Focus front noise

I suspect the front right disk of my 53K-mile, 2000 Focus LX 1.8 Petrol (with ABS) is bent. I reported on problems with the middle bearing 6 months ago which, through misdiagnosis, led to replacing all three front bearings and the right driveshaft.

The front right wheel bearing went again and was replaced under warranty 2 weeks ago, on the next day I realised the front right brake was slightly binding (fixed by repositioning and adding copper-grease) on a specific part of the disk; the caliper was deemed to be pushing back OK, by pressing it back with a wrench.

On the next day I started hearing periodic noises when braking and an occasional knock when first pressing or when releasing the pedal. The periodic noise matches the wheel speed and happens when the brakes are warm (urban use is the classic case) and the pedal is pressed half-way through (or thereabouts, but the point is that it doesn't happen when lightly pressed and it doesn't happen when firmly pressed).

So my questions are:

- Can a bad repair on the bearing have caused the disk-warp. No, I do not sit on the brakes after stopping and the car has always had Ford shoes fitted. The car did approximately 15 suburban miles, with three stops, while the brake was binding.

- I am pretty certain that, if I change the disk, I also need to change the shoes. Do I also need to change the other disk and pads?

- Is the caliper suspect? What is a good test?

- If it's not the brake, what else can it be?

Thanks,

Kostas

Reply to
Kostas Kavoussanakis
Loading thread data ...

you need to check that the hub is not bent/warped. buy new disks and mount them, bolted evenly on, then use a dial gauge to check run out, your vehicle is specced at 0.05mm (I would not accept that high a figure and would go with 0.03mm max)

Mrcheerful

Reply to
MrCheerful

Thank you Mr Cheerful.

Although an observant and generally clued up user, I am not the DIY type, certainly not when it comes to brakes, so please be patient. Is the dial gauge standard equipment at a (largish, MOT) garage? Would I need to have the measurement done when the brakes are hot (and exhibiting the symptom) or does the spec apply to cold disks?

Also, am I right I need to change disks on both sides? And is there a good test for the caliper operation? If that's to blame for the fault, it will just do it again on the new disks!

Thanks again,

Kostas

p.s.: Does the spec above apply to vented disks, like mine, or is it all the same (do all Focuses have vented front disks?)?

Reply to
Kostas Kavoussanakis

Very worn discs can warp, they then get thickness variations which give juddering brakes. Replace the discs and check runout. Running good disks on a wonky hub will cause the discs to wear unevenly and give thickness variations. replace discs and whatever is causing the wonkiness. from the sound of it your discs are useless. discs are a service item. you need to start with a new pair of disks, all foci are vented as far as I know and the runout would be the same anyway. with new discs on, you would measure run out, if excessive then it probably needs new hubs. when run out is in spec. check brake operation using the mot rollers, this will show up sticking calipers. Any good garage will have dialgauge set up for this job, if not, go elsewhere.

mrcheerful

Reply to
MrCheerful

Thank you very much, Mr Cheerful.

Kostas

Reply to
Kostas Kavoussanakis

As per Mr Cheerful's suggestion, we put it on the MOT brake tester. It was obviously oscillating on the wheel in question, but "not too bad". We changed pads and cleaned & greased both break slides. The caliper seems to operate properly. It seems fine so far, so, unless I write, the issue is cured by cleaning and greasing the slides.

On an unrelated issue, the 4 HT wires (sold separately) cost

3x16.85+19.61=70.16 + VAT! Had them changed because of missing around 2K revs under load.

Kostas

Reply to
Kostas Kavoussanakis

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.