Having the viscous become overly aggressive after driving some distance is a sign the VC is failing. Severe enough you will get tire scrub and excess mechanical wear of the drive especially the front CV joints. VC failing this way is usually the sign of it being abused. Miss-Matched tires is the usual cause. Excessive off road or other abusive driving is next. Make sure your tires are a matched set and using a high quality gear lube in the front differential may help reduce the heating effect that is bringing the problem on. You can remove the center drive shaft and drive with just the 2 wheel drive. Many folks install the drive shaft decoupler as it is usually less expensive to add that feature than it is to replace the VC. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Grant Johnson
Sent: Saturday, May 07, 2016 12:36 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Viscous Coupling

Hey, when I drive my syncro on the freeway, the front wheels are binding up when  I try to park. I don't have a decoupler. I'm trying to figure out if this is an emergency where I risk frying my transaxle, or if I can get away with driving for a while. I don't know how feasible it is to install a decoupler myself in the street.