Braking problem.

machinehead, May 17, 10:06am
Unless I apply the brakes slowly and very gradually, they grab. They even lock up if the road is wet.

This has come on slowly over the last couple of months. Before this, they were fine.

Any ideas?

Discs seem straight and free of warping, no gouging or scratches either. Tyres are new.

rbd, May 17, 10:13am
Blue car or red car?

I had this issue many years ago. Upon light application of brakes the rear disks locked and I fishtailed across the road. Parking on the other side perfectly, pointing the wrong way.

Turned out the sliding calipers had seized on the pins, meaning that the calipers could not unclamp correctly.

machinehead, May 17, 11:43am
Blue. 8-)

Discs at the front, drums at the back. Although, it is just the front wheels that grab.

Your problem sounded. "exciting"-
. Luckily I don't think that my problems is that dramatic (or heading that way).

msigg, May 17, 12:14pm
Yes some old cars did this with drum brakes on front and worn brake springs, your problem could be the caliper word or not sliding properly. Or possible master cylinder, I would look at the calipers first

jmma, May 17, 12:41pm
You may get better help if you state make, model etc as there can be many reasons.
I could say it would be the reaction disc if it was an HQ Holden :oP.

strobo, May 17, 1:50pm
yeah true that , reaction disc swells/wet day sounds familiar / there is an adjustable rod too there in between the vac and the master.But not knowing the vehicle in question op can be quite a few things.

tweake, May 17, 2:09pm
common problem is rear brakes out of adjustment, so you tend to have a very light pedal (as rears don't make contact) then it comes on hard as the fronts engage. fairly easy to apply to much pressure and lock the brakes.

also check the proportional valve is working (assuming its ute/suv)

4.11, May 18, 6:32am
my holden rodeo did this for about a week, turns out the pads had worn to metal, im so rough, just thought the brakes had gone bad, this caused really bad grabbing under heavy braking , cost me new rotors as well as pads, check one of your front pads has not worn to metal?

tygertung, May 18, 9:54am
I bought some new rotors for my Lancer as it had failed a WOF on them being worn, however after fitting the new ones, I measured the old ones and they were over the wear limit.

It was pretty cheap for new ones though, I bought them on TradeMe.

machinehead, May 20, 9:10pm
It's a '98 Transit.

Reasonably low km's for age (~75,000).

redhead18, Aug 6, 2:55am
Has 4 wheels so problem is front-or rear?
As they do have a lever by the rear axle which controls a proportioning valve.
Any piece of wood on the road can flick up and re-adjust oi?