How do you release the back brakes on a astra van there coming on before the front ones?
your back brakes are supposed to apply before your front brakes,
they do this so your car does not take a nose dive every time you
apply the brakes. but if it is very noticeable i would check the
adjustment of your rear brakes (if you have a disc/drum setup) or i
would check your proportioning valve if they are locking up