re: thunk sound/ Possible cause: improper towing?

[jkerouac@xxxxxxx]

re: thunk sound in E36
Ron,  you are the first person beside myself who used the word thunk to
describe a mystery thunk from the rear suspension.  Maybe your solution
will be the same as mine was.
    It drove me as nuts as you, and it was no fun driving an //M3 no
more spirited than a 318 with worn shocks for fear of something letting
go.
    The problem I found was a bent lower rear control arm on the rear
suspension.
The arm bent in a twisted manner so that one of the two split sections
was about 5 mm higher than the other.
When the suspension compresses then the bottom of the rear swaybar link
thunks its was into the gap between the two control arm segments.
    Most common cause:  A__hole tow truck operators who use big winch
hooks on the control arms rather than properly using soft winched fire
hose type fabric straps on the rims.
    Easiest way to diagnose:
Remove tire.  Unbolt shock bottom.  Look along length of top surface of
control arm to see if there is a scraped, rubbed, or gouged surface on
either the top of the seam of the control arm or the bottom of the sway
bar or link.
Also from directly underneath, look straight along the bottom of the
control arms.  The front and rear sections of the arm should be
perfectly flat and straight to each other.  Also the front section just
inside from the camber adjuster may show an obvious bend, especially
when compared to the arm on the other side.
    To see if an a__hole tow truck operator may have hooked your arm:
look on the plastic cover that snaps onto the leading edge of the arm.
You may see compression squeeze marks or dimples on the plastic cover.
    The bent control arm due to improper towing is a common problem,
locally Dinan's shop keeps a supply of these arms in stock.
    In my case, the tow operator was professional enough about it, and
had a AAA representative arrance an independant inspection at a AAA
approved repair shop, one that specializes in high end German cars.
    If the tow was AAA, seems AAA has a tow it right or fix it attitude
to its agents.
    My suggestion to the list if your car is getting towed is to watch
the car being set up on the flatbed, insist on a flatbed only, and only
with strapped rims or T hooks in the slots in the floor where the jack
pads snap into.
    In my case the tow guy was pulling the front bumper correctly with a
cable winch, so I went insid efor a minute.  Sure enough I come back out
and he's got that grappling hook yanking on the control arm.  Not enough
time to do it right but plenty of time to do it over?  His laziness is
costing his shop a few hundred dollars.
I had him remove it, and eventually AAA sent another tow shop who
strapped my car correctly.

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