[urq] Locking diff actuators - some history of options

[qshipq at aol.com]

 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.

I just used one of the old push pull vacuum switches (known to leak and make noise) on the Steamboat urq rear diff (only) and it would engage/disengage within a several feet, at 6900 feet and WOT.  26 year old actuator, new hose, and a dedicated IM feed to the switch.  IMO/E, I've seen a lot of folks bitch about the vacuum actuator system in the Audis.  Less than an hour with it and some really basic hand tools, can make it function like new, just btdt.  Don't mistake simple maintenance of a simple circuit for 'failure', or a reason to pursue something someone else thinks is 'better'.  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-----
From: Cody Forbes <cody at 5000tq.com>
To: qshipq at aol.com <qshipq at aol.com>
Cc: vittorio at mybares.com <vittorio at mybares.com>; bob at maxboostracing.com <bob at maxboostracing.com>; larichard at plguide.com <larichard at plguide.com>; laraa at sympatico.ca <laraa at sympatico.ca>; urq at audifans.com <urq at audifans.com>; quattro at audifans.com <quattro at audifans.com>
Sent: Sat, Feb 13, 2010 8:45 am
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)