[urq] Locking diff actuators - some history of options

[qshipq at aol.com]

 I'm not sure tire diameter has much to do with this as much as inHg in the system, and gear load.  IME, you can predict rear locker disengagement with a quick blip of the throttle.  If the tire diameters are different, you should have the same time engaging as disengaging the lockers.  Engagement and disengagement should be 'quickest' in a straight line.  IME2, just about every locker I've seen needs maintenance of some type.  Yes, the rear linkage should be lubed, because it sticks.  I didn't mention it because Cody claims it engages right away.  IME, a stuck linkage will usually stick in the disengaged position.

Figure 8's, and all the other notations here, indicate to me that many are low on vacuum in the locker circuit.  Get the highest vacuum you can in the system.  If you start there, you will find that locking and unlocking the diffs can be instant, and that the minor variable is gear load to inHg vacuum, not tire diameter.

Put a vacuum guage in the circuit, IME 15inHg is the lowest to engage a locker, and 20 something to disengage.  If you measure a constant 20+ in Hg, chances are you won't have to do anything fancy to get engagement or disengagement of your lockers.

My .02

Scott J




 

 

-----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; bob at maxboostracing.com; quattro at audifans.com; qshipq at aol.com
Sent: Sun, Feb 14, 2010 10:15 am
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