New C4 Road Race car
05-21-2017, 10:23 PM
#1
New C4 Road Race car
Hello everyone.
As the title says I'm building a new race car. Its going to be used in the WRL (endurance road races). I have been racing cars since I was 16, MOST of them have been GM. But this is my first Corvette. I have some questions and ideas, I hope you folks can point me in the right direction.
The car: Its an 84. Crossfire V8, 4+3 tranny. dana 44 rear end.
Engine: My last race car was a Camaro, it ran hot, I had to run an air duct on the car, run a high volume water pump, etc to get the car to keep its cool. Do these C4 Corvettes run hot? Anything I need to do to keep it from boiling over in a long race?
Trans: Atleast for the start I'm going to keep the 4+3 (I got other bills to pay!) MAYBE I'm missing it, but is there a button in the car to lock it in and out of overdrive? We do races at Road America, I'm afraid I will run out of gear on said track. Is there a cheap ("cheap") tranny I should be looking for to swap into the car? The power is going to be pretty low so I don't need to drop lots of cash on a ZF if there are other options.
Diff: I'll be doing races that are 8 hours long in some cases. I know the Dana 44 is tough stuff, but will I need to run a cooler? Any preference on fluid for this diff?
Wheels and tires: I read that the offset is different on these early cars. What I would LIKE to do is get the car setup to take the later wheels so I can get some 17s on the car. What is the max tire size I can get on this car and still keep the tires under the fenders?
Thats all I can think of for now.
Cheers.
As the title says I'm building a new race car. Its going to be used in the WRL (endurance road races). I have been racing cars since I was 16, MOST of them have been GM. But this is my first Corvette. I have some questions and ideas, I hope you folks can point me in the right direction.
The car: Its an 84. Crossfire V8, 4+3 tranny. dana 44 rear end.
Engine: My last race car was a Camaro, it ran hot, I had to run an air duct on the car, run a high volume water pump, etc to get the car to keep its cool. Do these C4 Corvettes run hot? Anything I need to do to keep it from boiling over in a long race?
Trans: Atleast for the start I'm going to keep the 4+3 (I got other bills to pay!) MAYBE I'm missing it, but is there a button in the car to lock it in and out of overdrive? We do races at Road America, I'm afraid I will run out of gear on said track. Is there a cheap ("cheap") tranny I should be looking for to swap into the car? The power is going to be pretty low so I don't need to drop lots of cash on a ZF if there are other options.
Diff: I'll be doing races that are 8 hours long in some cases. I know the Dana 44 is tough stuff, but will I need to run a cooler? Any preference on fluid for this diff?
Wheels and tires: I read that the offset is different on these early cars. What I would LIKE to do is get the car setup to take the later wheels so I can get some 17s on the car. What is the max tire size I can get on this car and still keep the tires under the fenders?
Thats all I can think of for now.
Cheers.
05-22-2017, 08:21 AM
#2
Le Mans Master
My $0.02 - sell it and buy a 94+ ( or bring a truck and empty my yard and storage shed for $10k)
You have a good start for an autocross car, for long runs the +3 automatic is the Achilles heel of that model. The crossfire is an OK engine, without work it will never have the HP of a newer model.
The goto car is a built C5, lots of those for sale.
If you really want to do this, check the c4 sections for ideas on what you will need to use later c4 or even c5 rims.
Good luck
You have a good start for an autocross car, for long runs the +3 automatic is the Achilles heel of that model. The crossfire is an OK engine, without work it will never have the HP of a newer model.
The goto car is a built C5, lots of those for sale.
If you really want to do this, check the c4 sections for ideas on what you will need to use later c4 or even c5 rims.
