[wutdhec]

Thanks everyone.

Were the spacers reinstalled with the new springs, they would offer a bit more clearance.

Not sure, it was installed by mechanic...I'll look for them.

if it bangs or clunks, more investigation is required, especially as you said it happens on even the slightest bump.

Its a clunk or a thud, not metal on metal. Happens more at higher speed and when there is some change in the road, like when getting on a freeway and the on ramp and freeway merge but they're at slightly different heights.

I'm going to check:
1. Bump stop condition
2. Presence of spaces
3. Sway bar bushings
4. Exhaust installation (there was some work in the last few years)

Any thoughts on these stock shocks (I'm not looking to invest much since I'll likely sell the car in a year):

Shock Set Original 105-115 | Centerline International

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models fr

centerlinealfa.com

 

[Ragnomaniac]

Any thoughts on these stock shocks (I'm not looking to invest much since I'll likely sell the car in a year):

I just ordered the springs and shocks package from Centerline. I was going to go with Koni Reds but found I needed springs as well so for the price of just the Konis I get springs too! My mechanic vouched for their quality and speaking to Ian from Centerline convinced me I would be happy with the results. They aren't adjustable but are set up to have the same dampening of the original Spica shocks with modern production quality and materials.

 

[wutdhec]

Folks I think we have a winner:

Have you had any exhaust work done recently? Contact between the left axle tube and the "hoop" in the rear exhaust section can sound and feel pretty harsh

This is exactly what I found...exhaust hoop hits the "reaction triangle" when compressed. Please watch this video to hear it and also let me know if you think the shocks are too "loose".

1991 Alfa Spider Rear Suspension Noise

Quick illustration of a clunking noise when I go over bumps.I thought the springs were sagging and the car was bottoming out but it turned out that the final...

youtube.com

The shocks are Koni reds...been on a long time. Seems loose to me...

 

[Gubi]

Looks like the shocks are working okay to me? They're damping the rebound properly.

You probably just have an exhaust alignment issue: either the hangers aren't adjusted right or the overall position needs adjusting or something. Look underneath, see where things are hitting, and see if you can move the exhaust appropriately.

 

[spiderserie4]

ok the bang is likely the exhaust
but what is that odd wheezing air noise as the car is pressed down and let back up?
My car doesn't make that noise
as though there is a hole in the shocks, air pressed out then sucked back in as car rises...

nobody hear that?

 

[Gubi]

I just assumed it was the fluid in the shocks moving through the valves. I can't remember how noisy my Koni reds are but I think they make a similar-ish noise? Will check tonight.

 

[wutdhec]

I was wondering about the wheezing sounds too...looking forward to learning if that is common to Koni's or not.

The front Koni's barely budge when I push down...not sure if PO wanted hard front and soft rear dampening, or ?

 

[Ranz]

+1 on normal shock noise as oil is forced thru the damping valve/shim stacks. If you get close to a shock while your assistant does the bouncing, it will be more obvious. If you have a shock off the car and extend it manually, you will probably both hear and feel it happening.
Re: hard front, soft rear…the front of the car has the engine in it, so it is much heavier than the rear.
This requires heavier springs at the front to stop the car bottoming out, which in turn requires shocks with stronger rebound resistance to match (control) those springs. When you push down, the resistance is almost all from the spring - the shock’s job is to stop the spring rebounding too quickly AFTER compressing. Your rear springs, carrying less weight, are made of much thinner steel, and shocks resist oil flow less in order to match that. Your front/rear Konis are valved differently inside in order to achieve this.
Glad you found the problem…it’s hard to beat having a bit of a look.

 

[Gubi]

Yeah, the rear springs are super soft, like 80 lbs/inch, so the rear is easy to push down. I forget what the fronts are but like 200 lbs/inch, some of the sport front springs are 800-1000 lbs/in if I recall correctly.

Note that the Konis are only adjustable in rebound, not in compression, so adjusting them stiffer wouldn't affect pushing down on them. With stock springs you'd generally leave them full soft to start with, you'd set them stiffer if you had stronger springs.

 

[Gubi]

I just assumed it was the fluid in the shocks moving through the valves. I can't remember how noisy my Koni reds are but I think they make a similar-ish noise? Will check tonight.

I checked and my suspension (Koni red shocks, stock springs) is actually pretty quiet when I do that, so I was wrong. I dunno if that actually indicates a problem with your car, though.

Anyway, start by fixing the knock, that should be free.

 

[AlfistiSA]

Years go as a student, my '69 GT 1300 Junior developed a bang going over an undulation. Turned out to be the U bend of the exhaust rocking sideways and banging the reaction triangle bolt on the diff. I could see a tiny shiny mark near the top of the exhaust bend & a matching mark on the reaction triangle bolt on the diff. I put a twist of wire from the left diff strap to the exhaust and that solved the problem. I was a penniless student back then.

It's probably still there, I can't quite remember, but I did get a complete new stainless exhaust for it several years ago. It's now in my resto queue. I've had it for 31+ years now.

Ciao
Greig