths. We all *know* these Camaros are slow at dodging cones – but what specifically makes them so slow? Some are convinced it’s the axle-tramping rear suspension; others are sure it’s the front suspension, still others think the car won’t really be making good power vs. its competition because of optimistic 60’s SAE Gross vs. today’s Net HP ratings. Or maybe it’s way too big and heavy, maybe the brakes can’t be made to work, maybe the steering is too slow.
Well, I am sure there are many possible reasons, and until I’ve got it running and tuned as well as I think I can, we won’t know which of the above are true. Maybe none of them apply if the car is built right; maybe all of them are true, regardless of all you do (at least within ST rules).
Though I haven’t gotten too far with it yet, there are two Very Big Things I see holding these cars back in the majority of cases, that I’ll address in this post. Hopefully with my advance knowledge of these shortcomings (queue G.I. Joe) and some efforts made in mitigating them, I can overcome. Here they are below, in no particular order-
BIG THING THAT MAKES EVERY AUTOCROSS CAMARO YOU SEE SLOW #1:
The person tuning and driving that Camaro you see, doesn’t know what they’re doing and/or didn’t build their car to “go fast”. Now, I understand that statement comes across as horribly arrogant, but let me explain-
We all (or most guys, at least) tend to think we know what we’re doing the first we get behind the wheel. “Of course I’m an excellent driver”, and we continue to believe it until we see the times of somebody who really is fast.
To use one of my favorite memes in illustration,
| First I was like- |
 |
| so I was like, |
 |
| but then I was like- |
 |
You just don’t tend to see the really fast guys driving old Camaros at SCCA events, and you almost never see the really fast guys at non-SCCA events. They’re often running more modern and closer to stock Miatas or Corvettes, or whatever the hot car is that year. The best drivers tend to flock to the platforms that are believed to be competitive, because they want to win! It’s super rare to see somebody really good (and please, don’t for a second take that to mean I think I am) driving an oddball platform. What this means is the general Good Driver rule still applies to Camaros- a “really good” autocrosser could hop in the driver’s seat of a “beginner/intermediate” Camaro autocrosser, and usually beat them by a few seconds on 50-60 second course. In some ways the non-competitiveness of Camaros, and many other interesting cars, is a self-fulfulling prophecy, as those who own them are likely to get discouraged by their early results and lack of any evidence they’ll ever be competitive, leading them to to not stick with the sport long enough to get any good at it. Who knows, perhaps with some success maybe I can change that – I sure see more Nissan 240sx’s out there today than I saw before 2006.
So there’s the driving element – if the person driving that Camaro wouldn’t be competitive in the Miata or Corvette or whatever, there shouldn’t be any expectation they’ll be fast in the Camaro. Subtract a few seconds for a really great driver, and maybe the car looks a bit less bad?
The other aspect of this relates to tuning and preparing the car to go fast in autocross, and skill in this area almost exactly parallels driving, though most people seem a little more willing to admit their shortcomings in this space.
There is an unbelievable quantity of parts out there for these cars, as they’ve been undergoing speed tweaks for over 44 years now. While as best I can tell the majority of effort into these cars for decades was around drag racing, the idea of making them go fast around corners has become very hot in recent years and the parts variety reflects this. The “handling” renaissance begat a staggering quantity of suspension parts but not a lot of good guidance on what to do with them. Individuality, limitless modification options with no rules boundaries, and differing levels of willingness to sacrifice street manners on the altar of speed, have prevented the crystallization of a “spec” setup for the Camaro. A good example of a spec setup, is that for the super-popular Street-Touring 1989 Civic Si, published by Chris Shenefield about 8 years ago:
http://www.redshiftmotorsports.com/RedShift%20Tech%20Page.htm
With no spec setup to start from and no prior experience assembling a proper-handling autocross car, it’s no mystery so many of these cars end up not working very well, driving aside. The Camaro as a platform is a deep dark hole to climb out of, too difficult to expect anyone to succeed with as their first autocross tuning project. You can put your faith in what your suspension vendors tell you, but their answers are going to be targeted to the middle of their demographic, who may care more (or less) about a comfortable cruising ride, than you do.
There are some people floating around out there in the old-Camaro world who kinda know what they’re doing around the cones, I think, but since there isn’t really any sort of rules in the old-car specific events, it’s impossible to tell who’s doing a lot with a little (bit of modification), or who’s doing less, with a whole lot more. Structure and rules are frowned upon in those circles, which is a shame because it makes results impossible to use in drawing conclusions.
I guess as a message to all my fellow old Camaro owners out there – if you really want to be fast in your Camaro at the autocross (and largely also, the track) – the best thing you could probably do, is park the Camaro for a while. Get a Miata, or an S2000, or a Corvette, and go run a ton of events (SCCA preferably). Figure out who the fast guys are in your region and track your times against theirs. Even better if you get a similar car. By getting a car that’s great out of the box, you can forget about setup and focus on driving. This will teach you the importance of driving, while at the same time familiarizing you with the characteristics of a proper-handling car. When you’re ready, then go back to the Camaro – I suspect the experience gained in a “good” car will better illustrate how far you have to go with your Camaro. It should also help you better understand the importance of different modifications, and get you to spend the next few bucks on tires or shocks, instead of a supercharger.
