Bigger battery and cutoff switch installed + weight placement musings
In the process of getting the car wired I must have left things in a slightly draining state overnight, which killed the Odyssey PC680 battery originally installed:
Which is a bummer, I’d hoped that thing would last a while. I let it charge for a long time using a good charger, but it failed to come back to life, and had difficulty getting the motor to turn over back on the day I first drove it.
Not wanting to have those kind of hassles when it “matters”, at an actual event, or somewhere out on the street, elected to get a much larger battery, until something like Nationals, when the 34lb. weight savings will be most meaningful.
So in went an Odyssey PC1200, a substantially higher-capacity unit. Still the same AGM technology allowing it to be mounted in any orientation.
Not quite enough room to mount it up on the “shelf” where the PC680 went, it ended up a little further back, to the right, and lower.
Also installed a battery cut-off switch. This will ensure the battery isn’t being drained when the car is not in use.
Left the old battery hold-down in place, this way I can swap to the 4lb. battery in about 5 minutes if desired.
Where should I put my battery?
Anybody building a car for a class that allows one to move the battery, likely ends up asking themselves this question at one time or another.
In some cases, advances in modern battery technology have allowed for such compact and lightweight batteries, you almost don’t even need to worry about it. There are batteries out there literally under 2 pounds, that can start small 4-cylinder engines. If the other needs of the electrical system can tolerate a battery like this, there is little to gain from moving it from wherever it was stock, assuming it is already pretty close to the starter.
For cars with bigger engines, or cars that have more demanding electrical requirements, the battery will end up having a significant impact on the static front:rear weight distribution of the car.
Let’s take an example 3000lb. car with front weight of 1600lbs. (53.33%) and rear weight of 1400lbs. (46.66%). Say this car has a 30lb. battery right at the front axle line, and we move it to the rear axle line.
Front weight is now 1570 (52.33%), rear weight 1430 (47.66%). That’s a whopping 1% shift in static weight distribution, just by moving the battery!
The reality too, with a car like this Camaro, is the battery starts out about 18″ in front of the front axle, and ends up a bit behind the rear, having more than a 1% effect (assuming those weights are about right).
A lot of people fuss over engine setback, and go to great lengths with firewall modification, custom motor and trans mounts, driveshafts, etc., to get the motor back another 1-2″. While those aren’t necessarily bad ideas for classes that allow it, moving 600lbs. rearward 1-2″, is only about 1/6th as helpful, as moving the battery to the trunk (11 feet or more in a Camaro).
If moving it rearward is good, why do I have it where it is, just about as far forward in the trunk as possible? There is room to go rearward another 2 feet or so?
While doing so would improve the appearance of the static weight distribution numbers, the picture above tells the tale.
Weight placed beyond the axles (ahead of the front, behind the rear) has some negative effects, at least for a car that expects to turn corners.
While placing the battery further back does put more weight on the rear tires (a good thing, especially at launch time), it takes load off the front tires – without actually reducing the amount of mass the front tires have to haul around the corner. The rear axle acts like the fulcrum in a teeter-totter; the further away from the fulcrum, the more leverage the battery’s weight has in “lifting” the front axle. This is a very important thing to keep in mind – while we might feel good about the lower registered front axle weight on a set of corner balancing scales as we move the battery further and further behind the rear axle, what we’re really doing is taking away some of the load those tires deserve to get, load which would add to front grip. While it is true (harken back to the CVD series for more on this) that a tire is more efficient (more grip per unit of load) when more lightly loaded, it still produces less total grip when more lightly loaded.
This is one of two reasons why weight/mass located outside of the vehicle’s wheelbase is a bad thing. The other, is that it tends to increase the polar moment of inertia – which may be okay for a Bonneville car that needs to be arrow-stable, but autocross is at the other end of the extreme, where a car’s ability to quickly rotate is paramount.
With this in mind, there are lots of micro decisions about where to place things in a car. Obviously there are requirements that things be usable, and reliable, and serviceable, but beyond that – when you have some genuine freedom on where to place things – here’s what I use to take creativity and aesthetics out of the equation:
- It should be as low as possible. This minimizes CG height which aids in cornering and braking.
- It should be as far rearward as possible, without being behind the rear axle. This puts more weight on the drive tires (for RWD), and helps unburden the front, without introducing the teeter-totter/lever effect described above. Some already heavily rear-biased cars, like a Porsche 911, may be exceptions to this.
