unusual brake problem..help!!

hi all,i have a very puzzling brake problem on my 1989 3.9 rangerover classic,ok here goes...my brakes are usually great,good solid pedal,and good stoppage,,BUT..now an again if i hit a pothole or big rut whilst braking my pedal vibrates like mad and i loose brakes for a few seconds,then they come back again,ive changed discs,pads etc,but even at 20 mph any big hole ,the wheels hit on the track or road including tarmac and the vibration starts an no brakes for a few seconds,its very worrying as you can imagine,so any ideas or similar problems?..maybe its a abs problem,bad fluid or something,,but its got me puzzled..any help would be great,,thanks and all the best,,wayne.

I get something similar in my Subaru Impreza - I have always put it down to something to do with the ABS, though I may be wrong!



Pete

I'd be checking all wheel bearings for any movement and the stub axle ball joints..

thanks for the replies lads,,ill have a look at the joints an w/bearings tomoz..

hi guys,thanks for the replies,well i checked the fuses and and relays under the passenger seat and heres what i found....the fuse holders were filled with grease(i mean filled lol),and one of the fuses was half way in,as the connector going into the fuse holder had popped out,so after a good degrease and clean out with a stiff paint brush i set of down our farm track(very rutted an bumpy),,i hit the brakes just as i dropped into a pot hole,and the pedal vibrated .BUT ..then the rangie stopped!!..yippeee,its worked,,i tried a few times and the alls ok,the abs shakes the pedal but she stops just fine now,,so id like to say thank you for all the replies and help guys,and i hope this helps any one in the future if they have the same problem,,all the best...wayne.