Good luck
05-23-2017, 08:27 AM
#4
Drifting
The 1984 Corvette ( and only the 84 ) is allowed in SCCA ITR class for road racing. As far as I know only one has been built and it was being raced on the tighter tracks in the NE. Probably not the best place for it. I think a well prepped one would be very quick at SE Div. tracks like Daytona, Sebring, Road Atlanta, Homestead, VIR etc. Handling should likely be better than the old Corvette Challenge cars, plus better rubber now available. Under the IT rules, the motors are pretty stock, but headers and better exhaust allowed, .040 over motor, some port matching and blue printing. I think a good motor might make 270-275 HP at the flylwheel...not much but the torque would be pretty good. The weal point will be the 4+3 tranny, which will require regular maintenance. If you want to run this class, the C4 could be pretty good, however in general a built c5 is likely a better all round value.
05-23-2017, 08:49 PM
#5
The 1984 Corvette ( and only the 84 ) is allowed in SCCA ITR class for road racing. As far as I know only one has been built and it was being raced on the tighter tracks in the NE. Probably not the best place for it. I think a well prepped one would be very quick at SE Div. tracks like Daytona, Sebring, Road Atlanta, Homestead, VIR etc. Handling should likely be better than the old Corvette Challenge cars, plus better rubber now available. Under the IT rules, the motors are pretty stock, but headers and better exhaust allowed, .040 over motor, some port matching and blue printing. I think a good motor might make 270-275 HP at the flylwheel...not much but the torque would be pretty good. The weal point will be the 4+3 tranny, which will require regular maintenance. If you want to run this class, the C4 could be pretty good, however in general a built c5 is likely a better all round value.
Thanks for the reply, I have read a TON of posts from you over the years in the various GT/V8 forums were I lurk some days.
I got the smokin' hot deal on my 84, I have always wanted to play with a C4 corvette so that is my plan. I love a nice C5 and I won't deny that they are a better car. Everyone points to the 4+3 as the problem child of this car. Besides making sure it has fresh fluid is there anything else I can do to help keep it alive? I'll keep my eyes open for a better option as time rolls on. Ive read up on people swapping in a T5, I'm not going to be making a ton of power so that looks the most interesting to me. The T56 or ZF is the smart way to go....but.
1. I'm not that smart.
2. Its spendy.
Matt,
05-24-2017, 07:45 AM
#6
Drifting
I would think that a Richmond super T10 could work just fine since the 4+3 is really just an old T10 with an overdrive unit slapped on the back. The richmonds are around 2K new.
I see two potential problems with that swap:
1. you would have to fabricate some kind of support for the C beam that attaches to rear of the 4+3. Maybe something coming down from the roll cage?
2. would need a custom driveshaft with additional length.
The T56 or ZF would not be legal in ITR, but you could also run the car in ITO with more liberal rules.
I see two potential problems with that swap:
1. you would have to fabricate some kind of support for the C beam that attaches to rear of the 4+3. Maybe something coming down from the roll cage?
2. would need a custom driveshaft with additional length.
The T56 or ZF would not be legal in ITR, but you could also run the car in ITO with more liberal rules.
Last edited by bosco022; 05-24-2017 at 08:02 AM.
05-24-2017, 03:20 PM
#7
Drifting
You are looking at endurance, so, you really need to manage heat and abuse. I'm not sure what the WRL regs allow you to do in whatever class you will be in, that's a good place to start.
If you are permitted:
I would get a big monster cooler on the OD unit. Along with frequent fluil changes, and don't buy the cheap stuff. I would also wrap or coat the exhaust until after you are past the transmission.
The other thing I've read to keep the OD living a longer life is to treat it as a 5th gear. Don't leave it on. Turn it on only when you need it. On the long straights once you top out 4th, push the clutch in, activate the OD and go. Same thing on the way down in braking zone. Turn the OD off while the clutch is in. (I think the 84 switch is on the console, for racing you may want to relocate the switch onto the shifter)
For cooling make sure the radiator is clean of debris, if allowed I would upgrade to a big aluminum one, making sure the shroud is sealed around the radiator so that all the air is forced over it.
