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MUST READ: The Definitive C5 Info Thread

Old 07-13-2018, 10:11 PM
Chris Draper
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Default MUST READ: The Definitive C5 Info Thread

This thread is an evolution of several old threads. Over the years, as these cars get older, some things change. Originally Posted by member "leaftye" in 2004. It was reposted in 2005 by "David426". I have been given permission to repost this in 2018, with updated and added links and information that have changed over the years. I will be maintaining this thread going forward if any info needs to be updated or added. Please send me a PM if you see anything that you think needs to be changed or updated, or if you have info you think should be included.

Common Problems:

Leaking Battery
Many C5's came with AC Delco Freedom batteries that had a tendency to have its case crack open near the battery posts. The leaking battery acid would drip down the side of the battery, down the funnel-like battery support, straight down onto the PCM and the wiring loom. It can also get onto the A/C lines. I believe they are the vacuum lines that control the movement of the interior vents, and usually the system will default to blowing out the defroster vent. Sometimes car crippling damage would occur, sometimes not. At worst it would mean replacing the battery, the PCM, the wiring harness, grinding the rust off the frame to repaint it, changing the A/C lines and possibly swapping out another computer as well. This mostly happened on early C5’s because later C5’s used a gel-type battery that cannot leak.

Check this out on any car you look at. Use an 8 mm wrench, preferably a ratcheting closed-end or short socket, to remove the battery cables. You will also need a 13mm ratchet with long extension to remove a holding block on the front side of the battery (1 bolt). The battery lifts right out. To remove the black plastic battery tray, you will also need a 13mm wrench (4 bolts). Look beneath the tray for rust or white powder. Signs of both are evidence of battery acid damage. If you see this on a Vette you are looking to purchase, it may be best to move to the next Vette unless you don't mind possibly tackling this repair in the future. It's possible the car will throw codes for no apparent reason. No matter what Vette you buy, just make sure you replace the battery with a gel-type battery.

Grounding Problems
Bill Curlee has a great thread on the problems that corroded ground connections can create, and how to clean out the grounds. The most problematic ground connections are behind the headlights on both sides. Check out Bill’s thread for detailed info. Bill's Thread: Important Electrical Information

Water Intrusion
Water leaks have several ways of getting in the car, and none of them are very difficult to fix. Proper adjustments and maintenance will prevent most leaks.

To Clean the C5 Udders (Rain Ducts)
HARD WAY: Removing the cowl to access from the top (also assess to the wiper motor)
EASY WAY: Access from the engine bay under the cowl. NOTE: You can’t reach the 3rd duct on the driver’s side using this method

Here’s a few TSB’s from the
1997-1998: Service Bulletin: Waterleak Above Door Glass (Reseal Blowout Clip)
1997-2002: Service Bulletin: General Waterleak Guide
1997: Service Bulletin: Water Drips into Rear Compartment After Hatch/Glass Has Been Opened

Corvette seats are delicate. Sliding hard across the bolster can break it, causing it to flap side-to-side. The leather is cheap, and there's little protection for it. It will wear out and form cracks, which is normal…for cheap leather. The wire springs in the seat bottom, and the bars in the bolsters can also wear thru the foam and leather, but that can be fixed by placing layer of burlap between the springs and the foam.

Check the black plastic surround on the bottom of the seat to make sure it fits snugly against the leather and isn't cracked. Older style plastic surrounds had a tendency to separate from the seat, but could be pushed back in. The newer style plastic surrounds can be used as a direct replacement, but one of the plastic studs may need to be ground off, or a hole will need to get punched into the leather.

The seats tend to rock back and forth by about a 1/4" during acceleration and braking. It can be fixed. The seat backs swinging forward under braking is normal, and not considered a problem.

DIY C5 Rocking Seat Fix

Seat Choice
C5s were available with 2 seat options, Standard and Sport. Get the sport seats if you can. The sport seats have a hole under the headrest. Some people put racing harness belts thru those loops. The seat frames and foam in both seats are interchangeable. Harness belt holes can be installed by an upholstery shop. The foam in a standard seat will need to be cut, and sewing will have to be done, but it’s an easy job. If you are serious about tracking your car, you may just be interested in replacing the OEM seats entirely. Check with your desired seat manufacture for models that will fit. Most likely you will need to buy new seat brackets as well.

Headlight Bezel Plugs
There are 1-1/2" plugs that are located on the headlight bezels that would fall off on the older C5s. The new style plugs, have a twist-lock to prevent them from falling out, but also requires new bezels. Only the new bezels & plugs are available now, and they are compatible with older C5’s.

Headlight Gears
The gears in the headlight motor are plastic and wear out over time. Ice, heavy Euro or projector headlights and twilight sentinel will cause the gears to wear out quickly. Fortunately, a few years ago, brass replacement gears became available. Purchase Brass Replacement Headlight Gear

Roof Noises
If you buy a coupe with a removable roof, you can expect wind noise and some creaking. The wind noise will never totally go away, but if there's creaking, you can eliminate that by thinly applying dielectric silicone grease to the weather-stripping. It also prevents cracking, so do this to all weather-stripping, on any car.

