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Poor alignment can cause the rear to feel 'loose' when changing lanes, etc. Is that what you’re referring to?

Also, your rear swaybar may have pulled from one of its mounts adding to a softer, more bouncy feel.
Vibration? It could be several things.


Find yourself a local tire and brake shop that handles the local race crowd if you can and have them put their most qualified to the task of a full checkup with test drive.
 

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Sweetsound2001 said:
Greetings all.

I have a 00 MY and my shocks were gone @ 77k. The car felt really unsettled over bumps and had a lot of body roll. Additionally, when I would hit a bump, the whole rear end would move side to side. It almost felt like it would lose control.

I had brand new Koni adjustables installed with the stock springs. I had them set at 1/4 turn from full soft. Now the car rides really stiff and the rear end is still doing that side to side motion. It also feels very bouncy when I hit speed bumps, etc.

Is there something else going on in my suspension that could be causing this problem? Sometimes I also experience a vibration between 50-65mph when driving. Are the Konis supposed to be so much stiffer than the stock shocks even on the almost softest setting? How can I make my suspension feel much tighter and composed...any thoughts are greatly appreciated.


Anton
The vibration between 50-65 is it there all the time or just when braking?
 

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1. Check the sway-bar brackets and links both front and rear. Look for broken brackets, cracks and play.

2. At 77 k miles, the rubber bushings (at least rear) are very likely ready for replacment.

Put the car on a lift. Have a really strong and heavy guy push and pull at each wheel in turn with full force, while a skilled mechanic checks for play in the rubber bushings. There should be zero play, just smooth damping.

David
 

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Discussion Starter · #6 · (Edited)
Thanks guys.

Actually, one of my sway bar brackets was replaced about 6 months ago. I checked them again last night and they're both good. The weird thing is that even with brand new Konis in the rear, when I go over a bump, rear end feels loose. On large bumps, not only does it go up and down like it should, but it feels like the whole rear of the car moves sideways.

I used to have a vibration in the steering, and had my front control arm bushings replaced, which cured most of it. Are there similar bushings in the rear that may be worn out and causing this problem?
 

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Discussion Starter · #7 ·
quickenough said:
The vibration between 50-65 is it there all the time or just when braking?
It seems like there is some slight vibration under hard braking.
 

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As the shock-absorbers (dampers) gave up, everything else in the suspension has been working hard too.

Apart from the rubber bushings, it could also be a loose or missing bolt among the rear-subframe or diff bolts.
Although unusual, it could even be a broken sub-frame. Look for cracks at the mounting points.

Does the car feel symmetrical between left and right hard turns?

David
 

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The Koni shocks are not the problem, unless the mechanic doing the work accidently set them to 1/4 turn from full stiff. They are great when set under 1 turn from full soft...or lower. Your rear Konis don't create such overdampening symptoms, even when installed on 525i cars that weigh 500 lb less. That said, the Koni's will NOT offer you a wallowing, underdampened ride quality like you felt with your blown out 77K mi shocks. If you became accustomed to that ride quality, you will only get that in a Lincoln Town Car or shocks with no hydraulic fluid in them.

I would advise you to have a professional mechanic test-ride and examine your car for problems. There is no way to diagnose this problem peering thru a PC on the web. An experienced E39 driver with Koni's could test drive and advise you whether the mechanic erroneously set them near full firm.

If the rear end of the car is side-stepping on the street as if something is defective, you have a serious suspension problem. My car did not even do that on-track hitting bumps at 120 MPH with Koni's foolishly set over 50% stiff.
 

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I'm going to bring up an old thread here..

I just recently installed Konis all around - well actually in steps. I did the fronts first, because they were easier to get out. I didn't know what to do with the bump stops because the stock suspension's shaft is slightly thicker, so the bump stop isn't tightly in there. There's also a metal piece above the bumps stop that I put back in, but now it makes a rattling soud - at least I assume this is what makes a little clink in the front end, as it was loose going in. So besides those issues, I felt great about the front end. Suddenly little to no brake dive and felt a lot more flat around the corners. One of my stock dampers was definitely bad at 130K, as it didn't have the rebound that the others did. However, because of the bump stop issue, I might take these out and figure out something else with those.

A week later, I got around to doing the rears. It was definitely a lot more involved. I held the Konis against the floor and did my best attempt to set them 1/2 turn from full soft. When I pulled the rears out, neither stock shock was obviously bad like the one front. I went ahead and threw the new Konis in, but sadly neglected to install the new shock mounts I had bought. I put the whole mess back together, and at the same time installed some BSW speakers in the back and eliminated a rattle from the decklid. Speaking of rattles - if you have a decklid rattle that seems to go away when the rear window shade is up, check the CHMSL. It is held in place by an easily accessible nut from the trunk, and moving the light towards the window cured my rattle.

Anways, now to first drive - I noticed a bit of bouncing around from the rear. While big road bumps seemed to be handled well, little pavement imperfections now seem to be repeated a couple times. I am now wondering if my shock mounts are actually causing that bouncing. I haven't heard of bad shock mounts contributing to slight bounciness (usually they seem to 'clunk' or something like that). The other thought is maybe I need to set the shocks a bit stiffer, maybe there is an underdamped response to small bumps. I have to say the stockers seemed to have better damping for the small bumps. After this experience, I might have just gone with some externally adjustable coilovers with front camber plates. I'd like to be able to set my caster/camber in the front, and I'd like to be able to tune the compression/rebound characteristics better. I'm going for a critically damped to slightly overdamped suspension response. Definitely don't want underdamped, but I'd like to not have it too firm either. Is the best answer to sell my Konis and go for the PSS9?

Any ideas?
 

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I kinda want to figure out what I need to do because I still haven't gotten my wheels realigned. It doesn't feel way out of alignment, except perhaps a little bit of wandering on the freeway.
 

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50-60mph vibration/noise is rear ball joints. $80 for parts, $250 labor at an indie.
 

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I don't suspect the rear ball joints at this time - I did a check on the rear wheels and couldn't find any play as described at http://www.beisansystems.com/procedures/swing_arm_ball_joints_procedure.htm. That said, since I do have 130K miles, I wouldn't be surprised if they were on the way out, and the parts aren't a lot.

However, I am interested in this underdamped response to small impulse bumps. Could the rear ball joints contribute to some bouncing? Would people recommend I keep the Konis at 1/2 turn from full soft while replacing the shock mounts and rear ball joints? I'm wondering if I need perhaps 3/4 to 1 turn?

Has anyone else felt that Konis were somehow bouncy in the rear? I don't mind a stiff response, and maybe it is the tires that are bouncing? I have Continental DWS tires, perhaps they are contributing to a bounciness. I have 40 psi in the rear.
 

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