85 Corvette comments needed
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,871
Likes: 6
From: Sault Ste. Marie Ontario
85 Corvette comments needed
Hi Guys,
I'm coming here from the C3 side to seek a little knowledge on a C4
My father in law just returned from a swap meet and it sounds like he pulled the trigger on an 85 Corvette.
The car is low mileage, well kept and looks good from the few picture I saw.
It comes with 2 sets of wheels & tires, has a new exhaust system and new brakes.
It has the 4+3 transmission in it that works well, but I've read this is a troublesome unit. True or false?
We will be travelling to pick it up next week.
If anyone here can give me a few pointers of things to look out for that would prevent the deal from going though I'd appreciate hearing from you.
Thanks
I'm coming here from the C3 side to seek a little knowledge on a C4
My father in law just returned from a swap meet and it sounds like he pulled the trigger on an 85 Corvette.
The car is low mileage, well kept and looks good from the few picture I saw.
It comes with 2 sets of wheels & tires, has a new exhaust system and new brakes.
It has the 4+3 transmission in it that works well, but I've read this is a troublesome unit. True or false?
We will be travelling to pick it up next week.
If anyone here can give me a few pointers of things to look out for that would prevent the deal from going though I'd appreciate hearing from you.
Thanks
Corvette Enthusiast
Joined: Oct 2007
Posts: 6,794
Likes: 2,706
From: So. Cal.
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
2023 C7 of the Year Finalist - Unmodified
Hi Guys,
I'm coming here from the C3 side to seek a little knowledge on a C4
My father in law just returned from a swap meet and it sounds like he pulled the trigger on an 85 Corvette.
The car is low mileage, well kept and looks good from the few picture I saw.
It comes with 2 sets of wheels & tires, has a new exhaust system and new brakes.
It has the 4+3 transmission in it that works well, but I've read this is a troublesome unit. True or false?
We will be travelling to pick it up next week.
If anyone here can give me a few pointers of things to look out for that would prevent the deal from going though I'd appreciate hearing from you.
Thanks
I'm coming here from the C3 side to seek a little knowledge on a C4
My father in law just returned from a swap meet and it sounds like he pulled the trigger on an 85 Corvette.
The car is low mileage, well kept and looks good from the few picture I saw.
It comes with 2 sets of wheels & tires, has a new exhaust system and new brakes.
It has the 4+3 transmission in it that works well, but I've read this is a troublesome unit. True or false?
We will be travelling to pick it up next week.
If anyone here can give me a few pointers of things to look out for that would prevent the deal from going though I'd appreciate hearing from you.
Thanks
Alot of 84's have been purchased recently here.
Le Mans Master
Joined: May 2003
Posts: 8,175
Likes: 237
From: Philadelphia Burbs
Cruise-In V Veteran
St. Jude Donor '06
Some questions and thoughts:
What kind of mileage do you classify as low? How far has the car been driven recently? How far do you have to go to get it home?
What are your father in law's intentions for car?
What time in the model year was it built?
What equipment does it have?
The 4+3 is very uneven - some folks have a great experience, others a terrible one.
What kind of mileage do you classify as low? How far has the car been driven recently? How far do you have to go to get it home?
What are your father in law's intentions for car?
What time in the model year was it built?
What equipment does it have?
The 4+3 is very uneven - some folks have a great experience, others a terrible one.
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,871
Likes: 6
From: Sault Ste. Marie Ontario
Well, I haven't seen the car yet, just two pictures and the comments from my FIL so here is what I know.
Some questions and thoughts:
What kind of mileage do you classify as low? 70K
How far has the car been driven recently? Locally driven
How far do you have to go to get it home? 4 hours
What are your father in law's intentions for car? Knowing him, he'll likely leave it in the trailer.
What time in the model year was it built? Enlighten me here. Is 85 a split year?
What equipment does it have? The car looks to be relatively stock. It has a targa top, some engine chrome, leather interior and I assume the standard assessories
The 4+3 is very uneven - some folks have a great experience, others a terrible one. Tell me a little more
What kind of mileage do you classify as low? 70K
How far has the car been driven recently? Locally driven
How far do you have to go to get it home? 4 hours
What are your father in law's intentions for car? Knowing him, he'll likely leave it in the trailer.
What time in the model year was it built? Enlighten me here. Is 85 a split year?
What equipment does it have? The car looks to be relatively stock. It has a targa top, some engine chrome, leather interior and I assume the standard assessories
The 4+3 is very uneven - some folks have a great experience, others a terrible one. Tell me a little more
Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
The general consensus is that if the fluid is changed regularly (every 10K miles) in the overdrive unit, The 4+3 will prove to be trouble free. The 4 speed section is bulletproof....the Doug Nash overdrive requires a little attention now and then.
As for the rest of the car, an 85 is a gen 1 SBC with OBD1 port fuel injection.....they don't get much simpler or more reliable than that. With 70K, if the car was well maintained since new, you should easily get another 100K out of the drivetrain.
The early C4's aren't as refined as the later ones, but they are damned good cars. Buy a good one to begin with, maintain it, and it will treat you right. But, like any old car, they break from time to time. The acid test with owning an old C4 (which is all of them) is can you do your own wrenching? If the answer is yes (or at least most of it), they can be kept running forever for a reasonable amount of money. If you have to send it off to a mechanic every time it coughs, it can and will bankrupt you.
