Serenity Or Sensor Killer
I’m interested in removing the run-flat tires on my ’98 Corvette. Since I would have no spare tire or run-flat capability, can I use the patch and solution that come with the new Z06? Is the Z06 flat-repair solution compatible with the ’98 tire-pressure sensors? If it is compatible, do you know the procedures for using it? My plan is to get a tire that rides quieter than the Goodyears and can be patched when needed. My local Chevrolet dealer was not able to provide an answer that made me feel confident they knew what they were talking about.
Any info you could provide would be appreciated.
Mike Doss
dossmbd@aol.com
This is something I know a lot of people are working on. Most people are opting for the cell phone and AAA flat repair or tow. As of now, the Z06 flat-repair solution will not pass through the current tire sensors and will probably damage them accordingly if it did. I believe the Z06 product will work to get you where you’re going, but you’ll need to replace the sensors with standard valve stems and forfeit the warning of a potential flat. You will set codes each time, if you remove them, due to no signal from the tire sensors, but this can be “turned off” by hitting the reset button. There are a few run-flat tires that some are changing to, such as Firestone SZ50EP-RFTs, and they claim they are quieter than the Eagles and handle better. You still have no spare tire, though. As with most things, there are trade-offs. You have to decide which is better for your particular situation.
Continuing Tire Trouble
I have a 2000 coupe and have been noticing a howling coming from my front end. I complained to the dealer, and he said the tires are wearing fine. The noise appears to be loudest at 38 mph. I suspect that the tire block pattern causes the tires to resonate and the noise is transmitted through the firm suspension and stiff body. I can actually experience a beat frequency when two tires are slightly out of phase. Depending on highway conditions, the sound is really loud and annoying. Above 40 mph the noise fades. The last time I had a car that made this noise, the belt separated and the tread came off. Is there a solution?
Glenn Anderson
zippo111@swbell.com
When talking about alignments, we have previously covered how important it is for the C5 and the Goodyears to have the proper settings. It’s always a good idea to check tire wear at all oil changes, and especially the first 3,000-6,000 miles, to avoid a tire-wear problem. I’ve seen the stock run-flats last 30,000 miles with minimal noise when properly aligned. Do your tires look chopped up on the inside? I would guess so, since this is the most common problem.
If you’re taking your C5 to the same dealer you bought it from and you still have low miles, they should work with you to resolve this problem. If they won’t help, go to another Chevy dealer. It may be a bit of extra work for you, but you might get the satisfaction you’re looking for. Watch those tires, folks, to avoid these problems before they happen.
Dimming Diagnostics
I have a ’99 coupe. It’s my second Corvette and a wonderful car, except when I drive at night and use the air conditioning, heater, or just put the windows down. I notice that the headlights dim when there’s an increased use of power for any of the reasons listed above. I’ve taken the car back to the dealer a couple of times for this problem and they tell me it’s normal. I have a hard time believing this is normal, especially considering that there is absolutely no other problem with the car. I just can’t believe that the flagship of the General Motors’ fleet can’t keep the headlights bright while using the air conditioning.
Any help you could provide would be great, and maybe then I can go to the dealership and inform them of the problem so they may help other Corvette enthusiasts like me. Your magazine is just great. The only problem is that the day it arrives, I sit down and read the whole thing and then I have to wait another month for the next issue.
Rick and Linda Mann
llrl.man@verizon.net
Well, we’re at 100 pages each month, but if you need a mid-month fix, visit us online at www.corvettefever.com.
Now, on to your concern: As with any vehicle, anytime you put a load on the electrical system, you’ll notice it if the lights are on. This is because the lights are quite a load on the electrical system. How much the lights may dim, or for how long, would be a determining factor to find out if there is a problem or not. If you have an automatic transmission and it occurs at idle, it would be more pronounced. I have replaced a few alternators, which has repaired a problem such as yours, and I’ve also found loose ground wires or connections.
Have you checked the gauges in your Drivers Information Center (DIC) to see what type of readings you’re getting in this situation? Some amount of voltage drop is inevitable. I’d suggest that if you feel you aren’t getting the proper diagnostics or information from one particular dealer, try another one. Perhaps there is a Corvette club in your area that can suggest a “reputable” dealer they feel comfortable with, and that may lead to some satisfaction for you.
Hope this helps.
Millennial Mileage
I have a 2000 Corvette coupe. After a year, I’ve put 6,000 miles on the car. If I continue this mileage per year, what are the maintenance items I should be taking care of, based on time rather than mileage?
