Suspension refresh

[rodster]

OK, I installed the Gabriel cartridges and achieved the goal of getting my car back on the road. Planning my next suspension step.

On a smooth road the car handles pretty nice but hit a dip in the road or a pot hole and you get a pretty harsh bump. I don't remember it being that harsh before it was taken off the road for awhile. I expected the new cartridges to perform a bit different but perhaps it's all of the other old components adding to the mix.

Do coil springs weaken substantially after 100,000 mile and 33 years? Could that be a large part of reason I feel the harsh bumps?

New springs and all new bushings are on the list as are new Koni's for the rear. Just trying to figure out exactly what I want.

The rubber on the factory lower control arms twist which probably adds some effective spring rate to the springs I suppose? If I go with a hard poly bushing, they should move freely so should the spring rate theoretically be increased?

I have a set of custom Fatman tubular lower control arms but haven't decided if I want to use them or go with a set of factory arms with new ball joints and bushings. Either way the goal is to keep things as stock as possible initially. I should be able to get a good alignment without CC plates?

When I get everything refreshed, the last step would be to swap in the new front Koni's that are sitting in the box waiting.

Thoughts, suggestions?

[Jack Hidley]

Coil springs almost never wear out. They may crack and break, but this is usually from a worn out spring isolater causing a stress riser in the spring or rust creating a stress riser. If a spring does sag from too many stress cycles, it only gets shorter, it will not become softer.

Worn out rubber bushings decrease the suspension rate. They have an affect of making the car ride harsher because they remove damping from the suspension. With soft worn out bushings, the control arm will move at the bushing end, since the bushing is a soft spring. The force from the tire is applied at the ball joint and the coil spring is fairly stiff, so the FCA just pivots around the spring and the inner end of the FCA moves in the opposite vertical direction that the ball joint end of the FCA does.

Low friction ball joints will definitely help the ride quality, but they are not available for SVO FCAs. You would have to install SN95 or MM FCAs to get them.

Polyurethane bushings in the FCAs will increase the wheel rate. They will make the ride harsher over rough surfaces, but smoother on low frequency bumps due to reduced friction.

[rodster]

Great information, thanks.

What I need is a time travel machine to go back to 1984 to feel how the car rode when new.

Next step is new bushings and continue to work to improve the car.