Frame selection for "modern car ride" vs "maximum autocross"

[davepl]

I have a '69 Camaro I've done everything on, so it's time to start over. That's how I ensure it's never done. :-)

My goal is to make a '69 Camaro as close to a modern GT car with respect to ride, noise, vibration, and harshness. I am not an autocross hero. I have a C6Z07 and no expectations or desire to build an old Camaro that competes with it (even if possible, not my goal). I do not care and will never know how many Gs it pulls on the skidpad. I might be admittedly curious, but it is -not- the goal.

Goals: get in, turn key, drive it like a Kia. Have it ride as as nice as a modern car - but not a sports car necessarily. I don't want a harsh ride. I don't want a stiff ride. I want a car that feels like it's carved from a single chunk of billet. When you hit a bump, I want the chassis to deal with it, not the dash and weatherstripping. I want one "thump" sound and not 4 squeak and rattle points. Like my Range Rover, I guess. Not my Corvette. And yes, I know a single chunk of billet wouldn't be the way to do it, you need some compliance somewhere - I just want that done in the suspension, not the interior.

I'll go LS power plant, likely IRS. Undecided on automatic (TKO-600 now, great trans, but not sure I want it to stay a stick this time around). So TKO-600 or 8L90E, not sure.

Budget isn't a primary limiting factor. Which is to say I can afford whatever I need, but I'm a cheap ******* (not cheap like compromise and cut corners, cheap like I'd rather keep my money than waste it where it's not needed).

I'm just starting to look at full frames, but the vast majority of what's in the aftermarket is apparently driven by handling and how many Gs you can make an old car pull, and that's just not what I want. It's a bonus to have, but it's not the target.

As an example, if I had to pick a BMW as my target, it wouldn't be the M3 or the M5. It wouldn't even be the 550. It'd be a mid-90s 528i, the six cylinder four door sedan. Didn't even have short side-wall tires. Handled like it was supremely solid and confident but not edgey, not skittish, not harsh, no aggressive turn-in. And it was, in fact, a uni-body.

So before I run off and pick the Roadster Shop because it's the beefiest looking, I'm turning you to folks for guidance on what I'm even looking for, now that you know my goals.

I have full weld-in frame connectors, front subframe connected to rear, tons of sound deadening, and that all improved it incrementally. But it's still an old car that rides a little better than it probably did stock. I want new-car smell. I want to hand the keys to my wife and not have -her- feel it as an "old" car. My wife driving it isn't a goal, just a metric!

Thanks for any guidance. I'm sure so many have gone before me that the path is well trodden and this might be a 'duh' topic, but I've searched and searched and just haven't found a build that really shared the same goals. I'd -love- to find one and pick the brains of the builder though! As they say, even the basest man learns from his own mistakes, a wise man learns from the mistakes of others also. Or something like that!

Cheers,
Dave

[dhutton]

Take a look at the Art Morrison IRS. It is available in a full frame or rear clip. Great reports of the absence of NVH and gear noise etc. I had their front clip in my Firebird and the ride quality was similar to a late model Corvette or BMW.

I'm building a 69 Camaro with Art Morrison IRS and front clip, an LSA and 6L90E. My goal is quite similar to yours.

Don

[davepl]

Take a look at the Art Morrison IRS. It is available in a full frame or rear clip. Great reports of the absence of NVH and gear noise etc. I had their front clip in my Firebird and the ride quality was similar to a late model Corvette or BMW.

I'm building a 69 Camaro with Art Morrison IRS and front clip, an LSA and 6L90E. My goal is quite similar to yours.

Don

Thanks! Was the FIrebird a car you'd owned for years before moving to the front clip? It's always interesting to hear from people who've been able to compare directly in the same car, but since project cars are often bought and built without living with the stock setup for long, it's hard to find those folks!

