[urq] Locking diff actuators - some history of options

[Cody Forbes]

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)

On Feb 13, 2010, at 9:35 AM, qshipq at aol.com wrote:

> The problem is unless locked and unlocked positions are energized  
> all the time, there is no "constant engagement" by definition.  In  
> every locking diff design I've seen (including Audi and Toyota  
> factory lockers), constant engagement is with a 'stop' for the dog  
> clutch fork, in the lock and unlock positions.  The two stop  
> positions are assured by either spring detent pressure (with worm  
> geared motor - toyota) or constant engagement (early audi manual  
> spring detent design, and later vacuum actuator design).  I suppose  
> you could use the spring design found in the pre-84 urqs on the  
> actuator rod to assure 'unlock' hold.  Easy to retrofit that to 84>  
> lockers.  But that would require constant energizing in the lock-on  
> position.
>
> Back when I looked at the solenoid locking option, I saw issues with  
> it's intended design.  Along with the concerns above, all locking  
> actuators should have a spring type cushion to allow a buffer for  
> equal gear speed.  In the vacuum actuator, the diaphram is the  
> buffer, in the toyota worm gear, it has a spring built into the  
> actuator rod.
>
> Can a solenoid work?  Sure.  Does it potentially have design  
> drawbacks over the vacuum actuator?  Absolutely, as fully unlocked  
> and fully locked dog clutch positions are not assured in a solenoid  
> system.  I'm not sure I really understand the need for solenoids.  A  
> properly functioning vacuum actuator has proven to work for millions/ 
> billions of miles in the audi.  You like electric switches?  Use the  
> 'smart box' found in the 91-94 rear diff actuators.  Put a (extra)  
> momentary contact switch for each diff where-ever you want.  Heck,  
> you could even put a ground diff-lock disable circuit (blue white  
> wire) in during braking.  Here's a early shot of the dual electro- 
> pneumatic locker setup I installed in my old 83
> http://forums.audiworld.com/album.php?albumid=37342&pictureid=46522
>
> At some point we need to look at that solenoid idea, and wonder why  
> it's not used in production/aftermarket locking diff actuation.
>
> Scott J
> 84 urq
> 83 urq ice track car
>
>
>
> -----Original Message-----
> From: vittorio at mybares.com
> To: bob <bob at maxboostracing.com>
> Cc: cody at 5000tq.com; larichard at plguide.com; laraa at sympatico.ca; urq at audifans.com 
> ; quattro at audifans.com; qshipq at aol.com
> Sent: Sat, Feb 13, 2010 7:39 am
> Subject: RE: [urq] Locking diff actuators - some history of options
>
> Confirmed - I found a pre-built circuit that allows adjustment of  
> rate and duration of the pulse. So when when the switch is in the on  
> position it pulses to ensure constant engagement.
>
> Then some switches that have momentary-on, and constant on (DPDT) -  
> that allows to hit the momentary to unlock, and constant on to  
> engage the timer circuit to keep it locked.
>
> I like the idea of the buttons on the steering wheel - but that'll  
> be in a later version.
> -------- Original Message --------
> Subject: Re: [urq] Locking diff actuators - some history of options
> From: bob <bob at maxboostracing.com>
> Date: Fri, February 12, 2010 3:46 pm
> 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
>
> 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
>
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>