New Konis = Rough ride!

[Cousinphil]

Most nights up here in this part of Maine temperatures are still below freezing but in the daytime the mercury has soared up into the low fifties and the sun is shining and people are out walking around and for me it has been time to get the Avant out of winter mothballs and get her back on the road. She started instantly and is running flawlessly.

The stock shocks were definitely OK and the ride was smooth and the handling was top flight. But in my quest for the ultimate ride to get me around my piano tuning route, I ordered four new Koni SFD shocks and had them installed a few days ago. I got the car back and got behind the wheel and immediately noticed that these shocks are quite firm. In fact more than just firm. Harsh, rattle your bones rough. I took my wife dancing on Saturday night and we took the back road and she didn’t like it at all. She suggested we take the smooth high road going home. I wondered if I had made a horrible mistake with the Konis. I considered calling the garage and having them pull the stock shocks out of the dumpster.

As I understand it, the Frequency Selective Dampening allows the shock to make quick small movements with minimal dampening but the shock will clamp down for any kind of deep movement, such as a body roll.

But then I remembered that on the bill it had said that they had checked the tire pressure. Maybe they had overinflated the tires. Sure enough, the fronts were at 32 cold and one rear was 33 and the other was 34. Sheeit! I lowered them all to 30 and what a difference! The harshness went away. The shocks are definitely firmer than the old ones but not objectionable. No noticeable body roll at all. The car is handling beautifully. Now I just need a new clutch and maybe some motor mounts. And an APR tune.

[tHatOne guY]

Wow really that big a difference just from 4 or 5 pounds..? Have only seen a couple instances of discontent after switching to the FSDs. Thinking about making that switch myself.

I can certainly understand wanting as smooth a ride as possible but do you think the lower tire pressure is worth it? You know vs. the safety concerns/risks of under inflation?

[Cousinphil]

Actually, 30 lbs, front and rear, is what is recommended. I'm running Michelin 215 55 R 16s. I imagine that the Koni shocks will eventually loosen up a bit.

[eljay]

Yes, 4-5 psi can make a difference in ride comfort. It also depends on the tires, their load rating, compound etc.
Did you also replace the shock mounts on all corners? Worn mounts will contribute to "trashy" ride as old and collapsed rubber mounts will transfer any noise/vibration into the chassis.

I love my FSDs!

[diagnosticator]

Koni FSD dampers are definitely not firm riding.

Who did the installation of the Koni FSDs? A crucial requirement of the install procedure, the suspension pivots points must only be torqued with the suspension at the loaded ride height position. If the suspension was torqued with the suspension at the fully extended unloaded position, the resulting ride qualities will be harsh and stiff, due to the excessive wind up in the rubber suspension pivot bushings.

If the suspension pivots were torqued at the unloaded extended position, the bushings will be ruined due to the excessive twist up in the rubber bushings.

I recommend you discuss the procedure used to torque the suspension with the installation shop. The suspension may need to be first loosened then retorqued at the loaded ride height.

[tHatOne guY]

Actually, 30 lbs, front and rear, is what is recommended. I'm running Michelin 215 55 R 16s. I imagine that the Koni shocks will eventually loosen up a bit.

I see. I assumed you were on the USP 18s.

I certainly would agree the suspension pivot points would need to be re-checked and torqued at static ride height level.

[jesse500]

Koni FSD dampers are definitely not firm riding.

Who did the installation of the Koni FSDs? A crucial requirement of the install procedure, the suspension pivots points must only be torqued with the suspension at the loaded ride height position. If the suspension was torqued with the suspension at the fully extended unloaded position, the resulting ride qualities will be harsh and stiff, due to the excessive wind up in the rubber suspension pivot bushings.

If the suspension pivots were torqued at the unloaded extended position, the bushings will be ruined due to the excessive twist up in the rubber bushings.

I recommend you discuss the procedure used to torque the suspension with the installation shop. The suspension may need to be first loosened then retorqued at the loaded ride height.

This was my guess reading the OP's first post.

[Cousinphil]

[QUOTE=diagnosticator;11568758]Koni FSD dampers are definitely not firm riding.

Who did the installation of the Koni FSDs? A crucial requirement of the install procedure, the suspension pivots points must only be torqued with the suspension at the loaded ride height position. If the suspension was torqued with the suspension at the fully extended unloaded position, the resulting ride qualities will be harsh and stiff, due to the excessive wind up in the rubber suspension pivot bushings[QUOTE]



####The installation was done by a professional auto repair shop in Ellsworth, Maine. Today I went back and talked to them about the shocks and they said the Diagnosticator is absolutely right about the installation process and they reassured me that that was exactly how they had done it. I have been driving on these brand new FSD shocks for a week now and they are definitely loosening up. Having the tire pressure a few pounds above 30 contributed to a harsh ride but that wasn't the whole story. After I had adjusted the tire pressure the shocks were still much firmer than the old stock shocks which were by no means worn out. But I've been tearing up the roads getting around to pianos all over the map, and on some bumpy roads at that. And the ride is definitely getting smoother. The way they are now, I have no complaint with them. In fact, I've thrown the car into some long sweeping curves just to see how much body roll there was and the car feels great. Stable as can be. ####