Dashpots

[Huw Powell]

> Now what exactly is this dashpot everyone is ranting about?  Is it the
> stop for the linkage?

on my 90Q it prevents the throttle from slamming shut when you lift
off.  That is, the last few degrees of motion are damped when part of
the rotating gear underneath it contacts the dashpots plunger.

> I think it's time one or two people actually STUDIED how the
> dashpot works and what it does.  The idea that it somehow
> got left in there when Audi converted from carburettors is
> ludicrous.

well, yeah, considering they weren't on most of theearly 80's cars I've
owned/seen...

> It doesn't slow the operation of the idle switch at all - quite
> the reverse.  It allows the idle switch to close rapidly but
> slows the butterfly valve, giving the ISV time to react.

the one on my NG motor (90Q) does.  letting go of the throttle the last
motion is slowed down and the switch does not close until the throttle
is actually shut.  It damps the same lever parts that actuate the
switch.  Now this may not be correct, of course!  I have seen many TB's
where the rotating parts seem designed to move independently of each
other, but don't, so it could be that there is some independent motion
that is not happening any more.  This is a 215k mile rust belt car,
after all...

> 
> If the system isn't working properly, removing the dashpot
> just breaks it more.  Introducing a compensating error
> because you're not up to fixing the real one is not good
> engineering.

and so what exactly is the purpose?  because once one understands the
purpose and function, one can alter it to suit taste if all else is in
order.

> Dashpots do wear, and often need to be advanced a turn or
> two to compensate.

in the direction of starting to damp the throttle sooner, ie at a wider
open angle? This is prolly in Bentley, I should look it up.  heck, if
there wasn't an engineless 4kq in the way, I'd opent he door and pull
the 90 half in to the garage and play, it's so nice out today...

-- 
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/