my engines done, trannys on the way. ( eventually) I have decided to stick with 15 x 6 wheels. now how do i start updating my 65s suspension, does it need it. or should i be more interested in restoring my suspension. I have no intentions of racing or autocrossing it. i just like to take the occasional hard ride. my car is a PB / PS car. I don't want to lower it because ;A i like the way it looks and B. i don't want to smash my hooker sidepipes . Should i just go with a quality gas shocks and some sway bars, composite rear spring. i don't know squat about car suspension stuff. Oh i won't do anything to the car I can't reverse with a few wrenchs and some time.
thanks
greg

 

The foundation of the suspension is tires, so that's where you start - the best performance tires available.

The OE base suspension is very good. If the springs are free of major corrosion, they should continue to be used. You should consider removing the rear spring and rebuilding it - disassemble, check for corrosion, clean and apply a corrosion resistant coating, and reassembly with new liners.

Install the spring with new link cushions.

For best performance (assuming you have decent tires) set camber at
-1 front and rear and install hard urethane bushings on the front anti-roll bar links. Set front caster at 1.5-2.0 degrees with manual steering and 2.5 with P/S. Greater camber improves straight line tracking and steering feel, but yields higher effort, especially at low speed. Establish front toe-in at 1/16" and rear toe in at 1/32" per wheel with radial tires

Top it off with a set of adjustable shocks like Spax.

http://www.spax.co.uk/

Spend your money on tires, shocks, rebuilding the OE suspension components as necessary and alignment tuning. The ride rates, roll stiffness and roll stiffness distribution is excellent as is.

Duke

 

I'd agree with Duke. For a driver that you just want to have fun with, keep the springs stock (soft) and spend your money on tires (for grip) and shocks (for ride). Unless you have a big block, NO rear sway bar! I've heard good things about the composite springs, but defer to those who have used them for experience.

 

Hey Duke,

What about poly bushings? I'm using them and I did notice an improvement in overall tightness - but a tad harsh - what are your thoughts?

Thanks! (for everything!)

pm

 

With the exception of the front anti-roll bar links, I would never install polyurethane bushings on anything other than a dedicated race car.

Available tire grip is 90 percent of the handling equation. Everything else in the suspension is just a matter of tuning to get the most out of the tires.

Bob Riley, one of North America's premier race car designers, says that 90 percent of setting a car up is tuning shocks, which is why I recommend adjustables.

Duke

 

Duke or others: why no rear sway bar on a small block, newer c3s had such as the 80 FE7 with 1-1/8 front bar and 7/16 rear bar coupled to the 255/60/15 tire package????

 

GM deemed that no rear anti-roll bar was required on SB suspension packages. BB C2s have rear bars because they have significantly more front weight bias. C3s have a lower rear roll center due to the redesign of the strut rod bracket. This results in less camber change with jounce and rebound, which was deemed necessary with the wider bias ply tires, and lowering the rear roll center reduces the inherent roll stiffness contribution by the spring.

The C3 FE7 package effects a dramatic increase in roll stiffness with both stiffer springs and much larger anti-roll bars. Recall that the anti-roll bars' contribution to roll stiffness is a function of diameter to the FOURTH power, so even a 1/16" change has a dramatic affect on the numbers and is definitely noticeable SOTP.

Note that the small FE7 rear bar is accompanied by a HUGE 1 1/8" front bar. (base supension C2 front bar is 3/4", 15/16" w/F40) If you install this setup on a C2 it will have higher rear roll stiffness distribution because of the higher C2 rear roll center. Installing the small rear bar (7/16") without at least a 1 1/8" front bar on a C2 will probably result in excess oversteer. The base SB suspension on C2s is quite neutral. In fact, if anything they are a little to tail happy at the limit. Installing urethane bushings on the front anti-roll bar links will mitigate this situation. Eliminating compression of the rubber bushings increases front bar effectiveness at high deflection, which will effect a bit more understeer at the limit and help keep the tail in line.

The one "upgrade" I would consider on the base C2 SB suspension is installation of the 13/16" front bar that was part of the later C3 base suspension package. This bar in combination with negative 1 degree front camber and hard link bushings will improve steering response with a little less roll and a little more understeer at the limit to keep the car stable.

Body roll is not all bad. It gives the driver feedback as to where the car is in the dynamic envelope. As you increase roll stiffness the car will become "edgier" and more difficult to recover if you step beyond the limit of its dynamic performance envelope.

An illustrative example is the relative setup of a formula car for wet road conditions. If a dry setup is used the cars are virtually undriveable in the rain. A wet setup is considerably softer - both springs and bars, which dramatically reduces roll stiffness.

Duke