Good luck with the decision.....post pics when he gets the car.
As for the rest of the car, an 85 is a gen 1 SBC with OBD1 port fuel injection.....they don't get much simpler or more reliable than that. With 70K, if the car was well maintained since new, you should easily get another 100K out of the drivetrain.
The early C4's aren't as refined as the later ones, but they are damned good cars. Buy a good one to begin with, maintain it, and it will treat you right. But, like any old car, they break from time to time. The acid test with owning an old C4 (which is all of them) is can you do your own wrenching? If the answer is yes (or at least most of it), they can be kept running forever for a reasonable amount of money. If you have to send it off to a mechanic every time it coughs, it can and will bankrupt you.
Good luck with the decision.....post pics when he gets the car.
Safety Car
Joined: Nov 2008
Posts: 4,328
Likes: 15
From: Jacksonville FL
Mine has almost 140K miles and the DN unit has been trouble free so far. Its about time to service it and I have major tune up materials built up. Your FIL can expect normal maintenance stuff but the car should be reliable and fun.
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Le Mans Master
Joined: May 2003
Posts: 8,175
Likes: 237
From: Philadelphia Burbs
Cruise-In V Veteran
St. Jude Donor '06
1985 wasn't a split year, but there were a lot of running changes during the year as Chevrolet engineers worked to iron out the kinks in the first real fuel injection in 20 years. In general, later in the year is better. The computer, by the way, is dumber than a bag of rocks.
I don't have the 4 + 3: my friends who do either have no problems or have so many that they end up replacing it with a 5 or 6 speed. You have to remember that the primary push for its design was mileage: Chevrolet couldn't get a 4-speed manual above the gas guzzler limits of the day.
I see 70k as medium mileage: my 1985 has just a little under that. I agree with Frizlefrak's "unrefined" comments.
I don't have the 4 + 3: my friends who do either have no problems or have so many that they end up replacing it with a 5 or 6 speed. You have to remember that the primary push for its design was mileage: Chevrolet couldn't get a 4-speed manual above the gas guzzler limits of the day.
I see 70k as medium mileage: my 1985 has just a little under that. I agree with Frizlefrak's "unrefined" comments.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Random thoughts on the 85
The 85, I have one, is a marked improvement in ride quality compared to the 84. Performance wise it is even better. First true TPI. The computer is not as dumb as a sack of rocks. It does everything as fast and as well as it needs to. It is, however, very slow to report what is is doing making it more difficult to gain data during short bursts of speed( can you say 1/4 mile?) During daily driving it functions very well. The computer used in the 85 is a single year use unit. Replacements are available but will likely become more scarce than multi use year computers. The 85 is a simple machine compared to later years. The HVAC system is cable controlled, no mini-computers to contend with. I am not aware of any changes made during the model year. I know very little about the Doug Nash trans. The MAF burn off is also a single year application. The Burn Off Module has been produced for years, replacements are both scarce and expensive. Fortunately the module is a very hardy piece.
The 85, I have one, is a marked improvement in ride quality compared to the 84. Performance wise it is even better. First true TPI. The computer is not as dumb as a sack of rocks. It does everything as fast and as well as it needs to. It is, however, very slow to report what is is doing making it more difficult to gain data during short bursts of speed( can you say 1/4 mile?) During daily driving it functions very well. The computer used in the 85 is a single year use unit. Replacements are available but will likely become more scarce than multi use year computers. The 85 is a simple machine compared to later years. The HVAC system is cable controlled, no mini-computers to contend with. I am not aware of any changes made during the model year. I know very little about the Doug Nash trans. The MAF burn off is also a single year application. The Burn Off Module has been produced for years, replacements are both scarce and expensive. Fortunately the module is a very hardy piece.
Le Mans Master
Joined: May 2003
Posts: 8,175
Likes: 237
From: Philadelphia Burbs
Cruise-In V Veteran
St. Jude Donor '06
The computer is not as dumb as a sack of rocks. It does everything as fast and as well as it needs to. It is, however, very slow to report what is is doing making it more difficult to gain data during short bursts of speed (can you say 1/4 mile?) During daily driving it functions very well.
...I count at least 5 driveline related TSBs (including the ever popular Minimum Idle Speed Adjustment Car Can Stall) and 4 different PROMs for my Federal automatic configuration.
That said, people who know me will vouch that I love my 1985.
Last edited by j3studio; Sep 27, 2010 at 09:38 AM.
Heel & Toe
Joined: Sep 2010
Posts: 20
Likes: 0
From: Panama City Beach Florida
The 1985 Corvette 350TPI / L98 engine is the last full year to have Iron Heads.
230 hp at 4000 RPM – Forged Aluminum Drive-shaft – 3250 lbs. Curb weight
Base Price $24,000.00 - 20 gallon fuel tank – 1985 Production was 39,729
Z51 Tire size P255/50VR-16 - Engine Compression 9.0:1
Highway average fuel mileage is 22.4 mpg for my 85 automatic with 3.07:1 gears.
