Focus wheel shudder under braking

2005 Focus II 1.6 Zetec 39k miles

Hi there,

I'm having this issue when I touch the brakes at motorway speeds (i.e. above 60mph). There is a distinct shudder felt through the steering wheel, but nothing through the brake pedal. The shudder is only present when I touch the brakes, and at speeds below 60mph there is no problem at all.

I originally suspected a slight warp of the front disk(s), but checks suggest this may not be the case and I'm now having some difficulty determining the exact cause.

So far I have done the following:

- Checked front disc runout with a DTI on both inner and outer faces of the discs. The runout is 0.03mm on both discs.

- Stripped & cleaned the front brakes. Nothing sticks or binds. The pads have been renewed recently and are in good condition. The discs also appear to be in good condition, although they are original and now approaching the service limit (they will wear out before the pads do).

- Inspected control arm bushes. The rearward bushes are staring to show signs of perishing at the outer edges, although they appear to be sound with no splits and no discernible play.

- Rocked the front wheels in both axis to try and detect any play in the bearings, bushes, track rod ends or ball joints. I can't feel any play whatsoever on either wheel.

- Spun both front wheels to look for signs of warp or buckling. Both seem fine and there is no sign of a balance weight having fallen off.

Anyone have any ideas or suggestions based on their own experience, please? My last idea is to have the front wheel balance checked, although I'm thinking this would produce a permanent wheel wobble, rather than just under braking, if it were the cause?

Stu

Reply to
Stu
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If you want to eliminate wheels/tyres from the problem, swap fronts to rears.

From your description, I would (figuratively!) eat my hat if replacing the discs didn't cure the problem.

There are lots of interesting (FSVO interesting) theories about disc brake surface contamination; Google if interested. The problem may be more likely if non-OEM pads have been used.

Personally, if the discs are near limit, I would change them for genuine Ford ones.

Chris

Reply to
Chris Whelan

Given control arm bushes have more effect on juddertan brake discs that's a clue. Not definitive, but worth checking.

Unless you're a superhero in your other life you won't feel anything until it's really bad.

That would get you when you wheren't braking

Reply to
Duncan Wood

You might end up doing because worn lower suspension arm bushes display the same characteristics.

Reply to
Conor

Possibly, but such wear is uncommon on a Focus, and the OP says there is no discernible play.

The OP has new, possibly not OEM, pads on worn discs. I've seen this cause judder on a number of cars, and might be attributed to the bedding in process coating the discs in some way. There are a lot of theories on this, some of them implausible, but in one case cleaning the discs thoroughly with a solvent did cure the problem for a relative's car.

Chris

Reply to
Chris Whelan

given the low cost and ease of changing then a set of new ford pads and discs would be the first logical step.

Reply to
Mrcheerful

If the bottom bushes are soft then changing the discs often cures it briefly.

Reply to
Duncan Wood

Absolutely!

The car that I cleaned the discs on had the pads changed by the owner on a Sunday, and the owner needed it for work on Monday. He asked me for help in desperation, as the vibration when braking from speed was pronounced.

I'd read about new pads coating old discs unevenly, and was sceptical, but cleaning them with isopropyl alcohol cured the vibration 100%.

Chris

Reply to
Chris Whelan

Thanks to all for your replies.

It would seem there are two possible causes and the jury is out on which is the more likely.

The pads are indeed non-OEM Lockheed items. They must've been on for a year as that was the last service the car had before I bought it, but they're virtually unworn. The discs, OTOH, have a pronounced wear ridge and using my rough & ready method of measurement (digital vernier with 2 drill bits to clear the ridge), the thickness is down to around 23.3mm - very close to the service limit. They really should have been replaced with the pads. At this mileage I can't believe they're anything other than OE.

I've done my best to identify weakness in the bushes, but it sounds like the only way to do this properly is to put the car up on ramps and use a long pry bar. Working on the drive, I really don't have enough clearance to do this. The car has a new MOT so I do have some evidence that nothing is *drastically* wrong here.

So I'll have to take the plunge and replace one or the other, hoping that I choose correctly. It makes more sense to me to do discs+pads, since it's the easiest job for me and I know for certain that those discs will need doing soon enough in any case.

Thanks again and I'll let you know the outcome,

Stu

Reply to
Stu

Really? That'd be a first.

Reply to
Conor

Mk4 Escorts used to be notorious for it.

Reply to
Duncan Wood

Fitted the new OE discs & pads today and took the car on a short bedding in run. It would seem that the problem has now gone. Obviously, I'm only touching the brakes gently at speed while bedding in takes place, but that was all it took to reveal the problem before and it's not happening now. So part, if not all, of the problem must have been the aftermarket pads not riding smoothly over the old discs.

I'll let you know if it comes back, but if it does, I'll know it has to be bushes. In any case, it's one less job that will need doing and I'm pleased with the effect of the new parts: The old brakes were strong but rather wooden. These new ones are equally as keen, but with more 'feel', IYSWIM. :-)

Thanks for your help

Stu

Reply to
Stu

PS if anyone else happens to want similar parts in future, I can recommend Paynes of Hinckley, who were selling the parts I need, along with other similar OE items, on eBay. The prices for both pads & discs were cheaper all-in than the ex-VAT prices at fordpartsuk.com! The service was also very good - got back to me straight away to confirm the right parts from my reg number and delivered next day.

They've also got some good discounts on OE oils and fluids. Not an affiliate and never used them before, just a satisfied customer. ;-)

Stu

Reply to
Stu

Thanks for the feedback. I lurked on this one, as other potential issues were brought in. I too own a Focus now on 160k miles and previous company one that did 70k before being moved on.

I also had two Fiestas that did circa 205k and 150k? - It was a while ago!

In all cases, I found that the judder was as a result of disc wear. Pads are hard these days relative to the discs. I also wonder whether folk leave their foot on the brake when they have come to a stop during hard use, (I'm guilty at times and swear at myself). This may cause warp due to unequal cooling.

Reply to
Clot

Useful to know, thanks.

Reply to
Clot

Thanks, it's reassuring to know that someone else cured the same problem with the same fix. I can be more confident of having put it to bed now.

Yes I believe they can warp because of the behavior you describe, but mine were definitely not warped - I checked them carefully using the proper tool. It must have been friction related - my best guess is that the pads were sort of dragging against the discs, producing a jerking effect that only becaime perceptible at high speeds, but I'll never really know.

Cheers,

Stu

Reply to
Stu
[...]

Phew! My hat is safe!

If interested, you might want to Google the theory that using new pads on old discs has the potential to coat the discs; if this coating is uneven, it gives the symptoms you had.

I was sceptical, until I had (second-hand) experience of it.

Chris

Reply to
Chris Whelan

Found an interesting article here:

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Stu

Reply to
Stu
[...]

Yep, and there are enough other references that it has to be the cause at least in some cases.

It certainly left the car on which I cleaned the discs trouble-free for a year or so.

Chris

Reply to
Chris Whelan

Thanks for that link. Very informative.

Reply to
Clot

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