Hood Rattles
During cold weather the rubber hood stops can also rub and rattle against the hood. Adjust and lubricate the rubber stops so when you pull the corner of the hood up, it doesn’t pull up, but the hood still closes.

Drivetrain Rattling
The valvetrain makes a significant amount of noise at idle. It may sound like sewing machine. Converting the valve rockers to true shaft-mounted adjustable roller rockers may help eliminate the valvetrain noise if adjusted properly. Installing a big cam and stiffer valve springs will make the noise louder.

On manual transmission cars (M6 or M12), the transmission sounds like it is rattling when leaving the line. It is normal. It is the clutch throwout bearing rattling around. Sometimes you'll hear a horrible rattle if you shut off the engine. If you press the clutch pedal in while shutting off the car, you won't hear it.

Shaky Breaking
A lot of people believe front brake rotors warp easily under heavy braking. StopTech did a whitepaper that says otherwise: Warped Brake Disk & Other Myths

This has been verified by lightly grinding the rotors with steel wool. Garnet paper is recommended.

If you insist the problem is warping, don’t turn the rotors since thinner rotors warp more easily. Resurfacing the rotors is only a temporary fix. One that is less effective each time your resurface the rotors due to the reduced thermal capacity of the rotors. Rotors are available for $25 at most auto parts stores.

Scraped Front Ends & Rocker Panels
Checking for scrapes is an easy way to tell if the car was treated well. It's almost impossible not to scrape the front end, but there are two metal crash bar loops that should prevent the bumper from scraping. The bumper itself should not have scrape marks on it. Check the underside of the tip of the bumper, and the bottom corners of the bumper. If the crash bar gets scraped enough, eventually it will wear down to the point where it needs to get replaced. It can be replaced in a couple of hours, just be sure to hook the hoses and electric connector back to the A.I.R. pump.

Here’s a list of ALL the parts you’ll need to replace the impact bar and the side air deflectors:
Part #------Qty---Description
10188023---001---Insulator (goes to bottom of radiator)
10278679---001---Insulator (goes to bottom of radiator)
10400765---001---Plate (the actual impact bar, unpainted)
10419312---001---Panel (air deflector)
10419313---001---Panel (air deflector)
Not all of these parts need to get replaced, and there will be a few leftovers, but it will get the job done.

The rocker panels tend to get scraped on lifts and big speed bumps. Two products have been invented to prevent damage from both kinds of scraping.
1 - They have wheels that attach to the crash bar, allowing the car to roll on driveways instead of wearing down the crash bar. It will still scrape the spoiler, but the spoiler is a cheap wear item that takes only 2 minutes to replace without a lift or jack. Purchase Skid Plate Wheels Here
2 - They have two aluminum strips that attached the frame next to the rocker panels, and they take the scrapes themselves instead of the rockers panels. Purchase Rocker Panel Skid Plates Here

NOTE: Neither of the devices are visible unless looking under the car, and they are discreet enough to possibly be missed anyway. If you see these devices installed, you can be pretty sure the owner took good care of the car. Without this extra protection, you can expect to replace the crash bar and repair the rockers several times over the life of the car.

WARNING: It won’t stop all scraping damage, just reduce the possibility of it happening, and reduce the damage when it does happen. Low hanging headers will probably still scrape. Also, if the car has been lowered, it will scrape even more than usual. Take extra precaution being over speed bumps, valley gutters, and driveways.

Hood Seal Weather-Strip
The sides and back of the hood compartment have weather-strip installed from the factory. The front is left open. Many owners install weather-strip along this front edge. You may not even notice it since it looks identical to rest of the weather-stripping. This extra weather-strip helps keep the engine compartment clean and may also help the air intake system work better. This is another sign that the owner took good care of the car.

A/C System
There are two kinds of climate controls. One is manual with *****, and the other is a dual-zone electronic system. The dual-zone system did cost more but is not as reliable as the manual system. A leaking battery can affect both systems. A strong system is when the vents cannot be switched. If the vent settings cannot be changed, the vacuum line is probably loose, clogged or broken.

Over time, and especially in humid climates, the system can cause condensation to leak onto the passenger side carpet. There are three udders under the driver’s side cowl, and 1 on the passenger side. There are slits on the bottom. Clean these out to ensure proper drainage. See “Water Intrusion” section above to links on how to do this.

Squeaky Steering Wheel
When you turn the steering wheel, you may hear a squeak. It's just the plastic surfaces rubbing against each other. A shot of lubricant fixes this.

Squeaky/Chirping/Grinding Wheel Bearings
Drive slowly, or coast along at low speeds with the windows open in a quiet location. Listen for a squeak from the wheels. Try turning in different directions. If you hear the rear wheels squeaking, you may have a worn wheel bearing. A replacement bearing costs $600 list, but you can usually find it for $400-450. AutoZone has a better replacement for $126 by Timken. The part is easy to replace if you can separate the ball joints. A specific tool may be required. It seems to be a common problem, and more so for the rear wheel bearing.

A broken emergency drum clip may cause a false diagnosis. Be careful when removing & replacing the rear rotors.

