How do I know if my suspension is up to par?

[johnssi]

So, I've been reading here about all the different posts regarding suspension but not any general questions. What I want to find out is if my suspension is up to snuff. I've had my car for about 3 years and done the front steering parts - tie rods and ends and alignment and also new Sumitomo summer rated tires ( I live in the South). But when I hit something in the road like a manhole cover there is a somewhat jarring bump. Not like anything is loose (shock towers) but it just seems like it should be a smoother transition in a bump situation. Steering seems to be fine with no wander and is tight. How do I know if the shocks/springs need attention or replacement? I know the old "bounce the car" scenario, but that seems a bit archaic. This is our "fun" car and not for rallying or racing so it's just for the street. Where do I begin to check for things? Any help or explanations would be appreciated.
John

[RRoller123]

What tire pressure are you running? I was running about 35 psi to help lighten the slow speed steering and the ride was way too harsh. Lowered it to 32 psi where I am now and it is much better and acceptable in both steering and harshness of the ride.

[johnssi]

It has always been my understanding that you should run the car manufacturers recommended tire pressure so I've been running @ 28 psi, even with the new tires.

[djape1977]

that depends on the size of the tyres. if you're running stock size than do follow manufacturers recomended values, but if you're running low profile wide tyres than you need a bit higher pressure.
troubleshooting of problem you describe is next to impossible via the net. try to find someone locally who knows his way around old fiats. experience will make it a lot quicker fix
also, if you can scavange a set of any wheels from any old fiat, swap them and go for a test drive. your tyres may be made of hard compound or just old. i've never had sumimotos, but when i swapped my goodyears for a set of yokohamas 4-5 years ago, i was amazed how softer and less jumpy the car had become.

[So Cal Mark]

is the car lowered? what shocks are on it? What size tires?

[johnssi]

Hey Mark, no the car has not been lowered. I believe the shocks are original, could that be? The tires are 205/60's. Any ideas?

[djape1977]

worn shock absorbers or hard tyres

[So Cal Mark]

the original shocks will seize if they sit for very long. I doubt any 40 yr old shock is any good. Modern low-pressure gas shocks are a great improvement on the Spiders

[Redline]

When I replaced the shocks (dampers) on my Coupe, I was quite amused by what came out. I had felt the handling was really quite alright (at least, I was having fun pressing on and raising some eyebrows in rearview mirrors). It turned out the front right was nearly empty, the front right was ok, the rear left was locked nearly solid and the rear right was stiff. Oh, and one sway bar link was cracked. Needless to say, taking all that junk out, fixing the bracket, re-bushing the whole mess and putting Spax adjustables in created a rather different experience.

[johnssi]

Thanks for all the comments and suggetions Guys. It looks like I'll be changing out the shocks. Any suggestions as to what brand or type. Again - I'm only interested in street driving, no need for racing equipment. I've heard Koni's and KYB but really don't know anything about the different types.