The computer MPG average reads 27.5 and instant will read 33 MPG at 60 mph on level road, but it’s not actually getting that good of fuel mileage, not when you put a pencil or calculator on the gallons of gas you actually put in the tank and the miles driven. (It did this at 72K and still getting that at 147K miles)
1985 is the first year to have TPI (Tuned Port Injection) (8 fuel injectors)
The 1985 C4 has a MAF sensor (Mass Air Flow)
The 1985 L98 engine comes from the factory with an aluminum Water Pump,
but a regular cast iron water pump will work fine when that one starts to leak.
(As you already know; the 1985 small Block and Heads date back to 1955)
The C4 with the 4 + 3 Overdrive manual has a heavy-duty Dana 44 8.5-inch differential ring gear.
The C4 with the 4-speed 700-R4 automatic has a smaller Dana 36 7.9-inch differential ring gear.
The 4 + 3 is a 4-speed with a second set of three planetary gears attached at the rear.
The Overdrive Switch moved during the 85 model year from the console to the gear shift ****. It has over-drive in the top three gears.
The 1984-88 Doug-Nash 4 + 3 manual transmission is not as reliable as
the 1989-96 German built ZF 6-speed manual.
The 1985 does NOT have ABS (Anti-lock Braking System)
The 1985 does NOT have VATS (Vehicle Anti-Theft System)
(1986 C4’s débuted with ABS and VATS)
The 1984-85 have an anti-theft security system, just press the electric Door LOCK Button to activate the system, which disrupts power to the starter and sounds the horns if either door is opened. To de-activate the alarm, simply unlock either door with the key.
Note: If anyone inside the car presses the electric Door LOCK Button without the key in the ignition, with both doors closed and then opens one of the doors; the alarm will be activated, the horn will blow and the key must be inserted in the outside door lock and turned to shut off the alarm. Don’t think it won’t happen…lol
The 16” Rims are directional; they are marked Left or Right on the back-side.
Rims can be swapped from front to back on the same side if the C4 has the Z51 option.
Z51 9.5” wide rims are all the same width and non Z51 C4’s have 8.5” rims on the front.
The Targa Top (One piece) comes off with fours Torx screws. (Acrylic or Fiberglass)
A small black ratchet with the Torx bit permanently attached comes with the car.
The 1984-86E (Early) Targa Tops will fit each other, 1986L (Late) C4’s will not fit the 84-86E. The 86L to 88 tops are the same and 89-96 tops are the same, I think…
The C4 débuted with a new brake design created by Girlock of Australia.
11.5” diameter rotors with quick change brake pads held by a single bolt.
(The front & rear brake pads are simple to change)
C4’s have power Rack & Pinion Steering. (Non-Z51’s have 15.5:1 ratio gearing)
The RPO Z51 option was designed for racing; it’s a stiff rough ride on patched asphalt.
The 1985 Z51 package comes with dual electric puller & pusher fans, quicker 13.0 ratio steering, lower ratio 3.07:1 ring gear for the automatic and even lower for the manual. (Non-Z51 = 2.73:1 Ratio)
Z51 comes with heavy-duty Bilstein Gas Shocks, larger f & r springs and stabilizer bars.
You get lightning reflexes and no body roll with the Z51; it corners like its on rails.
Consumer Guide wrote the new Corvette is a World-Class Sports Car.[sic]
Car & Driver, Road & Track & Motor Trend magazines published articles on the 1985 Corvette; they wrote the 85 Corvette with Bosch Fuel Injection was the fastest American Production Car with Speeds to 150 mph and skidpad lateral acceleration at 0.90 G.[sic]
The C4 steel structure is galvanized inside and out for corrosion resistance.
The fourth-generation C4’s have what GM calls a “Birdcage” for a rigid structure.
In other words it’s not a body on frame as C1’s to C3’s were.
The C4 has a Single Front & Rear reinforced-fiberglass (aka: Plastic) Leaf Spring mounted transversely. The plastic leaf springs are more durable than steel springs.
This plastic spring is capable of withstanding five million full jounce/rebound cycles, versus 75,000 full jounce/rebound cycles for the steel coils.
The 1984-86E valve covers usually turn an ugly brown color after 100,000 miles.
The factory Delco Gold Bose AM/FM Radio Cassette sounds okay, but will just quit sometimes and then the next time I drive it, it works again, ongoing for 18 years.
If anyone has long CRANKING before the engine will start; but then it runs like a scalded dog, remove the in-tank fuel pump and REPLACE the strainer/filter on the bottom of the electric fuel pump, it’s a simple fix. (Costs $9.00 for the Strainer)
----------------------------------------------------------------------------
The 1984 C4 has CFI (Cross-Fire Injection = dual throttle-body fuel injection)
The production 1984 C4 débuted on March 24, 1983 with 51,547 sold because it was such a long model year. No production 1983 Corvettes was sold to the public.
----------------------------------------------------------------------------
The Fuel pump is very easy to replace, it is so simple, just stand at rear of car to remove and replace, a T15 (Torx), flat screwdriver and 10mm socket with extension is all it takes to remove and replace the in-tank electric fuel pump.
Aftermarket pumps costs $60.00 for a 1 year warranty or $90.00 for a lifetime warranty.
In 1993; I purchased a $130.00 Genuine Delco fuel pump from a Corvette Dealer and
it lasted one year almost to the day. I installed an aftermarket fuel pump ten years ago.
----------------------------------------------------------------------------
Early 1986 Coupes still had iron heads until the convertible débuted in February of 1986.