- It should be as close to axle center line as possible. This helps reduce polar moment further. If you imagine looking at a car from above, it would be easier to rotate a car with its mass centered at the shifter, vs. one where the mass is all in the doors.
Obviously few things are as heavy as the car’s battery, but a lot of what makes a really fast car fast, is the incremental contribution of a large number of very small things. In this case, placing every other little thing you can a bit lower and a bit further back, could end up leading to that extra thousandth or hundredth of a second that separates first from second.
In the case of this Camaro, with ultimate freedom, I’d probably run the 4lb. battery where the passenger’s feet go (allowing for super-short cables), and with the big battery, would run it where the right rear seat bottom is. But since we can’t have the battery in the “passenger compartment” in Street Touring, instead chose to mount it just about as far forward in the trunk as possible. It could have gone more rearward which would have the benefit of making it lower and improving the appearance of static weight distribution, but the negative effect on front tire loading is something I wished to minimize, particularly in light of these cars’ known penchant for push.
The other big question mark is fuel level – the difference between full and low fuel levels is probably 80lbs., and it’s all back behind the rear axle. If I can find a way to run it with a low tank, it could have benefits on handling well beyond the pure weight saving element.
Oh, since I know everyone is anxious to see the Rhoades Camaro out dodging cones, here is the young Rhoades showing dad how it’s done 🙂
It runs!
Spent every spare moment I had today on this thing, and at last, it runs!
Much of today’s work was in mounting and wiring the ignition coil, which we are allowed to replace in ST.
Since the car is heater delete, the heater blanking panel makes a nice convenient spot for mounting both the coil and the Moroso catch can, without making any new holes in the firewall – which after 45 46 years, has seen a bit of tinkering.
Stock/ST also allow for catch cans, so long as factory PCV/emissions functionality is retained. In this case, the “input” to the can is from the PCV valve, while the “output” goes to the vacuum port on the carburetor. For those not familiar with catch cans, the idea is to have something that captures the misty oil vapors that escape a PCV system under load, and separate out the oil from the air. Any oil consumed by the engine will combust, but it does so at a lower temperature than gasoline, and can lead to detonation/preignition. This is bad on a normal engine, even worse on a high compression engine like this 302, and extremely bad on a forced-induction car.
With the catch an in place, the oily mist is turned into regular oil, which can be emptied out when needed. The engine continues to enjoy a functional PCV system, but through it, only ingests clean air.
The remainder of the work was spent under the dash, getting the DL1 and DASH2 all wired up and talking. Still figuring out the exact song-and-dance needed to get the DASH and DL1 to talk properly, was able to get what I wanted after some effort, but there is probably an easier way.
With the plugs out, verified the motor made oil pressure just using the starter, and that the sender/dash combo reflected the pressure. Still haven’t wired in the fuel gauge or coolant temp sensors, hence their bogus readings.
Later, put the plugs in and ran the spark plug wires. The MSD wires I have are all wrong, will need to get different ones, and route them more carefully. But at 9:09PM, it started and ran! Since the 20 month old was just getting to sleep I shut it off right away.
Still lots to do, but this was a gratifying step, and I met my goal to “have it running by New Year’s” – even if it was New Year’s day. 🙂
Many obstacles overcome, still more to go.
About a month ago I posted a list of stuck-points on the project – fortunately since then, with a lot of effort and tool purchases, progress has been made! Have put more time into the car this past month, than in any month so far. First, an update on each of the old sticking points-
Power steering leakage
New pump was purchased and super-carefully installed. All lines cinched up, and no leaks after a couple weeks, yay! Still have to see how it holds up under the pressure of real use with the pump cranking away, but so far so good.
Brake line fitting leakage
This was due to an incorrect flex line in the rear – correct part ordered and installed, and the brakes were bled, no leaks! My brake bleeding assistant, who’s never driven a manual car, had some trouble with my instructions to “push the pedal in the middle” – since the throttle pedal was sunken to the floor, the clutch appeared in the middle of the e-brake, clutch, and brake pedals. I’m going from corner to corner, wondering why fluid is barely eking out as I hear her pumping away! 🙂 A little revised instruction and it’s good to go.
Still had some air after a couple passes, at which point I realized the multi-piston Wilwoods need to be bled at the top of both caliper halves (inner and outer) to get all the air out. Last few bubbles gone and the brake pedal feels very firm inside.
