Creak/knocking noise when breaking to a stop only on warm brakes

[onobeka]

So, I am having this issue every now and then. I have had it from the moment I've bought the car and realized it only when arriving home, 200km away from the pick-up location. My Ranger was 1y old, full warranty. I've been several times in the shop, once they've found broken brake pad clips. Then they've cleaned the hubs, rotors, sliding pins in the caliper. The noise did come back. Since then, I've done this several times myself, it always cures it for a while (maybe a month or so). I am not driving it every day, rather 2-3 times a week and in general short distances: 40-50km or shorter, but no 1-2km trips.

The noise is not there when the brakes are cold, it appears after a trip of longer than 10km and only when braking gently, coming to a stop, traffic lights, crosswalks, 90degree turn, basically stopping gently. The noise is not the regular screeching noise, squealing, grindy, rusty brakes. It happens twice per tire revolution, front brakes only. It does not happen in reverse, so it has something to do with the load on the front, yet it's not suspension. It's not bearings. One was replaced in warranty as I've convinced them it's warped. The rotors are a bit warped, at least they are not dead straight, I've measured them with a comparator watch. The runout is not 0.000, rather 0.0030", which is over the 0.0015" recommendation. There is no pulsing feeling in the pedal, it's not dramatic.

I've just passed another MOT two weeks ago, brakes are and were measured as being very efficient, no difference left to right. All suspension components are ok, no loose screws, no play. I do have a lift and wheel spacers, yet the problems were there since I've bought the truck without those mods. When I've bought it it had 17.700km and now it has 25.600 km. So in two years, including the lock-down, I just did 8kkm . There was a recall on my truck on a possible problem with the front brake lines, they were changed and the fluid was replaced. This was about 5000km ago.

I am tempted to swap out the brakes, but before I do that I would like to have some opinion. The service is useless, I do not want to waste more time with cleaning.
My truck has a manual gearbox, so I am also using the engine brake => lots of thickness on the pads and discs. I could try to find a shop to turn them on a lathe.

Your opinions are very much appreciated.

Sponsored

 

[Motorpsychology]

have you tried bedding in the brakes? (beat Phil to it)
I copied one of his posts where he describes the process.

You have said that the retaining clips were replaced, which is what I would have thought it was. I would try the bedding in process, but with that many km's it may not be very effective. It sounds like you have been through every possible fix except replacing the pads.
Try the bedding first, then replace the pads if unsuccessful.

 

[onobeka]

That bedding in, otherwise called an italian brake tuning was what I've done in the beginning while experiencing this issue. It did not help. I've also sanded a bit the pads. It did help for a while. The pads have no cracks. The discs have a minuscule lip. I've cleaned the discs from rust, as well.

One thing that I did not do and I guess it can be a cause of the noise is to grease the back of the pad (which touches the pistons) with copper grease. This noise happens at half pressing the brake pedal. If while experiencing the problem I push the brake harder, it disappears - may be difficult to judge as the travel speed was anyway very slow and applying the brake hard would cause an immediate stop.

I've made this video before convincing the workshop that there was a noise in the first place, you can observe a serious wheel wobble as well:

Then they've cleaned everything, and said that the wobble could be the rust buildup behind the brake disc. So I've took it home, noise almost gone, yet I still observed the wheel wobble. Much much less wobble, same wheel, same disc, pads, hub and bearing.


So, they've replaced the hub and bearing. I thought my troubles were over.

As you can see these movies were made 1y ago. Since then I have been living with this coming/going noise. If I remove the wheels and put them back, while not having spacers, the disc moves with every operation, which cures it again for a while. I've swapped wheelsets (summer/winter), rotated wheels many times. I've greased the swaybar bushings as well.
I have 8 factory rims (same type), two sets of tyres.

Bonus in the videos: you can hear the 4cyl diesel . In the first video the engine was a bit colder. Now that I think of it, maybe the noise is there all the time, but from the cabin I can definitely hear it more after some 10km or more, not when I take the car out to drive.

 

[onobeka]

the whole wheel wobble, clearly evident in the video, has me perplexed.
I was wondering if the rubber just wasnt seated on the rim properly, but it looks like the wheel and rubber move the same.
that tells me it's something to do with the hub, the wheel seating, spacers or something.

I dont know where you should go from here. you've done everything i could think of apart from trading it in on a new one.

Me too, gave me a heart attack when I first saw it. As said before, the hub/bearing assembly was replaced (after the third visit for this issue), May last year, right after the second video. The wheel is as straight as it can be now. The workshop tries to get the easy way out, they did not want to use the comparator dial until I've made the second video after their first intervention.

NOW, there is no wheel wobble, the noise is there.

 

[halligan1201]

Control arm bushings in good shape? The other thing I'd check is that the spring clips that hold the pads to the bracket are on in the correct orientation; I've seen cars with the springs at the wrong end, which allowed the pads to be installed but causes a small gap that gets closed every time you come to a stop.

 

[onobeka]

Control arm bushings in good shape? The other thing I'd check is that the spring clips that hold the pads to the bracket are on in the correct orientation; I've seen cars with the springs at the wrong end, which allowed the pads to be installed but causes a small gap that gets closed every time you come to a stop.

Yes, both are fine. There is absolutely no sign of rubbing in the caliper. The suspension is fine, there are no squeaks, knocks or anything loose. The noise happens only with soft braking.

 

[onobeka]

Today I tried to address the brakes but I need to wait a while to see if the problem is fixed.
I've unbolted the calipers, greased the sliding parts of the pads, the back of the pads, cleaned the pins and greased them. I've used copper grease that is supposed to last up to 1100C. The grease is very thick, honey looking and very thick. I did a short trip afterwards and of course, the brakes are noise free, drove next to tall walls, windows down. There's absolutely no noise, yet I've been here before.

 

[onobeka]

next step....upgrade stereo and speakers with a sub woofer and let her rip some good tunes.

Not sure it is derogatory … yet appreciated. Audio is done long ago: https://www.ranger5g.com/forum/threads/vibe-powerpack-phoenix-gold-sx65cs.13373/
I will never block a mechanical malfunction. Maybe I should be grateful my ears are healthy, despite my truck!

 

[onobeka]

I'm happy to report back. I have had zero issues since the greasing up. I hope this helps some colleague in the future. I believe what made the difference is the copper grease on the pins, yet I've done the sliding parts and back of the pads too. It's not the cold moist weather, these issues were there during winters as well. Of course, I will report back if the issue comes back.

Sponsored