1986L (Late)Coupes and all 1986 Convertibles have aluminum heads.
1987 C4's have Roller Lifters.
----------------------------------------------------------------------------
My 1985 Z51 Corvette with automatic has 148,703 actual miles and is fun to drive,
its stock, even has quiet OEM type mufflers and it’ll catch 2nd gear every time on dry pavement. Nothing has been rebuilt or replaced on the drive train, all original except for the radiator, starter, alternator, power steering pump, one headlight gear; the original mufflers were replaced when the car was 20 years old, front brakes twice, rear brakes once, windshield, rear tires several times, air conditioner compressor, Fuel injectors, but that was not the problem, it was the ECM, radio antenna twice, and the computer once.
It needs the rubber around the rear glass and targa top replaced as well as the seats.
230 hp at 4000 RPM – Forged Aluminum Drive-shaft – 3250 lbs. Curb weight
Base Price $24,000.00 - 20 gallon fuel tank – 1985 Production was 39,729
Z51 Tire size P255/50VR-16 - Engine Compression 9.0:1
Highway average fuel mileage is 22.4 mpg for my 85 automatic with 3.07:1 gears.
The computer MPG average reads 27.5 and instant will read 33 MPG at 60 mph on level road, but it’s not actually getting that good of fuel mileage, not when you put a pencil or calculator on the gallons of gas you actually put in the tank and the miles driven. (It did this at 72K and still getting that at 147K miles)
1985 is the first year to have TPI (Tuned Port Injection) (8 fuel injectors)
The 1985 C4 has a MAF sensor (Mass Air Flow)
The 1985 L98 engine comes from the factory with an aluminum Water Pump,
but a regular cast iron water pump will work fine when that one starts to leak.
(As you already know; the 1985 small Block and Heads date back to 1955)
The C4 with the 4 + 3 Overdrive manual has a heavy-duty Dana 44 8.5-inch differential ring gear.
The C4 with the 4-speed 700-R4 automatic has a smaller Dana 36 7.9-inch differential ring gear.
The 4 + 3 is a 4-speed with a second set of three planetary gears attached at the rear.
The Overdrive Switch moved during the 85 model year from the console to the gear shift ****. It has over-drive in the top three gears.
The 1984-88 Doug-Nash 4 + 3 manual transmission is not as reliable as
the 1989-96 German built ZF 6-speed manual.
The 1985 does NOT have ABS (Anti-lock Braking System)
The 1985 does NOT have VATS (Vehicle Anti-Theft System)
(1986 C4’s débuted with ABS and VATS)
The 1984-85 have an anti-theft security system, just press the electric Door LOCK Button to activate the system, which disrupts power to the starter and sounds the horns if either door is opened. To de-activate the alarm, simply unlock either door with the key.
Note: If anyone inside the car presses the electric Door LOCK Button without the key in the ignition, with both doors closed and then opens one of the doors; the alarm will be activated, the horn will blow and the key must be inserted in the outside door lock and turned to shut off the alarm. Don’t think it won’t happen…lol
The 16” Rims are directional; they are marked Left or Right on the back-side.
Rims can be swapped from front to back on the same side if the C4 has the Z51 option.
Z51 9.5” wide rims are all the same width and non Z51 C4’s have 8.5” rims on the front.
The Targa Top (One piece) comes off with fours Torx screws. (Acrylic or Fiberglass)
A small black ratchet with the Torx bit permanently attached comes with the car.
The 1984-86E (Early) Targa Tops will fit each other, 1986L (Late) C4’s will not fit the 84-86E. The 86L to 88 tops are the same and 89-96 tops are the same, I think…
The C4 débuted with a new brake design created by Girlock of Australia.
11.5” diameter rotors with quick change brake pads held by a single bolt.
(The front & rear brake pads are simple to change)
C4’s have power Rack & Pinion Steering. (Non-Z51’s have 15.5:1 ratio gearing)
The RPO Z51 option was designed for racing; it’s a stiff rough ride on patched asphalt.
The 1985 Z51 package comes with dual electric puller & pusher fans, quicker 13.0 ratio steering, lower ratio 3.07:1 ring gear for the automatic and even lower for the manual. (Non-Z51 = 2.73:1 Ratio)
Z51 comes with heavy-duty Bilstein Gas Shocks, larger f & r springs and stabilizer bars.
You get lightning reflexes and no body roll with the Z51; it corners like its on rails.
Consumer Guide wrote the new Corvette is a World-Class Sports Car.[sic]
Car & Driver, Road & Track & Motor Trend magazines published articles on the 1985 Corvette; they wrote the 85 Corvette with Bosch Fuel Injection was the fastest American Production Car with Speeds to 150 mph and skidpad lateral acceleration at 0.90 G.[sic]
The C4 steel structure is galvanized inside and out for corrosion resistance.
The fourth-generation C4’s have what GM calls a “Birdcage” for a rigid structure.
In other words it’s not a body on frame as C1’s to C3’s were.
The C4 has a Single Front & Rear reinforced-fiberglass (aka: Plastic) Leaf Spring mounted transversely. The plastic leaf springs are more durable than steel springs.
This plastic spring is capable of withstanding five million full jounce/rebound cycles, versus 75,000 full jounce/rebound cycles for the steel coils.
