Ford discs-sticking caliper?

[ndevans]

I have a Ford based disc brake setup on my Minor. Recently, a rhythmic grinding/grating noise has appeared, clearly related to road speed.

With the wheels off, the nearside disc is noticeably noisier than the o/s when turning by hand, and when the brake pedal is pressed, although the wheel locks well enough, there is barely any movement noticeable on the pads. On the o/s, the disc is a lot quieter when turned by hand, and there is noticeable pad movement when the brake is pressed.

The discs look clean, little wear and do not appear warped or discoloured, and there is plenty of material on the pads. There's also no noticeable loss of braking effectiveness, and it's not pulling to one side. I've checked the rear drums, and am happy there is no problem there. I've also checked for anything rubbing on the wheels.

So I'm guessing that the n/s caliper/cylinder is sticking. How do I free it off? Do I need to get the caliper assembly off, strip it, clean and reassemble?

Cheers N

[paul 300358]

It may be worth removing the pads and spinning the hub to check its not the wheel bearings.

[oliver90owner]

Which side is making the noise? I might suspect it is the off-side wheel bearings that require attention. The pads should not move any great distance. Is this at every application while on blocks, or just a first check after a run?

But first thing you need to sort out is that of from where the noise is emanating.

A simple check, that you should have already done, is to check the brake temperatures after a run in the dry. If a caliper is sticking that side will be warmer than t’other.

[ndevans]

I don't *think* it's a wheel bearing, as both seem to run smoothly, with no visible play. The n/s is definitely noisier than the o/s when turned by hand, I'm fairly sure this is pad noise rather than bearing noise, but I haven't had the pads out yet. I've not noticed any discs running hot, but will do another check today.

Cheers N

[Declan_Burns]

It could be the inner wheel rubbing. That was the case with mine and they do mention the wheel spacers required in the instructions that I got from ESM.
Regards
Declan

[Bowie69]

Could well be just a stone stuck in the caliper, quite common, either that or something has moved this can happen because of:

- Wheel bearing as above
- Worn caliper casting allowing pad to contact central 'hat' of the disc
- Loose bolts
- Rust built up
- Aforementioned stone
- Bent stub axle
- Bent brake disc shield, if you have one fitted.
- One side of the caliper has siezed, wearing the pad to the backing steel and ruining the disc -normally the inner one, so not immediately apparent.

[ndevans]

It could be the inner wheel rubbing. That was the case with mine and they do mention the wheel spacers required in the instructions that I got from ESM.
Regards
Declan

Do you mean the inner edge of the road wheel? I can't see anything that is rubbing on, and there is no evidence of scrubbing on the tyres, or obvious marks on either the brake hose, or the inner or outer wings. The discs have been on for 6 years, and this has come on over the last month or so.

[ndevans]

A road trip at lunchtime revealed that the noise is definitely coming from the front, though not easy to differentiate between right & left. Also I stopped a couple of times to check the discs, and each time, they were too hot to touch comfortably, on both sides. I guess there's going to be some warmth there, as it's obviously not easy to stop the car without using the brakes, but they were too hot to touch both after stopping in a lay-by from 60mph, on a minor road where speed hadn't risen above about 30mph for some time, and when I got back home.
So I guess the problem is either sticking calipers, or worn bearings.

[liammonty]

A road trip at lunchtime revealed that the noise is definitely coming from the front, though not easy to differentiate between right & left. Also I stopped a couple of times to check the discs, and each time, they were too hot to touch comfortably, on both sides. I guess there's going to be some warmth there, as it's obviously not easy to stop the car without using the brakes, but they were too hot to touch both after stopping in a lay-by from 60mph, on a minor road where speed hadn't risen above about 30mph for some time, and when I got back home.
So I guess the problem is either sticking calipers, or worn bearings.