Fred Lopez
Santa Barbara, CA
Per the Chevrolet Service Manual, it states that you are to change oil as indicated by the oil-life monitor or every 12 months, whichever comes first. It doesn’t state any special intervals for severe, high, or low-mileage situations. The oil-life monitor can pick up a “severe operating condition” and cause the “Change Oil” message to come on before 3,000 miles. It goes on to say the vehicle “MUST NOT” be driven more than 10,000 miles or 12 months without an oil change.
During oil changes, always check all fluids and tire pressures, as well as the air filter, and replace as needed or at 30,000 miles. Check your tire wear at each oil change, as tires can get a bit expensive. The automatic-transmission fluid does not need to be changed until 100,000 miles, unless you’re using the Corvette in hot, heavy traffic, hills or mountains, or high-performance use. In these situations, it’s recommended to change the fluid at 50,000 miles.
Now that Chevrolet’s “official” word is there for you, here are a few personal recommendations. Change your oil and filter at three months or 3,000 miles. Change your air filter (or clean and re-oil a K&N or similar) once a year. Change your automatic transmission fluid every three years or 36,000 miles. I would also consider changing your engine coolant every three years. Once again, always check your fluids and tire pressures with each oil change. This may seem to be a bit of overkill, but it was the way I was taught, and this works very well in performance applications. Does it cost more money this way? Yes; but I would rather have peace of mind knowing that my Corvette will be around long after the warranty has run out.
After-Cat Query
I enjoy your magazine and the articles on upgrades. I have a ’99 convertible and I’m looking at after-cat exhaust systems. Some of the systems I’ve looked at claim various increases in horsepower—10, 15, 20, etc. How can I verify that these increases are accurate? Do you evaluate any of these systems to this extent?
Some of the companies claim a 45 percent increase in flow, but they don’t state if this is with the after-cat system or with an overall system. If the catalytic converters are the bottleneck in the system, then installing an after-cat system may not give any increase in power.
Also, one site on the net (www.c5-corvette.com/other.htm) had an article on cross pipes. They claim a 10hp increase if you connect the pipes in front of the cats. I cannot verify this. If I’m going to spend $1,000 on an after-cat system, I would like to get some extra power, which I feel the car could use.
Brian Foreman
brian@ForemanFab.com
The only way to verify these things is to use one vehicle and swap out each individual exhaust, X-pipe and/or cross pipe. Gains that companies claim can vary just like fuel-mileage ratings on new cars. Each car has a different “personality” and may react differently from another. One thing to consider is that you can’t look at only peak horsepower and torque numbers, but how they increase along the complete powerband.
An example of this would be similar to a camshaft swap. If someone puts in a Brand X cam and “only” gains 5-10 hp and 25 lb-ft at the peak rpm, they figure it wasn’t worth the money. But if you look at the complete powerband and find a 35hp gain at 4,500 rpm and a 60-lb-ft increase in torque at 3,000 rpm—that is significant. A combination of an after-cat system with an X-pipe may show “only” a 5-8hp increase at 5,800 rpm, but also have a 15-20hp increase at 3,000 rpm. The big picture is more important than just peak numbers for a smooth powerband.
In reference to the catalytic converters being a bottleneck, they actually flow very well. Gains in the area of only 5-10 hp have been seen with deletion or replacement with high-flow cats. This applies to both stock applications and those with major mods such as heads/cam/headers.
Blower Benefits
Do you have any information on supercharging kits/suppliers for C5s? How about doing an article on this topic and comparing the different packages available? The one brief story I saw was in your Dec. 2000 issue on an SVI supercharger package sold by X-treme Motorsports (www.xmotorsports.com) in Dallas.
Love the magazine and always read it cover to cover the day it arrives. Thanks.
Doug C. (owner of a ’99 hardtop)
carlson@cray.com
The company, SVI, went out of business and was bought by Performance Technical Center in Elk Grove, Illinois (www.performancetechcenter.com). This is the same company that did most of the R&D for SVI, and since buying the products, has made several changes to help improve the complete package. It still uses a Vortech centrifugal supercharger and a liquid-cooled after-cooler.
There is also Carroll Supercharging (www.carollsupercharging.com) using a water-injected system, and Mallett (www.mallettcars.com) with a non-after-cooled version. You can also check out my site (www.geocities.com/norrismotorsports) for some supercharging package info and pricing.