Wierd brake pedal kick\judder

[Hacksawbob]

Noticed on a few occasions the brake pedal kicks once or twice then continues to work ok. Disks calipers pads arent that old and ive fitted new front water guard shield things on the front. Seems to be in the wet and first major brake of the day. Cant think what it would be! Any ideas?

[Simon Baxter]

When you say kick, what do you mean?

[California Dreamin]

Non ABS? I had to ask.......some do have it!

I don't have to tell you that 'a kick' can only be the brake fluid pushing back hydraulically through the the master cylinder..so along the lines of: the sliding calliper catching the wheel....or wheel cylinder moving on the back plate. Something that could physically shift fluid back to the master cylinder.

Martin

[Hacksawbob]

No abs, there is feedback through the pedal from the brake. I feel the pedal move up suddenly as i'm pressing on it, its very slight but noticeable and out of the ordinary. The only work ive done recently was a rear bearing replacement , but i left all the brake parts attached to the back plate. After its happened once in a journey that seems to be the last of it. Only thing i can think of is with all the wet weather it slips while the disk dries off, but i guess that would be just a lack of braking rather than a sudden change in bake pedal feel. Or the vacuum system?

[California Dreamin]

Hiya mate....just thinking of ways you could isolate and diagnose where the fault lies......If this is a consistant fault (one you can get at will) then it may be possible to clamp off (with extreme caution) each flexi hose in turn...start with the rears as they can be done fairly safely.
Road test on a quiet back street...if the kick disapears you have found the 'corner' with the fault and you can focus your attension in one place. Be careful with clamping off the fronts as this will promote severe pulling under braking.

Martin

[Hacksawbob]

Thanks, brake judder is maybe more accurate. It's not repeatable at will, It only happens with heavier braking, maybe after a when I haven't used them for a bit. I'll get under and have a poke, check the caliper torques maybe? clutching at straws really!

[Aidan]

caliper sticking on the pins perhaps,girling or ATE ?If girling have you got a split boot ?

[Ian and Lins]

A bit unlikely but it might be a warped or damaged disc. Can you check them for run out?

[California Dreamin]

BUT.....disc runout and drum ovality both produce 'continuous' pulsing of the brake pedal, in varying degrees (depending on severity and speed).
You describe a 'SINGLE' kick?

incidentally...a 'pointer' as to whether the fault in at the front or rear is.....does the kick effect the steering wheel? if not, then I would be inclined to think you have a rear brake fault.


Martin

[Hacksawbob]

Seems not to have occurred in the las few days. Definitely not a warped disk . Disks calipers pads bearings and pipes have all been replaced with newin the last year or so. I can never remember girling or ate differences is one more prone to certain problems than the other? Feels front end to me, you can feel it feed back through steering but not enough to affect steering as its so sudden and then all better again.

[California Dreamin]

Few suggestions:
A balance weight catching the suspension upright (a bit of play in the wheel bearings making this sporadic)
Your wheel bolts or security bolt, too long (maybe going all the way through the disc catching the hub)
Bent sliding calliper pin or pins.
Problems with wheel bearings

Time for investigation...

Martin