The 1984-86E valve covers usually turn an ugly brown color after 100,000 miles.
The factory Delco Gold Bose AM/FM Radio Cassette sounds okay, but will just quit sometimes and then the next time I drive it, it works again, ongoing for 18 years.
If anyone has long CRANKING before the engine will start; but then it runs like a scalded dog, remove the in-tank fuel pump and REPLACE the strainer/filter on the bottom of the electric fuel pump, it’s a simple fix. (Costs $9.00 for the Strainer)
----------------------------------------------------------------------------
The 1984 C4 has CFI (Cross-Fire Injection = dual throttle-body fuel injection)
The production 1984 C4 débuted on March 24, 1983 with 51,547 sold because it was such a long model year. No production 1983 Corvettes was sold to the public.
----------------------------------------------------------------------------
The Fuel pump is very easy to replace, it is so simple, just stand at rear of car to remove and replace, a T15 (Torx), flat screwdriver and 10mm socket with extension is all it takes to remove and replace the in-tank electric fuel pump.
Aftermarket pumps costs $60.00 for a 1 year warranty or $90.00 for a lifetime warranty.
In 1993; I purchased a $130.00 Genuine Delco fuel pump from a Corvette Dealer and
it lasted one year almost to the day. I installed an aftermarket fuel pump ten years ago.
----------------------------------------------------------------------------
Early 1986 Coupes still had iron heads until the convertible débuted in February of 1986.
1986L (Late)Coupes and all 1986 Convertibles have aluminum heads.
1987 C4's have Roller Lifters.
----------------------------------------------------------------------------
My 1985 Z51 Corvette with automatic has 148,703 actual miles and is fun to drive,
its stock, even has quiet OEM type mufflers and it’ll catch 2nd gear every time on dry pavement. Nothing has been rebuilt or replaced on the drive train, all original except for the radiator, starter, alternator, power steering pump, one headlight gear; the original mufflers were replaced when the car was 20 years old, front brakes twice, rear brakes once, windshield, rear tires several times, air conditioner compressor, Fuel injectors, but that was not the problem, it was the ECM, radio antenna twice, and the computer once.
It needs the rubber around the rear glass and targa top replaced as well as the seats.
Last edited by 1985 L98/Z51; Oct 3, 2010 at 11:48 AM. Reason: Corrected an error in spelling & added 1987 C4's have Roller Lifters.
Burning Brakes
Joined: May 2005
Posts: 1,091
Likes: 35
From: Coldville
The 1985 Corvette 350ci / L98 engine is the last full year to have Iron Heads.
230 hp at 4000 RPM – Forged Aluminum Driveshaft – 3250 lbs. Curb weight
Cost new $27,000.00 - 20 gallon fuel tank – 1985 Production was 39,729
Tire size P255/50VR-16 - Engine Compression 9.0:1 -
City/Highway average fuel mileage is 22.4 mpg for my 85 automatic with 3.07:1 gears.
The computer MPG average reads 27.5 and instant will read 32 MPG at 60 mph on level road, but it’s not actually getting that good of fuel mileage, not when you put a pencil or calculator on the gallons of gas you actually put in the tank and the miles driven.
1985 is the first year to have TPI (Tuned Port Injection) (8 fuel injectors)
The 1985 C4 has a MAF sensor (Mass Air Flow)
The 1985 L98 engine comes from the factory with an aluminum Water Pump,
but a regular cast iron water pump will work fine when that one starts to leak.
(As you already know; the 1985 small Block and Heads date back to1955)
The C4 with the 4 + 3 Overdrive manual has a heavy-duty 8.5-inch differential ring gear.
The C4 with the 4-speed 700-R4 automatic has a smaller 7.9-inch differential ring gear.
The 4 + 3 is a 4-speed with a second set of three planetary gears attached at the rear.
The Overdrive Switch moved during the 85 model year from the console to the gear shift ****. It has over-drive in the top three gears.
The 1984-88 Doug-Nash 4 + 3 manual transmission is not as reliable as
the 1989-96 German built ZF 6-speed manual.
The 1985 does NOT have ABS (Anti-lock Braking System)
The 1985 does NOT have VATS (Vehicle Anti-Theft System)
(1986 C4’s débuted with ABS and VATS)
The 1984-85 have an anti-theft security system, just press the electric Door LOCK Button to activate the system, which disrupts power to the starter and sounds the horns if either door is opened. To de-activate the alarm, simply unlock either door with the key.
Note: If anyone inside the car presses the electric Door LOCK Button without the key in the ignition, with both doors closed and then opens one of the doors; the alarm will be activated, the horn will blow and the key must be inserted in the outside door lock and turned to shut off the alarm. Don’t think it won’t happen…lol
The 16” Rims are directional; they are marked Left or Right on the back-side.
Rims can be swapped from front to back on the same side if the C4 has the Z51 option.
Z51 9.5” wide rims are all the same width and non Z51 C4’s have 8.5” rims on the front.
The Targa Top (One piece) comes off with fours Torx screws. (Acrylic or Fiberglass)
A small black ratchet with the Torx bit permanently attached comes with the car.
The 1984-86E (Early) Targa Tops will fit each other, 1986L (Late) C4’s will not fit the 84-86E. The 86L to 88 tops are the same and 89-96 tops are the same, I think…
The C4 débuted with a new brake design created by Girlock of Australia.
