How well could a g-body actually handle? What's the limit?

[CopperNick]

From your notes and comments, sounds like you have reached the cross roads between having a good streetable vehicle that can surprise the unwary, and the next tunnel down that proverbial rabbithole, which in your case is going to involve some serious front suspension upgrades. So not going to get into the pros and cons such as have already been mentioned above. They have just hit the hi-lites in their comments; there are serious books and multiple videos out there that can be employed as research tools.

One important point here is that you mentioned having already boxed your stock frame. You can go ahead and do the suspension upgrades that have been discussed but at the end of the day, you are doing them to a stock frame no matter how highly, it, of itself, has been modified. AT the end of the day it's inherent design is still essentially factory, with all the limitations that the factory engineers put into it to keep the bean counters happy.

Beyond that point, and yes it has already been mentioned, lies the land of Schwartz where anything is possible and people with deep pockets have empty wallets and redlined credit cards to prove it.



Nick

 

[403Olds]

Pushes when? Under braking? Throttle? Steady state? Understeer and oversteer are something the driver is able to manipulate.

Pushes at the limit going thru corners. Throttle induced oversteer is easily executed, but doesn't make for fast corners.

 

[bs009]

Really appreciate the honest feedback here.

I'm definitely at a cross roads myself here. The car has all the power I could want right now but the handling and the way it drives just hasn't left me very happy since I've had the car. The car almost feels a bit like a see-saw when it goes over larger bumps even after swapping over to pretty stiff springs and sway bars. Despite the floatiness it has a lot of vibration and rattling but that's probably coming from the poly body mounts too.
Basically I'm at the point where I could put another $6,000 in the car's suspension and hopefully be happy with the suspension finally or I could just go buy an E46 BMW shell for like $2,000, swap in an LS or other random motor of my choosing, upgrade the rear end and possibly have a much better driver's car than what I have now. Was mostly just trying to see what experiences others have had who've gone down the rabbit hole of that kind of upgrade to see if it would get the car close to where I'd want it to be and I think you've all confirmed that it would take a new chassis or a serious front suspension redesign

Did you think about looking at UMI's Green Machine thread on what they did to get that '79 Monte to handle?
https://gbodyforum.com/threads/our-79-monte-carlo-pro-touring-project.40563/
Not saying using all their parts but use their set up to help give yourself an idea on what you could do to get the handling you want.

Thanks, haven't seen it yet but it looks like I'd need a lot of time to sift through it. Might try to take a look if I get some free time at work tomorrow.

Without re-engineering pickup points to alter camber curves and roll centers/roll axis inclination, you're going to be a bit limited in what you can achieve. That's what the custom frames are addressing. That and being stiffer than a wet noodle. That's not to say a set of coilovers wouldn't put a smile on your face, but if you want to embarrass a modern car it's going to require big money and big determination. Being competitive in autox is going to be an uphill battle, but being fun on a mountain road has some wiggle room since it's subjective. What's your competitive driving background? If it's minimal or non-existent, I'm willing to bet you can make the car something you really like without going bonkers.

I'm just starting to get into autocross myself. I've done some drag racing in the past for fun and have done plenty of spirited driving on mountain roads.

I feel your pain. I have a series of back to back curves on my drive home. I can compare corner speeds thru this section. I can tell you that my Wbody will surprisingly do well, against my Cutlass, which is pretty equally setup as yours, but I have the 5660 springs in the front, versus the 5662. The tall upper and lower balll joints did help the camber curve. You might look into that. I would be interested in what you think of the 5662's, if you had to cut them at all. My limiting factor is the 15" 60 series tires. You don't state what tires you are running, but a set of sticky low profiles will help also. I have the Hellwig rear bar, but it still pushes a little, but I think that is the flex in the sidewall's mainly.

I cut a half coil off the 5662's and could really cut some more off of them really. I have a turbocharged v6 in the car though so it might be a little lighter in the front than most v8 cars. Honestly I wish they were a lot stiffer because the front still feels really floaty to me.

i'm running 245/40-18 BFG sport-comp2 tires in square stance right now. I have a set of 18x9.5's on order for the rear but I'm doubting they're going to arrive anytime soon.

 

[Streetbu]

Really appreciate the honest feedback here.

I'm definitely at a cross roads myself here. The car has all the power I could want right now but the handling and the way it drives just hasn't left me very happy since I've had the car. The car almost feels a bit like a see-saw when it goes over larger bumps even after swapping over to pretty stiff springs and sway bars. Despite the floatiness it has a lot of vibration and rattling but that's probably coming from the poly body mounts too.
Basically I'm at the point where I could put another $6,000 in the car's suspension and hopefully be happy with the suspension finally or I could just go buy an E46 BMW shell for like $2,000, swap in an LS or other random motor of my choosing, upgrade the rear end and possibly have a much better driver's car than what I have now. Was mostly just trying to see what experiences others have had who've gone down the rabbit hole of that kind of upgrade to see if it would get the car close to where I'd want it to be and I think you've all confirmed that it would take a new chassis or a serious front suspension redesign


Thanks, haven't seen it yet but it looks like I'd need a lot of time to sift through it. Might try to take a look if I get some free time at work tomorrow.

