mobird

Ok so this is more of a general discussion point with some questions scattered in.

I've had my 79 for a couple years and have focused almost exclusively on performance mods for the motor (Brodix heads, intake, Lunati cam), weight savings (removed front and rear impact bumpers, replaced seats with C5 seats, fiberglass rear spring, etc...) and some rear suspension stuff (fiberglass rear spring...again, Bilstein shocks). I also have 18" wheels and tires.

I have noticed that I don't drive the car as often as I want to or could (and my wife practically never drives it) for a couple reasons. The main reason I think is the carburetor and exhaust smell (running side pipes, no catalytic converter, and work in an office where it feels rude to show up smelling of exhaust fumes haha, plus leaving at 6 in the morning I don't want to wake the neighbors). I plan to fix that issue this year as I'm planning up swapping in a 6.0 fuel injected LS motor.

The other reason though is the way the car rides and handles. There is ALOT of wind noise and rattles, it tends to "bump-steer" a bit, and it bounces over every imperfection in the road.

I have new front springs and shocks in the garage waiting for me to find time to install them. I also am about to order all new bushings for the car since mine are so rotted out, and I have a full weatherstripping kit waiting for me to install as well. So what I am wondering from you experienced forum members who have "modernized" your C3 chassis (springs, shocks, bushings, etc...), do upgrading these components make a significant difference to the way the C3 drives and make it more "liveable" as a driver? Was there anything in particular you did that REALLY improved the driveability on a daily basis (strut brace? Steering upgrade? Brakes?)?

I realize that this is a 40 year old car, and if this is how a 40 year old car handles no matter what basic upgrades are done to it, I'm willing to accept that. But if I can improve it to a more liveable level fairly easily, I'd like to do that so that I will enjoy the car more often and my wife will want to drive it occassionally as well.

Thanks for the input, and sorry for the book!

jb78L-82

From another post on suspension and Wheels that I posted a while back:

I have a 78 L-82 4 speed car with the gymkhana sport suspension (67,000 miles) that I have owned for 34 years and I have tinkered with the suspension one part at a time over all those years to achieve the perfect balance of superb handling, steering response and a firm but not harsh ride. Not knowing if you have a base suspension (most likely since most did not have the sport suspension from the factory) or the sport suspension, below is what you need for truly sportscar handling with a great ride for your 78:

Front:

550 lbs front coil springs/1 inch lower than stock-$100
1 1/8 inch solid front sway bar (OEM Bar size)-$200
poly upper and lower control arm bushings-$50
Bilstein HD shocks-$150
Front Spreader Bar-$100
Custom blueprinted/rebuilt OEM steering box- GTR 1999-Gary Ramadei-$300
This modification will make your OEM box about as good as it gets with the OEM steering and very close to a borgeson.....not quite but close

Rear:

360 monospring-$300
Bilstein Sport shocks-$150
OEM Style Rear Sway bar (not the aftermarket type bars. I highly discourage NON OEM/GM style rear sway bars)-7/16 or 9/16 or 3/4 inch (I have this one replacing the stock 7/16 inch bar)-$200
Competition adjustable strut rods with heim joint ends-$200

Total Cost $1750

This suspension will get you a FAR SUPERIOR suspension than what came on the car when it was new, X3 if the car had a base suspension from the factory. You will need to add 17/18 inch rims and tires (ZR rated only W/Y sub rating) later to maximize the superior suspension setup. I have ultra high performance summer only tires Front-255/45/17 ZR and rears 255/50/17 ZR's.






The front spreader bar and a similar heim bar I have anchoring the floor seatbelt mounting to the shoulder seat belt mounting (hidden by the interior molding) which ties the bird cage to the floor is VERY helpful with structural rigidity and NO SQUEAKS! It's amazing for a 40 year old car but you do need to make some modifications/additions to the suspension/chassis.


This is ^^^the basic C3 suspension design pretty much unmodified from its original design but maximized for handling, steering, response and grip....I will say this again, the ride is far superior to the OEM gymkhana suspension that came on the car with 255/60/15 crap tires and is very compliant. A neighbor who has lexus LsS460/430 sedans recently rode in my 78 and he commented more than once about the power is great BUT he could not believe how well and tight the ride was....kept saying it.

BTW-the SLP rims and tires above weigh LESS than the OEM aluminum 15 inch rims and 255/60/15 tires..I weighted them both.......................just saying

I said this way back in the beginning of this thread...This ^^^^ will get you a fantastic ride, superb handling, all with basically a stock designed suspension with 17 inch ultra high performance summer only tires.............

