[s-cars] RE: [s-list] Nose-down brake diving

[Richard Tanimura]

I think rear brake activation will not reduce dive at all. And if you bias
it wrong, you risk ugly trail brake oversteer which is spooky. I contend
that the last thing you want in a braking situation is to risk having your
rear end lock up as you begin to threshold brake on the front. Yikes.

Dive and squat are two expressions of longitudinal weight transfer. You get
dive when you brake because weight is transferred forward. You get squat
because weight is transferred to the rear when you accelerate. Note that you
will get forward weight transfer whether you brake with the front or rear
brakes or both. It is a function of acceleration, not which axel is doing
the work.

Two really good books on this are "How to make your car handle" by Fred Puhn
and "Tune to win" by Carroll Smith.

Rich

-----Original Message-----
From: s-car-list-admin at audifans.com
[mailto:s-car-list-admin at audifans.com]On Behalf Of CyberPoet
Sent: den 26 april 2003 08:19
To: russ at s-cars.org
Cc: s-car-list at audifans.com
Subject: [s-cars] RE: [s-list] Nose-down brake diving


I agree with Russ that rear brake activation prior to the front brakes
triggering would improve both the dive characteristics and the general
handling (provided you prefer to slide you car around like a rally
driver). But best way to help prevent dive would be to use a set of air
or hydraulic shocks with a linked pressure system (front to rear), a
booster driven by the brake pressure system, and a higher compression
ratio springs. I know that Monroe and Gabriel both manufacture such
linkable-shock creatures, although whether any of their solutions would
bolt up to the Audi is beyond my knowledge realms...  I suspect if you
pirate the system from the '04 RS6, you would have a guaranteed fit
system that does exactly that.
I could also see at least a few of our list members placing an
electrically driven air compressor and air shocks on their ride to
adjust the ride height in transit if it were available -- up 4" all
around for off-road, down 2.5" for high speed highway cruising --
hoopty thought it might be (doesn't the current avant have such a
feature built-in?). The real question is whether any list member would
ever admit to having done it to their non-avant... Owned a citroen once
that was similar and I liked the concept (although I detested that
everything was pneumatic -- including the wipers, the door locks, etc).

Cheers
=-= Marc Glasgow
Tampa's Best Mac Specialist since 1990
www.cyberpoet.net


Russ wrote:
I would think stiffer rebound damping would tend to make the suspension
"pack
down" and keep the nose down once it dives.  It seems to me that more
compression damping up front would resist brake dive.  My trick for
helping
reduce brake dive is fitting rear brake pads with greater initial bite
than
the front pads.  That ought to fuel some debate!

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