no_radio

This may be the next update for my '74 (already has VBP Touring Suspension with 16X8 Vintage 45s and 245-50-16 KDW tires)
I'll let ya know if I do it!
Jeff

Chuck Harmon

Man, if we can get this up by another $10, we can get a pizza. I think we are getting somewhere! Call Dep :lol:

Chuck

VegasJen

not that i'm looking for a point deduction ;) there's alot of things ddecart said i agree with and a few i don't.
first, ddecart is dead on about the wet noodle frame of the car. where i disagree is this is the first thing that should be addressed. stiffening up suspension parts to make up for chassis flex just masks the problems from a handling standpoint but exaserbates other aspects like ride quality, nevermind the abuse the car takes resulting in all those creeks and crap that we love so much. as a result, a stiffer chassis will result in comparable handling capabilities with a much more compliant ride.
as i stated before and has already been echoed another half dozen times: tires, tires and tires! 'nuff said.
the differences between the c-3 and c-4 chassis are really minimal. the c-4 is simply an evolution of the c-2/c-3 chassis. as to what is different between the two, as ddecart stated, in the rear the c-4 uses two pick-up points instead of one trailing arm. the only other substantial differnence is the addition of a rear toe link. the late c-3 had a very similar 3rd member to the c-4 with the single biggest exception being the c-4s use of a torque arm. the c-4 still uses the half shafts as upper arms in the suspension (undesirable). the front suspension differences are even less discernable. aside from the pick up points the only difference is the transverse spring.
as for brakes, i'd agree that bigger is better but i take issue that the c-3 system 'sucks' in any way. if you look at a modern race inspired system, it looks just like a c-3 system, except the calipers are aluminum. and everything is bigger. i believe the single biggest mod you can make to the system is an adjustable proportioning valve. you don't believe these brakes are worth a crap, come ride with me ;)
i can't speak to the differences of R&P as opposed to recirc-ball but the theory that transmitting energy through more devices absorbs energy, i.e. numb feeling and response. the R&P is a much simpler design which more directly links the steering wheel to the road and the feed back to the driver.
as for overall handling, i feel much more comfortable driving fast in my c-3 than any of the other cars i've had including an '85 camaro HO, '92 camaro RS and '81 T/A (RTS). taking advantage of some of the improvements that are specifically designed for the corvette and general automotive advancements there is no reason why the c-3 can't more than hold it's own against 90% of what else is out there :yesnod: :cheers:

mrvette

Clutch, that's just it, everyone condemns our T-arm suspension, and I can see getting rid of the 'squat' it induces, but the rest of the system is comparable to anything else out there, afterall, what's the differance NOW the camber and toe is set, held, as long as it's set/held???

being shims or a screw adjustment on toe....same thing....
changing t-arm for the 4 link.....welll OK, but no big deal....
what does adding two extra links above the axel and using them for camber location, buy you??? as long as camber acts the way you want in the system, what does link location have to do with it..??? our system is easily changeable with the VBP system?? NO???

mechanically speaking I fail to see any advantage of say the C5 system, except maybe having coils....

GENE

ddecart

What did I say that you disagreed with? I didn't catch anything from your response.

Thanks for the "toe link" on the C4, I knew I was missing something. By going to a pair of trailing links, it was possible to add a toe link to better control toe during suspension movements. Was that a major change? No, not really. An incremental improvement is what I'd call it.

You didn't interpret anything I said as meaning the brakes suck, did you? I'm thoroughly impressed with teh C3 brakes. I have manual brakes on my car and you'd never know by how well they work. A bigger swept area would be the biggest bonus to going with a larger diameter rotor.

Gene: The toe link on the C4 affects not just HOW the toe is set, but it also affects the kinematics of the suspension and what happens to toe during suspension movements. I tried to find some old C3 suspension test data, but came up dry. All the rear suspension info I could find was for C3's with C4 rear suspensions in them.

