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Discussion Starter #1 (Edited)
Good afternoon Alfaholics,

I have an itch to improve the ride comfort on my 147.

Currently, on Bilstein B4's paired with ST Suspension lowering springs(-40mm/-30mm). 17-inch wheels with 225/45/17 Reinforced tires. Pre-facelift, 103KW, 1.9JTD.

The front, while very planted, makes the front of my car extremely harsh, bone breaking harsh, over potholes. The rear doesn't make the same crashy noise. Front wishbones have been changed, the upper ones at least, lower ones are in good condition, shocks are few months old, lower engine mount has been replaced. Everything on the rear has been switched out as well.

My question is - what could be causing "crashy" noise over bumps which is accompanied by the feeling my wheel is dropping in the pothole and hitting it so hard it's about to detach? I can describe it as if a lot of unsprung weight drops in there and I can feel it through the steering wheel. Any other road imperfection - dips, a road with a lot of small humps or just uneven surface - no issues. Only potholes.

Neither ARB bushes nor drop links have been changed though I don't know if they can achieve the aforementioned earthquake in the cabin.
 

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Sport spring, 17s + standard shocks = poor ride

Hi, I'll try to answer your informative post as best I can.

The links would produce a rattling sound. The ARB bushes would produce a knocking sound if they are worn but neither really affects ride quality.

The lowering springs make it firmer so more road shock is transmitted to the cabin. The front of these cars have relatively heavy suspension and hub components relative to the sprung or body weight. The 17" wheels are heavier, as are the reinforced XL tyres. I've not tried the ST springs so I cannot comment on their effects but it does sound like a cumulative issue. More importantly, the larger wheels have more mass further towards the tyres' circumference which creates greater gyroscopic mass which means a greater moment of inertia when the wheel moves up or down for bumps in the road. The main effect of that is the suspension must work harder simply to control the wheel and maintain tyre contact with the road.

I think that deals with the principles of the bad news. The good news is links and ARB bushes sound like they are ok.

Without resorting to changing suspension components, I'd suggest lighter tyres. Amazon is a good place to get tyre weights as things like shipping weight are listed. I'd suggest a non reinforced tyre. You don't need the extra load capacity. Also, a lighter tyre should help. I don't know what tyres you are using or if they are touring or sports tyres. Touring tyres tend to ride better. I like the Pirelli Cinturato P7 tyres. They ride well enough, are quite light and grip and handle well for what they are. However, beware the homologated version for the Giulietta (marked AR or ARR) as Giulietta owners say they may as well be carved from wood. Perhaps Michelin Primacy 4 or loosing sport feel, Avon ZV7 may work.

For something sportier, Michelin Pilot Sport 4 pr Dunlop Sportmaxx RT or RT2 if you can get them. They are not too heavy or noisy and still wear fairly well.

That may sort the issue. If not, I'd suggest using firmer front dampers. From my experience, a firmer damper does not make the ride worse (unless it is poorly developed). Either Bilstein B8 (for lowered springs) or Koni Str.T or Sport should help. Some people think with firmer springs the Konis have a little more give than Bilstein as Koni are twin tube and Bilstein are monotube.

The Konis would raise the front of the car 20mm as Koni set the spring perch higher. Years ago, people couldn't work out why the then in thing; Koni FSD dampers made the from of the car higher. All the Koni front dampers do that on 147, 156 and GT cars. I do not recommend Koni FSD dampers for you though. They are expensive, can only be bought as a set of 4 and have the initial comfort valving set way too soft for sport springs. They don't work that well with Eibach Pro Kit and work best with standard springs.

I'm currently testing Koni Str.T front dampers. They work well and control the front better than knackered standard units or good standard ones. I'd say the ride quality I better than standard also. I'm about to fit the Eibach Pro Kit lowering springs (with the Str.Ts). I cannot yet say how they work with mild sport springs but I think they should work nicely. The are £116 delivered from Larkspeed but I appreciate having just bought B4 dampers, you don't want to pay twice. That's why I suggested tyres first, possibly lighter rims and lastly the dampers.

However, as these cars are underdamped at the front as standard, the first front suspension modification should be uprated dampers which is doubly essential when sports lowering springs are fitted.

I realise it's not what you want to hear but I think I've given good advice and leave you with the choice of what to do and when.
 
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