No they are not adjustable. ( Get an Haynes manual 1st!)
In fact you will need to remove to bearing carrier and take it too a local friendly garage to ask then to replace the bearings using a powerful hydraulic press. Do not try and get them in and out at home or using a vice or hammer!( it will end in tears with broken new bearings, if you are lucky, or a broken hub carrier if you are not lucky!)
mrmardy.( renault owner.2001 scenic 1.9 dci), January 2011