11.5” diameter rotors with quick change brake pads held by a single bolt.
(The front & rear brake pads are simple to change)
The Fuel pump is very easy to replace, it is so simple, just stand at rear of car to remove and replace, a T15 (Torx), flat screwdriver and 10mm socket with extension is all it takes to remove and replace the in-tank electric fuel pump.
Aftermarket pumps costs $60.00 for a 1 year warranty or $90.00 for a lifetime warranty.
In 1993; I purchased a $130.00 Genuine Delco fuel pump from a Corvette Dealer and
it lasted one year almost to the day. I installed an aftermarket fuel pump ten years ago.
C4’s have power Rack & Pinion Steering. (Non-Z51’s have 15.5:1 ratio gearing)
The RPO Z51 option was designed for racing; it’s a stiff rough ride on patched asphalt.
The 1985 Z51 package comes with dual electric puller & pusher fans, quicker 13.0 ratio steering, lower ratio 3.07:1 ring gear for the automatic and even lower for the manual.
Z51 comes with heavy-duty Bilstein Gas Shocks, larger f & r springs and stabilizer bars.
You get lightning reflexes and no body roll with the Z51; it corners like its on rails.
Consumer Guide wrote the new Corvette is a World-Class Sports Car.[sic]
Car & Driver, Road & Track & Motor Trend magazines published articles on the 1985 Corvette; they wrote the 85 Corvette with Bosch Fuel Injection was the fastest American Production Car with Speeds to 153mph and skidpad lateral acceleration at 0.90 G.[sic]
The C4 steel structure is galvanized inside and out for corrosion resistance.
The sixth-generation C4’s have what GM calls a “Birdcage” for a rigid structure.
In other words it’s not a body on frame as C1’s to C3’s were.
The C4 has a Single Front & Rear reinforced-fiberglass (aka: Plastic) Leaf Springs mounted transversely. The plastic leaf springs are more durable than steel springs.
This plastic spring is capable of withstanding five million full jounce/rebound cycles, versus 75,000 full jounce/rebound cycles for the steel coils.
The 1984-86E valve covers usually turn an ugly brown color after 100,000 miles.
The factory Delco Gold Bose AM/FM Radio Cassette sounds okay, but will just quit sometimes and then the next time I drive it, it works again, ongoing for 18 years.
If anyone has long CRANKING before the engine will start; but then it runs like a scalded dog, remove the in-tank fuel pump and REPLACE the strainer/filter on the bottom of the electric fuel pump, it’s a simple fix. (Costs $9.00 for the Strainer)
The 1984 C4 has CFI (Cross-Fire Injection = dual throttle-body fuel injection)
The production 1984 C4 débuted on March 24, 1983 with 51,547 sold because it was such a long model year. No production 1983 Corvettes with a VIN was sold to the public.
Early 1986 Coupes still had iron heads until the convertible débuted in February of 1986.
1986L Coupes and all 1986 Convertibles have aluminum heads with roller rockers.
My 1985 Z51 Corvette with automatic has 148,703 actual miles and is fun to drive,
its stock, even has quiet OEM type mufflers and it’ll catch 2nd gear every time on dry pavement. Nothing has been rebuilt or replaced on the drive train, all original except for the radiator, starter, alternator, power steering pump, one headlight gear; the original mufflers were replaced when the car was 20 years old, front brakes twice, rear brakes once, windshield, rear tires several times, air conditioner compressor, Fuel injectors, but that was not the problem, it was the ECM, radio antenna twice, and the computer once.
It needs the rubber around the rear glass and targa top replaced as well as the seats.
It’s more of a grocery getter now because it much better on fuel than my wife’s Z71 Tahoe 4x4 or my F-150 4x4 truck with 35” tires.
Hope some of you got some new information out of this long detailed post,
it brought back many great memories while typing, I’m thinking about running through the quarter mile or at least catch 2nd gear on my way to the store in a few minutes.
230 hp at 4000 RPM – Forged Aluminum Driveshaft – 3250 lbs. Curb weight
Cost new $27,000.00 - 20 gallon fuel tank – 1985 Production was 39,729
Tire size P255/50VR-16 - Engine Compression 9.0:1 -
City/Highway average fuel mileage is 22.4 mpg for my 85 automatic with 3.07:1 gears.
The computer MPG average reads 27.5 and instant will read 32 MPG at 60 mph on level road, but it’s not actually getting that good of fuel mileage, not when you put a pencil or calculator on the gallons of gas you actually put in the tank and the miles driven.
1985 is the first year to have TPI (Tuned Port Injection) (8 fuel injectors)
The 1985 C4 has a MAF sensor (Mass Air Flow)
The 1985 L98 engine comes from the factory with an aluminum Water Pump,
but a regular cast iron water pump will work fine when that one starts to leak.
(As you already know; the 1985 small Block and Heads date back to1955)
The C4 with the 4 + 3 Overdrive manual has a heavy-duty 8.5-inch differential ring gear.
The C4 with the 4-speed 700-R4 automatic has a smaller 7.9-inch differential ring gear.
The 4 + 3 is a 4-speed with a second set of three planetary gears attached at the rear.
The Overdrive Switch moved during the 85 model year from the console to the gear shift ****. It has over-drive in the top three gears.