Normally, if a caliper is sticking, the disc will heat up very noticeably, and it will ultimately lead to clear issues with braking performance. It's quite normal that the discs will be hot to the touch - if they are properly binding, they will be really hot. By design, discs do 'bind' a little bit, as the pads don't retract as shoes do with drums, as there are no return springs - the pistons just stop applying pressure, meaning the pads remain in gentle contact with the discs at all times. I'd check it again, and unless you notice a difference in temperature between the discs (as per Oliver90Owner's message above), I think it's unlikely you've got a sticky caliper, particularly given that you say they aren't binding when cool. Ideally, get the car jacked up and check for friction after you've been for a run and they are warm, as the problem will of course be exacerbated as the discs warm up and expand.

[ndevans]

I've had the n/s caliper apart this evening. It was stiff, so I've cleaned it up, and put some silicon grease on the sliding pins. The bearing runs smoothly and quietly without the disc on it, so I think I can rule that out. However, with the disc and caliper reassembled to it still seems to bind a little, and I'm not sure it looks right. A picture says a thousand words.

N/s caliper, bottom of outer

IMG_20210318_204906130~2.jpg (451.87 KiB) Viewed 2149 times

Top of outer pad:-

IMG_20210318_205014661_HDR~2.jpg (336.71 KiB) Viewed 2149 times

I'm not sure that the caliper body is actually binding on the disc, but it seems pretty close, and it doesn't look right. There seems about 10mm material thickness on the pads, though I've not actually measured them, but I assume that's ok?
Is the cylinder itself sticking? If so, does that mean disconnecting the brake hose and dismantling the caliper completely?

Cheers N

[oliver90owner]

And the other pad?

My wife’s car had the rear brake discs changed and the cowboys apparently refitted a bent pin. Cost a hundred quid to repair as one pad was gone inside a year (can’t remember how many (or rather, few) miles the new discs and pads lasted. One h*ll of a job to get the bent pin out and a new set of pads for just one worn out of the four. I can’t be sure if it the dodgy work was done by Lodge Tyre or by Kingsway Tyres. Lodge took over/bought out (or something or other) Kingsway, either shortly before or just after the work was done.

The reason I suspect the off side wheel bearings is because of the reported large movement of the pads - to me this likely indicates the disc is pushing the pads back too far. A sticking caliper will usually result in a warm wheel after a long run. I would never feel a disc immediately after braking heavily! Nor if I found one wheel warmer than t’other.

[ndevans]

I wouldn't say there is *large* pad movement on the o/s, but movement can be seen, compared to the n/s, where I couldn't see any movement. Both sides got very hot after a run, about the same at an unscientific guess.
Not checked the o/s pad thickness yet, that's a job for tomorrow.
For the sake of completeness, here are photos of the inner pad on the n/s.

Bottom:-

IMG_20210318_210450896_HDR~2.jpg (469.66 KiB) Viewed 2143 times

Top:-

IMG_20210318_210544233_HDR~2.jpg (408.5 KiB) Viewed 2142 times

It's like the body of the caliper isn't properly centred about the disc.

[kennatt]

The bottom of the caliper on the photo looks to be very close to the disc,and MAY be causing the noise.Just put a few dabs of tippex or similar non silicon product round the disc and spin it ,it will be scrapped off if it is touching. Compare it with the other side,could be the angle of the photos but does look out of line,does the gap alter when you spin the disc ie warped. Could be the stub axel is bent,unlikely, but if so would put the disc out of line with the caliper

[ndevans]

Good idea, I'll try the tippex trick. No, the disc does not appear warped, I've tried spinning it. I'll check the gap on the other side today.