Leaf Springs
This was a rather labor intensive process. In typical easier-said-than-done fashion they were cut down 2.25″ in length; bushings were trimmed or hogged out to fit appropriate sleeves for mount bolts; the front spring eyes were flipped and ground for clearance; initially the rears were flipped also but it looked like clearance would be an even bigger problem, so they were left upright, but still got some grinding.
This has an ultra-scientific “one to two finger gap” in the rear. Added about 65 lbs. of fuel (more on that later) which only brought it down about 1/8″. Only weight left to go in is the headliner and door glass, so this is where it’ll be for now. It’s not likely this spring rate will be the one I wish to keep forever, so for the next pair of springs, it should be easy enough to request an additional ride height decrease, in addition to the spring length decrease. Bushing work will swap over.
Oh, and in the picture above, the rear wheel has 3/4″ of spacer. There’s room to go inboard or outboard bit if needed, but this provided a more athletic appearing stance, while still providing for tons of wheelwell clearance in all directions. At this setting rear track width is 70.75″, which still, isn’t *that* wide. It’s about 4″ wider than my 240sx was, and about 7″ narrower than the Viper.
Road Draft Tube
Have to thank my buddy John Coffey for talking me through this one. Tried several different things and took a long time with this, and ultimately found a solution. This item was holding up permanent installation for a lot of simple things in the engine bay, so once it was out of the way a lots fell quickly into place – carburetor, fuel lines, distributor, throttle and choke linkages, etc. The tube coming off the road draft vent hole is the black one fuzzily visible in the passenger side carb photo below-
You may note, the stock-style valve covers. These are actually the third set of valve covers I have for this thing – the first set didn’t fit the bolt pattern (they’re for an even older small block) and the second set were a bit bigger and made of thicker material. They *look* nice and original, but caused all kinds of interference problems with things like the fuel line and the bracket for the power brake booster vacuum line, visible above. While in general I’m not a fan of extra chrome, these are at least very lightweight, and totally stock.
Coolant Temp Sensor Port
This problem begat a bevy of tool purchases. After nothing could convince the old plug to come out, began drilling with ever-larger holes. The largest thing I had on hand for going through metal was 3/8″ (bits and chucks), so it was time for some upgraded hardware. Now have a new 1/2″ chuck drill, and an array of drill bits up to 1″ in size.
Also bought a 1/2″ NPT tap to repair the threads, and a special 45/64″ bit as the final pass before using the tap. After using the 45/64″ bit, all that was left of the plug was like foil and I could pull it out with needle-nose pliers.
Hooray! Coolant temp sensor in its appropriate location!
Also visible in this pic, is the new oil pressure sensor. This is a 1/8″ NPT sensor occupying a small port in the block previously filled with a small square plug. This too necessitated some tool purchases since it was a 7mm square plug, so none of my 6-point sockets would fit it, and the only way to fit a wrench on it, would be to pull off the water pump; no thanks. Ended up buying one of these universal socket things, advertised to work on 1/4″ – 3/4″ bolt heads of all shapes and sizes. After some monkeying, it got a grip on the thing and got it out. The tool earned its keep in that one action!
Perhaps apparent from the way the wires for the oil pressure sensor have been run, am making a big effort to keep the wiring tidy and professional in the car. Bought a ton of heat shrink tubing and overlay sheathing, in an attempt to keep everything clean, bundled, and protected.
Vent Windows
No progress on here from last time. The passenger vent window is just about ready to go in, been focused on what’s needed to get it running.
New Progress
Lots of other progress has been made in addition to getting the above accomplished.
First Fuel Purchase
One of the simpler ones – the fuel line installation was completed, so it made sense to get some gas. We happen to have a very neat retro gas station just a few miles from the house, that sells all sorts of good gas right at the pump, and comes complete with a smiling young man offering to clean your windows or check your oil. It’s mostly frequented by the well-to-do’ers of RSF, topping off their Range Rovers and exotic sports cars. I felt out of place with two crummy 5 gallon plastic jugs in the pickup, but the Camaro will look right at home there.
Oh, and this is the only station I’ve bought gas in, in the last 10 years, where you don’t have to pre-pay. Got a lucky click-off of the pump, no coins! Hopefully a sign of good ProSolo reaction times to come. 🙂
Windshield Wipers
This is another that seems like a no-brainer…which of course wasn’t.
