Re: 2-piece turbo manifold, mity vac

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

   Robert, I don't know for certain which is your text, but I have a question
   for the writer of the notes on checking the operation of the diff lock
   actuation.  IF it is you, please respond, if not, please forward it to the
   appropriate party.

'Twas not I . . . and don't know who 'twas either . . . 

   The Center diff doesn't lock on my 86 4kCSQ, but the rear does.  What
   problems did you have on yours?  How did you fix it?  Any ideas how to
   troubleshoot?

Are yours the vacuum-actuated type? Do you have a three-position vacuum
switch in the console that you pull (or turn on some cars I've seen) to
position one to lock rear, and then pos 2 to lock both?

On my UrQ, both vacuum servos are mounted on the rear diff assembly. The
rear diff lock has a nice short direct throw and locks/unlocks almost
instantly. The center diff lock however has this long snakecable that
runs half the length of the car from the rear-diff-mount position all the
way up to the "tranny" for the center diff lock. This incredibly stupid
arrangement leaves lots of "flex" in the "cable" (it's not a cable, 
really, but a "shaft" in a "sleeve", but it sure flexes like a frigging
cable!), and thus really shitty [pardon the Japanese...] diff lock ac-
tuation. There is some adjustment to try to take up the slack, but it
is an inherently loose design, in my opinion.

Also, being vacuum servos, the rubber diaphram will die after a few
(5-10 typical) years. The diaphram is separately replaceable (You don't
have to replace the whole servo), but ya gotta get to it first . . .
You can "test" the diaphram by hooking up your trusty MityVac to the
diff servo vacuum line and sucking it dry (so to speak) to see if it
holds vacuum, or just vents atmosphere through the cracked and kroaked
rubber . . .

And of course, Audi electrics being what they are, I'd place about as
much trust in the diff lock indicators being correct as I would in a
stock Audi being able to dust a stock 3000GT/VR4 . . .

Blah Humbug.

					-RDH