[Steve Phillips]

First thing I would say is this style of brake setup has the disc front mounted (unlike the old marina setup with rear mounted discs) so as soon as you remove the road wheel the disc tends to move outwards so if the disc is not retained you will show a smaller gap one side to the other, the front discs normally have a counter sunk drill hole in so the disc can be retained to the factory ford hub you might not have that and as its only one screw it doesn’t always hold the disc flat against the hub,

So replace at least two wheel nuts without the road wheel fitted (opposing nuts rather than adjacent) this should pull the disc back to its correct running position, now you can visually see if the disc is central to the calliper, if it is then all good, if it’s not then if there’s no dirt between the disc and hub or anything is bent / damaged and the hub bearings aren’t loose then possibly the setup was machined wrongly in the first place, let’s face it a lot of aftermarket parts don’t have anywhere near the quality control of O/E parts,

Regards the grinding I would remove the pads spin the disc/hub do you still have a noise? Do you have excessive bearing play? If no fit the caliper without the pads spin the wheel do you have a noise?

Your ford single piston caliper is a very simple unit, and can be checked easily, do the two slide pins slide in and out easily, they should not be tight but also should not be sloppy, there’s a small white PTFE sleeve in the casting sometimes with age they break down and allow the pin to slop about in the casting. If they are ok, check the piston, it should have a rubber dirt seal around the piston, check it’s not ripped as a ripped seal will let in dirt and moisture and make the piston stick, now using a small piece of wood over the piston face and a small cramp, you should be able to pull the piston back into the caliper with minimal force, if it is sticky you might need a bit more pressure to get it to initially move then I suggest wind it all the way in with the cramp. And get a trusty assistant to pump it out using the brake pedal, now this is where it can go wrong, either put a piece of wood in the caliper body that will stop the piston coming all the way out or loosely reassemble the caliper pads and disc so you can’t fire the piston out. Repeat the procedure of piston in and out half a dozen times and normally it will then be ok,

Do remember this is brakes and if you’re not confidant in what your doing don’t risk it get a garage on it,

Steve

[ndevans]

O/s done tonight. With the wheel off, there is a slight binding noise, but only what I'd expect from a disc. With the caliper and rotor removed, the bearing runs smooth and quiet, as the n/s does.
I stripped, cleaned and reassembled the caliper. Again, the sliding pins were dry and a little stiff, but not as much as the n/s. I also put a piece of wood in the caliper to limit the travel of the piston, and tried pressing the pedal slowly. As it's the drivers side, I was able to watch the piston come out and go back in. I had to push it back in all the way with a clamp, but I'm happy it's working. I need to repeat this on the n/s now.
The gap between the caliper body and the rotor is more normal. The photos don't really show it, but the caliper is more or less perfectly centred on the rotor. I think I need to strip the n/s caliper and check that I've got it assembled properly.

Top of caliper

IMG_20210319_204701853~2.jpg (853.86 KiB) Viewed 2079 times

Bottom of caliper

Photo

IMG_20210319_204952018_HDR~2.jpg (267.06 KiB) Viewed 2079 times

[ndevans]

Question. Would a worn or faulty wheel bearing only be noisy with the weight of the car on it? Or would it be noisy when the wheels are off and the bearing is spun on its own as well? They are roller bearings.

Cheers N

[oliver90owner]

Question. Would a worn or faulty wheel bearing only be noisy with the weight of the car on it? Or would it be noisy when the wheels are off and the bearing is spun on its own as well? They are roller bearings.

Cheers N

If this is with the disc and pads in situ, probably not, but that is not the way to check a wheel bearing.

[ndevans]

Both front wheel bearings feel smooth and quiet when spun on their own without discs or calipers. With discs and calipers, there is the slight scraping noise of the pads lightly bearing against the disc, but that's all.
When I drive the car, I can hear a rhythmic grinding/scraping sound, that is related to road speed not engine speed, and present whether the car is in gear or not. It maybe changes slightly under braking, but difficult to say.
I can't tell whether it's front or rear, but my wife is adamant it's front, but not sure which side. There is nothing anywhere near the wheels that could be binding on them.

[paul 300358]

You could put the rear on axle stands, run it and see if you can hear the noise. This will tell you if its the front or rear