I'm thinking of getting an '88-'91 corvette sometime after school's out. What options should I look for and what do they mean? (z51, Fx3, etc., etc.) What's the removable glass top called? The body changed in '91? What's the difference? Interior changed in '90? What's the difference? One more, what's a 4+3 transmission? I've heard of T-5 and T-56, just not 4+3...or is the 4+3 an automatic?

 

I'll start...

The 4+3 is a 4 speed manual with a 2 speed automatic gearbox attached that only works in 2nd, 3rd, and 4th gears. So you have 1, 2L, 2H, 3L, 3H, 4L, 4H, while you only actually shift 1, 2, 3, 4. I've not heard good things about it.

Z51 is a handling package. From what I hear you should definitely try to get this.

The removable glass top is called a... removable glass top. :lol:

All I know about the body changes is that the front and rear bumpers and the gills changed. The newer style has rounded square taillights instead of round and the 3rd brake light was moved down off the roof and into the rear bumper. I don't know exactly what year the changes were made. Others will fill in the blanks for ya. Welcome to the forum.





[Modified by TJR, 12:13 AM 10/15/2001]

 

I thought removable glass top was called a targa top or something like that? or is that something completely different? and wow...that sounds like a really weird transmission. Doesn't sound bad...just sounds...weird...

 

Get Z51! Its so many things, aux fan, oil cooler, Bilstein shocks, better sway bars, extra frame, better mufflers.

Here are excepts from an article I wrote a while ago:

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Why 1987?

A lot of research went into this car. When buying a Corvette, you want the newest car you can afford, starting at 1987. Why not 1984-1985 you ask? The 1984 is a completely different engine, with a throttle body injection. In 1984, it was an excellent sports car...but in 1985, the new Corvette blew it away. In 1985 the Corvette was refined very much, and most of the electrical problems from 1984 had been shut down, an engine with more torque, and a much better fuel delivery system(the Tuned Port Injection). However, the 1985 was still leaning heavily on old technology, Anti-Lock brakes were not an option, and cast iron heads weighed the front the car down. In 1986, Cheby implemented Anti-Lock brakes on the Corvette, and started to use some aluminum heads. However, not all of the 1986 cars got aluminum heads. You also have to understand that all sorts of little things were updated in this time period also, such as better relays, a better steering rack, and many other things. By 1987, the Corvette was a refined sports car. The Anti-Lock Brakes, and aluminum heads were always standard, and the car still sells for about the same price(although blue book is higher).

Why an Automatic?

That is a good question. I love manual sports cars as much as the next enthusiast, but the Corvette doesn't suffer much with the automatic over the manual transmission of the time. Doug Nash implemented an overdrive unit behind the regular four-speed transmission, effectively giving the car 7 speeds, and referred to, as the 4+3. To shift the transmission, you go from 1-2-3-4, then turn on the overdrive, and go from 2-3-4. In 1984 through 1986, both the transmission and overdrive were very prone to failure, and each carries a $1,500 price tag to rebuild. In 1987, the overdrive and transmission were rebuilt, to much better standards, and have a much better reliability record, although it is still not perfect. In 1989 Chevrolet abandoned the idea and started putting a 6-speed in the manual Corvette's. Many people don't like the 4+3 due to its long throw shifter. This is an easy and cheap($50) with a short shifter, from Mid-America Corvette's.(See the bottom of the page for links)

On the other hand, the TurboHyrdramatic 700R4 found in the Corvette from 1981-2001(although in 1992 it was switched to computer control, effectively changing the name to 4L60E, but don't be fooled, it is still basically a 700R4). Though the years, the 700R4 has been updated with better clutches, and generally better things. If the transmission goes out in your older car, always have it rebuilt with modern parts, as they are always better. It is not uncommon for the THM700R4 to go over 150,000 miles without any problems at all. However, hot-rodded Corvette's often see rebuilt transmission around 100,000 miles.
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Luckily, Chevrolet implemented a lot of things as standard equipment in Corvette's. The Corvette has always been Chevy's Flag Ship(it is Iron that Corvette is named after a small French Sailing Ship), and it gets all of the goodies.

Standard, you will find:

Power Door Locks
Power Windows
Power Mirrors
Air-conditioning
Removable Roof(fits nicely in the back of the car)
Telescoping/Tilt Wheel
Cassette
Digital Dash

But, there are something’s you can't live without, and others that are simply unnecessary.

What do I absolutely need to have?
There are two types of Corvette's. There is the Non-Z51 cars, and the Z-51 cars! The Z-51 option is a must. You will read this from the center consol, under Z. If it is not there, you better get a screaming deal on the car to still get it.

