Cracking Noise

[Acid-burn]

Hi all, im hoping someone can help me

I have 2001 yaris t sport. over the last few months my car has developed a very loud Cracking noise everytime i press the brakes. It sounds to be coming from the rear drivers side. Everytime i press the brake i hear a single loud Crack. its doesnt happen happen when going over bumps, turning corners or when in reverse. If i reverse the car and press the brakes there is no noise, but the moment i go forward again CRACK when the brake is pressed. I replaced the rear pads about 6 weeks ago and it solved the problem instantly (i was thinking it was pad rattle) but over the last 4 weeks its come back, quiet at first but its back to being very loud now. I have checked the pads and there is a few millimeters movement up and down but thats the same for both sides. Please can anyone help

Leanne

[alfiejts]

I think you've tried to solve this in a very logical way.

As you say, it sounds like brakes not suspension, as it is linked to brake application and not to normal suspension movement.

It does sound like something "moving" when you apply the brakes - such as the disk or caliper.

I'm struggling to thing of anything specific, but my next step would be to get the right "torque" settings for the various caliper bolts, to remove the caliper from its mount and then to put everything back together, checking all the bolts in the complete assembly (the swivel bolts, the caliper mounting bolts), anything on the disk and the wheel nuts) were all loosened and then re-torqued up to the right settings.

All that said - when it is up on the jack, double check for a broken suspension spring.

There's just a chance that if the spring is broken, it could cause an issue although like you said, logic says this is brake related. Worth a check though.

Actually, thinking about it, the forces on the suspension arms are different betweeen when the car going over a bump (up and down forces) versus when you apply the brakes - front & rear forces.

Maybe it is a suspension arm - worn bush, etc. - that has play in the "forward/rearward plane" so its more affected by braking forces than up and down bump forces...

Any if it went away when you jacked the car up to change the pads - that would have had an impact on the suspention, changing it slightly until the car settled down again.. (after being jacked up you'll notice the car never settles down to its original position straight away...)

Makes you wonder....

[Raeman]

I would agree with alf on the suspension theory. Does sound a likely culprit.

Check the rubber boot what the actualy rear spring sits on aswell.

These can wear, i changed mine few years ago but there not expensive from Toyota.

Keep us informed of the progress. :)

[Acid-burn]

Ok i have fixed it ------ again

I jacked it up and checked all of the suggested things, all bolts, suspension and srings and everyhing was fine. so i went back to the pads, took them out and looked at the verticle play - about 3mm. so instead of buying yet another set of pads that would be exactly the same size i thought what could i do to modify the existing pads. what i did notice is the paint that covers the pad backing had come off at the top and bottom (indicating that the pad had been knocking up and down) then i had an idea. so i welded a small amount of weld on the top of the pad and ground it down to exactly the right size. making the pad fit snuggly in the caliper, i did this to the other pad and reassembled. i then took it for a drive and --- it was silent -- however the other rear brake was cracking. it must have been doing the same thing (the play was about the same) only it wasnt as loud so i hadnt heard it. so back to the garage and i did exactly the same for the passenger side rear pads. another drive later and --- total silence. so it was pad rattle. a pain in the ***** to fix. but it is fixed. i just hope it lasts. im thinking the paint had been enough to stop the noise when i first put the new pads in and over time as the paint chipped away it started knocking. so if anyone else has this problem it is pad rattle.

Thank you all for the advice

Leanne x

[Raeman]

Glad you got it sorted then.

Can't help but wonder though, why are the rear pads rattling in the callipers in the first place?

Could it be the calliper springs that hold the pads in tight that are worn?

Seems a bit extreme to be welding blobs on brake pads to me. But hey it worked for you so good fix!

[gar]

Perhaps there was supposed to be some "shims" in there, somewhere to eliminate the rattle/crack? Also, a little copper grease, in the correct places can help eliminate noises in the brake system!

KEEP IT WELL CLEAR OF THE PAD'S FACES, THOUGH!!!!!!