Had the body shop install the wiper motor and attach to the wiper arms at the body shop, as doing so requires having the cowl panel off, and installation or removal of a body panel, is a big opportunity to scratch up the paint on said panel.
Unfortunately the wiper arms were not “clocked” to the motor correctly, causing the wiper blade to want to swing down initially, instead of up. So off came the cowl panel, some time spent futzing with the mechanism orientation, but ultimately, the wipers made it in, and I managed to get the cowl back on without messing anything up too badly.
The car had no wipers when I got it, now it has working ones, ha!
Pedals and Header-back Exhaust
The car has four functional pedals at last! Well, the gas pedal may not make it go yet, but it does open the throttle, now that the road draft tube shenanigans were handled.
Brakes were made ok with the bleeding a little while back, and the clutch was okay, as the pressure plate provides most of the springing, but the complementary clutch return spring that keeps the pedal up against the stop, has also been installed.
The parking brake pedal was the last to be made functional. The Wilwood rear disc brake setup on the car has a complete functional parking brake, but comes without a means of adapting it to the factory cable system. Fortunately the solution was pretty simple, with a pair of Lokar “Explorer style” clevises, drilled out to accept the factory parking brake cable. The entire parking brake system is not entirely new, from the rubber of the pedal pad, to the drum lining at each rear wheel.
As you can tell from the second picture, at this point, the exhaust ends at the mufflers. When I get the car to an exhaust shop, will have to see what can be done to extend the exit either to the traditional location, or out the sides. The panhard rod in the rear suspension complicates things.
Ride Heights
They still aren’t right. Rear is too high, as discussed above. I’ve raised the front “2 turns” (haven’t done the math to figure how that equates to inches), but it probably needs to come up more.
This picture was taken a few days ago, before fuel and coolant were added, so both front and rear have since come down a little bit.
You’d think moving the car around a garage floor on dollies like this would be easy – nope, big effort required!
Before trying to drive it anywhere, I’ll probably raise the front another 2 turns.
The Vintage mags with 27+” tall tires will fill the wheelwells better than the Jongbloeds and AD08 rubber. The shorter /35 series front tire vs. the /40 series on the rear, exaggerates the ride height difference.
No problem turning to full lock, even at this ride height-
Pic inside of the front suspension with the wheel turned- contact point at extreme bump, is the lower control arm to the factory bump stop bracket, welded on the frame. At this ride height, it has about 1.25-1.5″ of travel there, equating to about 2″ of travel out at the tire.
Oh, and a funny one-
The family car had to go in for service (Infiniti is paranoid after the Toyota/Lexus unintended acceleration debacle, and is issuing recalls on the new JX35 like crazy. The car needed 5 recalls done, which necessitated an overnight stay) – and since they were busy and out of branded loaners, we got a crummy rental – the Chevy Sonic. The Sonic is one of these economical small cars – not micro like the Smart or Scion IQ, but subcompact like the Toyota Yaris, Mazda 2, or Honda Fit. When my Tundra was serviced I got a Yaris SE loaner, which was actually decent, but this Sonic LT was crap! Anyway, it got to park next to the Camaro one night.
What amazed me was how TALL the Sonic is! Check out this picture-
It only looks a few inches taller than the Camaro…until we see the Camaro is sitting on 5″ tall dollies! Will have to measure the Camaro once it’s back on the ground, but I’m pretty sure its roofline is around 48″, the Sonic (and lots of other cars like it) have rooflines about 60″. Wow.
Battery
Ok, so I put it in the trunk, not very exciting. This is an Odyessy PC680, common in the aftermarket. It’s 13-14lbs., vs the 35+ of the stock battery, hanging way out past the nose. Here’s it’s mounted fairly high, but more or less at the rear axle centerline.
Have more thoughts on general battery placement, will have to share another time.
This battery was bought to get the car going (figuratively, not literally) – since in the beginning it is likely to get cranked a lot without much chance to charge normally, and this should stand up ok to that use. The *real* battery I plan on using is the C680 XS Power battery, which is only about 4 lbs., and is the same form factor as the PC680, meaning it will fit in that mount.
Interior
The insides of the car received some attention, mostly in the instrumentation area.
Steering was a bit out of whack, had to purchase a puller to get it all apart and re-clocked correctly, but it could at least be buttoned up-
The wrap will come off soon! Still getting my hands dirty doing stuff, just not as bad as before.
Note the cover plate over the center of the dash – bare as a no-option car can be.
