I'm starting to think I need to get my head check out...
This morning I bought myself a ratty '85 Corvette... sans engine & transmission, for cheap. It's to be my one real project car. It's a big, red, over-sized paper-weight and yet I'm happy with my purchase.
I must be nuts.
I kept eying my Fiero parts car, and thinking I could hack and weld it in to the perfect car for me, but that's more work than I have time for and probably beyond my skill level. I'd love a tube-frame Fiero-like car, but it isn't happening. My frequent searches for bare-framed Fiero pictures would regularly bring up the C4 chassis, and looking at it got me thinking. And it kept popping up, so I kept toying with the thought of starting with one as the base for my project. I've been frequently, but not particularly seriously, looking for an affordable C4 for months. I could have bought several drivable, but rough ones in the 2-3k range, but it wasn't worth that much to me just to end up pulling out the gas-guzzling boat anchor in the front after enjoying a few fun drives. And the guys parting them out never had titles nor would they part with a mostly whole one for a decent price. I found this one last week and probably drove the PO nuts with all my emails/questions, but in the end I wound up with it, at even less than he was asking (which was perfectly reasonable).
Now I can get rid of all the poor-man's substitute cars(with exception of the Fiero) I've collected and put my work into something worth the effort; The C4 comes out of the box with most everything I'd want in or to add to a car, without the hassle and expense. Big tires, big brakes, low-slung 2 seater on a strong yet minimal frame with a plastic/fiberglass (and therefore easily modifiable) body. The FMR layout is a close second to RMR in my book, and makes for a sexy look. Admittedly, if I was going to buy a corvette to drive as-is, I would have gone for a C5 and gotten both a look I prefer and decent highway mileage (and, of course, more power), but I'd rather have a cheap project that I'm not afraid to screw up rather than have a fancy car that needs nothing changed about it. I'm messed up like that.
My plans for it will make me look even crazier, so I'll keep those to myself for now. I'll update this thread with photos of progress once in a blue moon (as I expect it will take me forever to accomplish anything appreciable), and in the meantime I'll bother anyone reading this with technical questions: info I haven't managed to find for myself on the internet. The more I've learned about these cars, the more I like about them. It's too bad they didn't put all-aluminum, higher-revving engines in them until the next generation. They had just about everything else done right when they came out with the C4.
First curiosity is about differentials. This was an automatic, so it should have the "Dana 36", 2.73:1 ratio, if I'm not mistaken. I've seen ring and pinion kits for the Dana 44, not sure what there is out there for the 36.
What's the diameter of the ring gear on the 36, and are there any affordable options for increasing the ratio? Did the Dana 36 get used in any other applications that I could use parts from? I'd probably want a 4.11 ratio. And do they make them any higher than that?
Just trying to figure out which way to go. Looking for ideas on a manual transmission. doesn't have to be corvette specific. IN fact, I'd be looking for something common and affordable. With the 2.73:1 rear end, I was thinking a first gear with at least 4:1 ratio, if not higher. Otherwise choosing one would be easy. Needs to be able to handle, say, 250hp/250ft-lbs. High revving, not a lot of torque. Bell-housing doesn't matter, it'll need an adapter anyway. Something reliable.
I was thinking from a small truck, to get the higher ratio first gear, but it can't have the long handled, long shifter they tend to have. Thoughts?
Rather not fork out a few hundred bucks to change the rear end ratio if I could make up for the difference in the trans.
Have fun with the C4! I bought an 87 'Vette a couple of years ago (complete, running car), and it is a blast to drive, if a bit harsh over any bumps. Between it, my 88 Fiero GT, and my 88 Porsche 928S4, I always have fun driving!
------------------ Rod Schneider, Ball Ground, Ga. "You can't have too many toys!" 1988 Fiero GT 1988 Porsche 928S4 1987 Corvette 2001 Chrysler 300M Van's RV-6 airplane
Have fun with the C4! I bought an 87 'Vette a couple of years ago (complete, running car), and it is a blast to drive, if a bit harsh over any bumps. Between it, my 88 Fiero GT, and my 88 Porsche 928S4, I always have fun driving!
Harsh at full weight? Great! It's going to be really bad if I manage to drop the weight as low as I'm hoping to. I can change the springs in the front, but doubt there is much I can do with the rear and that composite thingamajig.
