[urq] Locking diff actuators - some history of options

[bob]

No, its not that critical at all. Theres plenty of leeway. Besides, if 
thats a concern you can just power the solenoid for 100% duty cycle 
(with the right solenoid) and alleviate that problem.
Bob

qshipq at aol.com wrote:
>
> 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 lock 
> button the solenoid engaged, but I found that with an adequate 
> flogging they would eventually come undone.  Version 2.0 had a timer 
> circuit in it, that kept pulsing the solenoid a few times a second to 
> keep it engaged, and it worked perfectly.
> Bob
>