re adjusted everything all seems fine, took out on a test run and paid attention to the speed i was doing and the "noding dog effect" seem to go when i kept speed down 40 ish on a good quality road, when i went on a few
country roads it came back which i thought was strange, then i noticed the caravan was sitting nose upon towball, never used vectra for a caravan before only a trailer so i'm thinking the noding dog is in fact the dogs tail trying to lift rear end of car up when going over bumps etc
brakes are working fine and i can feel them coming on, stopped on a down hill and took car handbrake of no problem with any binding, shoes look new so maybe not bedded in yet
I used to tow with a Vectra T reg and yes you will get a slight nodding dog effect , try replacing the cars rear dampers and fit Grayson spring assistors . Glad to hear you've sorted the caravans brakes out .
Can i first say many thanks to all who offered advice
now the answer to the problem was the expander lever, i'll explain
when i got the caravan just over a month ago the first thing i
did was to check the breaks and bearings as it was an old van, took them to bits and cleaned and reassembled them, never took it out as i was waiting on new tyres and had a lot of resealing that i wanted to do.
when i did take it out i noticed the noding dog effect but just thought i needed to re adjust brakes, asmy hols got closer and brakes were no better i started looking at everything else when i should have started al;lover again.
was doing some other stuff to van today and was checking wheel nuts when the solution hit me.
when i took the brakes apart at the begining the brake expander just fell of the cable and i assumed that it went onto the trailing shoe, well 6 days later and a lot of blood sweat and tears the answer was there had a look at the alko handbook but it wasnt clear so checked web and there it was the break expander should work on the leading shoe, swapped it over readjusted the breaks out for a test result was perfect and the noding dog effect was away.
if any one is not familar with the brake expander
the brake cable attaches to it and when brakes are applied it forces the shoe onto drum. on my alko 1536 drum the leaver just attaches to the brake cable and then in between the 2 shoes, nothing to say what way round it goes and not very clear in handbook