VegasJen

GENE, i'd agree, especially in the case of the c-5. trying to adapt a c-5 suspension to a c-3 would surely not be worth whatever gains are recieved, if any. the c-5 suspension was designed for the c-5 and it's super ridged frame. i like it better than our design but without reinventing the wheel we have to figure out what will work best for our cars. i still believe that if it were possible to get the c-3 frame as ridged as the c-5, our cars capabilities would be comparable overall. without that, it is possible to have either/or with the c-3. it can either handle really well, requiring much modifications at the expense of comfort, or it can drive nice and soft (for a touring car) but yeild some of the handling capabilities.
i know i get alot of disrespect (at first) when i show up to a track day in my c-3. i do see quite a few surprised looks in c-5 rear view mirrors going through the turns though! :D

Ganey

If one wants to compare handling of C3 to other cars, then one needs a standard for comparison. A good standard of handling is the Road & Track slalom course.

77 set a new record in 77 with 63.6 mph. "hampered by stock air pressures"
Surprisingly, R & T did not try or publish performance with increased air pressure. They were aware stock air pressures were meant to keep the less astute out of the weeds.
For reference, Mario Andretti turned 63.4 in a 1999 Corvette.

The 77 was later matched by a Ferrari 512BB. 84 C4 did better, but not all C4 did better, the main improvement being the larger wheels & better tires.
The 77 had FE-7. A large part is the driver. Even if they hang w/ you in the corners leave 'em in the straights !

:cool:

PS Remember the laws of physics have not changed.
Most of the above is on my website under 77 Facts.

71roadster

I'll jump into this...looks fun.

I to have driven a number of modern european cars (2001 bmw 3 series, 1998 volvo s series, 1998 jag) and have competed against C5's at autocross. Those cars I drove had nice rides (even at 100mph+) but were not at all close to my C3 competitive wise, even in 'sport mode'. And I am close to catching some of the fastest C5's at the autocross course - I just need the slicks that they are running and I'll be within a second of the fastest cars, at least I think I will based on my current times.

That said, I agree that the frame is the weak link in all of our cars, especially the 76 and later as they had even thinner frame material to save weight. I am running the front brace bar and I still get considerable flex up front. The front suspension could use some lower mounting points for the upper a-arms or some taller spindles but until that happens all you can do is get a good alignment and run good shocks, swaybar, and springs.

The rear suspension is far superior on a road coarse to even a modern solid axle car. Using the half shaft as an active component in the suspension is not that bad and is not the source of woes for our cars. It is the toe steer that is inherent to the geometry of the design. There is NOTHING that can be done about it, even the bext 4/5/6 link suspensions have toe steer. Only parallel A-arms (or solid axle) in the rear can eliminate that. And you will only find that on full out road race cars, at the expense of the battery and storage compartments.

Granted I have made a lot of mods to my suspension curtesy of Vette Brakes and Products, but my car handles GREAT! and I mean GREAT! I have pretty much a GT grade suspension and added good, not great, 17 inch tires and the ride is good even on long trips (the 880 is just too rough with all of the construction - hitting those lane-wide cuts in the road square on can rattle the teeth). I would say the worst part about it now is the steering box and power steering, and I am trying to work out some mods to address that. I will post whatever it is I end up with. But all in all, my car handles flat, predictable, controllable, and much faster and more fun than any of the other cars I have driven or owned. It is not as soft however, but I can live with that.

Get some good 17 inch tires and have a blast.

Chris

battsup

ya but we are talking corvettes, there made to scare the crap out of you, whats the point in going fast if you dont get scared.

ddecart

Chris,
I'm not sure I follow you with the toe-steer thing in the back. Can you explain why you view it as such a problem?

Stoge

I took a 140 mile trip today, and about 10 miles were nothing but the twisties. The shark handles pretty dang well if you ask me. I wonder how it compares to say, a Z28, Mustang GT, etc...

