brakes grabbing

[my1tonrat]

for the past month or so my front brakes (pretty sure it is drivers side only) have been acting up.  It will grab and lock the wheel up with VERY little pressure on the pedal.  The weird thing is that it only happens roughly once a week or so, and never under the same circumstances.  Sometimes it is when it is cold, other times after it has warmed up.  It is pretty violent when it happens, knocks the truck sideways if there is ice on the road.  It really confuses me that there is no consistency either with how often it happens or the circumstances.  95 percent of the time they work perfectly, but when they grab it's rough no matter how ginger I am when I apply the brakes. 

It is pretty cold here, so I have not yet bleed the lines or do more than a brief inspection.  I do not know a whole lot about brakes, but the master cylinder is topped up, I am not losing any fluid.  I have not yet looked at the pads or discs.

it is an 85 one ton 4x4. 

Any ideas on what this could be caused by, before I start a decent inspection?  What would you guys check first?

Thanks,
Trev

[DnStClr]

It sounds like the caliper piston on the left front brake is not returning after you apply the brakes and let off the pedal. Take a test drive on a road without too much traffic and check to see if the rotor is hot after applying the brakes a few times. It won't tell you that the caliper piston is sticking but it will give you a starting point.You'll have to get the truck up off the ground to see it operate better. Have a helper apply the brakes and release. See if the wheel turns free immediately. The caliper piston should have returned and freed up the wheel.
Check for a bulge in the flexible rubber hose going from the caliper to the truck frame.It connects to the steel brake line on the other side of the frame. Sorry -poorly written- I meant on the other side of the frame member-That rubber hose can collapse after a few yrs. and cause your problem.It may not have a bulge and still be collapsed.Best check is to disconnect the hose from the caliper and have a helper apply the brakes to see if fluid squirts from the hose. Tell helper not to let upon the pedal until you retighten the hose.
New caliper = @$20.
new hose   = @$15.

[Blazin]

I agree I would look at both, have seen the hoses do that in the past on one of my Camaro's Looked fine but was internally collapsed. Would not let the pressure back out of the caliper 7 or 8 times out of 10. Go to take off from a stop, and the front brake would be locked up. I replaced the caliper thinking it was that. Still did it. Next replaced the rubber line, never happened again.

[the_legend_1981]

Something like this happened to me a couple of weeks ago.  I put a post on here, i thought it was the caliper but I tried the brake hose first like people said on here.  That's all it was, simply a brake hose internally collapsed. I was skeptical to think it was that but I trusted these guys and it worked, so i would try that first.

[ccz145a]

Yep, it makes a perfect little check valve.

[my1tonrat]

Thanks a bunch for the input guys.  I will definitely check the flexible hose and replace it before trying anything else....hopefully it warms up a little outside soon, hehe

[VileZambonie]

If it happens when a particular tire is in contact with ice it will lock up. Stay off the brakes on ice or prepare to go for a slide ride. If it doesn't happen on dry pavement then there is no problem.

[my1tonrat]

It definitely happens on dry pavement.  (we have lots of winter with way too much ice driving here, so I know what that's like all too well, hehe).  The funny thing is that the second I am off the brake it releases like normal, but even if I barely touch the pedal it jerks the truck to a violent stop. 

[Bitzer!]

maybe air in the passenger side or brake pipe passenger side making the drivers side work harder. Have u bled them?