How am I going to avoid this common problem? By drawing on my experience as a driver and a tuner from many other cars, to dig this thing out of the deep dark hole it starts out in. I don’t have any success stories to look to, but that’s part of the fun/challenge.
BIG THING THAT MAKES EVERY AUTOCROSS CAMARO YOU SEE SLOW #2:
The stock front suspension really is as bad as you’ve heard. There’s a lot of things wrong; below I’ll attempt to explain just one facet of the wrong-ness 🙂
Most of the old Camaros you see at the autocross look awful – they are too soft, and the front suspension looks like it’s doing the opposite of what it should.
Not trying to pick on this car or driver here – this photo pulled from http://www.milesspeed.com/ – a neat site I stumbled across in researching these cars. Car is owned/driven by cool chick Liz Miles, and this was taken very early on in the car’s development. Using it just to illustrate some of what’s wrong with the car’s front end; odds are if you’ve seen an old Camaro on an autocross course, it looked a lot like this.
Here’s another one from a 1967 magazine article on the original Z28:
That thing has no grip on the crap OE tires, but it still manages to showcase how utterly whacked its front suspension is.
Front grip is tremendously important in autocross. At the track if you’ve got way more power than everyone else, you can maybe get away with a pushy (understeering) car, heck, it’s more stable. But not in autocross. You need to generate big yaw/rotation, and you need to be able to change direction quickly. The front tires do all this work and it’s the front suspension’s job to keep the tires as happy as it can.
Pretty much nobody with one of these old cars is giving them enough front tire. I’ve seen cars with $10k+ in aftermarket grafted-on C6 subframes, uber expensive shocks, and mega-$ forged wheels … wrapped in 245 width tires! With 335s out back! That sort of stagger might work on a 911, with over 60% of its weight on the rear axle, but it’s a recipe for terminal understeer (and a frustrating/boring driving experience) in a 55% front-weight Camaro. If you want one of these things to turn, you need to give it all the front wheel/tire you can, and nothing made today with a DOT stamp is “too much”. My Viper had about the same front weight as most of these Camaros, and it had 335s up front! At that size things were just starting to work right. 🙂 Obviously packaging is a problem but with all the effort put into everything else, I don’t see why more of those guys aren’t running at least 285s up front.
So to the subject of analysis here – the motion ratio – and boy is it TERRIBLE! To many that may not mean anything, so let me attempt to explain. Below is a photo of a stock ’67 Camaro lower control arm. At the far left, the rod illustrates the axis upon which the arm pivots. At a bit past 8.5 inches down the tape measure, are the two bolts that hold the shock. When installed, the spring sits concentrically around the shock. At the far end, just under 16 inches, is the lower ball joint’s pivot point. Though you can’t see it here, there’s a hole for the stock swaybar attachment at about 13.5 inches.
So what’s the motion ratio, and why do I care? Well, the motion ratio, is the ratio between how far the wheel moves, compared to how far the shock absorber (or spring) moves. The further out on the arm the spring/shock attach, the higher (and better) the motion ratio. To calculate the motion ratio, you take the distance from the inner pivot to the spring/shock attachment, and divide it by the distance from inner pivot to lower ball joint pivot. If we round the pictured measurements a bit, we get:
Motion Ratio = 9/16 = .5625
This means, for every inch of wheel movement, we only are going to see .5625″ of spring/shock movement. Okay, so why’s that bad?
It’s bad because we depend on our shocks to damp the motion of both our unsprung (wheel/tire, 1/2 our suspension) and sprung (the rest of the car) weight. The better a job the shock can do, the more consistently loaded our tires will be, the more grip we’ll have, the faster the car will go around the corner, the lower our laptimes. This motion ratio is about 30% lower than the motion ratio of a good modern car.
Below is a pic of a Viper’s front corner – look at how the spring and shock attach waaaaay out on the arm, right next to the lower ball joint:
The Viper enjoys a much much better motion ratio than the Camaro.
Shocks depend on velocity to do their job – if they are not moving, they are not displacing fluid, which means they aren’t doing anything. The more shock travel we can get per unit of wheel travel, the better we can control every microscopic bit of that wheel travel. This also allows us to control things with lower shock forces, which makes it easier to find reasonably priced units.
In an autocross car with a good motion ratio, we’re generally looking for what the shock does at about 3 inches/second on a force vs. velocity graph (explained somewhat here: http://farnorthracing.com/autocross_secrets20.html ). Most of the movements the suspension sees on an autocross course are in this speed range, so that’s where we care about what our shocks are doing. Shock velocities above that speed (bumps) are important too but somewhat less so, they’ll be a subject for a later day.