71roadster

The toe steer comes from the pivot points of the rear suspension. The front of the trailing arm is one and the inside U joint is the other. The whole wheel/hub assembly effectively rotates around this axis which is about 45 degrees from paralled with the centerline of the car. In a corner, as the outside tire swings up and rotates about this axis, it starts to toe out in the front resulting in built in oversteer. As the inside tire starts to swing down, it also toes out but since all the weight is on the outside tire the cancellation is negligible. If the pivot point of the trailing arm could be moved inboard, the effect would be minimized, but even the aftermarket 6 link suspension have pivot points similar to the stock suspension. This built in toe is far and away the most detrimental factor of the suspension arrangement, more so then even the built in camber change.

As I said before, there is really nothing we can do about unfortunately.

Chris

MassVette

Single biggest improvement-----------TIRES!
Get rid of the 15" high, sidewall-rolling antique tires. Then you have a TOTALLY different handling vehicle; BELIEVE ME. I wouldn't trust my '67 over 85 mph with those huge section 15" tires. It wanders and tracks everywhere! The '79 with the Z/rated/45 section 17" tires is rock-steady-all the way up to burying the 140 speedo-- And BOTH cars are built on the SAME chassis!
my 2c.
:yesnod: :chevy :yesnod: :chevy

Ron R

I have both a C3 and a C6. The C3 (not stock) actually produces more HP & torque, but the C6 will beat it every time because it can transfer its power to the ground better.. Tires, wider stance, active handling, suspension, it all adds up. If I put the C3 pedal to the floor, my tires will spin and the car will turn sideways, the C6 just goes... and if it starts to slide a little the traction control kicks in to keep it straight. At high speeds (120+), the C3 feels like it's going to take flight, and the slightest tap of the steering wheel would result in a roll-over, while the C6 is saying "That's it? I was built for more than this, you know..." And lets not even get into braking... ever try to autocross in a C3? Its great for the first few minutes until brake fade kicks in.

Yeah, you can upgrade all of that stuff, but to me when you do you miss out on the essence of what the C3 was and why I like them so much. I don't want to compare a 68 to a 2009. I like that classic handling, the smell if your mix is just a little off, the whole package. For what I spent to turn an 80 into a track car a couple years ago, I could have bought an 05 C6 and it would still kick the 80's *** in autocross with the same guy driving it.

turtlevette

yea, but

the z3 has paint.

Gale Banks 80'

When my 80 was new I took it to a Goodyear Store for a new set of Tires and the guy asked what other car the Tires had been used on cause all 4 were bald at 16K. I didn't tell Him that a Dealers Wife drove it the 1st 11k and I had only put 5k on em! Maybe it was on the cloverleafs where You could have one foot on the Gas and one on the Brake and put the Car from full understeer to full oversteer back and forth. Car and Driver and the rest of the Mags made fun about how bad the late C3's handle'd compared to the rest. Even proved the F-41 Cars were worse than the Stock ones. Only problem was on the race track Vettes still did very well. The C4 Rear suspension is basicly a copy of the Dick Gulstrand C3 setup. Other than ABS I wouldn't take C4 Brakes I'll stay with my 4 Piston C3's. The front Suspension is older than 63 the A-arms are a direct take off from a 58 Impalla. When the C4 came out with 1 G cornering I got on the band wagon and modified my suspension with new hardware of the Day. Today I have the VB&P products front and rear with C4 Wheels and Tires. In Auto Cross I can beat my own C4 GS with my 80' anyday mostly from more power and grip. I have bigger and better Tires on my 80. My 80 rides pretty good to. Where C4 is way ahead is in refinement. It dose everything well bone stock and is easy to drive. I have driven C5's and 6's and they are more of the same more refined the the C4's. The biggest change the Corvette ever had was the C3-C4 Jump. However our old C3's really wake up with Suspension and Tires of today installed on our classics of yesterday.