Z51 includes so many good things. The Corvette is first and foremost a road racer, so turning is what you are looking for. This is where the Z51 comes in. Instead of 23 mm sway bars front and back, you get a 26 mm sway bar in the front. You get Bilstein AutoX(the X stands for cross) shocks. And your steering is noticeably faster. Instead of turning the wheel 2.75 times to go from full left to full right lock, you only need to turn the wheel 2.25 times. Along with the turning factors, you get extra cooling features, such as an Oil Cooler, and an auxiliary fan.

For about $700 you can turn a non-Z51 car into a Z51, but it is much easier just to buy a Z51 in the first place.

Next on our list is the G44 Performance Axle. Believe it or not, in 1987, this code was a $22 option. Instead of getting the standard 2.59 axle you get the sportier 3.07 rear axle. I opted for the 2.59 rear axle, thinking that since I couldn't afford to rebuild an over-revved engine, the 2.59 would be better for my applications. But, after doing more research, the 3.07 only increases highway rpms by 300, and really livens the car up at lower speeds. It lightly hampers the top speed, to 154 with the manual, and 147 with the automatic. All manuals came with the G44. The automatic with the 2.59 will hit the same speed.

So, again, unless you get a screaming deal on the 2.59, go for the 3.07. It only takes about 2 mpg off of the Vette's incredible 30 miles per gallon fuel economy. If you choose a 2.59 and decide you would rather have a 3.07, you'll be paying about $1,400 to convert!

How about those sport seats? They are nice, and offer lumbar. But they are certainly not a must. I do not have sport seats, and I have no problem without the lumbar, as it is a very supportive seat. And yes, I do have problems in other vehicles without Lumbar, so it is not just me. I *think* that the car came with power driver seat standard. It is really an unnecessary item...as too would be the dual power seats. The passenger is always sitting all the way back, and legroom is not an issue. The Corvette has legroom to spare even for the tallest people.

So, sport seats and dual power seats are not necessary, however, they are a nice addition if you do happen to find a car with them.

Next is the glass roof. The glass roof is just a fun addition. It also weighs a lot less. Many, many Corvette's came with both a glass roof and a solid roof, but they usually are separated by now. The glass roof is very prone to cracking, and they are certainly not cheap. Sometimes insurance will cover it, but usually not. The glass roof also adds some headroom. I don't think it is worth it, and if you get a glass roofed Corvette, make sure you get the solid roof too.

Bose teamed up with AC Delco(Chevrolet) to develop a nice sound system for these cars. And did they ever! Many people hate the Delco/Bose system, do to its complexity and prone to crackly sound. It is true, the amps do wear out after time. But they are easy to replace, and you can get an upgraded set from Bose for $56 a piece. The Bose cassette requires a $60 adapter when installing a CD player, and is DIN and a half, so only a select few CD players will fit. However, it is not hard at all to have a stereo shop make a regular din player fit, and for only a few extra bucks.

Option UU8 and UQ4 are a must, because when it is working, the 6 (only 4 are Bose amplified) speakers fill the cab with a beautiful full sound. However, if the car didn’t come with this sound system from the factory, many have been upgraded with better systems. Don’t rule the car out because it doesn’t have this, but it is a very nice addition.

And lastly, we come to option C49 and Z6A. Depending on where you live, these may not be necessary. For me, they are lifesavers. These are the rear window, and mirror defrosters. It is very easy to tell if the car has these by looking at the drivers mirror, if it has heat-waves, the mirror is heated(most are), and if the rear hatch has lines going front to back, it has a hatch heater. They quickly defrost the mirrors and hatch, and the windshield defroster also defrosts the side windows.

There are a few other options, such as cruise control, and obviously interior and exterior colors.

Try to get a service manual, but if you can’t get it with the car, they are $49, and an invaluable asset to have.
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That was written a long time ago, but to the best of my knowlege everything is correct.

 

Yeah it's a targa, it has no bar in the middle like a t-top, but I don't think they actually call it a targa.

P.S. I edited my original post about the body changes if you want to read it again.

 

Check out:
http://www.geocities.com/MotorCity/4310/vetfacts.htm

for a history of C4s. And:
http://www.rjsmith.com/rpo_indx.html

for a list of options.

Mark

 

Ahhh.... it is a $19.95 fix!!! The kit is only $19.95 and shortens the throw from 8" to about 4.25". It is a huge and awesome difference. :D

The 4+3 is a Borg Warner Super T-10 4-speed transmission mated with a 2-speed automatic tranny. The 1987/1988 models were VERY reliable compared to 84-86 models.

It is a pretty cool and sturdy little transmission if you are willing to overlook all the bad publicity those who do not maintain or understand it say. These are also the transmissions used in the 1987 and 1988 Callaway Twin Turbo cars, so they CAN handle the horsepower and massive torque.

It takes a little time to get used to how to operate it, but is quite fun once you have it down. It's the best of both worlds. :yesnod:

 

General Motors cannot call it a Targa Top because Porsche copyrighted "Targa". It is a Removeable Roof Panel.

 

cool. Thanks for clarifications, everyone :)