[urq] Locking diff actuators - some history of options

[Keith Lloyd]

On my old coupe quattro (not sure what it was designated in the states) I 
had a problem with the rear diff lock not engaging. It wasn't a vacuum 
problem it was the linkage corroded at a pivot point. Once soaked in plus 
gas, dismantled, cleaned and reassembled it worked fine. It's worth just 
checking the how free the  mechanical movement is as well as for vacuum 
leaks.
Regards

Keith

'87 WR
----- Original Message ----- 
From: "Louis-Alain Richard" <laraa at sympatico.ca>
To: "'Cody Forbes'" <cody at 5000tq.com>; "'Tony Hoffman'" <auditony at gmail.com>
Cc: <urq at audifans.com>; <quattro at audifans.com>
Sent: Sunday, February 14, 2010 4:15 PM
Subject: Re: [urq] Locking diff actuators - some history of options


I'm sure you know it, but unlock can be slow if you have a tire of a
different diameter on the car (wear, underinflation, etc) so even in a
straight line, there is some rotational differentiation in the driveline. On
my urQ, unlock of center is instantaneous (thanks to the spring Scott spoke
of) but the rear usually needs to be helped by a little zig-zag.

Louis-Alain



-----Message d'origine-----
De : quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] De
la part de Cody Forbes
Envoyé : 14 février 2010 10:17
À : Tony Hoffman
Cc : urq at audifans.com; bob at maxboostracing.com; quattro at audifans.com;
qshipq at aol.com
Objet : Re: [urq] Locking diff actuators - some history of options

I'll hook mine up to the smoke machine next time I get a chance. I
just figured that was the norm because all of the 6 5ktq's I've owned
acted the same way.

-Cody (mobile)

On Feb 14, 2010, at 9:15 AM, Tony Hoffman <auditony at gmail.com> wrote:

> 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)
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