[dhutton]

Thanks! Was the FIrebird a car you'd owned for years before moving to the front clip? It's always interesting to hear from people who've been able to compare directly in the same car, but since project cars are often bought and built without living with the stock setup for long, it's hard to find those folks!

I built it without driving it first but I've had a few first gen F bodies (including a frame off restored 69 Z28) over the years and the difference was night and day.

Don

[davepl]

I built it without driving it first but I've had a few first gen F-bodies (including a frame off restored 69 Z28) over the years and the difference was night and day.


Thanks! I have a frame-off '69 Pontiac 2+2, but that's a full-size B-Body that probably rode a lot better than the F-body did back then. The B-Body isn't that bad, actually, except for the brakes and steering. With those updated I could drive it daily, as it rides decent, and with polygraphite bushings and the F41 front and rear sway bars, can at least follow modern SUVs on on-ramps. In fact, that's about all I care for handling, and I bet a factory F-body was fine for that. It's just a tin rattle-trap.

The Camaro I have now is a bit of a hodge-podge. It was cosmetically restored by someone else. It has a Currie 9-inch, a 502, and headers. The subframe connectors, solid bushings, and sound deadening helped. There's only one scenario where you can get any tire rub, but even so it's no fun to drive. The suspension is all rebuilt to original specs, and there's nothing wrong with that. It does have "slide a link" bars but I made sure they're currently dialed back far enough to be out of the equation.

I guess my assumption, and PLEASE people check me before I spend 2 years and $50K on the wrong solution, is:

- If I build a modern chassis as a sound and solid foundation, I can put pretty much anybody on it, and as long as that body is solid enough in its own right, the car will ride with a solid feel like a more modern car.

And again, that "solid feel" to me means that when you hit a bump like a sewer grate that's raised a quarter inch, you feel it and hear it twice: once for each tire. Part of that is IRS. But a lot of it is torsional rigidity. I think.

I worry that a lot of the frames are built with C5 or C6 Corvette gear; I guess as long as they're willing to work me on spring rates and dampening rates, doesn't matter where they're from (ie: Corvette origins do not dictate a harsh ride, right?)

My brother's C5 convertible rode way better than my C6ZO6, except for flex. Of course, the C6ZO6 will lap it all day long, but I've beat to death the point that lap times aren't the goal. I haven't been in a magnaride car, but I bet they're even better (not part of this equation unless someone has reverse engineered it!)

[Schwartz Performance]

There are a lot of other factors that go into this besides just the frame. The old bodies aren't all that well put together, we recommend stitch welding some of the seams such as the factory frame rails in the back, and some inside the pillars, behind the rear seats, etc. Also a rollbar will help tie it in from another plane.

Also how the car is put together. Most modern cars use a lot of plastic parts and plastic clips, and lots of rubber or other dampening material in the panels to make it not so noisy. Dynamat and other materials such as Lizard Skin help it feel and sound like a modern car as well.

Our chassis tie into the factory unibody structure in the rear of the car, to further strengthen it. Of course all of the suspension/drivetrain mounts to the chassis, so most of the beating is taken out by that instead of the sheet metal.
We use long-travel coilovers up front to get away with softer spring rates which gives a better ride.. also the use of Ridetech's adjustable coilovers you can dial in the damping settings to a desired feel on both ends of the car. Our front & rear splined sway bars control the lean.

If you have any questions about our products Dave, give me a call or email.

Check out our chassis here: www.GMachineChassis.com

-Dale
(815)206-2230
[email protected]

[ace_xp2]

Any suspension that has lots wheel motion in the front to back direction should help, you want the wheel to not just move up in bump but also move toward the back of the chassis, that way when encountering a bump the suspension not only moves into the chassis but also away from the bump. That's where luxobarge suspension design gets tricky, battling between reducing nvh while at the same time trying to damp the motion of rubber everywhere through all kinds of durometer tricks and carefully placed load paths.

It helps to use subframes as well, that provides the opportunity to have an additional set of bushings to further isolate nvh.