Harsh at full weight? Great! It's going to be really bad if I manage to drop the weight as low as I'm hoping to. I can change the springs in the front, but doubt there is much I can do with the rear and that composite thingamajig.
You may be in for a surprise--the front end uses the same type composite leaf spring as the back C4 Corvettes are known for great handling, but not for a smooth ride............
Edit to add: There is a small possibility that a previous owner installed coil over shocks in front, but not likely. Pre 88 models are harder to modify this way. ------------------ Rod Schneider, Ball Ground, Ga. "You can't have too many toys!" 1988 Fiero GT 1988 Porsche 928S4 1987 Corvette 2001 Chrysler 300M Van's RV-6 airplane
[This message has been edited by Rodrv6 (edited 11-26-2014).]
seriously though, I'd be very careful. When you have 3 money pits, you can run out of money quick and STILL have no dependable car (been there, no fun) . Try to get one finished before putting too much into the other 2. Personally, i'd try to do the 'vette first depending on what kind of shape it's in. Good Luck
seriously though, I'd be very careful. When you have 3 money pits, you can run out of money quick and STILL have no dependable car (been there, no fun) . Try to get one finished before putting too much into the other 2. Personally, i'd try to do the 'vette first depending on what kind of shape it's in. Good Luck
They're not finished because I'm not letting them become money pits. Having the Vette has stopped me wanting to go too crazy with the Fiero GT. The one on the left is my parts car. Right now, I'm thinking finish my engine swap on the Fiero and put in the poly bushings and call it done. Before I got the Vette, I kept hesitating, wondering if I should put a different engine in or what. Get her going and enjoy her again. Though I was tossing around the idea of simply doing an auto to manual swap to be done with it even sooner...and I've got my Miata as my daily driver. Haven't touched it for that reason.
Hey, look...something's missing... What could it be? ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Can't quite put my finger on it... ... ... ... ... ... ... ... ... ... (probably because it isn't there) ... ... ... ... ... ... ... ... ... ... Eureka!
The wiper motor is missing! WTF! Sumofabeech ripped me off! I want at least half of my money back! (Would probably cost half of what I paid for the whole car if I went to GM and bought a new one)
The interesting ones are the Z51 (Performance handling package) and G44 (3.07 axle ratio).
My butt hurts just thinking about the high-performance suspension, but the quick-steering that goes with it will be fun. And the 3.07 diff ratio is a bit of a relief...the usual 2.73 sounds...disgusting. I might be able to live with 3.07...it's not the 4.11 I'd like, but it's an improvement. I'd have to swap out the diff to get the Dana 44 and swap out the ring & pinion in it to bump it up to 4.11. That'll cost me...more than the car did! Ha, no thank you.
Still...my aching backside. Time to look in to coil-overs and other such options.
Missing wiper motor--oh no! (Probably had to remove it to get clearance to pull the engine--not much clearance around the firewall!)
Yeah, that's what I thought. I didnt actually notice it missing. I noticed the linkage dangling there. I thought it was broken until I lifted it up and saw it wasn't attached to anything.
8000rpm, 3.4:1 1st gear, 3.07:1 final on 26" diameter tires...59.3mph. 60mph in first gear?! oy. Not sure that's going to work. With enough torque, sure... My poor brain.
Well, I think I've puzzled out a transmission that meets my requirements: The T5.
It's found in many applications, most notably the F-body's and the Mustang. It's pretty common, only weighs 70lbs or so, and the post '88 versions found on V6s and V8s is rated for 300ft-lbs. I'd want a tall first gear, so one that came on an '89-up F-body 2.8L or 3.1L V6 would be best, or a close second would be from a 3.4L or 3.8L F-Body V6. I could use one from a 4-cylinder mustang, but it'd probably only be good for 240ft-lbs, unless they changed that after 88 too. Still some research to do on it. There's also plenty of after-market support for them.
Well, now I have an idea of what to keep an eye out for. If anyone has one they'd be willing to part with, let me know!
For those who don't know much about them (I didn't know squat about them a couple of months back), here's the C4 "uniframe":
Which translates in to this: And a high-res one: Click to show
As you can see, not a lot of spare metal. Ok, practically none. Exactly what I like about it. Chassis only weighs 300lbs, from what I read. I'd have thought they would have made the floor pan and the firewall too(for strength and heat resistance), but apparently not. Maybe so you never have to worry about rusted out floor pans? Not likely to happen on a galvanized chassis anyway, IMO. I can't see thick fiberglass weighing less than thin steel, either, but what do I know? Maybe it's more rigid for the same weight...