Oil Woes
Many late 2000 thru 2001 Vette's burn a lot of oil when the engine is kept constantly over 4,000 rpm's. This is caused by ring flutter, which allows extra oil to seep past the oil control rings but doesn't seem to cause any extra wear to the engine. Chevrolet had rebuilt and replaced engines for owners that complained about excessive oil consumption. Their policy was that while the engine isn't normally operated like that outside of racing, it is the owner's prerogative to drive around in second gear all the time if they want to. It was covered under the warranty, however C5s no longer have warranty.

The PCV system also has a tendency to suck oil back into the intake at high rpm's. The newer style PCV system can be installed, but this requires removing all the components in the top of the engine valley. Usually only racer's bother with the hassle. Several generations of PCV systems have had the problem.

All LS based Corvette engines suffer from oil "blow-by" from the PCV valve. This oil vapor makes its way through the throttle body and leaves an oil residue on the throttle plate and intake manifold, that will eventually damage your spark plugs. An oil catch can removes that blow-by and keeps the engines internal components free of this unwanted oil residue and extends the life of your sensors, spark plugs, and manifold. Several manufactures make catch cans and they are relatively easy to install.

The oil-sucking problem will also cause carbon buildup in the cylinders. The dealership sells GM Top End Cleaner, or you can buy SeaFoam from many auto parts stores. The Top End Cleaner is not available in some smog states like California. Run a tube from the bottle into the hole for the PCV system behind the throttle body on the passenger side. Start the car, then start slowly sucking the solution into the engine. Don’t go too fast or the engine could lockup. As soon as the solution is gone, stop the motor for at least 4 hours, but preferably 12 hours. Be aware that when the engine is restarted, there will be a LOT of smoke!

Overheating & Burning Smells
Even though the engine can heat up to 220, even 240 degrees Fahrenheit, this is normal. The radiator will keep the engine cool enough unless the radiator is blocked. Reprogramming the PCM can allow the fans to turn on earlier. If the fans also cool an aftermarket oil cooler, make sure the oil occasionally gets to 220 degrees to allow condensation and fuel to evaporate away. Fan settings and oil thermostats are two different ways to do this.

It's not uncommon for plastic bags to get sucked up under the front bumper, and cover the radiator, thus causing the car to truly overheat. If this happens, take a quick peek under the bumper, and remove anything under there. Sometimes bags get stuck to the exhaust pipes too, causing quite a stench as they burn away.

Locked Steering Column
All C5’s, particularly manual transmission C5’s, and early C6 steering columns have a tendency to lock and stay locked. Usually it can be unlocked once, but just once. Some owners claim that vigorously shaking the steering wheel can unlock the steering wheel. Dealers are able to disable the locking mechanism with a modified locking plate. Currently this is the only real method to disable the locking mechanism. Basically, the wheel will still try to lock, but there will be nothing for it to lock to. It’s like a door dead bolt with a slot cut into the door jamb. There is a $100 kit that disables the steering column lock, and can be installed easily, but enough car vibrations can cause the lock to fall into the locking plate, even while driving!

GM has a part (#88952428 or 88952428) that has a harness wiring jumper and different lock plate.

Manual transmission C5’s & C6’s are still in danger, even if the lock is disabled. The lock can vibrate out over time and get trapped in the locking plate. Auto transmission cars that have undergone the recall and new auto’s will not have the locking plate at all, so they are safe.

Corvette Forum - Column Lock Harness K Installation
Corvette Forum - Column-lock again even with CLB!
Corvette Forum - Has anyone ELSE beat column lock?

Faulty Gas Gauge
If you have bad gas, the fuel sender can be affected by the high sulfur content in the fuel and cause the gauge to read empty. The car will still operate normally, and the gas gauge will work again if you use better gas. A bottle of Techron, sold at any auto parts store, will also resolve the issue in most cases. Worst case, a new fuel sender will fix the problem.

Noisy Fuel Pump
There are two fuel tanks, and two fuel pumps. One fuel pump continually pumps gas from the passenger side tank into the driver side tank and is quiet. The main fuel pump is directly behind the driver’s seat, and can be annoying loud, especially on early C5’s. It's normal, and not a sign of a failing fuel pump. Chevrolet does have a bulletin out instructing how to better insulate against the sound of the fuel pump. A newer, quieter pump can also be installed.

Extremely High Oil Pressure Reading
The oil pressure sensor can fail, but it is still okay to drive. Turn the car off, but with the key in the “on” position and check the oil pressure gauge. It should read “0”. If the oil pressure sensor is bad, it will show a positive reading. The oil pressure sender is located behind the intake manifold and will require removing the intake manifold. The sender costs about $40 and part # 12573107 or 12562230.

Suspension Squeaking
In cold weather you may hear the suspension creak when you go over speed bumps. To fix this, clean (optional) and lubricate the sway bar bushings. The adjustable metal sway bar end links on Hotchkis and T1 bars can also create loud clicking sounds. Most adjustable end links are quiet initially but wear out and get noisy over time. Greasing and protecting the end links from dirt may prevent wear.

