How bad is this idea? Autocross C4 concept...

Long time lurker.  Long time grease monkey.  

Ran into Mini Copper (200x) offered for ~$2g, which seemed reasonable or so.  Thoughts of autocross popped into my head.  In searching for what kind of beater I could get for Solo events, it seems C4s are dirt cheap.  I've seen some at near challenge money.  A couple have needed motor work, some were just higher mileage, likely needing suspension component refresh. Is picking up one of these seeming bargains a horrible idea?  I know the answer is always Miata but that secret seems to be out and prices reflect it.  

SBC parts are dirt cheap, C4 parts don't seem outrageous or unobtainable, am I missing something?

PS: Just because it is a bad idea doesn't mean I won't. 

In reply to GeddesB :

Having built & owned a Challenge C4, just don’t. 

That said, you’re here, so you’ll most likely avoid any sense of sanity or reasoning. In that case:

1. Buy the newest car you can. Absolutely avoid an 84 if you have any intentions short of gutting it completely and/or building a Vettekart. They got slightly better in 87, and actually started becoming decent cars into the 90’s.
2. You know how bad 20-year old GM interiors can get? Add another decade to that, and realize that GM also crammed all the “latest” tech into the Vette, which doesn’t age well either. 
3. The chassis is rather floppy, & the suspension geometry isn’t great. They were gradually improved on the later cars, but still pale compared to the C5.
4. I’ve heard the 4+3 manual doesn’t shift great, to the point I’ve seen multiple recommendations to just get an automatic, but I’ve never driven one. The later 6-speed is reportedly pretty good. 
5. It’s an SBC. So while parts are cheap, making anything close to modern HP numbers from one really isn’t economical, and LS swaps cost enough to make an early C5 a much better option. 
6. They can fit a lot of rubber, but that can get expensive. 

And don’t get me started on my experiences with other Vette owners...

I am currently running a 91 Corvette L98/6 speed in a vintage class with a B-street PAX and have done fairly well.  My very capable co-driver has 'out-paxed' C5 Z06 vettes on occassion.  I have been told by a few people they didn't know a C4 Vette could be that fast.  My previous autox car was a fairly well setup STS NA Miata.  I do not regret going from the Miata to the Corvette, but there are some things that have changed.  With the Miata I never bothered to take a toolbox with me to the track, with the Corvette I have found it necessary to have tools on hand.  The C4 feels a bit fragile, at least in comparison to the Miata.  I have had many more minor mechanical issues with the Corvette, and working on the Corvette is much more difficult than working on the Miata.  You have to learn the Corvette way to do anything on the car and most jobs take much longer than you would expect.  If you have questions regarding a suspension setup on a Miata, there are many great sources that can spell out every detail on what parts you need and how to adjust them.  With the C4 Corvette there is a lot less information on setting up the suspension, or what are the best part combinations.  Consumables on the Corvette are going to cost more than the Miata.  On paper the Miata is going to win out on the comparison with the C4, but there is a feeling you get when you mash the throttle on the Vette that just isn't there in the Miata.

In reply to GeddesB :

I owned a 1986 C4 the 4+3 manual transmission does not like fast shifting and if done frequently you'll be replacing syncros. The stock clutch is good for maybe 50,000 miles.  When replacing the clutch you will have to have the surface of the flywheel refaced.
Dealerships just replace the flywheel  so if you are considering DIY it's actually  the same cost to have it surfaced as replaced. 
Buy the Z51 packaged one. The sway bars just work and the shocks will easily go over 100,000 miles. Unlike the stock suspension which if you're lucky the shocks are done at about 30,000 miles and the swaybars are too small. 

Plus the wheels are bigger. 
The dash is going to fail.  I was lucky and got 100,000 on mine.  
I know what you mean about the power!  While I felt like a stock car driver instead of a sports car driver,  it was a good feeling. 

1988 got a brake and suspension upgrade, Z51/52 card even more so. I had a 4+3 car and it shifted great for me. I did put a short shift kit in though. The O/D unit can have issues and are expensive to rebuild, but a failed unit just means you don't have overdrive, the car will still go. Manual trans cars got better gearing a a stronger diff too.

The C4s are a lot of performance for not very much money but the also have all of the quality, assembly, questionable engineering choices and parts bin design issues that defined GM in the 80s.  If they weren't so cheap I'd suggest a hard pass.

I don't know any of the technical details on it, but there's a later year C4 that runs in CAM at the local events here. I've ridden in it before and it seemed very well sorted, and was a blast.

It's definitely not a challenge priced C4 though. However, with C5 prices continuing to fall. I'd be hesitant of putting to much into a C4 when you start with a much better platform (C5).

Although I haven’t finished my sort-of C4 project, I think that you can have LOTS of fun with one very inexpensively. Near “answer” money and weight with 2x’s, 3x’s, even 4x’s the power. 

https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/i-know-another-copycat-corvette-kart-build/141870/page1/

Pete Gossett said:

In reply to GeddesB 

That said, you’re here, so you’ll most likely avoid any sense of sanity or reasoning. In that case:

Should be the subtitle of this forum....