The 1984-88 Doug-Nash 4 + 3 manual transmission is not as reliable as
the 1989-96 German built ZF 6-speed manual.
The 1985 does NOT have ABS (Anti-lock Braking System)
The 1985 does NOT have VATS (Vehicle Anti-Theft System)
(1986 C4’s débuted with ABS and VATS)
The 1984-85 have an anti-theft security system, just press the electric Door LOCK Button to activate the system, which disrupts power to the starter and sounds the horns if either door is opened. To de-activate the alarm, simply unlock either door with the key.
Note: If anyone inside the car presses the electric Door LOCK Button without the key in the ignition, with both doors closed and then opens one of the doors; the alarm will be activated, the horn will blow and the key must be inserted in the outside door lock and turned to shut off the alarm. Don’t think it won’t happen…lol
The 16” Rims are directional; they are marked Left or Right on the back-side.
Rims can be swapped from front to back on the same side if the C4 has the Z51 option.
Z51 9.5” wide rims are all the same width and non Z51 C4’s have 8.5” rims on the front.
The Targa Top (One piece) comes off with fours Torx screws. (Acrylic or Fiberglass)
A small black ratchet with the Torx bit permanently attached comes with the car.
The 1984-86E (Early) Targa Tops will fit each other, 1986L (Late) C4’s will not fit the 84-86E. The 86L to 88 tops are the same and 89-96 tops are the same, I think…
The C4 débuted with a new brake design created by Girlock of Australia.
11.5” diameter rotors with quick change brake pads held by a single bolt.
(The front & rear brake pads are simple to change)
The Fuel pump is very easy to replace, it is so simple, just stand at rear of car to remove and replace, a T15 (Torx), flat screwdriver and 10mm socket with extension is all it takes to remove and replace the in-tank electric fuel pump.
Aftermarket pumps costs $60.00 for a 1 year warranty or $90.00 for a lifetime warranty.
In 1993; I purchased a $130.00 Genuine Delco fuel pump from a Corvette Dealer and
it lasted one year almost to the day. I installed an aftermarket fuel pump ten years ago.
C4’s have power Rack & Pinion Steering. (Non-Z51’s have 15.5:1 ratio gearing)
The RPO Z51 option was designed for racing; it’s a stiff rough ride on patched asphalt.
The 1985 Z51 package comes with dual electric puller & pusher fans, quicker 13.0 ratio steering, lower ratio 3.07:1 ring gear for the automatic and even lower for the manual.
Z51 comes with heavy-duty Bilstein Gas Shocks, larger f & r springs and stabilizer bars.
You get lightning reflexes and no body roll with the Z51; it corners like its on rails.
Consumer Guide wrote the new Corvette is a World-Class Sports Car.[sic]
Car & Driver, Road & Track & Motor Trend magazines published articles on the 1985 Corvette; they wrote the 85 Corvette with Bosch Fuel Injection was the fastest American Production Car with Speeds to 153mph and skidpad lateral acceleration at 0.90 G.[sic]
The C4 steel structure is galvanized inside and out for corrosion resistance.
The sixth-generation C4’s have what GM calls a “Birdcage” for a rigid structure.
In other words it’s not a body on frame as C1’s to C3’s were.
The C4 has a Single Front & Rear reinforced-fiberglass (aka: Plastic) Leaf Springs mounted transversely. The plastic leaf springs are more durable than steel springs.
This plastic spring is capable of withstanding five million full jounce/rebound cycles, versus 75,000 full jounce/rebound cycles for the steel coils.
The 1984-86E valve covers usually turn an ugly brown color after 100,000 miles.
The factory Delco Gold Bose AM/FM Radio Cassette sounds okay, but will just quit sometimes and then the next time I drive it, it works again, ongoing for 18 years.
If anyone has long CRANKING before the engine will start; but then it runs like a scalded dog, remove the in-tank fuel pump and REPLACE the strainer/filter on the bottom of the electric fuel pump, it’s a simple fix. (Costs $9.00 for the Strainer)
The 1984 C4 has CFI (Cross-Fire Injection = dual throttle-body fuel injection)
The production 1984 C4 débuted on March 24, 1983 with 51,547 sold because it was such a long model year. No production 1983 Corvettes with a VIN was sold to the public.
Early 1986 Coupes still had iron heads until the convertible débuted in February of 1986.
1986L Coupes and all 1986 Convertibles have aluminum heads with roller rockers.
My 1985 Z51 Corvette with automatic has 148,703 actual miles and is fun to drive,
its stock, even has quiet OEM type mufflers and it’ll catch 2nd gear every time on dry pavement. Nothing has been rebuilt or replaced on the drive train, all original except for the radiator, starter, alternator, power steering pump, one headlight gear; the original mufflers were replaced when the car was 20 years old, front brakes twice, rear brakes once, windshield, rear tires several times, air conditioner compressor, Fuel injectors, but that was not the problem, it was the ECM, radio antenna twice, and the computer once.
It needs the rubber around the rear glass and targa top replaced as well as the seats.
It’s more of a grocery getter now because it much better on fuel than my wife’s Z71 Tahoe 4x4 or my F-150 4x4 truck with 35” tires.