I will also add that Karol on this forum with his base stock suspension,L-82 4 speed, and 15 inch aluminum OEM rims with 255/60/15 Radial T/A's, just this past weekend rode in my 78 ^^^^ and then in a back to back comparison we rode in his 78 unmodified base suspension L-82 and he could not believe how much BETTER my car rode than his car (not to mention handle). He loved the rebuilt/upgraded 355 L-82 but raved about the ride....This example is an immediate comparison of real world results, no theory here, with a direct comparison of the 2 suspension types...

Matt Gruber

Tires make the most difference on most any car. I read Consumer Reports tire tests and pick the best value for what i want.
Went over RR tracks in my 61 and i was STUNNED how nice it rode. 90% of the rattles are GONE.

MelWff

which Bilstein shocks, Sport or HD? HD is the softer ride.
which rate rear spring, which rate front springs?
what cold tire pressure?
if your willing to sacrifice power for quiet switch to reverse flow inserts for the side pipes.
is the carburetor correctly jetted and has the correct power valve or spring depending on whether a Holley or Quad or something else?

mobird

Agreed, and I have some good max performance summer tires on 18" rims. I could definitely have BETTER tires, but that isn't really the base issue as these tires are MILES ahead of the old 15" rubber that was on there.

mobird

Good questions.

Bilstein sports all around (did some research and found the Sports work better with the 360 pound rear spring because of the extra dampening. Many found the HDs to be "bouncy" with that spring). i have Sports for the front that I will install when I put in the new springs (waiting on my bushing kit so I can do the control arm bushings when I have the front suspension out). I'm fine with the "firm" ride that the Sports give. I'm more worried about the rattling, bouncing, wandering feeling (which some times feels more like frame flex to be honest). On that note, have any of you installed frame stiffening components? Did you notice a difference?

Cold tire pressure is ~30 PSI

Not willing to sacrifice power, in fact planning to make some more power haha. I'm more concerned with having the car be more controllable.

I've read through Lar's Qjet papers and have tuned the carb (I have a wideband O2 in the exhaust to help with tuning).

Good questions, thanks for asking them.

So to sum up, basically just concerned with "tightening" up the car a bit so it's less of a "nervous driving" car. Shocks, springs, and bushings are the current upgrades, looking to see if there are any other suggestions to help (such as frame stiffening possibly)?

mobird

Were you a used car salesman or work in advertising at some point? You talk (type) like you are trying to sell me something!! haha

All joking aside...



Why do you discourage aftermarket bars? Is there some inherent flaw I'm unaware of? seems like they are a pretty simple design.

I was planning on doing a front spreader bar, though I wanted to do some more research first to see how well it would clear with an LS motor in the bay (hopefully this year). I think it will be fine with electric fans. Any pics of the floor to ceiling bar you installed? I've never seen that before!

NewbVetteGuy

I feel like the 78-79 Corvettes had a lot stiffer frame than the early C3s and that there was some sort of OEM frame stiffening that was added; then the weight savings focus started with the 80-82s and some components were moved to being more light weight.

My understanding is that the 79 is one of the stiffer frames to begin with, but I'm interested in the answer, too.


Adam

jb78L-82

I was trying to convince some folks when I originally posted what you read.......good observation. I just did not want to write it all again for this post.

Aftermarket rear sway bars do not use the endlink assembly like GM used for the C3 vettes. The OEM GM style rear sway bar endlink allows more trailing arm movement and less binding which reduces unwanted oversteer.

Unfortunately, I do not have a picture of the heim joint bar connecting the upper and lower seat belt mounting since it is under the interior trim and carpeting...I can get a picture without removal.

The bar looks like the Heim jointed bar in this picture for the shark bar:

http://www.vetteworksonline.net/cata...products_id=20

mobird

I have heard similar things, but at the same time, the "stiffest" C3 from the factory could still be really loose compared to what it should be optimally, you know what I mean?

I've seen those weld in frame gussets sold too, so I guess I should go do some research and see if I can find some before/after opinions from some people who have tried it

NewbVetteGuy

Warning: You're walking into a Holy War here with this issue. There's two suspension "Schools" that you'll probably quickly see on this thread:

#1. "Gymkhana School"/"Stiff springs, light sway bar(s)": The first camp that sticks to the more Gymkhana suspension "school" that says you should go with stiffer front and rear springs and lighter bars and maybe even keep in a bit of the understeer "safety" that was engineered into the OEM gymkhana package- especially if you have a much-more-powerful-than-stock engine.

#2. "Light springs, heavy, thick sway bars": The idea here is that many modern cars are coming with lighter spring rates to give you a more cushy "streetable" ride and then rely upon the sway bars to provide good handling.


