[s-cars] Suspension/steering stiffness question

[Ivan Demkovitch]

Taka,
 
You absolutely right. I still have original 15" wheels with all season tires that I use for winter.
Those feel much softer because of higher tire wall. But I see your point. Yes, it feels like
the change is in a suspension characteristics also.. I didn't weight those wheels, but my "arm dyno"
tells that there is not much difference.
 
I like my 17" wheels and not really planning on changing them. How should I change suspension components to accomodate?
Also, where fo I revalve Bilsteins? I don't think existing ones will work. They all rusty on a bottom (rear) and have 65k on them. Probably makes sence to get new ones.
 
What will be a good combo?
 
Thanks!

----- Original Message ----
From: Taka Mizutani <t44tqtro at gmail.com>
To: Ivan Demkovitch <idemkovitch at yahoo.com>
Cc: s-car-list at audifans.com
Sent: Saturday, April 8, 2006 10:19:29 AM
Subject: Re: [s-cars] Suspension/steering stiffness question

Ivan-
comments inserted within:


On 4/8/06, Ivan Demkovitch <idemkovitch at yahoo.com> wrote: 
List,

I'm about ready to overhaul suspension on my 93' UrS4

Currently car has 133k miles and PO installed Bilstein SP + H&R at around 75k.
My feeling is that shocks already done. Also, I don't like current stiffness. 

1. To me it's too harsh and I don't see this benefiting handling. It almost feels like wheels disconnect from the pavement on a
bumpy road when I go into tight turns.

However, I like ride height and hate to raise a car since it will look silly with my 17" RS4 style wheels. 

So... What do you suggest for suspension components? I like firm but soft ride. Not too much body roll but without go kart feeling.
Different springs? Shocks?

I think you're experiencing a few things here: 
1. Bilstein Sport and H&R spring combinations are not properly matched- the Bilsteins should ideally be revalved for the H&R springs. I believe this hypothesis to be correct due to my direct observations that the Eibach (lower spring rate)/ Bilstein Sport combo works very well- the damping is nearly spot-on for the spring rate. 

2. The 17" wheels you mention may be significantly heavier than your stock wheels- increased wheel/tire weight results in increased unsprung weight, which will cause ride quality to suffer. If you can, find someone to borrow some lightweight wheels & tires and see how that impacts your ride quality- I'll bet that ride quality will be improved if you reduce the weight of your wheel/tire combo. Easiest way to validate this (if you don't have big brakes) is to borrow a set of the 15" forged BBS ( 15x7.5" ET 35) from a '91 200q or '90-94 V8q- if the suspension seems to work much better due to the 15 lb. wheels and lighter tires (less crashing over bumps- the taller sidewall height will soften up the overall ride), then the heavier wheels/tires are not helping your goal. 

Personally, I think even the Bilstein/H&R combo is not stiff enough in roll stiffness, I'd definitely pull the shocks and have them rebuilt and revalved to spec through either the CT or CA offices of Bilstein USA. 

I would also replace the steering damper- if you use the Fox part, it's really cheap and will help reduce steering kickback over bumps.

I will leave the other suspension diagnosis to others who are much more qualified to answer. :-) 

Taka