S4 big brakes - new wheels won't fit
glenahan at vfemail.net
Sun Aug 20 15:18:32 EDT 2006
Let's start with the basics. Changing offset may be OK, but it is not
desireable. It changes both steering and suspension geometry, and
unless you think Audi made a terrible mistake that you are correcting,
not for the better. You'll get lots of incorrect advice, mostly from
wheel shops, that you can and should change offset to clear brakes and
other obsticles. That said, small changes - on the order of 5-10mm,
should not have a big negative effect, but I have felt it, and it will
- minimally - increase kickback, increase strain on all suspension
mounting points, decrease the effective springing and damping, and
increase scrub radius and thus scrub. If you are wondering, do a mind
experiment and place the wheels at the end of 5 foot spacers. Think
abou;t how they would travel, especially when the steering knuckle
turned on a pivot point 5 feet inboard of the wheel center. Extreme?
Yes, but exactly what is happening on a smaller scale. Do the math.
'nuf said on that topic.
Spacers are simply a means of changing offset. They have the added
problems of doubling the opportunity to get an eccentric mounting and
create balance and runout issues. Plus it weakens the mounting.
But if you are intent on proceeding, at least get the facts. Your S4
should have an offset of -45mm, regardless of wheel size (again,
despite what you will hear, since its measured from the centerline).
What is the offset of the ones you got? They may be offset less (more
negative, say -50mm) or, more likely, they will already have added to
your offset by 5-10mm, since -35mm was a popular offset for the larger
Audis, such as the S6, A6 2.7t and others. So if you were to space
that out, you would be adding the spacer width to the 10mm
(-35mm-(-45mm)) = 10mm you might ALREADY be offset.
Generally its best to solve these problems with wheels that have a
spoke shape that accomodates big brakes.
On Aug 20, 2006, at 1:57 PM, Lincoln Rutledge wrote:
> My friend upgraded his S4 brakes, he calls them Big Reds. I'm sorry, I
> don't much about them. I believe it's a 2002 model.
> Anyway he got some new 18" wheels, I believe off a newer car (A6
> maybe?). When we went to bolt them on, the face of the caliper hits
> inside of the spokes of the wheel.
> Now he is thinking spacers.
> Is that a good idea?
> Does anyone have an idea how big they should be?
> Will they make the tire hit the wheel well on the lip?
> I can get more specifics.
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