Sudden loss of brakes!

[ollieboy]

I was driving today in Traffic and my brakes stopped working, they sort of worked but only just, I ended up rolling into the back of a car at about .5km/h, no damage though luckily- he said it was his work car so noone cares anyway. What I am worried about however is that it actually happened, it was the first time I had ever hit another car and I have this thought that next time it could be a person so I want to fix it ASAP.

I'm not sure where to start however. I'm thinking it could be the brake pads, they started screeching about 2 intersections before I rolled into this guy but I've got no idea how fast brakes wear down after they have started screeching.

Could brake fluid have any impact at all on the brakes effectiveness? Theres plenty of fluid but it is most probably really old stuff.

Any other ideas?

Also the pedal has alot of resistance so I don't think its a vacuum problem.

Cheers for help guys.

[Rick]

Have you checked the level of the brake fluid in the reservoir (make sure there are no leaks around the master cylinder), next I would be looking at the condition of the brake pads and making sure that the calipers are not seized, leaking etc...

[rollaholic]

what kind of car is it? and what was the brake pedal doing when you hit the guy?

the screeching depends on if you have wear indicators or not - if the sound you are hearing is the metal backing plates touching your rotors, then the brakes arent long for this world - but two intersections would not be the end of them. had you been doing lots of heavy braking before this happened?

the more info you can give us the better, but at this stage my money is on heavy glazing on pads / rotors or a booster problem, or both.

[Leon]

the screeching noise might have been the pad being spat completely out of the caliper. Thus practically no brakes immediately afterwards.

Tow truck time.

[ollieboy]

Yep theres plenty of brake fluid in the master cylinder and I can't see any leaks around it.

Its an AW11 mr2, when I hit the guy the brake pedal was fully down and it felt like it normally does on the brakes. Hadn't really been doing any braking for at least 10 minutes before hand, I was just sort of rolling along in traffic.

How would I tell if the pads or rotors were glazed? Can I tell by look or touch? I just want to know before I go taking the wheel off.

[Caveman]

That sounds odd, probably wont get any anwsers without pulling the braking system apart.

On my aw11 the brakes were absolute shite when I bought the car. Had to rebuild all the calipers and change all pads + fluid to get average braking. If youve blown a seal on the piston its not difficult to rebuild then, send me pm and ill give you some pointers.

Also might want to check hand brake cables if your concerned about teh brakes. I had to replace 2 out of 3 of the cables because they were seized or I snaped them. The one that I didnt replace looked like it had been by the previous owner.

Since you lost all braking power im guessing its probably got something to do with the master cylinder, however id give the whole system a check just to be sure.

[Pelo]

Possibly a hole in a brake hose? Check the wheels for sprayed out fluid. When this happens the brakes feel just fine until you need to stop quickly, then the pedal goes to the floor... not good!

[KinLoud]

Maybe you popped a piston out of the caliper. This happened in my racecar on a trackday (silly me!). Wore the pads down to metal (and beyond) the piston could move so far that the piston seal popped out of the cylinder and the fluid leaked out front the front brake circuit! See the pics here.
viewtopic.php?t=43987&highlight=cook
He, he

Ken
Ham
021 408 863

[rollaholic]

by fully down you mean like, halfway to the floor? you can tell a lot about what the brakes are doing by the feel of the pedal.

take it to a mechanic imo.

[ollieboy]

by fully down you mean like, halfway to the floor? you can tell a lot about what the brakes are doing by the feel of the pedal.

take it to a mechanic imo.

Yeah I will probably do that but I don't want to drive until the brakes work at least a little. I suppose I could come flying through the wall at the mechanics get out and say, "Well as you can see, I have a problem!"

Yeah and I meant halfway to the floor, it feels no different to any other time I've driven it.

I'll pull wheel off tomorrow anyway and have a look, see if its anything you guys suggested. Thanks heaps aye.

[ollieboy]

Pulled it apart today. All the brake pads and disks are glazed, also some parts of the system were seized, I got them unseized and have a wee bit of braking power back, but I still dont stop in a hell of a hurry. I took it to a mechanics to double check and they said yeah its the glazes pads and disks thats making it stop not too well.

So now I know the problem, I have to replace all the disks- they are too far down for machining.

[sergei]

Pulled it apart today. All the brake pads and disks are glazed, also some parts of the system were seized, I got them unseized and have a wee bit of braking power back, but I still dont stop in a hell of a hurry. I took it to a mechanics to double check and they said yeah its the glazes pads and disks thats making it stop not too well.

So now I know the problem, I have to replace all the disks- they are too far down for machining.

Glazed rotors will not cause sudden loss of brakes, they might cause poor overall performance of the brakes.
But siezed calipers might. That is both front calipers are semisiezed.

[ollieboy]

Yeah they were seized but I manged to work them free, the braking is still crap but at least it works a wee bit now.

[Caveman]

you need to rebuild your brakes for reliable performance. if your piston boots are split they are getting filled with dust and generally fcukign the pistons/cylinders.

glazed pads wont cause major braking failures which you suggested at the start of the thread.

[ollieboy]

I said in a few posts up that some parts of the system were seized and thats why the total failure, I've now rectified that but I still have the glazed disks and pads so its still crap but at least it works now.

[Bling]

sand the pads, i'm sure the rotors will be ok

[ollieboy]

Nah tried that before I drove it yesterday- I do anything to not spend money but the car has done over 200,000kms and they are original rotors so I'm not really surprised

[AE82 FXGT]

Nah tried that before I drove it yesterday- I do anything to not spend money but the car has done over 200,000kms and they are original rotors so I'm not really surprised

200 000kms and original rotors?
They'd be about as thick as a CD wouldn't they?
Disks have minimum thicknesses that when below would compromise their performance (not syaing thats what happened cause clearly it was a bigger issue).

[ollieboy]

Nah tried that before I drove it yesterday- I do anything to not spend money but the car has done over 200,000kms and they are original rotors so I'm not really surprised

200 000kms and original rotors?
They'd be about as thick as a CD wouldn't they?
Disks have minimum thicknesses that when below would compromise their performance (not syaing thats what happened cause clearly it was a bigger issue).

They're not too bad but clearly worn and yeah they can't be machined because they are past their minimum thickness

[sergei]

Do not save money on stuff like brakes. You can save money on paint, stereo, well even oil, but brakes, wheels (as in good tyres) and suspension is the stuff that makes the difference between being alive or dead (or someone else being dead with your "performing" brakes).
Too worn rotors allow for too worn pads to be spat out, resulting of loss of braking (even rears will not brake because all the fluid will go the easiest path - in the big hole where the piston was)