Tough Shifting
The shifter in manual transmission Corvettes takes a strong arm to get it into gear. You really have to make sure that the shifter is fully in 1st and Reverse, or it will pop out of gear when you let the clutch out. This is not the fault of the car, but rather the fault of the driver.

Replacing the transmission fluid often helps shifting. Early transmissions have paper blocker ring that require Dexron III compatible (usually organic) fluid because some synthetics will destroy the paper blocker rings and subsequently the transmission. Later transmissions, and all rebuilt transmissions, have Kevlar/carbon fiber parts that allow the use of synthetic fluids. The 98-00 transmissions have the paper blocker rings. The safe transmission fluids seem to be: GM Synchromesh PN #12345349, Honda ATF-Z1, Royal Purple Synchromax, Amsoil ATF, O’Reilly Dexron III ATF. The following transmission fluids may be unsafe for early transmissions: Redline D4 ATF, Mobil 1 ATF, Royal Purple Max ATF.

Related threads: - Ending the speculation: Blocker rings, who's had them fail?
Corvette Forum - Mobil 1 Synthetic ATF for a M6?

If it is especially tough to shift into 2nd or 4th gear, it's possible that the synchro's are worn out or the forks are bent. Do NOT force it into gear. Abuse creates and aggravates this problem. You can still drive, even quite well, without synchro's....or a clutch for that matter if you know how to rev match.

Some aftermarket shifters make it easier to make sure you're fully in gear, and prevent gear grinding, but they also vibrate, and require more effort to shift. The stock shifter has a tuned weight damper that changes the vibrations to a non-audible frequency. The shaking doesn’t annoy some people, and there are some fixes.

Leaky Butt (Differential)
The differential can leak from the side covers. The problem has to do with the design. The lip on the casing is not wide enough to create a proper seal with the cover. Resealing the covers can be successful, but many dealers do not use the correct sealant.

Inside/Outside Tire Spinning
If one tire spins while turning, adjust the friction modifier ratio. Aftermarket gear fluid from Royal Purple, Amsoil and Redline do not require additional friction modifier. GM’s friction modifier is PN #12377916. Too much friction modifier and the inside tire will spin/skip/hop. Too little friction modifier and the outside tire will spin/skip/hop.

Tire Hop (Wheel Hop)
Tire hop during hard acceleration in cold weather is common, even if the same tires don’t hop in warmer weather. Tire rubber when viewed thru a microscope looks like a web. Normally parts of this web grabs onto objects on the ground and stretch until either the car moves forward, or the web breaks, resulting in tire spin. In cold weather, the web is too stiff for either of these events to occur, so the tires hop.

Interior Rattles
The visors may rattle when they are put up, but if you flip them down, the rattle goes away. Squeezing the mirror lid down seems to take care of it. Try glueing a piece of felt or velcro between the mirror and lid to see if that fixes it. Caravaggio also makes replacement leather visors, but they go for $400.

The stereo is Bose, and to go along with the historically crappy build quality of Bose products, Bose has graced the Corvette with Bose emblems on the door speaker covers that rattle when you play music with bass. A Bose system doesn't exist that puts out good bass, but the system still manages to rattle the emblems when playing Country, Hip Hop, or Techno at moderate volumes. Check this problem by having a passenger and yourself putting a finger on the emblems with music playing. Glue the emblems down to fix it.

If the roof isn't tightened down enough, it will rattle. There are some adjustment screws in the roof to make this adjustment.

Belt Chirping
During cold weather, the belt can chirp. Goodyear Gatorback belts (now called "Continental Elite") from AutoZone don’t chirp.

Sticky Hatch
During cold weather, the hatch may pop up slowly, or not at all. Spray the latches with silicone grease until they come up properly. If the struts do not hold up the hatch, try lubing the strut bars.
1997: Service Bulletin: Hatch Will Not Pop Up When Activated in Cold Weather

Rocker Failure
The needle bearings in the OEM rockers have been known to fail. Usually the problem is noticed with extra valvetrain noise and needle bearings stuck to a magnetic oil plug. Nasty Performance will rebuild OEM rockers with Harland Sharp bearings. This seems to be one of the better solutions since the stock rocker is very good at high rpms. Most aftermarket rockers are nose heavy and require grinding the heads and valve covers to fit. Currently Harland Sharp rockers are having problems with c-clip retainers falling off and causing problems on the way.

LS1Tech - Harland Sharp Rocker Failure
LS1Tech - Install or not install HS rockers?

Other Information

Active Stability Control
This allows you to keep some control of the car even when you do really stupid stunts. It doesn't bend the laws of physics but will keep the car pointed where you are steering. You may still slide off the road, but at least the car will be pointed in the direction you were steering! One of the sensors is located around the passenger seat and needs to be considered when installing a racing bucket. If you move that sensor, Active Stability will not know how to balance the car and can be very dangerous. Active Stability came out around '99.

The C5 was the first car to use hydroformed frame rails. Hydroformed rails are now a common platform for new cars, but many shops may not be prepared to lift these vehicles. The C5 requires an adapter for regular jacks and lifts to fit the jacking points. Make your own adapters with a hockey puck (or two) with a 1 1/2" eye bolt screwed thru the center. Stick the eye bolt thru the slit in the jacking point, turn 90 degrees, place jack under adapter and jack away if you can get the jack under the car. You may have to use ramps. The C5 is so low that most people make their own wooden ramps. Rhino ramps are too steep.