Both approaches can be made to work well, but you have to philosophically stick with an approach and not mix-and-match. #1 requires a good and correctly matched shock to help mellow the ride quality. I like "school #1" simply because my car came with the gkmkhana package and I think it maintains the ride "character" that the car came with.




Adam

NewbVetteGuy

I've never, ever heard of such a thing before; is this common on these cars? Do you have any pictures of this? Is this an off-the-shelf set of parts or something you custom made up with some threaded rods and heim joints?

I thought the bird cage was already welded to the main frame; what does this do for you and how?

This all fits behind the stock, unmodified moulding, too?


-What did you experience before and after this modification? How did the car feel/ behave differently?


Really interesting.

Adam

jb78L-82

I simply answered the OP's question about the different endlink design between the OEM GM rear sway bar and aftermarket NON OEM rear sway bar endlinks....................

There is a lot more to C3's using a rear bar and those that do not.....not to derail this thread but simply the Gymkhana cars had both stiff springs (550 front/292 7 leaf steel spring) AND a BIG front bar (starting in 1978-1 1/8 inch front sway bar was unheard of back then) and the small 7/16th inch rear factory bar. Stiff springs AND big bar.

Lastly, almost all modern cars are VERY stiffly sprung compared to a C3 corvette. My Chrysler 300 has BIG front and rear sway bars and is very stiff riding with the sport package, much more so than my 78 setup as it is today. My 2012 Lexus IS350 F sport is as stiff as my 10C6Z06 believe it or not and has BIG FRONT AND REAR sway bars. In reality, my 78 is MUCH closer now with its setup to modern cars than the traditional C3 but rides firm, not harsh....

jb78L-82

I sourced the parts from the shark bar link I provided above (don't ask how, please). The connection simply ties the bird cage more firmly to the chasiss frame and eliminated most of the interior squeaking....my car with the front spreader bar and the birdcage connection does not squeak at all over rough roads. You would never know that the car is 40 years old riding firm with no harshness and no squeaks....remarkable!

NewbVetteGuy

That's awesome! I've definitely got some squeaks. If you come across any receipts / the list of components you put together for this, I'd definitely appreciate it; pictures would be great to, and I've got a shark bar sitting and waiting to be installed so I definitely have some parts to reference.

Sounds like a great, and invisible mod.




Adam

NewbVetteGuy

Mobird, I know you're hoping some folks chime in here, but here's a couple of super detailed threads where people did some gusseting / frame upgrades that have great photos to boot:

https://www.corvetteforum.com/forums...ed-frames.html

https://www.corvetteforum.com/forums...es-guys-2.html


I also came across a site detailing the from-the-factory changes in the C3 frames over the years, which may come in handy (with pictures!):

http://www.71corvette.com/frames.html


Adam

MelWff

I guess I'm not clear on the OP's goals. It sounded like you want a softer ride yet you are using a 360 Lb rear spring with Bilstein Sport and went with 18" wheels which necessitates a very low profile tire. All of those specs are contrary to a softer ride.

mobird

Thanks for the info man, really good stuff there, and those links were very helpful! I'm gonna do some more research on the suspension setups. Since my shocks/springs are already on the car or in my garage, that part is pretty much set (looks like what I have picked out will work fine on the "stiffer" side of the spectrum) and I can hopefully adjust sway bar size to suite.

Thanks!

mobird

Not a softer ride, but a more confidence-inspiring ride.

Right now, the ride is bouncy, the steering wanders alot, and it's harsh over any surface and it creeks and rattles. I believe most of this is due to worn out bushings and shocks, so I'm hoping between switching to poly bushings and modern springs/shocks it will fix alot of those.

I mostly started this thread to see what others added/replaced that improved the ride quality or got rid of rattles, squeaks, or otherwise stiffened up the frame and improved the quality of life on the C3.


I think I have some good ideas! Once I finish installing bushings and the front suspension I obviously want to drive it around a bit and see how it feels. If it is not where I want it, I plan to add a spreader bar, adjust the steering box (will probably do that anyway), and look into weld-in frame gussets. I also want to do some more research on something along the lines of the shark bar.

Thanks for the input guys! And if anyone else has anything to add, feel free to chime in

Matt Gruber

"confidence inspiring" to me this means you take a tight corner really fast and drift a bit with a big grin on your face! The minimum for this is to replace the camber strut with a stronger strut with spherical bearings, not bushings. Same as on a race car.
One time i cut out in front of an SUV, and then drifted around the corner on my street.
A minute later that SUV with a blonde driving pulls in my driveway. She said she liked my driving, but didn't think i'd make it around the corner, i was going so fast. Then she drove off never to be seen again, as she left, she said "i should of married you"