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Horizonblue

A squeaking noise is coming from the front right wheel, almost constantly. I can make it go away by doing a little slalom, but it soon re appears. When I press the brake, it goes away, but as soon as I release the pedal, it's back. After a 2 mile trip, the wheel is hot, so the brake calliper is probably hanging. But I don't understand why.

I have just had the brake pads removed and installed (because the calliper was hanging and the wheel was hot after a short trip.......) I greased all the metal to metal surfaces, except for the backside of the pads. The piston was easily pressed back, with a water pump plier.

So it was quite a surprise that I was barely out of my driveway, before the squeaking noise came.

Any suggestions on what is wrong?
_________________
Euro 924, 1976

"If you can't fix it, don't break it"

/P.G. Andersen

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

When was the last time you changed the brake hoses? They can swell shut and cause a "hanging up" situation.

!tom · Posted: Sun May 25, 2014 3:10 pm Post subject:

Could a tired caliper seal cause this?
_________________
78 924 NA
5-lug

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

Horizonblue · Posted: Sun May 25, 2014 5:29 pm Post subject:

The brake hose has not been changed for many years. I didn't get the impression that there was anything wrong with it, when I was working on the brake. But I have a new set laying around, so I can change it anytime.
_________________
Euro 924, 1976

"If you can't fix it, don't break it"

/P.G. Andersen

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

Horizonblue · Posted: Mon May 26, 2014 4:34 am Post subject:

There was actually also a rumbling sound now and then, when driving. Like a faulty wheel bearing. This made me think and two things comes to my mind, that I need to rectify first.

1. The wheel is a bit loose, the centre nut/hub nut needs to be tightened. Will see if there is any noise from the bearings, when it's tightened.

2. The wheel alignment is bad. The cross member and wishbones were dis assembled when I installed the new engine. I installed them where they seemed to have been, but checked today with a string from the rear wheels and especially the right wheel was pointing a lot inwards.

Maybe a loose wheel and bad alignment will cause the pads to touch the disc and make the sound ?

The sound is not new, these pads has always had a sound now and then, when stepping gently on the pedal, but goes away when pressing hard.
_________________
Euro 924, 1976

"If you can't fix it, don't break it"

/P.G. Andersen

musicalannette · Joined: 21 Feb 2012 Posts: 413 Location: UK

brakes can squeel.

disc drakes usually rub slightly when ther pedal isnt pressed.

some disc brakwes have an anti squeek plate between the piston and the back of the brake pad. the chatter that goes on between the pad and the caliper caused but the rotating disc surface can be annoying.

you can either try to stop the chaTTER BY PUTTING IN A DIFFERENT BRAKE SURFACE (DISC /PADS). OR BY ADDING A DAMPER TO SLOW/CHANGE OR REMOVE THE OSCILLATION (usually grease). THATS WHAT THE PLATE DOES. ADDING GREAse to the brake piston/pad contact area can act as a damper, so can adding it the pad/caliper contact areas, dont use too much.

tryu something that will be tacky, not too liquidy when it gets hot. copperslip (copper grease)has usually worked well.

best thing to do is wait for a really wet day and see if goes away.

if you live in nevada, i guess youll just have top wait.

hope this helps
_________________
I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

If the wheel bearings are loose, you will be able to make the squeal go away as you swerve. The hub & rotor will rock pressing the pads in making the sound go away. You also notice a spongy pedal. The alignment won't have an affect on the squeal, the bearing will though. The bearing may also be a source of the heat.

Horizonblue · Posted: Thu May 29, 2014 8:36 pm Post subject:

Well, I decided to replace the brake hose, that went quite easy. But I was having a hard time believing that this was the problem. After bleeding the brakes, I could feel that the left wheel spun freely, but there was a slight resistance in the right wheel.

So I tried again to press the piston back, with the water pump plier. Thinking about it, maybe I needed to apply too much pressure, to press it back. So I took the calliper of and started dismantling.

