FSD and Eibach woes

[Lemon3]

This is my first post but really hope someone can help with this one as i have searched everywhere
and my experience seems to be at odd with what others are saying about the above combo

I have a 2007 A4 B7 Avant 170 TDI only 35k on clock (standard suspension originally) which my mechanic fitted with the Koni FSD and Eibach Pro spring combo
and also fitted an RS4 anti-roll bar.
Driving away, the car seemed much better than with the standard suspension and initially I was happy with it.
On normal roads it seemed to sit quite well and go nicely around corners,
but if I meet a depression or rise in the road, the car will lose its composure,
throwing me from side to side in the car it will dip and rebound aggressively,
taking almost takes a few second to get composed again.
A lot of energy from the road seems to be transferred to the car rather than
being soaked up by the suspension. I got my mechanic to take 1.2 inches off
the bumpstops in case it was hitting them, but this doesn't seem to have
improved matters.
My last car was a Golf Mk4 150 TDI, remapped to
about 190bhp. It was fitted with Koni Sport (yellow) and Eibach Pro Springs, which
I really loved. The car stuck to the road and was predictable no matter what was
thrown at it and although it was a bit firm it was not uncomfortably so.

Any help on this would be appreciated.
Thanks

[koolade9]

What specs did you have it aligned to afterwards?

[wpod]

I love it. I also added a Neuspeed REAR anti-roll bar and I don't experience any of the problems that you describe. Is the RS 4 bar that you refer to a front or rear sway bar? If it is a heavy duty FRONT anti-sway and you didn't change your rear sway bar to at least 22mm, that might be your problem . On my Passat wagon, in stock form, there is NO sway bar in the rear, so the Neruspeed really tightened things up.How long ago was the work performed, I'd double check all of the fasteners just to be sure nothing came loose. I'm quite sure that you will figure this out. Good Luck, regards, Paul

[Lemon3]

Thanks for the replies. I upgraded the rear sway bar only from an S-Line bar. all the work was completed at the same time, Sept 2010. I have about 3,000 miles on it since. The wheels were laser aligned at my local tire centre. I didn't specify any requirements just that they were checked for alignment as I had new suspension fitted.
The thing is, the car corners nicely and handles pretty good most of the time. But any change from a smooth surface and it gets hairy.

[wpod]

I upgraded the rear sway bar only from an S-Line bar. Not sure I understand what you are saying here, Does this mean that you removed your stock rear sway bar and replaced it with an S-Line rear sway bar? If so, is the S-line swaybar the same thickness as an "S" rear swaybar (17mm?). If so, than you need to know that the Hotchkis rear sway bar is 22mm thick (but hollow) and is adjustable in that it has two settings. I recently purchased a 2002 S6 and installed the Hotchkis antisway bar kit beginning with the front bar. I drove it around for a hour or so and at that time realized that I didn't want to postpone the install of the rear bar due to the handling characteristics. I can't guarantee that a bigger/thicker rear bar will cure your problem, but I'll bet that it helps at improving the overall situation. Good Luck and please keep us posted on your progress. thanks, Paul

[Lemon3]

Hi Paul

Thanks for the input. I didn't change the front bar. The rear sway bar i had fitted is standard on the B7 RS4 and is 22mm in thickness. The car had a standard S-Line bar fitted when i bought it, the S-Line bar is 18mm, the S4 bar is 20mm and the standard SE bar is 16mm. Maybe the fact that the RS4 bar is so stiff is why I'm getting the harsh ride. I'm also on 18" wheels which probably doesn't help matters. Lets be clear here, i'm not talking about on the edge driving and pushing the limits of the car, I'm talking about fairly normal stuff with my family on board. I would love to find someone who has a similar setup to me and let them drive my car, but im a bit isolated here in the west of Ireland.

[Mike@PureMS]

What you're feeling is a bumpstop problem.
Did you start with non-sport, or sport bumpstops?
Did you trim them?

When the FSD shock encounters the bump stop, it gets rock hard, and makes the car feel like crap.
It's why I hate and never recommend FSD shocks with ANY lowering spring. Even the Eibachs. Stick with the KONI Sport shocks with any lowering spring.

[jj_estrada]

What you're feeling is a bumpstop problem.
Did you start with non-sport, or sport bumpstops?
Did you trim them?

When the FSD shock encounters the bump stop, it gets rock hard, and makes the car feel like crap.
It's why I hate and never recommend FSD shocks with ANY lowering spring. Even the Eibachs. Stick with the KONI Sport shocks with any lowering spring.

Mike, I actually bought my FSDs from you this past summer. With all the reviews I must have missed the comments about not mixing them with lowering springs. I put them on with my H&R sports on my 2000 A6 4.2L. Unfortunately the Koni installation instructions must have been written by the same people from IKEA. All pictures no text. I have the stock sport bumpstops on the Konis and I have had a few issues with bottoming out on a few roads in Chicago. When you say trim the bumpstops, how much do you recommend trimming off? Will that increase my chances of damper failure?

As far as alignment specs, I haven't had the alignment done yet since I lowered the car. I haven't driven this car much this year. When I bring it in, where or who can I get the specs needed for laser alignment if it differs from stock specs?

[Mike@PureMS]

Unfortunately the Koni installation instructions must have been written by the same people from IKEA. All pictures no text. I have the stock sport bumpstops on the Konis and I have had a few issues with bottoming out on a few roads in Chicago. When you say trim the bumpstops, how much do you recommend trimming off? Will that increase my chances of damper failure?

As far as alignment specs, I haven't had the alignment done yet since I lowered the car. I haven't driven this car much this year. When I bring it in, where or who can I get the specs needed for laser alignment if it differs from stock specs?

Funny you mention Ikea, since both KONI and Ikea are Scandinavian companies. lol.

I'd trim about 5-10mm off the bumpstops if you have the factory sport stops. It'll help the problem, but won't eliminate it. It won't have any effect on the lifespan of the shocks. Encountering the bumpstops on FSD's is probably more detrimental to the shock.

For the alignment just have them put the specs as close to stock as they can. They'll have some limitations, but that's a good starting point to try to achieve.

[Lemon3]

Thanks for the input Mike.
I had standard suspension originally, so it probably had standard bumpstops. i got my mechanic to cut 30mm off all round in line with the 30mm drop of the Eibach springs.
I like the slight drop of the Eibach but i'm seriously thinking of putting the original springs back in with the FSD's

[shoppingcart111]

I had FSD's on my B6 saloon with H&R springs and it was downright scary on certain bumps, the rebound seemed way to aggresive to the car and had to remove them. Went back to OE sport shocks till my Bilstiens arrive. I heard the FSD's were better on the wagons though.