[urq] Locking diff actuators - some history of options

[Tony Hoffman]

Cody, and all,

I've owned over 10 Quattro's over the years, all the old two locker
setup, with the exception of the V8. It has Torsen rear and an
exectronic locker in the center.

I'll have to 100% agree with Scott on this one. If your vacuum lockers
aren't working properly, it's a vacuum issue. You have a leak
somewhere, either the actuator on the locker, a line going to it, or
something in the feed of the switch (including the check valve). Check
the front actuator closely, I've seen them have a hole worn in them
(don't recall from what) and slightly leak. That's on the disengage
side of the center actuator on an 85-87 4000Q, BTW.

Two of the ones I've owned had slow unlocking, and they both turned
out to be a slight vac leak. One of them was the check valve. That one
took half the trip back from WI to OK to unlock. If they are
functioning properly, they are almost instant in their action. And, as
Scott said, they are constantly held in place. That's a pretty big
deal when you tear into one and see what the design is. I'd sure hate
to have one slightly engaged on wet/gravel and hit the power hard. I
can just imagine what it would do to the locking mechanism. The
Germans tend to overbuild things, but even the strongest design is no
good when abused.

Tony

On Sat, Feb 13, 2010 at 10:02 AM,  <qshipq at aol.com> wrote:
>
>  Cody, a properly working vacuum actuator is instant, with enough vacuum, btmt.  A second or so to turn on is normal, as the 2 gearsets have to be traveling the same speed for engagement.   A mile to turn off, you have another problem, likely due to low vacuum.  First, make sure your ck valve is working properly.  I just replace them (Napa/autozone sells generics cheap).  Second, make sure you have no leaks in the vacuum system.  Old connecting rubber hose is the biggest culprit.  Then ck the actuator itself, it should hold vacuum on both nipples.  A strategically cracked housing can cause one side of the actuator to be good, the other not.  Lastly,  if running a lot of boost environments (track or mountains) find an old vacuum resevoir from any car (I like the egg crate style vw ones) and T it into the system.
>
  That actuator circuit is simple, bulletproof, and requires very
little maintenance to function in a full race abuse environment.  btdt
>
> HTH and my .02
>
> Scott J
>
>
> -----Original Message-----
> Subject: Re: [urq] Locking diff actuators - some history of options
>
>
> The only thing I see wrong with the vacuum actuators is that they are slooooowwww. My 5ktq takes a second or so to turn on, and sometimes takes a mile of driving to turn off. That doesn't do the job when you need it to turn off on corner entry then on again within a few tenths of a second.
>
>
> -Cody (mobile)