The rear frame section/bumper beam (just past the rear wheels that's not attached on the second photo but is clearly evident in the first) is made of aluminum and bolts to the uniframe. Well, kind of hard to weld aluminum to steel, but it probably makes for an easier time replacing it when you get rear-ended. Assuming the gas tank(that sits on top of that aluminum frame) doesn't rupture and burn you to death. Ok, I don't know if that actually happens, but that was my first thought when I saw the gas tank mounted just above the rear bumper. Might make people think twice about following too close...
There's a fair bit aluminum elsewhere. On the drive-train, anyway. Aluminum half-shafts, aluminum diff housing, & aluminum drive-shaft.
The drive shaft was included with, but removed off of, my C4. I took all the loose parts out, to prevent theft. I had a laugh when I picked up the drive shaft -- the shaft weighed nothing. The slip yolk on the end of it seemed to weighed as much or more than the shaft itself. I could see the u-joints on the half shafts weighing as much as the shaft itself.
And the suspension uses a single leaf spring for the front and one for the rear, made of fiberglass. That's pretty nifty. Saves weight, won't sag, and (on the front of the C4, at least) also works like/as an anti-roll bar. Main point here is the weight saving, though.
All that effort to save weight, and the dang things still weigh in at a porky 3240lbs. Granted, the engine and transmission account for a third of that, but there's an awful lot of...excess...(and unnecessary)...material on these cars, in my opinion. Maybe it comes from building them to have a higher level of luxury than I think is necessary in sports car. Maybe. More likely it was done in typical GM fashion...put all this effort in to making something great, then stop putting any more effort in and just go with whatever's cheapest. Like an boat anchor of an engine that's been around, in one form or another, for 30 years by the time it made it's way in to this, their "flag-ship" model. Just like they did with the Fiero...
(Yeah, I'm not a fan of gas-guzzling, stupidly heavy V8s. Hence why I wasn't interested in Corvettes before this. Rather glad this one didn't come with an engine! Sure' it would be fun on the weekends to have nut-busting torque, but it's not worth the disadvantages in a daily driver, to me. Whatever, to each their own)
Have you seen the most recent episode of Roadkill on YouTube? Basically took a cheap 350 and shoved it in the front of a totally stripped down C4 and caged the rest of it up Mad Max style. Pretty bitchin'
I still remember reading the magazine reviews of the C4 with Z51.
Something to the effect of transforming the car from "harsh" to "bone jarring". They really only recommended it for track cars.
I'm not sure what all the differences are. You might get lucky and it will just be the shock valving.
From Web-Cars.com on the '84 Corvette:
quote
One common technique for improving handling is to specify very stiff springs and/or shock absorbers. This was done on the standard Corvette and the optional Performance Handling Package (RPO Z51; $600.20) was equipped with even stiffer springs and German made Bilstein shock absorbers. As is often the case, there can be too much of a good thing and the 1984 Corvette is an excellent example. The Corvette had outstanding handling but a steep price was paid in the form of reduced ride quality. Terms such as "teeth rattling" "bone jarring" and "brain scrambling" were often used by passengers and drivers alike, many of which were not used to performance suspensions.
It also includes the faster ratio steering, from what I read earlier. Hence handling package, I guess.
What I want to know is if you could make the fiberglass leaf springs thinner, thereby lowering their spring rate, or if that would just kill their structural integrity. They're like 4" wide...if you took a router to 'em and shaved them down to 3.5"...?
[This message has been edited by Stubby79 (edited 12-04-2014).]
Roadkill is seriously my favourite show nowadays. Quality over quantity. ]
mine too! I was a huge fan of "Big Muscle" on the /Drive Youtube channel but they've gone commercial. Now the videos are <5 minutes long and they tell you at the end "Go to our website for the full video" - But they're website is now a subscription site. lame...
[This message has been edited by OKflyboy (edited 12-04-2014).]
Originally posted by skuzzbomer: Roadkill is seriously my favourite show nowadays. Quality over quantity.
Anyways, this is the video that shows where the car started and what they did to gut it initially...