Key Fobs
There are two different kinds of key fobs, and they are not compatible with each other.
97-00, and 01-04, but 00 does not have the Passive Lock feature

Both remotes use a CR2450 coin type battery. I found replacement batteries at Office Depot. To replace, use a coin to wedge between the seam, and twist.
Ref: Service manual, page 8-747.

FOB Programming
1-Turn the ignition to RUN
2-Turn the radio off
3-Press the RESET button in order to clear any IPC warning messages
4-Press the Option button on the DIC until the IPC display is blank in order to enter the program mode
5-Press and hold the Reset button for 3 seconds
6-Press the option button until FOB Training message is displayed
7-Press the Reset button in order to begin the programming sequence.
8-Simultaneously press and hold the lock an unlock buttons on the first transmitter for 12 seconds. The IPC will indicate when that transmitter is programmed and when to proceed to the next. Repeat this step for each transmitter.

Spark Plugs
The OEM platinum plugs, along with other plugs have had problems with the pucks falling off. It is recommendation to use silver tipped plugs. Basically, of all spark plug tips, platinum is the worst conductor, copper is good, iridium is even better and silver is the best. For longevity, platinum, iridium and silver do have an advantage over copper, but plugs foul up after ~10K negating any difference corrosion would cause, and no plug will run well after 100K miles.

To make the spark plugs easier to change, get the Snap-On double-swivel sparkplug tool and remove the coil packs. Here’s all you need to know about sparkplug changes:

Alternator Replacement
’98 AC Delco part #10246634
Originally Posted by Evil-Twin
If you have the original alternator, it is clutch-less. Newer C5's with automatic ( A4) came with a clutch at the pulley to address belt squeal when putting in and out of gear. You have a Valeo 110 amp alternator made in France... it is a good unit. Your specs seem to be OK. The alternator is not your everyday alternator, it communicates with your PCM, the PCM that came with your car.,. GM came up with a clutch type A4 alternator with 140 amps, made in Mexico... the alternator works OK, but does not communicate well with your pre 2000 PCM. Many people experience charging system fault messages with this unit..The PCM thinks it is a 110 unit.
AS our Resident Electrical guru has mentioned, and I concur, if you have a problem with your alternator, the PCM will flash you a message stating you have a "charging system fault".,.,.If you do not have this, then I suspect you are ok...
The latest word I heard from the people who sign my pension check is that they have a fix for this: and its is the new Mexican made clutch driven 140 amp alternator, and a PCM reflash.... But to be honest... this is from the same group that said they have a fix for the column lock disaster... If I were you, I would never give up my original alternator.
You have a smart alternator, here is how it works:

The L-terminal circuit from the generator is a discrete circuit (a discrete circuit has no splices and only one Src and destination) into the PCM. The PCM applies ignition voltage to the generator L-terminal circuit. A small amount of current flows from this circuit through the generator windings to ground to create a magnetic field which starts the generator process. When the generator is at operating speed and producing voltage, a solid state switch for the L-terminal circuit in the generator opens and the PCM detects that the initial startup current flow has stopped.
The PCM expects to detect low voltage on the L-terminal circuit prior to the generator rotating at operating speed and conversely expects the circuit to be at ignition voltage potential when the generator is operational. When the PCM detects a fault (circuit shorted to ground, or circuit shorted to voltage), the Driver Information Center will display Charging System Fault.

The generator has an input to the PCM called the F Terminal to indicate the percentage of total capacity that the generator is producing. This signal is detected by the PCM as a duty cycle from the generator and displayed on the scan tool as a percentage. The PCM can monitor the generators output under all conditions to determine if it is functioning normally.

When there is low demand from the electrical system on the generator, a low duty cycle percentage will be displayed. As more accessory load is placed on the generator, the duty cycle output detected by the PCM will approach 100 percent. A normally functioning generating system will never reach 100 percent as indicated on the scan tool.

The L and F terminals are the red and grey

I tried to make this as simple as possible so those thinking 1960's/70's alternators/gen will throw all that old stuff away, clear their head and rethink smart alternator/gen. systems.

Thanks Bill Curlee for the vote of confidence...

Good Luck
Bill aka ( ET )
________________________________________ ________________________

These problems, and many others, are addressed at the in the Tech Center -> Knowledge Base.

While these problems do sound numerous and severe, just remember that JD Power considers this a very reliable car. If you buy a Corvette, consider yourself fortunate that there are many resources available to help you locate and correct problems.

________________________________________ _______________________

First you need to know how your car is doing. A trip to the dyno can give you quick answers.

Tuning software can diagnose and tune your car. LS1Tech and HPTuners are two popular tuning packages. Both packages will be able to do scanning with incorporated wideband sensor support.

