I have a 73 smallblock convertible and I amlooking for feedback from anyone who has upgraded to stiffer springs. Corvette America has grand touring springs rated at 550 inch/ lbs which they clam is the f-41 upgrade. I am also looking to pair them with the 7 leaf rear spring and bilstein shocks. This seams like a good inexpensive way to improve handling for under $500 and retain stock appearance. My question is there a real notable difference in handing and how do they ride compared to stock. Fiberglass springs are unfortunately out of the budget.

 

It will ride like a buckboard. If you're driving fast enough to notice any difference in handling, you should be on a race track track and not the street.

Save your pennies until you can afford the composite rear spring, much better ride.

 

I drove my car for years with the F-41 suspension. It is a bit harsh over railroad tracks etc, but just fine everywhere else. Your driving a sports car not a Buick electra. Also the 550 springs will lower your front about 1 inch also a good thing. Mack sure NOT to buy the Bilstien extreme shocks. They are set way to high on rebound. You also do not need a rear sway bar, no matter what the sales people tell you.

 

Unless maintaining ride comfort is a far higher priority than improved handling, you'll be very glad you stepped up to the 550's. As mentioned, they'll beneficially lower your front ride height approx. an inch from original. Thus, I highly recommend that you also make a similar adjustment to your rear ride height, making sure not to allow your rear "D" height to fall below the front "Z" height (see pic below) at curb weight and with driver's weight aboard.

Don't go overboard with rear spring rate (the more power you have, the more important that becomes). Better shocks will make a noticeable difference, but I recommend not going beyond Bilstein Sports at the firmest with 550's on the street (springs are often blamed for harshness actually due to shocks). Don't forget to replace any and all worn steering components, and to tune-up/overhaul/replace the steering box as necessary. Also, while you're at it (dangerous words, I know) you ought to eliminate as much compliant rubber in the suspension as is practical, particularly in the front control arms. IMHO, important as they are to tuning balance, bars are still a crutch which ought to be the last consideration after you see where you are with everything else done. And, no suspension will perform optimally without a precision alignment using appropriate settings (see Guldstrand or VB&P recommendations).

Ultimately, what is the right call for you here depends mostly on whether that sensitive instrument on which you sit is tuned more towards spirited driving or for sitting on a cushy sofa. FWIW, my lowered BB street shark has been on 860's for many years, and my backside wouldn't have it any other way.

 

I appreciate everyones feedback. My main goal is to improve the cars handling, and the stiffer springs seem like the logical choice. I am not to worried about ride comfort, since I don't drive the car much anyway. Thats what the family car is for. The time that I do get to drive is mostly on twisty back roads with very little traffic, so the temptation is always there to push the limits of the car a little. I won't be auto crossing the car, (yet) but would like a little more stability in the turns. The upgrade to poly bushings and a good align seem like great advice. Thanks Keep the opinions coming! thanks Mike, Jim and Skunk.

 

My 78 originally had a totaly stock F-41 suspension when I bought the car in 1983. Over the years I made progressive changes to the stock suspension in order to improve the ride and handling. Over 25 years I slowly made small incremental changes to the suspension. In the front, I ultimately ended up replacing just about every suspension component as noted above which is vital if any parts are worn. I currently have new 550 springs with Bilstein HEAVY DUTY shocks, not sports, poly sway bar bushing mounts and end links on the original 1 1/8 in front bar, and most recently poly upper and lower control arm busings in the OEM control arms. In the rear, 23 years ago I replaced the 7 leaf spring with a 360 monospring (greatly improved ride with handling, still have it in there, by the way), Bilstein SPORTS, not heavy duties, originally OEM strut bars with poly bushings (they squeeked for 23 years and now have Heim joint competition strut bars (they are fantastic, no squeeking, hold the camber setting, but ride slightly harder), and the OEM 7/16 in rear sway bar with poly mounting bushings. Recently I replaced the OEM 7/16 in rear bar with an OEM style (not aftermarket with different end link mounts to the trailing arms) with a 3/4 in rear bar with poly mountings to the frame. the overall effect is that the car handles unbelieveably better than the OEM could ever even think about with a slightly harsher ride on rough payment but perfectly acceptable to me on smooth roads. I would highly recommend an OEM rear sway bar similar to the size that came with the SB Gymkhana/F-41 suspended cars of 7/16 in with poly bushings initially and you can go to a larger bar (OEM style, not aftermarket end links) later if you see fit. The aftermarket rear bars with the different end links to the trailing arms changes the effectiveness of the bar dramatically and may upset the handling negatively but I would not recommend no rear bar at all for the best balanced handling with minimal understeer. Even with the OEM 7/16 in rear bar with Poly mounting bushings with the above setup, my car still understeered at 10/10th's driving. With the 3/4 in rear OEM style bar the car is very neutral unless driven stupidly! I recently went to 17in SLP rims with 255/45/17 ZR'sin front and 255/50/17ZR's in the rear. The handling is sooo much better from mine and other C3's I have driven it is unbelieveable!