Ha, well...I'd read the blog or whatever it was about that. I didn't equate hot rod magazine with Roadkill as the video you originally mentioned was my introduction to them. Now I'm going to sit down and enjoy watching this...
Random observations from things learned from these videos and elsewhere...
The doors are interesting. They're all fiberglass, with the exception of the impact beam and the mounting plate for the window regulator. Fiero doors are noted for being heavy. I'd wondered if having the shell made out of fiberglass instead of steel (as the corvette's doors are) would save weight. Well, apparently not. Certainly not worth the effort for the difference. A fully loaded corvette door weighs ~83lbs, about the same as a Fiero's. Not notably lighter than an all steel door would be. Conclusion: Carbon fiber or aluminum would probably be the only way to do it, unless you simply had much thinner fiberglass.
(BTW, I'm convinced/obsessed that any part of a car that doesn't add structural strength or safety should be made as light as reasonably possible)
It seems the lightest reasonably possible for a car to be - with full size wheels/tires/brakes, no flimsy suspension/hubs/etc - is around the metric ton mark. Any less, and you'd have to compromise safety, strength, or handling...or use exotic/expensive materials. Look at a Miata for a good example. And a geo metro for example of what you have to sacrifice to get under that kind of weight.
The ~2100lbs of the chopped up 'vette could be dropped maybe another 400lbs with a smaller, lighter engine and trans, but you'd put that 400lbs right back on by making it a streetable daily drive. (Body panels and glass and minor conveniences like seats).
It's too bad Chevy didn't engineer "lightness" in to the Corvette. I could see these thigns being 500lbs light from the factory, if they had tried hard enough. They went for comfort and bells & whistles instead.
What's up with that long nose on these things?! Must be from trying ti make them look like previous generations, and to get that wedge-shape to come down as far as they could. There's really nothing in the space past the front tires. Maybe it's so you have a larger crumple zone in case you hit a brick wall at 150mph, so you don't end up pushing the engine in to the passenger cabin. Who knows, it just looks silly to me.
The 20 gallons of gas the tank can carry weigh about 125lbs. Putting it as far back as possible is one way to get your 50/50 weight balance, I suppose...
Early C4s have a different wheel offset to later ones. Peculiar, if you ask me. Means I might be able to use BMW wheels. The jury is still out on that one, though.
The C4 has that nice curved windshield that is one particular dislike I have about the Fiero. It's the one thing thats difficult to change about the Fiero that dates it.
The early C4s have a belt line, something that died off on all cars in the 90s and mostly still persists today. Interestingly enough, I saw a brand new Honda Fit the other day, with a belt line on it. At least from the front wheel well to the rear. I'm rather fond of them, as long as they don't have an antiquated look to them.
Haven't done anything to it yet. Got myself set up to start dismantling the next of my "donor" cars(Aka projects I lost interest in) last night. Hope to get on with that over the next days as the weather has warmed up.
you got what im looking for right now, if i find a c4 minus motor with a stick shift id be happy, i have a pretty stout 327 that needs something that handles better than the montecarlo its in now
Too bad I don't have a built Chevy v8 laying around, it would make this a lot simpler.
On another note, it looks like my backside won't be hurting as bad as I thought. I found a chart showing the spring rates by year:
Assuming this chart is accurate (it's not like I have anything else to go by!), the '85s had some of the softest suspensions of any year, including the Z51. I'm guessing the '84 Z51s were the ones that gave the C4s the "harsh ride" label, considering they're about 2/3rds firmer than the ones that should be on my '85. I can always keep an eye out for softer ones, now that I know what years to look on.
I like a firm ride, just not a teeth chattering one. I had a car like that for a while...kept clenching my jaw whenever driving it, and took me a while to figure out why my jaw hurt and I had a headache all the time. That's a little too firm.
This chart even shows the wheel rate, which is great. I hadn't even thought about how the distance from the end of the spring to the wheel would affect the spring rate felt. ~150 lbs/inch at the front wheels, if the converter I used is correct. That sounds very...squishy. But if that's what it is, that's what it is, in spite of the spring itself being rated at ~360 lbs/inch...which sounds pretty dang firm.
Well, whatever...I won't know until it's almost finished how well it's going to sit while weighing hundreds of pounds less. Still interesting, if it proves to be accurate.