88 Z51 previous owner here. Sold it to a forum member when I got tired of it. the 88-96 had the better brakes and steering geometry. 88 was also the last year of the 4+3. An interesting trans, basically a T-10 4-spd with an autmatic OD unit bolted on. Not bad, not good, it just was. 

It handles great IF you are smooth. C4's dont like ham fisted drivers like myself. Brakes were strong, complete suspension rebuild will be in the cards for a cheap car. The clamshell LOOKS like it should be easy to work on and have room. It's a lie. You must be limber to get into and out of one in a parking lot. 

The L98 is a torque beast. Seriously, the auto is fine with this engine. It makes ridiculous torque off idle and is done before 5k so who cares. 

If you're smart your won't buy one. But if you do have fun. They can be fun but also frustraiting as hell.

Mostly stock 1993 Vette runs in our region.  The owner (Shawn) has been competing for a while and is incredibly fast - consistently 10 seconds faster than us over a minute long course.

A guy in my region runs a C4 in CAM.  His is a '90, so its a bit of an odd bird, being the post-facelift body and the 6-speed manual, but with a 350TPI. His has headers, an exhaust and a bigger throttle body, and he estimates it makes ~250whp tops. Stock chassis but he was talking about ditching the mono-spring for coilovers. But he has big Falken 200tws under the stock fenders and the stock brakes are terrific. He won our condensed Street Touring/CAM class this year, and out on Pineview Run, me and him typically turned similar lap times and beat up on newer pricier equipment. In discussions, we agree that ~400hp (either an LS engine or a hotter SBC) and RE71Rs will really make it something. That being said, it does have its share of gremlins. The T-Tops leak like a bastard, it broke the tilt steering column at one event and jammed the steering wheel near vertical while at speed (the aluminum ears fatigued and snapped) and had an ignition module die and end an event. He has taken to trailering it

I think they're the nicest looking "modern" Vette ... but that's all I can contribute. Never driven one.

Never driven one either, but th elong and short that I've gotten from people is pretty much that it's objectively kind of a crappy car, but tons of fun...like most GM v8 products before 2010. 

APEowner said:

The C4s are a lot of performance for not very much money but the also have all of the quality, assembly, questionable engineering choices and parts bin design issues that defined GM in the 80s.  If they weren't so cheap I'd suggest a hard pass.

Doesn't that depend on who is going to do it?  I know guys who are wheel to wheel racing them on  a budget teenagers would complain about. They throw Stock car 15 inch tires on them and get at lest a full season if not more out of the tires.  
They get rid of all the stock interior parts including the dash and go to a few mechanical gauges. The fuel rejection is replaced by a carb 

My only experience was instructing a guy at an HPDE who was the original owner of a nice 1986 Vette.   In the interest of brevity and trying not to be snarky, my impression of the C4 platform was...not good.

TBF,  MINIs are objectively kinda crappy cars as well -- (I can be snarkier there because I owned one.) 

Neither are the easy button or renowned for high quality, so buy them only if you like them.  I think the low end of a C4 or MINI is going to put you at 'nice Miata' money, once you get them sorted. 

V8 RWD GM would have me looking a Camaros to avoid the Vette tax.

A well-driven C4 w Z51 or Z07 will absolutely keep up in autocross with any stock C5 except Z06. If engine mods are on the menu, it’s way easier to add power to the LS in the C5.  The easiest C4s to live with are the 91-96, and the most comfortable is a 94-96 with base seats. I don’t get the strong negative opinions on C4s but to each his own.  

C4 corvettes have been some of the best and most successful autocross cars out there. Also remember that the corvettes were booted out of the world challenge series in the 80s cause they were so successful hence why the scca created the corvette challenge series.

Nothing cures the desire to own a C4 Vette like owning a C4 Vette.  I had a ZR-1.

It was a 175 mph weapon of mass speed and acceleration....  it was not a fun car to drive more than 15 minutes.    

GeddesB said:

Long time lurker.  Long time grease monkey.  

Ran into Mini Copper (200x) offered for ~$2g, which seemed reasonable or so.  Thoughts of autocross popped into my head.  In searching for what kind of beater I could get for Solo events, it seems C4s are dirt cheap.  I've seen some at near challenge money.  A couple have needed motor work, some were just higher mileage, likely needing suspension component refresh. Is picking up one of these seeming bargains a horrible idea?  I know the answer is always Miata but that secret seems to be out and prices reflect it.  

SBC parts are dirt cheap, C4 parts don't seem outrageous or unobtainable, am I missing something?

PS: Just because it is a bad idea doesn't mean I won't. 

 

 

I'd rather have the cheapest C4 than a Mini.  Minis have this amazing ability to fail in new and amazingly expensive ways, and they drive so nice that they sucker you into continually throwing money at it, like the arcade game that wants another quarter and before you realize it you've dumped a whole roll down the chute.