Hope some of you got some new information out of this long detailed post,
it brought back many great memories while typing, I’m thinking about running through the quarter mile or at least catch 2nd gear on my way to the store in a few minutes.
Here's alittle more:
The 1985 iron head first year TPI was as quick or quicker than the later C4'S with more advertised Hp.
Even with iron heads flat tappet cam and less compression, you say how? (weight).
5.7 0-60-1985
6.0 0-60-1986
6.0 0-60-1987
5.9 0-60-1988
5.9 0-60-1989
5.8 0-60-1990
5.7 0-60-1991
But some times may be due to rear gear selection and options.
Heel & Toe
Joined: Sep 2010
Posts: 20
Likes: 0
From: Panama City Beach Florida
I know what you mean rad928music
1985 L98 230 hp rating is at 4000 RPM and shifts at 4800 RPM.
1992 LT1 300 hp rating is at 5000 RPM.
I have one of those G Tech Performance Meters from Tesla Electronics.
I staged and ran my 1985 L98 Z51 through the 1/4 mile 7 times back to back in 1996.
During this time I did have a ADS Stage 1 Super Chip, K&N Air filter, Air Foil, modified MAF (Removed the screen), Mobil 1 Synthetic 15W-50, Slick 50, 180F thermostat. 3.07:1
It was 82 F, 74% Humidity, 29.93 Baro. pressure and with me in the car it weighs 3,440.
Stock mufflers with 113,000 on odometer, Full tank of 93 Octane fuel.
The average 0-60 was 5.63 seconds Lowest was 5.41 & highest was 5.77.
The average 1/4 mile E.T. was 14.27Lowest was 14.14 and highest was 14.38.
The average 1/4 mile Trap Speed was 99.6 mph
Lowest Trap Speed was 98.9 & Highest Trap Speed was 100.2
FYI - I have a toggle switch to turn on one of my electric fans to keep the engine at about 190F, if it gets to 210F or higher it does not perform as well.
149 mph at 4500 RPM
If I stage at 1600 RPM and floor it, it does not spin too much, it will launch.
The 1985-92 stock Mustang GT or LX 5.0 was not a match for my 85 C4 or the 87 Grand National 3.8L Turbo.
An 1989 Camaro IROC Z 350TPI & 1987 Trans AM GTA 350TPI could not stay with either of us.
I do not have the chip in it now.
1985 L98 230 hp rating is at 4000 RPM and shifts at 4800 RPM.
1992 LT1 300 hp rating is at 5000 RPM.
I have one of those G Tech Performance Meters from Tesla Electronics.
I staged and ran my 1985 L98 Z51 through the 1/4 mile 7 times back to back in 1996.
During this time I did have a ADS Stage 1 Super Chip, K&N Air filter, Air Foil, modified MAF (Removed the screen), Mobil 1 Synthetic 15W-50, Slick 50, 180F thermostat. 3.07:1
It was 82 F, 74% Humidity, 29.93 Baro. pressure and with me in the car it weighs 3,440.
Stock mufflers with 113,000 on odometer, Full tank of 93 Octane fuel.
The average 0-60 was 5.63 seconds Lowest was 5.41 & highest was 5.77.
The average 1/4 mile E.T. was 14.27Lowest was 14.14 and highest was 14.38.
The average 1/4 mile Trap Speed was 99.6 mph
Lowest Trap Speed was 98.9 & Highest Trap Speed was 100.2
FYI - I have a toggle switch to turn on one of my electric fans to keep the engine at about 190F, if it gets to 210F or higher it does not perform as well.
149 mph at 4500 RPM
If I stage at 1600 RPM and floor it, it does not spin too much, it will launch.
The 1985-92 stock Mustang GT or LX 5.0 was not a match for my 85 C4 or the 87 Grand National 3.8L Turbo.
An 1989 Camaro IROC Z 350TPI & 1987 Trans AM GTA 350TPI could not stay with either of us.
I do not have the chip in it now.
Last edited by 1985 L98/Z51; Mar 25, 2011 at 07:28 AM.
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,871
Likes: 6
From: Sault Ste. Marie Ontario
Thanks for all the great info Gents.
We are planning to pick it up on Saturday if all checks outs.
I'll posts some good shots of it once we get it home.
Maybe even a side by side with the C3
Thanks Again,
Ian
We are planning to pick it up on Saturday if all checks outs.
I'll posts some good shots of it once we get it home.
Maybe even a side by side with the C3
Thanks Again,
Ian
Safety Car
Joined: Oct 2007
Posts: 4,426
Likes: 229
From: Pennsylvania
Just one rule with the 4+3 to make it shift into O/D smoothly. ALWAYS use the clutch when shifting in or out of O/D. You'll like it I'm sure. The 1985 is a good model year for the Vette. If you need any advice on it, be sure to address your question to those of us here who actually do own 85's. It seems there are alot of us now judging by the posts. 
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,871
Likes: 6
From: Sault Ste. Marie Ontario
Just one rule with the 4+3 to make it shift into O/D smoothly. ALWAYS use the clutch when shifting in or out of O/D. You'll like it I'm sure. The 1985 is a good model year for the Vette. If you need any advice on it, be sure to address your question to those of us here who actually do own 85's. It seems there are alot of us now judging by the posts.
Safety Car
Joined: Sep 2002
Posts: 4,971
Likes: 9
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