Mysterious metal block underneath engine

[molgrips]

On my AAZ, on the rear sub-frame there's a metal block about 6" square sticking out backwards, underneath where the downpipe comes down.

Wtf is it?  Some kind of vibration damping counterweight perhaps?

[gldgti]

you got it in one - its a dead mass presumably for changing some harmonic vibration frequency...

i actually recently pulled mine off, thinking "how much difference could it make?" infact, it has seemed to make a difference - i used to feel some mild steering vibration under high load (like driving up a big hill on the freeway) - now its GONE!

i'm leaving mine off.

[molgrips]

I'm getting a small amount of buzzing and noise at higher revs, when cruising.  I might experiment with it.  Maybe I can tune it some more by adding weight

Question is, why would it stop doing whatever job it was designed to do in the first place?

[mattbondy]

rust?

[molgrips]

The plan is to put the front wheels up on ramps and tie some string or something to the accelerator cable, so I can lie underneath the car and rev it up to 2.5krpm and listen for any noise.  Can't hear a thing from the top apart from normal engine noise.

[RabbitJockey]

my sisters 2.0 has one, i am curious what they are, made it a pita to get the passenger axel in.

[8v-of-fury]

my 91 golf donor car has this as well.. I like the idea of not having to move it over when i do the gas->diesel swap i am planning.