There are guys running 11" wide wheels and 315s all around, it's a tight fit and it can depend on the tire and the suspension setup (camber, ride height...) . 275 to 285 is no problem, 275 front 315 rear is good with the right wheels too.
You mentioned preferences on fluid, I'm a big fan of Red Line.
If you are permitted:
I would get a big monster cooler on the OD unit. Along with frequent fluil changes, and don't buy the cheap stuff. I would also wrap or coat the exhaust until after you are past the transmission.
The other thing I've read to keep the OD living a longer life is to treat it as a 5th gear. Don't leave it on. Turn it on only when you need it. On the long straights once you top out 4th, push the clutch in, activate the OD and go. Same thing on the way down in braking zone. Turn the OD off while the clutch is in. (I think the 84 switch is on the console, for racing you may want to relocate the switch onto the shifter)
For cooling make sure the radiator is clean of debris, if allowed I would upgrade to a big aluminum one, making sure the shroud is sealed around the radiator so that all the air is forced over it.
There are guys running 11" wide wheels and 315s all around, it's a tight fit and it can depend on the tire and the suspension setup (camber, ride height...) . 275 to 285 is no problem, 275 front 315 rear is good with the right wheels too.
You mentioned preferences on fluid, I'm a big fan of Red Line.
05-24-2017, 10:04 PM
#8
You are looking at endurance, so, you really need to manage heat and abuse. I'm not sure what the WRL regs allow you to do in whatever class you will be in, that's a good place to start.
If you are permitted:
I would get a big monster cooler on the OD unit. Along with frequent fluil changes, and don't buy the cheap stuff. I would also wrap or coat the exhaust until after you are past the transmission.
The other thing I've read to keep the OD living a longer life is to treat it as a 5th gear. Don't leave it on. Turn it on only when you need it. On the long straights once you top out 4th, push the clutch in, activate the OD and go. Same thing on the way down in braking zone. Turn the OD off while the clutch is in. (I think the 84 switch is on the console, for racing you may want to relocate the switch onto the shifter)
For cooling make sure the radiator is clean of debris, if allowed I would upgrade to a big aluminum one, making sure the shroud is sealed around the radiator so that all the air is forced over it.
There are guys running 11" wide wheels and 315s all around, it's a tight fit and it can depend on the tire and the suspension setup (camber, ride height...) . 275 to 285 is no problem, 275 front 315 rear is good with the right wheels too.
You mentioned preferences on fluid, I'm a big fan of Red Line.
If you are permitted:
I would get a big monster cooler on the OD unit. Along with frequent fluil changes, and don't buy the cheap stuff. I would also wrap or coat the exhaust until after you are past the transmission.
The other thing I've read to keep the OD living a longer life is to treat it as a 5th gear. Don't leave it on. Turn it on only when you need it. On the long straights once you top out 4th, push the clutch in, activate the OD and go. Same thing on the way down in braking zone. Turn the OD off while the clutch is in. (I think the 84 switch is on the console, for racing you may want to relocate the switch onto the shifter)
For cooling make sure the radiator is clean of debris, if allowed I would upgrade to a big aluminum one, making sure the shroud is sealed around the radiator so that all the air is forced over it.
There are guys running 11" wide wheels and 315s all around, it's a tight fit and it can depend on the tire and the suspension setup (camber, ride height...) . 275 to 285 is no problem, 275 front 315 rear is good with the right wheels too.
You mentioned preferences on fluid, I'm a big fan of Red Line.
Biggest radiator I can fit into the car with a large scoop built into the nose of the car. I always seal the nose on the car up, that always makes a huge difference in cooling.
Treat the overdrive as a 5th gear, I'm going to wire it up to its own switch, basically hotwire it. The ONLY track we will need that much gear is Road America. Which will NOT be the first track I take it to when I'm done building it.
We are allowed coolers in the WRL so I will look into getting something for the overdrive, maybe the diff as well.