There is no speed limit for the diff lock. It should not be engaged when there is a big difference in speed between the front and rear prop shafts - i.e when turning at any speed or when one wheel is spinning. Driving on hard, good gripping surfaces for long distances with it engaged will cause excess tyre wear and may eventually cause problems with parts of the drive train, and may also alter handling.
Some advocate engaging it whenever travelling on rough surfaces such as corrugations to avoid repeated shock loading of the diff - the dog clutch is a lot tougher than the centre diff.
To disengage if it doesn't want to come out, stop, and reverse a short distance - usually works. Wheels must be straight ahead.
John
JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol
Bookmarks