These suddenly cheap gas prices are annoying. I thought I had my engine plans done for this thing, but with cheap gas prices, I could shove something big and powerful in there and be able to afford to enjoy it...I just wish I knew when prices would go back up.
Probably right after I finished putting this thing together with a big engine, that's when.
Hmm, I might be tempted to put a V8 in it, if I could get my hands on one from a Land Rover. About the same weight as the V6 in our Fieros. Not a lot of HP (still more than the original engine in these early C4s though), but plenty of torque. I'm probably dreaming though.
As you are looking at transmissions, be aware that the C4 Vettes do not have a rear transmission crossmember to support the end of the transmission. They have a long aluminum C channel that connects the transmission tail housing to the differential housing... most non-C4 transmissions do not have the needed attachment point for this C-channel. There are some aftermarket brackets to adapt other transmissions, but its something to get figured out before dropping $$$ on a transmission that won't work.
I had an 86 Vette for about 6 years (21st birthday present to myself). I ended up putting a TPIS Minirammed 406 in it... It was a very fun car at the time!
Hmm, I might be tempted to put a V8 in it, if I could get my hands on one from a Land Rover. About the same weight as the V6 in our Fieros. Not a lot of HP (still more than the original engine in these early C4s though), but plenty of torque. I'm probably dreaming though.
The older '90s LR V8, the BMW V8, or the Jaguar V8?
Hmm, I might be tempted to put a V8 in it, if I could get my hands on one from a Land Rover. About the same weight as the V6 in our Fieros. Not a lot of HP (still more than the original engine in these early C4s though), but plenty of torque. I'm probably dreaming though.
Look at the Volvo V8. It is 4.4 liters and weighs in at about 419 pounds. Ford designed it and Yamaha built it. It uses an Aisin transmission ( the brand Toyota uses) so might be able to match the bolt pattern to possibly a 6 speed Lexus/Toyota transmission. Noble uses this engine in their M600 and they get over 600 hp out of it.
Assuming this chart is accurate (it's not like I have anything else to go by!), the '85s had some of the softest suspensions of any year, including the Z51. I'm guessing the '84 Z51s were the ones that gave the C4s the "harsh ride" label, considering they're about 2/3rds firmer than the ones that should be on my '85. I can always keep an eye out for softer ones, now that I know what years to look on.
I'm pretty sure the article that I read, that mentioned the harsh ride, was about the '84.
Looks like they re-thought the '85 by softening up on the springs and using huge sway bars, instead, to keep the car flat on the ground. Remember that this was an entirely new design for '84. Very radical, compared to what everyone was used to. I would suspect that they got better with the later years, and GM's constant tinkering. (This was their flagship, after all.) As long as they didn't make any major redesigns, the newer parts should be bolt-ons.
Look at the Volvo V8. It is 4.4 liters and weighs in at about 419 pounds. Ford designed it and Yamaha built it. It uses an Aisin transmission ( the brand Toyota uses) so might be able to match the bolt pattern to possibly a 6 speed Lexus/Toyota transmission. Noble uses this engine in their M600 and they get over 600 hp out of it.
Shelby
Is that the same Yamaha built V8 they stuffed in to the Taurus SHO or whatever it was?
Is that the same Yamaha built V8 they stuffed in to the Taurus SHO or whatever it was?
The engine from the original SHO was a V6 Ford designed and Yamaha built unit as well. The Third Gen Taurus did have a small V8 built by Yamaha with Cosworth heads.This of the same family of designs but two more cylinders. Than one and more displacement than the other. I am thinking about one for the Fiero as it is a 60* V8 and originally a FWD.
Shelby
[This message has been edited by ARFiero (edited 01-06-2015).]
It's going to be really bad if I manage to drop the weight as low as I'm hoping to. I can change the springs in the front, but doubt there is much I can do with the rear and that composite thingamajig.
. Try to get one finished before putting too much into the other 2. Personally, i'd try to do the 'vette first depending on what kind of shape it's in. Good Luck 
And the 3.07 diff ratio is a bit of a relief...the usual 2.73 sounds...disgusting. I might be able to live with 3.07...it's not the 4.11 I'd like, but it's an improvement. I'd have to swap out the diff to get the Dana 44 and swap out the ring & pinion in it to bump it up to 4.11. That'll cost me...more than the car did! Ha, no thank you. 
