Hello,

I recently bought a 1972. The frame on it is trash and with the purchase I got a whole new frame to rebuild the car from the ground up. I figured now is the best time to change/upgrade the suspension since there is no body on it. I currently own and drive a 1984 with the Z51 suspension package. As a young buck, the stiffness doesn't bother me much on long rides (I've driven it across the country and back) and I really have fun with its cornering performance. My question is, how does the 1972 base suspension compare to the 1984 Z51 performance wise? How much better is the 1972 ride quality? What are some upgrades I can do to the 1972 to get better performance or ride quality? Thank you for any input!

 

Performance and ride quality I interpret as being opposites. The Z51 is equivalent to the F41 in a C3. Stiffer springs, shocks, and larger front sway bar plus rear bar. So not sure what your goal is handling or softer ride or some combo?

 

I do think Performance and ride quality are opposites, especially on these older cars. And thank you for the knowledge of the F41 package as I didn't know the name of it for C3s. I'm trying to see what sort of money pit and what parts I'd need to get close to the rumored 1G skid pad result of the '84 Z51. Or if it's completely ridiculous to try that as the C3 and C4 were built with completely different design intents. If it's impossible to get close to Z51 I'd be looking more at just marginal performance improvements and go more for ride quality. Besides just stiffening the springs and sway bars, would coil overs help both ride quality and handling slightly?

 

Is your purpose to take the car to track events? Going to modern 18" tires and summer only tires is something else to do. Yes, you can also redo both front and rear to coilovers. I'm sure other's will have more to add.

 

I'm not going to track it. I just really like taking mountain curves fast and fell in love with the feeling of the '84 taking tight turns at speed.

 

Start with larger, 18" , wheels and tires 245/45x18 before doing anything else, summer only tires if practical. Also performance shocks. Make sure you get a 4 wheel alignment using specs for modern tires.

 

You really don't need to get crazy with after market parts on these cars. What you do need is someone who can weld unless you can. One of the main things is chassis stiffness. Get The Chevy Power Book. Start there. The biggest drawback to these cars are tire size. Even bone stock with everything like new and some fat tires the handling is very impressive. The problem is most cars are worn out. And a lot of time people rebuild the worn out pieces with the wrong stuff. So read up and spend wisely

 

I was thinking of going to 235/60/15 to fit on the stock 15×8 rims. What advantage does a larger rim size give besides bigger brakes? Im not well versed in handling.

 

My car has come with an extra chassis and I did notice the welding looked funny on it. Thank you for the info. I'll defintiely have a look at stiffining it. And what do you mean by tire size? Are you talking tire width, side wall height, rim size, etc?

 

Even the factory used 255/60 x15. You are not going to get Z51 handling with the available 15" tires. It's not the rim size, 15" tires are no longer available in true performance ratings.

 

I like the idea of using the 255/60 x 15 for the rears and 235/60 x 15 for the front (I've read 255s up front may cause rubbing at full turn). Even if that set up isn't ideal for handling I'd really like to keep the stock rims. Do you think using the F41 suspension set up, the chassis stiffening, and the 255/60s would give a decent upgrade in handling for the price? I really appreciate all the help you've been giving me.

 

245/60x15 in the front and 255/60x15 rear. F41 will give you a stiff ride. Front and rear sway bars and a front spreader bar along with Bilstein shocks.

 

Are you saying to add Front and rear sway bars, spreader bar, and bilstein shocks along WITH the F41 package, INSTEAD of the F41 package, or that those are what makes the F41 package different from base suspension? Sorry if I'm a little illiterate on this. Suspension is not my forte as you've probably noticed.

 

I have a feeling you Don't want the F41 suspension because it will give you a stiff ride. All the other modifications should have minimal effect on ride quality.

 

Perfect! I really apprecaite all your advice!

 

We owned a small block 1972 for a long time. When I thought it would make the car handle better (in what respect, I don't know), I added F41 front springs, the largest front sway bar from GM I could find (IIRC, the FE7 1-1/8" bar from 1975) , and the big-block rear sway bar.

It rode horrible, crashing down hard over the slightest bump, rattling me to my bones. I returned the suspension to stock after suffering for a few years.

Don't be me.

 

Van Steel has staged handling packages, from stock to mild to wild.
See what they offer.

But performance tires are always your #1 biggest improvement, and the good rubber compounds are no longer available in 15" sizes. Long gone.
16" ones are pretty much gone now, and now even the 17" performance tires are beginning to be phased out.
That basically means 18" wheels if you want the tires with the best compounds for the best handling.
And then the wider wheels and very short sidewall tires also greatly improve handling response, by supporting the tread better.
Everything else comes after, and is really to help support the tread patch.

So I would recommend that you decide how extreme you want to get with a performance tire, from standard Radial T/As to Pilot Sports to Road Race or Autocross specials (D.O.T. zero treadwear ratings). Then pick a wheel to support it, the bigger & wider the better of course.
Decide on that first and then we can help you with a suspension package to support it and optimize it. You will need wheels & tires at least as big as your 84 for it to feel similar.

IIRC the 84 Z51 has very stiff springs, much like the F41 in the C3s. The difference is in the details, like fiberglass springs, aluminum suspension parts and much better (Bilstein) shocks. Without those parts the C3s ride very harsh with those stiff F41 springs.
Shock tuning is your best friend to improve the ride, with Bilsteins or adjustable shocks and / or a rear fiberglass spring you can make it ride very similar to your Z51.

You can make it handle close to or even better than that one, but you will have to work at it.

 

The only tires available with 15" rims are essentially all season passenger car tires, the Radial T/A and the Cooper Cobra GT.

 

Hello Leigh! I've actually been reading some of your comments on other forums and appreciate your insight. My original goal of this post was to get subjective opinions on how the base C3 suspension compared to the 84 Z51 in terms of ride quality and performance, and how big of a gap there would be to close, but I think I articulated it poorly. I've since thought things over in a slightly more objective way. The thing I love about my Z51 was taking curves rated at 30mph at 60+ mph, taking winding downhill roads at whatever the speed limit was and a little faster, and doing donuts, and not feeling like the car was even close to flipping or sliding out from under me. Basically a really fun street machine. I more or less want the 72 to be able to safely take those turns. I have no intentions of tracking the car in any serious manner. That said, I want to keep the 15x8 rims to maintain factory look but will be going with 245/60R15 fronts and 255/60R15 rears using the high performance all season tires.

With all that preamble out of the way, what could help me reach that goal? MelWff suggested the front and rear sway bars (I'm guessing they meant the 1 1/8" front and 7/16" or 9/16" rear), front spreader bar, and Bilstein shocks. reno stallion suggested following the Chevy Power book for frame strengthening. I've also read about Heim struts and all poly bushings. I'm always open to new ideas and may change things later after putting the car back together, but I thought it'd be nice to get things pretty close to what I want since I currently have a bare frame and suspension components and that seems the easiest way to work on this stuff. Thanks in advance!

 

Heim joints and poly I would stay away from based on your goals.