Couple other things to see – the switch at bottom left, and of course the DASH2 dash. The switch will be an independent control of power for the DL1 and DASH2. The idea is, I can keep it on, to help let the DL1 keep GPS lock between runs, or any other time I want to have the engine off but instrumentation on. Modern cars tend to have as their key positions, Off -> Accessory -> Ignition -> Run. This car has Off -> Accessory + Ignition -> Run. Want to be able to keep some of the electronics going, without all of it going.
Speaking of the DL1, it got its own custom bracket, just below the dash, to the right of the steering column.
That silly bracket took a ton of time to measure and bend up, and I’m still not totally happy with how it ended up, as I had to change its position slightly to avoid having to use a serial extender between the DASH2 and the DL1.
With this configuration, the DL1 will be recording information from sensors (like coolant temp, RPM, and oil pressure) in addition to the things it can figure out on its own – speed and accelerations – and present this data to the DASH2, as configured, over an RS232 serial connection. This is handy, because you can’t really look at gauges while autocrossing. You might have a chance to look at the tach when doing an initial 1-2 shift, but that’s about it really. On the track you can take a glance for a second or so while on a straightaway, to ensure systems are still healthy, possibly even changing your approach if you see oil temps climbing, or something like that. In autocross you go out and hope the car makes it through the run without self-destructing. If you are having momentary drops of oil pressure, there’s no way you’ll see it, without some kind of alarm light programmed in, but that can be tricky, since 20psi might be OK at idle but death at 6k RPM. With the data acquisition, you’re watching the gauges 100 times per second, and if there are any concerning fluctuations, they can be correlated to other events, like hard right-handers following a braking zone, for instance.
In this photo it isn’t yet talking to the DL1, so it only knows to output fuel level, which it will get from the main vehicle harness, and will not be datalogged. Common Camaro Lore dictates one most always autocross a first or second gen Camaro with a completely full gas tank. I’m hoping that’s not actually the case, will find out soon enough.
The DASH2 is mounted to the steering column via a custom bracket I made. When I envisioned the bracket, it had to be carbon fiber, and making it so, took extra time. In trying to get a photo of it tonight, I now realize now silly that probably was, you can only really see it when looking down through the windshield. Here it is, from roughly the middle of the car up against the windshield, looking back and left-
Even if the aesthetics aren’t perfect, pretty happy with how it turned out functionally. The size and positioning of the bracket and DASH2 unit, allow the wheel its full range of tilt adjustment, without bind or interference. Here it is fully tilted up-
With the steering wheel in a normal position, eye level is slightly above the unit, which is supposed to be optimal for its viewing.
Race-Technology was very supportive in sending me out a loaner so I could get the car fired up, while they send my bricked unit back to the UK for repairs. Thanks Al Seim and R-T USA!
Belts
Not very exciting, was able to get a good length PS belt on the second try, looks like I’ll need a third attempt to get an alternator/fan belt of the right length, this one is a bit too long-
Looks like I may need to spend some time shimming the PS and water pump pulleys to get perfect alignment. Like so many things, you think belts will be a 5 minute deal, and it turns into hours… 🙂
###
The plan for the moment is to get it running, and solid enough to not fall apart or puke its fluids out everywhere on a short drive. Want to make sure it builds oil pressure by free-cranking it with the plugs out, before they go in and I try to fire it. It *should* be fine as it ran great on the engine dyno, but that was over 2 years ago, and it has since received a new oil pan.
It’ll need to go to an interior shop to get the headliner put in (it’s a least a 2-person, if not 3-person job on these cars), then to an exhaust shop (have some tweaks to the Magnaflow system I need/want), and to ProParts USA for some shocks. I want to have the car ready for the San Diego National Tour, which is a short three months away!
Let there be light!
Decided to take a few days off work, partly to get a little more time to work on the car. As so often happens when you take time off, I got the flu! Ugg.
Still managed to spend a little time today hooking up some basic wiring. One amusing aspect of this car, is how little wiring there is. When I bought the car, the wiring was some poorly installed Ron Francis aftermarket thing, a big mess. It now has all new OE-replacement harnesses, of which there are four:
- Engine harness
- Front body harness
- Dash harness
- Interior and rear body harness
If the car had a center console, or a stereo, or A/C, or any of several other packages, then it’d have more wiring, but this is all. The dash harness has maybe 40 wires altogether, with the others each having only 10-15.
Amazingly simple!