Popular upgrades:
Cold air intakes: Vararam, Halltech, Blackwing, zip-tie mod
Intake manifolds: LS6, LS2, LSX, Fast, Wiend, sheetmetal
Cat-back exhausts: Cora, Borla, Magnaflow, B&B, Z06 Ti
Long tube headers: LG, Kooks, TPIS, Stainless Works, Breathless, Jet-Hot, GHL, QTP
Superchargers: ATI (go to A&A), Vortech, Magnacharger
Stroke & bore
Head & cam packages

OEM Tires:
The convertible and coupe come with run-flat tires, with 17" wheels in the front, and 18" in the rear, with tire pressure sensors. The Z06 comes with non run-flat tire, but has a tire repair kit. Switching from run-flat tires to regular tires typically allows the C5 to ride softer, accelerate faster, and corner harder, but if you use the tire repair kit (goo) on wheels with the unobtainium tire pressure sensors, you'll destroy the sensors. No C5 has a spare tire. The best way to improve the handling of any car is usually thru the tires.

Aerodynamics, gearing and top speed:
The hardtops (FRC) and Z06 have shorter rear windows, are less aerodynamic, noisier, and weigh less than the standard C5 couple. Even though the Z06 has more hp than standard C5’s, they have a lower top speed than manual C5 coupes. This is due to both aerodynamics and gearing. All C5’s top out at redline in 5th gear, so a taller 5th gear, or much shorter 6th gear, or taller redline is required to go faster. All else being equal, a coupe will still go faster than a Z06. Above 190 mph, air builds up under the front of the car. This can be solved with a vented hood like the ACP C5-R or MCM hoods.

Last edited by Chris Draper; 07-29-2018 at 02:19 AM.
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Old 07-13-2018, 10:12 PM
Chris Draper
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Secrets of the C5
Copied from

● The little yellow “helper light” on the bottom of the rear-view mirror that illuminates the shifter area.
● That you can put your key in the driver’s door and turn it twice towards the front to unlock the passenger door and a third time to pop the trunk.
● That you can pop the trunk and also pop the gas cap cover by pulling on metal lines hidden in the back.
● The little slotted cover on the dash behind the steering wheel is where the inside air temperature sensor is located.
● All of the option codes are in the glove box.
● Tire inflation recommended pressures are on the driver’s door.
● The thing that looks like a little LED near the DIC buttons is a light sensor.
● The thing that looks like a little LED near the defroster vent is a UV sensor for determining A/C usage to compensate for the heating effect of the sun.
● The build sheet is in the front re-bar.
● If you leave your turn signal on, in about 1 minute it will start to ding (loud enough to hear over the stereo) to let you know you have old timers disease.
● You can reset the oil life by pumping the gas pedal 3 times (but not with the engine running).
● Hold down the reset button while on one of the trip odometers and it changes that reading to the miles you’ve traveled since last starting the engine.
● Hold down the Active Handling button for 5 sec. to engage “Competitive Driving” on cars equipped with active handling (2000 and previous years must be stopped.)
● If you pull the seatbelts all the way out while you’re buckled in, they ratchet back in to hold you tighter into the seat. (then move the seat forward to make it extra snug -- Leafty)
● Simply remove fuse #2 under the hood and your DRLs will be out permanently. Only thing affected is that when you unlock at night using the key fob your front turn signal lights and back up lights will not flash. Your front turn signals will operate normally, however.
● The side-view mirrors can twist both forward and backward, decreasing the chance of damage if struck.
● There is a release opening with a flap to let air out of the car when the hatch is closed. It is located just above the driver side rear compartment behind the carpet and on the side of the car. Not that it really works well.
● Also you can ground your amp to a screw/bolt that holds the rear middle compartment to the frame.
● If you have a 6-speed car you can pop the trunk when the car is running by lifting the e-brake.
● There is a spot on the driver side just out of the middle compartment under the carpet for the lug nut key. You should have a compartment on the drivers & passenger’s side (in the trunk) and a center compartment. On the left (drivers) side of the center compartment, on the left side where the center cover fits, there is an ‘indent’ that holds the wheel lock key.
● If you turn on the headlights, then go to parking light position, the lamps remain up but the headlights are not left on.
● If you have the passive entry feature: If you lock the keys in the car, wait a few minutes and then shake the car. That will unlock the car.
● HUD has a shift light for the manuals.
● You can easily shift the M6 trans up or down without the clutch if you match revs. (Not great for longevity, however.)
● You can eject the cd from the in-dash player without turning on any power. Don’t even need key in the ignition.
● The cruise will disengage if you purposely make sharp side to side turns while cruising at say 60-80 mph.
● When the engine is shut off, you can get the odometer reading by turning on the parking lights.
● You can program setting #3 (both memory buttons at once) in the seat memory to run the seat back and steering wheel forward for getting in/out of the car with the engine running.
● If you hate DRLs you can pull the e-brake ONE click and they go off.

