pretty sure the 780 has gas struts in front. rears were nivomats. it also had very nice light alloy rrims, the Desones 15x6 ET25, like these...

 

Nice wheels. I'm sure lighter, alloy wheels will increase and improve strut travel. I have Borbet type E's, 16x7, with Volvo offset and bolt pattern. I did go to 1 size taller on the tires so I wouldn't lose 1/2 inch of sidewall.
Since your 780 rode so well and my 940 has the same front end I've got to assume I have a basic problem that I'm over diagnosing. But let me throw out 1 final question. Since all rubber to metal contact points can affect ride quality, could it be my strut mounts? They're original and they look ok, no cracking or splits and the bearing rotates smoothly and freely, but the rubber is 25 years old.

 

a minor thing, perhaps, but my understanding is 760/960's have an extra reinforcement on the front half frame

FWIW, my 92 740T wagon, when I got it, it had a quarter million miles, so I went through it and replaced nearly ALL the rubber in the suspension front and rear. this greatly tightened up the ride. I also installed the lower cross brace from IPDusa (but not the top strut brace). I put IPD's sport sway bars on it, that may have made the ride a little harsher (but man, it cornered well), and Bilstein TC (touring) shocks (which also were a little harsh). I put 16" Hydras on it, with Michelin Premiere tires in /55, this also may have made the ride a little harsher. net result was a car that tracked bad roads really well, but did ride a bit jiggly at speed. oh, also I put IPD's 'overload' wagon rear springs on it, which sure made it nicer when I was packing heavy for road trips, but again a bit harsh riding empty.

 

OK, thanks. I don't think a stiffer body would make my car ride smoother. Handle better, probably. Maybe I'm trying to make my car something it isn't. But, the basic suspension layout has been used by many different makes and they've been able to figure it out. The never ending quest.

 

stiffer chassis definitely improves the ride, as any chassis flexure translates to vibrations. The chassis on the contemporaneous Mercedes 124's (300E, etc) is like a brick, incredibly rigid, which makes for a very smooth quiet ride, even while hurtling over bad roads.

 

Just curious, would you know the spring and load rates on your front coils?

 

I don't have any numbers. I don't even have the Volvo anymore, sold it to my son's GF, they live in Nevada so I only see them a couple times a year.

 

No, I meant for the Mercedes cars.

 

ah. no, I don't have the spring rates, they aren't in any of the parts catalogs

 

Seems like Mercedes follows everyone else's lead - don't reveal spring rates - the secret of the universe. Thanks anyways.

 

they appear to be a speciality manufacture of custom springy bits for things like headphones (the head band is a 'spring'), I don't see anything on their site about standard automobile springs.

most aftermarket springs for Volvos are sport or lowering springs.

why do you think your springs are 'shot' ? most suspension problems are worn due shock absorbers ('dampers' in UK parlance), and/or worn rubber bushings, spring pads, etc.... steel coil springs don't sag or wear out unless they are seriously abused, or badly corroded.