[urq] Locking diff actuators - some history of options

[qshipq at aol.com]

 The problem I see with solenoids is that without constant tension on that dog clutch, the timer circuit could be too late.  The locking gear is very narrow, and very little 'relaxed' movement from fully locked on the dog fork, could prove catastrophic.  Exploring a lot of options back in the day, I see no reason not to use the vacuum actuators with the 'smart-box' found under the rear seat of any 91-94 rear quattro.  It defaults to off when the car is shut off, has the 'smart light' system built into the switch and graphic panel, and has been in my 83 urq without a single repair for almost 10 years now.  

BTW, I also looked at having the manual locking levers built, which used spring tension and locking notches to keep the levers in their locked position.  At the end of all the research and futzing around, I decided that Audi chose the right hardware for the job.  IME, the best way to keep a vacuum actuator living a long life, is to replace it's mounting screws with stainless.  The biggest failure with the actuators (other than overconfident mechanics thinking they won't break off the vacuum nipples with a clutch change), is the rusy screws eventually cause a crack in the housing, and it then fails.  I have several actuators on cars over 10 years old, working just fine with SS mounting screws.

More actualatorizing nerding

Scott J


 

 

-----Original Message-----
From: bob <bob at maxboostracing.com>
To: qshipq at aol.com
Cc: cody at 5000tq.com; larichard at plguide.com; laraa at sympatico.ca; vittorio at mybares.com; urq at audifans.com; quattro at audifans.com
Sent: Fri, Feb 12, 2010 4:46 pm
Subject: Re: [urq] Locking diff actuators - some history of options


  Thats exactly right... in version 1.0, when you hit the diff lockbutton the solenoid engaged, but I found that with an adequate floggingthey would eventually come undone.  Version 2.0 had a timer circuit init, that kept pulsing the solenoid a few times a second to keep itengaged, and it worked perfectly.
Bob