So getting back to the Camaro – with a motion ration of .5625, we’re only getting about 2/3 the shock travel or velocity, of a “good” suspension car. So whereas they get to build their shocks to work at 3 in/sec, ours have to be doing the same quality of control, with 2 in/sec. The problem is, accurate control and large forces at these low shaft speeds, are very hard to come by – any of the common shocks available over-the-counter just aren’t going to get it done, at least not very well. But wait, it gets worse!
Spring rate by itself is a not very good indicator of how stiff a car is – what’s more useful is the “wheel rate”, or maybe the “natural frequency” of a suspension. Here’s an online calculator if you’re interested to find out yours: http://www.racingaspirations.com/?p=292
Those that have ever ridden in an unladen 1-ton pickup truck, and been bounced all around, have experienced a high wheel rate, and a high natural frequency. The high natural frequency is caused by a very high wheel rate, combined with not much weight on the spring (an empty truck bed). If you’ve ever then loaded up that bed with a few thousand pounds and noticed the truck suddenly rode much more comfortably, it’s not because the wheel rate went down (in some leaf systems, it might actually have gone up) – it’s because the natural frequency has gone way way down due to the weight/load in the bed.
We arrive at wheel rate by taking the motion ratio, and multiplying it by itself – “squaring it”, in math terms, then multiplying it by our regular spring rate. In the Camaro’s case, .5625*.5625=.316. That means that for every 1 pound of spring rate, we are going to have .316 pounds of wheel rate.
Wheel rate and natural frequency are concepts you can use to compare the stiffness of any two cars, regardless of suspension type. You’ll often see sliding scales where 1hz is “comfy street car”, 1.5hz, “sporty car”, 2.0hz “race car”, 3.0+hz “race car with aero downforce” – something like that. Those are really just broad generalizations and by no means limits on what you can do with your car.
If you’re setting up a car to handle well, 2.0hz isn’t a terrible place to start. If you’ve driven other prepared-suspension cars that you really liked, that were of a similar layout (RWD, FWD, AWD), it might be worthwhile examining that car’s frequencies and consider it as a baseline. For instance, my 240sx used a 550lb. front spring when it was in STS (street tire) trim. It had a bit over 700lbs. of total weight per front corner, about 55lb. unsprung. It used a strut front suspension which granted a motion ratio of about .96. Its 550lb. spring netted a ~500lb wheel rate, and with the car’s weight, its natural frequency was around 2.7hz. While this was way higher than anybody is likely to recommend for a daily driver, it wasn’t terrible on the street, but more importantly, it wasn’t so stiff that the street tire wasn’t working well. The car worked great!
A similar calc on the rear of an STS Civic I built, puts the frequency around 3.5hz! Some guys I know are running springs up in the 4-5hz range on the rear of those cars.
So getting back to the Camaro, now knowing the 240’s numbers (500lb. wheel rate, 2.7hz) as a ballpark. With our Camaro’s motion ratio, to get a 500lb. wheel rate, we’d need (500/.316)=1582lb. springs! Even at that rate, our frequency is only going to be a bit over 2.5hz, in some ways softer than the 240sx. To get to the same frequency I’d need springs up around 1820lb./in!
Ugg, now we’ve got not much shock velocity to control our wheel motion, and on top of it, we’re going to have to run crazy stiff springs to get this thing to the stiffness level we want.
There are a lot of things “less than ideal” about the Camaro’s front end geometry – bump steer, camber curves, etc., that I can’t really fix in ST, and that you can’t really fix with the stock subframe. In an earlier post I mentioned my plan for dealing with these was to set the static numbers good and “not let it move much”. You can see now why people hadn’t really tried that approach before – they couldn’t! No normal shock you could buy off the shelf would damp a 4-digit spring given an equal motion ratio; things that stiff were just outside the bounds of people’s thinking. About the stiffest I’ve seen anyone run is 800lb. springs, for a 250lb. wheel rate, about half what I’ve depicted above. It’s no wonder people were so concerned with bump steer and camber curves – at that low a wheel rate, the suspension would experience large (double to triple) the quantity of travel as the more stiffly sprung version, so the negative effects of bad bumpsteer/camber curves would also be doubled or tripled. It also means they had to run their cars a lot higher, which is a Big Bummer for them, we’ll explore later.
So to bring this home-
Bad motion ratio gives shocks poor control of sprung/unsprung motions, leading to inconsistent tire loading
Bad motion ratio creates a lot of suspension travel at “normal” spring rates, exacerbating the problems with the stock suspension’s camber and bumpsteer curves and necessitating higher front CG
How am I going to avoid letting this screw me up? Simple answer – great shocks! The 28-series Konis I have, were originally designed a few years back for high-downforce Indy cars, where there are very large forces needed at very small suspension displacements. Even though an autocrossing ’67 Camaro is a long ways from a recent Indy car, the characteristics needed end up being quite similar. There are many other high-end brands (Penske, Ohlins, Moton, AST, JRZ, Sachs, and more) than can get this done too, Koni just happens to be the one I’m most familiar with. With a little bit of revalving, they are going to allow me to run these really high spring rates, while maintaining good wheel control, something a lower-end shock wouldn’t.
Lots more wrong with front suspension, more to come on that later…
