what effect does strut-tower brace have on '88 80 Quattro? (a nd other stuff)

[Kaklikian, Gary]

I've heard the same theory about the front strut tower brace, although I
have an aftermarket one on my 4000 and the factory one on my other car.  I
can't tell you how effective the strut tower brace is without other changes,
because it was part of many simultaneous suspension mods to my car. I also
plan to have a rear brace installed when the rollbar is welded in.

 But,  my alignment guy, who has a lot of experience with pure race cars,
tells me the weak link in the front suspension is the upper strut mounts.
You should be using the blue UrQ upper strut mounts at least in the front of
the car if not all the way around. Blau also sells a similar upgraded rubber
mount.  Also, I have searched for upper strut plates with spherical bearings
for my 4000 to no avail, although rumor is an Audi tuner will have some
available shortly.   

I use a very sticky, well worn street tire on the track and have never had a
problem with chunking. And I do run the front pressures 5-7 lbs higher than
the rears.   In my one experience with track tires on this car - Kumho
V700's - I toasted both front tires in one day at the track.  The outside
shoulders got so hot the tread delaminated.  I attributed this to both
non-optimal alignment settings and failure to heat cycle the tires properly
(but I may have been overdriving the tires or they may simply have been too
narrow as well.)  So, I would think a competition tire would be more
susceptible to damage from a heavy understeering Audi than a street tire.
If you're making primarily left hand turns, it would make sense that the
right front would take most of the abuse.

I plan to try the Kumho's again as soon as I figure how how to fit a decent
size tire under the 4000's fenders. But, I've spent a lot of time minimizing
the understeer on the car,  so hopefully the fronts wouldn't take the abuse
they did previously.   Plus, I'm going to run -1.5 deg camber in the front
and possibly a slight amount of toe-out.  In your case, the rear swaybar
should have helped, but you also need to make sure the front suspension is
sufficiently "stiff" to minimize roll, camber changes, etc. Check your upper
strut mounts (blue UrQ?), control arm bushings (delrin),  swaybar bushings
(urethane for subframe attachment), alignment settings,  and of course tire
pressures. There are others on the List will a lot of experience racing
nose-heavy front-drive cars with strut suspensions. I think they'll agree
stiffening the front suspension helps reduce the load on the front tires.

HTH

Gary Kaklikian
86 4ktq
92 S4


 

> ----------
> From: 	Tessie McMillan[SMTP:tessmc at drizzle.com]
> Sent: 	Sunday, July 15, 2001 12:18 PM
> To: 	Quattro at Audifans. Com
> Subject: 	what effect does strut-tower brace have on '88 80 Quattro?
> (and other stuff)
> 
> Hi listers!
> 
> All these problems I've had with street (and now competition) tires on my
> Quattro at SIR -- where I chunk JUST one tire: the right front -- have
> started me thinking about any more things I can do to stiffen the front of
> my car to even out tire wear. I have to admit I learned to drive on a
> friend's '87 911 Carrera that was totally bulletproof. So these problems
> I'm
> having with the Audi are ... challenging. And sometimes frustrating. No,
> it
> really BUGS the HECK out of me that I ruin specifically one tire and one
> tire only in half a day when I run at the track -- elevation change or
> not.
> 
> A friend of mine who is a mechanical engineer claims that adding a
> strut-tower brace to my car would not help tie the two sides together. His
> opinion is that the firewall already provides this stiffening, and since
> the
> strut towers are so close to the firewall, adding a strut-tower brace
> would
> not be increasing the stiffness beyond what the firewall actually does.
> 
> Does anyone have any comments on this? I DO have Blaufergnugen's 22mm
> anti-sway bar in the rear (which is AWESOME, I HIGHLY recommend it). If I
> added a strut tower brace, would this undermine the improvement I've
> achieved in the rear? I've also lowered the car all around, but I have not
> stiffened it. Should I try stiffer front struts? Or do I need to go with
> all
> four stiffer struts?
> 
> Take care -
> 
> Tess
> in Seattle, WA, USA
>