UrQ PMS, Wheels, Offsets

[rdh@sli.com (Robert D. Houk)]

My UrQ has developed yet another bad habit. Starting a coupla days ago,
at highway speeds (60-70mph, won't do it at 55mph, yet anyways...), the
front end will intermittently (and irreproducibly) start a violent vi-
bration that lasts for 1/4 second to maybe a coupla seconds, then smooth
out again. It's much higher frequency than wheel rotation (as if I had
thrown a balance weight), like I was suddenly on corrugated pavement.
Nothing I can do seems to instigate the misbehavior (except staying be-
tween 60mph to 70mph), throttle on, throttle off, coast, neutral, curving
left or right or straight. The car doesn't seem to pull to the left or
right during these episodes; the steering wheel is not yanking right or
left especially hard, although I can feel the vibration pronounced via
the steering wheel. Put the car up on a lift and pulled/poked/prodded/
yanked/pounded/andotherwisetriedtoperturb tierod ends/ball joints/subframe
mounts/struts/bearings/etc/andsoforth, nothing seemed amiss. The strut
top bearings/mounts are worn and will be replaced in a week or so, and
the left outer CV joint "might be just a tad loose/worn but nothing un-
usual" (short of actually taking it apart!). I have this feeling that if
I immediately stomp on the gas or the brakes, the vibration stops (as a
result of my accel/brake action), but can't prove it yet.

Any ideas? Is this kind of behaviour the failure mode of CV joints? Dying
struts? Massive Cosmic Ray Flux?

Has anyone ever found adjustable [front] strut top mounting plates (to,
e.g., allow adjusting of camber, et al)? Just thinking . . .

I vaguely remember some past discussion on wheels and offsets for the
UrQs, but all I can find squirreled away is the following table:

> Type      Bolts     Bolt Circ(mm)  Dia.(in)  Width(in) Offset ET(mm)
> Ronal R8       5       112         15          6         45
> Ronal R8       5       112         15          7         37
> Ronal R8       5       112         15          8         24
> Ronal R8       5       112         15          9         12
> Fuches forged  5       112         15          7         45
> Fuches forged  5       112         15          7         20
> BBS crosswire  5       112         15          7.5       35
> BBS crosswire  5       112         16          8         35
> S2             5       112         16          7         37
> Fuches new S4  5       112         15          7         45
> Fuches new S4  5       112         15          7.5       40
> Fuches new S4  5       112         16          8         40

The ('83) UrQs use the Ronal "R8", right? Thus, I would want a 37mm offset
for, say, 16x7 wheels, right?

					-RDH