Re: Low grade rumble at idle when center diff locked

["Jeff Goldberg" <jeffgold@erols.com>]

Steve,

Thanks for the reply. Still trying to digest the info in an effort to
understand hoe the diff lock actually works.

BTW did you get that strange chain letter?? Wonder how that got started.

Thanks,

Jeff
86 4KCSQ Daily Driver
86 4KS      Spare
----- Original Message -----
From: Buchholz, Steven <Steven.Buchholz@kla-tencor.com>
To: 'Jeff Goldberg' <jeffgold@erols.com>
Cc: 'qlist' <quattro@audifans.com>
Sent: Tuesday, December 14, 1999 5:11 PM
Subject: RE: Low grade rumble at idle when center diff locked


> > Can someone explain to me where this rumble sound / vibration is coming
> > from? What effect should a locked differential have on an idling engine
in
> > neutral? There is certainly something I am not understanding here. Can
> > anyone help? - 86 4KCSQ
>
> I've experienced that on my ur-q and a bit on the '85 4kSQ.  Check your
> engine, tranny and rear diff mounts.  Since clutches last so long in these
> cars, tranny mounts are usually still original.  When I did the clutch on
my
> '85 (@ 206K miles) there wasn't much left of the tranny mounts.  Remember
> that when you lock up differentials you can actually build a static torque
> between wheels and drivetrain.  This can end up causing driveline parts to
> move relative to the body of the car ... even with the car idling in
neutral
> ...
>
> HTH!
> Steve Buchholz
> San Jose, CA (USA)