Last edited by Chris Draper; 07-13-2018 at 10:13 PM.
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Old 07-13-2018, 10:12 PM
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Weight Reduction
You can achieve substantial weight reduction with the following modifications, while still having a car that's very comfortable to drive. Most of these modifications will directly increase (and decrease in a few cases) the safety of the car, while safety is indirectly improved due to the better handling and limits of a lighter car. Fighter pilots say "speed is life". Acceleration, deceleration, and lateral acceleration are all forms of acceleration, and lighter cars accelerate better in each of these ways because the tires have less mass to control....thus a lighter car is a safer car. Lighter cars have better moments of inertia which allows them to turn in more easily and roll less. Lighter cars are also easier on the tires and gas.

All the stage weight estimates are approximate.

Stage I: Streetable weight reduction mods
Non-popup headlights (~40 lbs)
Braking rotors with an aluminum hat, or titanium rotors (unproven on street cars) (~20-30 lbs)
Carbon fiber hood (~12 lbs)
Z06 (thinner) windshield and side windows (~5.7 lbs)
Non runflat tires (~20 lbs)
Slicks (~30 lbs)
Z06 wheels (~4 lbs est.)
Corsa titanium exhaust (~35 lbs)
Long tube headers (~20 lbs)
Halltech aluminum alternator & bracket (10 lbs)
Carbon fiber driveshaft (~2 lbs)
Newer torque tube
Less options [HUD, elec AC, Active Stability, seat/mirror/steering wheel memory, cd changer] (~50 lbs)
Less gasoline & wiper fluid (No wiper fluid=9lbs, 6 lbs for every gallon of gas in that 18 gallon tank....~81 lbs for autocrossing)
Remove cargo net
Remove targa top (~20 lbs)
Remove BCM’s
Remove C5 "appearance mods" - exhaust plates, doorsill covers, etc.
Remove fuel rail covers
Replace stock crank pulley with aluminum aftermarket pulley
Replace steel dampener with aluminum dampener
Replace stock targa top with lexan piece (coupes)
Replace water pump with electric water pump
Replace battery with smaller battery
Replace non-stressed fasteners with aluminum or titanium fasteners
Replace leaf springs with coil over shocks with titanium springs
Replace steel shifter with aluminum shifter and delrin or titanium shift ****

Stage II: Hardcore semi-streetable weight reduction mods
Aluminum flywheel (~10 lbs)
Lighter clutch like Exedy or Quartermaster (~10 lbs)
Racing buckets (40-50 lbs)
Remove tire repair kit (Z06)
Off-road x-pipe (10 lbs)
Replace stock hood, fenders, doors, roof, hatch and bumpers with aftermarket carbon fiber pieces
Tire repair kit (Z06)
Floor mats
Fog lights

Stage III: Track only weight reduction mods
Racing steering wheel & delete both airbags (~30 lbs, but get a 4-6 point harness)
Use unpadded aluminum or carbon fiber steering wheel
Run open headers
Replace stock front and rear glass with polycarbonate “glass”
Rebuild motor with Al or Ti connecting rods, Ti valve spring retainers and pushrods
Port the heads
Replace valve covers with magnesium or carbon fiber parts
Strip entire car, acid wash chassis, put car back together.
Column locking hardware
Interior – passenger seat, carpets, speaker panels, head liner, dash, center console, glove box, door panels, sun visors, rear view mirror, insulation, etc.
A/C Compressor
A/C controls and ducting
AIR pump system
Factory radio, speakers, and/or CD changer, and unnecessary wiring
HUD projector
Windshield wiper fluid reservoir and pump
Windshield wipers and motors
Stock cat back
Power steering pump
Front sway bar (drag only)
ABS, TC, AH hardware and sensors (drag only)
Fender wells
Headlight assembly, turn signals, taillights and reflectors
Shave side mirrors
Torque tunnel cover
OEM seat belts
Parking brake
Side windows and motors
Power locks and power windows
Side impact beams
Casting flash from engine, then polish

Reducing unsprung weight—not all is streetable
Forged 1-piece wheels
Use 3-piece wheels by Jongbloed, Kodiak, CCW, BBS
Skinny front wheels (drag only)
Ti fasteners on 3-piece wheels (~1 lbs per wheel)
Lighter non-runflat tires, or even track only synthetic corded slicks
Lighter calipers
2-piece, unvented or titanium rotors
Titanium wheel studs
Aluminum or titanium lug nuts
Remove tire pressure sensors
Remove rubber valve stem cap
Balance the wheels without tires or balancing weights, and then mount tires

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Old 07-13-2018, 10:12 PM
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Coming soon

Last edited by Chris Draper; 07-13-2018 at 10:15 PM.
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Old 07-13-2018, 10:13 PM
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Other Info

Common Sway Bar Sizes:
C5 Base: Front: 23mm, Rear: 19.1mm, Thickness: 3.81mm/2.00mm
C5 Z51 (97-99): Front: 25.4mm, Rear: 21.7mm
C5 Z51 (00-04): Front: 28.6mm, Rear: 23.6mm, Thickness: 4.15mm/3.00mm
C5 Z06: Front: 30mm, Rear: 23.6mm, Thickness: 4.5mm/3.5mm
C6 Base: Front: 25.5mm, Rear: 22mm
C6 Z51: Front: 31mm, Rear: 25.4mm
C6 Z06: Front: 31mm, Rear: 28.8mm
C5 Hotchkis: Front: 31.75mm, Rear: 25.4mm, Thickness: 4mm/4mm
C5/C6 Addco: Front: 32mm, Rear: 25.4mm
C5/C6 Addco: Front: 35mm, Rear: 25.4mm
C5 Pfadt (Adjustable): Front: 32mm, Rear: 26mm
C5 Pfadt (Adjustable): Front: 35mm, Rear: 28.5mm
C5 T1 (GM Racing): Front: 38.4mm, Rear: 27.5mm, Thickness: 6.35mm/6.35mm

Identifying LS1 vs LS6 Intake Manifold:
If the manifold is off the block:
-LS1 intake has a hump on the bottom.
-LS6 intake is flat on the bottom.