As soon as I touched the bellow, it disintegrated...

Ok, here was the problem. Dirt had over time made it's way into the piston and there was also dirt behind the piston.

So I have ordered a piston repair kit, and believe that the noise and heat issue is gone, when I assemble the calliper again.

_________________
Euro 924, 1976

"If you can't fix it, don't break it"

/P.G. Andersen

ThomasJoseph315 · Guest

The "dirt" is the hose breaking down. What happens is that the inner lining of the hose over a period of time flakes apart from the heat and vibration floating down into the caliper and gets ground down like sand paper against the piston O-ring. All cars do this and it's just a matter of time before they need to be replaced. This is why when you use the brake the car is fine, it's because your applying a lot of pressure and absorbing the vibration with the pad. But, when you let off the brake peddle the flakes act like a wedge and keep the caliper piston slightly pressed onto the rotor, hence the heat up you're getting. Generally you see this more common after a fresh brake job or any time you remove the caliper and let it hang or twist it in a way that is outside the norm.

Change the hose and bleed the system out with fresh new fluid and yes since you will be bleeding it anyway, change the "O-ring" on the caliper piston. It's pretty easy to do.

Pro Tip: Whenever you replace a hose, replace the caliper or at a min the caliper o-ring while cleaning out the "dirt" inside the caliper. Simply replacing the hose will only cure the problem, not the effect of it. It's all down hill,..

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

The piston is probably difficult to depress because the hose is swollen (it will be difficult with a swollen hose). You should always open the bleeder screw when pressing the piston in, especially on an abs car. Opening the bleeder screw or removing the line will give you an accurate feel of the pistons stiffness when compressing.

musicalannette · Joined: 21 Feb 2012 Posts: 413 Location: UK

Hi,

if you do have the sort of heat at the wheel caused by the pad being pressed by bad flexible hoses, then all sorts of things could happen.

you dont have a seal gone otherwise you would have leakage.
the brakes dont usualluy stick "on" either, they usually stick coming on.
meaning if you brake slowly only one piston works until you press really hard.

if the flixible hoses are shot, they could crumble, tear, or perrish in anyway imaginable. the most unusual one i have seen is a flap of rubber acting as a one way valve! maybee you have that.

the squeeking i mentioned above usually happens when there is a very small amount of contact pressure, allowing chatter between the disc and the pad.

if the wheel is getting hot to the touch, then this is not what i am talking about and there is something more serious.

HAVE YOU JACKESD THE CAR UP AND CHECKED THE WHEEL BEARING IS NOT LOOSE? checked for play?

sorry for the caps lock.

if the brake hoses were weak and started to bulge through lack of reinforcement then i would also expect the brake pedal to be a bit soft then pressed hard? is it?

changing the brake flexi rubbers cant hurt. neither can changing the brake pistons/slave cylinders and master cylinder seals.

there not expensive.

but i would check the wheel bearing first.
_________________
I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

musicalannette · Joined: 21 Feb 2012 Posts: 413 Location: UK

just another thing,

are you sure your pads are seated correctly?
that they are fitted squarely in th caliper? nothing between them and the caliper? no baked on dirt etc?
_________________
I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

Horizonblue · Posted: Sat May 31, 2014 6:49 am Post subject:

The brake pedal is as it has always been, hard. The wheel bearings were a bit loose, but not as bad as I expected. I tightened the hub nut as per Haynes, so that is fine now.

Now that I have dismantled the caliper, I think that the fault is obvious. The piston is dirty because of the faulty bellow and it can hardly move in and out of the housing, even though I'm standing with it in my hands (no oil to be pressed back through the system)

I will clean the piston and assemble with a new gasket and bellow (and the new hose I have already installed)

Will take the left side also, now that the car is jacked up anyway. It is very easy to work on.
_________________
Euro 924, 1976

"If you can't fix it, don't break it"

/P.G. Andersen