I'm just starting to get into autocross myself. I've done some drag racing in the past for fun and have done plenty of spirited driving on mountain roads.

I cut a half coil off the 5662's and could really cut some more off of them really. I have a turbocharged v6 in the car though so it might be a little lighter in the front than most v8 cars. Honestly I wish they were a lot stiffer because the front still feels really floaty to me.

i'm running 245/40-18 BFG sport-comp2 tires in square stance right now. I have a set of 18x9.5's on order for the rear but I'm doubting they're going to arrive anytime soon.

I'm running 18x9.5 all the way around with 275/35's. Also the front coilovers are 750lb springs yet it rides MUCH better than it did when I had cut coils. I think you can still get much closer to what you want....

 

[Built6spdMCSS]

The limit is your bank account. As mentioned it takes some coin to make it happen.

I thought about it at one point, got a rough idea and did some research.
Then I put that money into a car that if I need to build upon, it'll take a fraction of the work.

I do want to try this car out with a sticky tire on an Auto X course. 😎

 

[Built6spdMCSS]

Once you get past a modified C5 Vette, and into C6, C7 or know even a C8 Vette, once they are modified, and given a good driver, they will be faster than your G body on an autocross track.

I know you're saying that as a hypothetical but the later generations don't necessarily mean those cars are faster. C8 is heavy. C6Z06 is the second lightest Corvette made. C5Z06 is the 3rd lightest, heavier than the C6Z06 by 50lbs. Aluminum Frame in the C6Z06, Carbon Fiber stuff too. Buddy of mine does Auto X a lot and some of the fastest Corvettes out there he has seen are C6 bodies on C5Z06 Chassis. That's a thing apparently.

My C5Z06 on scale is 3085lbs, and I haven't even done any weight reduction besides changing the exhaust to stainless long tube headers and taking off all the emissions crap.

That's why I'll invest into that car all day over the Gbody for cutting the corners.

 

[scoti]

Better than most, and a better ROI than a Schwartz chassis.

Could have been even better with an UMI Sales sponsorship.

How about a parts & mods list so that people have a better idea of what it might take to achieve higher level performance? Obviously the 'driver mod' is something everyone should invest in as well but many (most?) don't.

 

[airboatgreg]

Great info. What I did with my El C is good front end parts. When I did the rear end I had it made 2 inches wider and added a sway bay. The handling difference exceeded my expectations. 60 series BFG tires

 

[81cutlass]

What shocks? A set of double or even triple adjustable will help tighten it down if you say it's bouncy. I can assure you my Viking DA's will 'float' at 2 comp 6 rebound on the street but 8/14 which is 'soft' autocross the thing feels like a little red wagon when I hit bumps. VERY firm.
Do you have OEM hard rubber lower bump stops on the front LCA? They tend to bounce if you hit them hard. Foam zq8 help dampen that out
What does your camber look like? Stock arms with stock ball joints? The tall lower ball joints and a taller upper, or aftermarket upper arm with taller upper ball joint helps camber gain immensely.

I have almost the same setup as you but double adjustables on all 4 corners with foam front bump stops and MCAR adjustable front UCA with 1" extended ball joints and LS1 front brakes. The car is more than I can handle (driver skill wise) and I need a lot of practice & tuning to take advantage of it.

 

[bs009]

What shocks? A set of double or even triple adjustable will help tighten it down if you say it's bouncy. I can assure you my Viking DA's will 'float' at 2 comp 6 rebound on the street but 8/14 which is 'soft' autocross the thing feels like a little red wagon when I hit bumps. VERY firm.
Do you have OEM hard rubber lower bump stops on the front LCA? They tend to bounce if you hit them hard. Foam zq8 help dampen that out
What does your camber look like? Stock arms with stock ball joints? The tall lower ball joints and a taller upper, or aftermarket upper arm with taller upper ball joint helps camber gain immensely.

I have almost the same setup as you but double adjustables on all 4 corners with foam front bump stops and MCAR adjustable front UCA with 1" extended ball joints and LS1 front brakes. The car is more than I can handle (driver skill wise) and I need a lot of practice & tuning to take advantage of it.

I'm using KYB GR-2 shocks right now. Figured it would be a budget performance option back when I installed them about 15,000 miles ago. It's not really a bounce, maybe a better way to describe it is a lot of front to rear chassis roll in bumps compared to a lot of other modern cars I've driven. The stock springs felt floaty and numb like a boat so these stiffer springs did help with the front/back roll, but it doesn't feel as planted and nimble as a w-body on lowering springs.
Stock bump stops too at the moment. stock control arms, stock bushings, stock replacement ball joints. The only thing I've changed on the frontend for geometry is the anti-bump steer kit which helped out with that a lot.

Not sure where the alignment sits on the car, that hasn't been done in a while but when it was done I went to a shop that does performance alignments and they told me it should handle better but I didn't know what was ideal for these cars at the time. Don't have the paperwork anymore on that one.