If the manifold is installed on the block:
-LS1 intake you can fit your finger between the intake and the block.
-LS6 intake you can NOT fit your finger between the intake and the block.

Part Numbers:
#12561269 or 12560688 (LS1 F-Bodies 1998-00)
This is the LS1 intake found on all LS1 F-Bodies from ’98-’00. It clearly has an EGR provision just behind the air inlet. The bottom of the intake is curved.

#88894095, 12557846, 12556333 (LS1 1997-00 Corvettes)
Here is the part number for the deceptive ’97-’00 LS1 Corvette intake manifold. It does not have EGR, and when installed, looks identical to the LS6 intake. The bottom of the intake is curved.

#88894339, 12573572, 12561184, 88890524, 88890523. 88894339
This part number is for the LS6 manifold found on all LS1-powered ’01 and ’02 Camaros and Firebirds, ’01-’04 Corvettes and Z06s, ’04-’05 CTS-V, and the ’04 GTO.

OEM Cylinder Head Info:
806 was used on 97-98 LS1 engines.
853 was used on 99-00 LS1 engines.
241 was used on 01-04 LS1 engines.
853 and 241 are basically identical.
They both have a 66.67 cc combustion chamber (10.1 CR), 200cc intake runners, and 70cc (round) exhaust ports.

The 243 head is the 01+ LS6/LS2 head.
It has a smaller 64.45cc chamber for more compression (10.5 CR on LS6), 210cc intake runners, and 75cc D-shaped exhaust ports.

The 799 heads are the same casting as the Z06's 243 heads, but did not come with the sodium filled valves. These heads came on the early LS2 engines in the C6 and can often be found cheaper than 243 heads.

All came with 2.00" intake valves, and 1.55" exhaust valves.

The 243/799 heads are the most desirable for flow, and the most popular base for further porting/modifying. Not many people mess with porting LS1 heads anymore.

5.3 truck heads (casting #862 and 706) are also a very popular base casting for porting/modifying, due to their even smaller (61.15cc) chamber size which raises compression when used on a LS1/6 engine..

6.0 truck heads (casting #317) are popular heads with the forced induction crowd, as they are basically the same as 243 heads, but with larger 71.06cc chamber size, which lowers compression when used on a LS1/6 engine.

Fuel Injectors
1997-98 LS1 part number 12554271 , 24.7 @ 3 bar & 28.5 @ 4 bar
1999-00 LS1 part number 12555894 , 22.3 @ 3 bar & 26.3 @ 4 bar
2001-04 LS1/6 part number 12561462 , 24.7 @ 3 bar & 28.5 @ 4 bar

Last edited by Chris Draper; 08-20-2018 at 01:55 AM.
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Old 07-13-2018, 10:39 PM
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Thanks for taking this on, Chris!
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Old 07-13-2018, 11:06 PM
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Great stuff Chris, thank you.
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Old 07-14-2018, 01:52 AM
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As Iíve said in comments to your YouTube videos, your contributions to the c5 community are invaluable.

thanks Chris!

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Old 07-14-2018, 07:36 PM
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Great post!! As someone already posted, between your My Corvette Life YouTube channel and this type of post you are an absolute credit to the Corvette community!!!

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Old 07-17-2018, 12:15 AM
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Common sway bar sizes added to post #5

LS1 vs LS6 intake manifold info added to post #5

Last edited by Chris Draper; 07-17-2018 at 12:23 AM.
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Old 07-17-2018, 02:23 AM
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Thank you for all that work. Very helpful.
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Old 07-17-2018, 11:59 AM
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Originally Posted by Route99 View Post
Thanks for taking this on, Chris!
Thanks Chris!
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Old 07-17-2018, 04:23 PM
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Good thread. Under the "Belt Chirping" section, Goodyear Gatorbacks are now called "Continental Elite" belts.
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Old 07-18-2018, 11:25 PM
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Making this a sticky. Thanks for all the updates, Chris.
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Old 07-29-2018, 02:19 AM
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Cylinder head info added to post #5.
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Awesome info here! Iíll definitely be referring to this quite a bit! Thanks!
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Great info!! Thanks
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Old 08-14-2018, 07:34 PM
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One of the best threads on the internet.
TMODcustoms Specialty CNC Products

New ZeroSlop Shifter Linkages
New Clutch, not without a TIGHT LINKAGE!

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Old 08-20-2018, 01:56 AM
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Fuel injector info added to post #5
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