Jim_Harrison

I very successfully AutoX'd my 72 for many years at the National level. It was set up to SCCA street prepared rules allowing poly bushings, bigger springs, bars, wheels and tires. It could maintain 1.2 G's with Hoosier A-6's on it and was a Hoot to drive. A stock C-5 Z06 on A-6's is faster using the same driver, as I've have had Z06 drivers familiar with my car drive it and I drove their cars. I now own a stock C-5 Z06 and it is much better. The cornering ability of both cars is about the same but it is much easier to drive the C-5 due to much better steering, and the rear suspension. This is a handling string but the LS engine in outstanding.

aaroncorvette

I've got a modded C3 and it doesn't feel as stable as the less modded '71 Camaro we had, the Camaro had de-ached rear springs, Spax shocks, poly bushes, uprated front springs, bigger sway bars + 275/40/17 Kumhos and 245/45/17's on split rims
Man did that Camaro handle! I raced a newish porsche on a few long straights and round a few big roundabouts, the Porsche guy must have been gutted, it would slam you into the door round bends ( not good if you've just eaten), i would have gone up against anything in that car

I put this mainly down to two things, firstly the monocoque body, the car felt so much stiffer, and two, the front steer design of the Camaro.

The main difference being that i could drive the Camaro faster and felt safer in it, it wasn't so affected by bad roads as the 'vette is, it may just be that my 'vette is a little twitchy and the Camaro was previously owned by a racing driver?

A c3 needs a full cage to make it stiff enough IMHO. I still love the 'vette though

jb78L-82

Some great points here!

My 78 L-82 4 speed has a completely stock designed suspension but I have upgraded everything where possible to minimize bushing/chassis flex.

In the front:

1. Poly bushing everywhere including the shocks, upper and lower control arm bushings, and stock 1 1/8 inch sway bar. (Bilsteins Heavy Duty)
2. TIRES-255/45/17 ZR's. Get rid of the crap 255/60/15 S/T rated tires.
3. 550 springs 1 inch lower than stock.
4. VERY IMPORTANT-OEM steering box custom blue printed/rebuilt-zero play now and great steering feel-YOU MUST DO THIS MOD for great handling and steering feel-UNBELIEVEABLE!Better than when new by far!
5. Front Shock tower brace-helps immensely.

Rear:

1. 360 monospring with Poly bushings.
2. TIRES-255/45/17 ZR's
3. Bilstein Sports
4. Competition adjustable Strut Rods with Heim Joints (no busihings to flex). get rid of the strut rod bushings which can alter camber drastically when cornering hard.
5. 3/4 OEM type rear sway bar with poly mounting bushings.

The car is so responsive with no wandering/minimal flex, incredible grip, MUCH better ride, and tremendous handling/steering response. The difference between a stock C3 (any year) and my car is beyond compare. Is it like my 2010 Z06-No. Is it better than just about any 70/80's car-YES!

As I have said before, the C3 brakes are excellent, much better than the C4's which frankly were a step backwards and sucked. GM eventually tried to address the C4 brakes in the later years with bigger discs and dual front calipers since they knew that they had made a mistake versus the C3's (4 piston calipers on 12 inch discs). For the street, the C3's brakes are really terrific, even today!

Jim_Harrison

My car had all the poly bushings, all new steering box, tie rods, etc., 800lb springs in the front and custom Penski shocks. 295/35/17 Hoosiers on all 4's. The only Camaro type Street Prepared car that consistantly ran faster than it was Marc Madarash from Texas, in his exceptional 1988 Firebird. Marc is in that top 5% of Drivers, wish he could have driven my C-3 to get his opinion. I don't beleive there were any C-3 Corvettes at last years Solo Nationals. The car just isn't competitive in any of the classes it can run in. It is just a bit slower than a properly set up BSP C-4 but they both get creamed by the Mitsubishi Evo's. Nothing like actual timed competition at a National Chanpionship to make a determination. That is why I sold my C-3 there was no way within the rule book to make the car competitive. Same reason Danny Popp and Phil Currin both several time National Champions stopped running their C-3's at Nationals.