Car feels bumpy?

[edkellock at juno.com]

I experienced this in my V8.  I went from stock worn shocks to 
Bilstein HD's while I still had snow tires on.  When I replaced
the snows with Dunlop SP5000's.  I began to notice much more
low frequency bouncing around at sub highway speeds.  I tried
higher tire pressures and lower tire pressures to no avail.  Once
I changed to 17" wheels and tires the bouncy behavior went away.
I attribute it to the interaction between the firm shocks and the
15" Dunlops which allowed more sidewall flex than the 17's but less
than the snows.  After all, the tire is a part of the suspension system.
And it seems the Bilstein's and the those particular tires (compound,
size, etc...) were not quite compatible.

Ed
Colorado Springs

On Thu, 28 Jun 2001 07:45:57 -0400 (EDT) Andrew Duane USG
<duane at hunch.zk3.dec.com> writes:
> Hairy green toads from Mars made Martin Suryadarma say:
> 
> > I have a question about my 89 Audi 100. Lately I notice that 
> sometimes,
> > only sometimes, my car feels like it's riding on bumps especially 
> in
> > low-speed. Not huge bumps, but more like frequent small bumps. In 
> highway
> > speed it never happens, only during very slow speed like in city 
> traffic
> > driving. Again this doesn't happen all the time. 
> 
> I used to get this on my old '89 100Q and my less old '95 A6QA.
> I always assumed it was some kind of "resonant frequency" on the
> shocks that would magnify small surface irregularities.
> 
> I only noticed it after I put in new shocks (Boge Turbo Gas both
> times), not with the old worn shocks.
> 
> Never really bothered me enough to look into it.
> 
> -- 
> 
> Andrew L. Duane (JOT-7)                        duane at zk3.dec.com
> Compaq Computer Corporation                (603)-884-1294
> 110 Spit Brook Road
> M/S ZKO3-3/U14
> Nashua, NH    03062-2698
> 
> 
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