Want to run something by you folks and see what you think of it. I've got newish pads and rotors on my car which have done about a month of driving since installation. Anyway, while I was doing the latest repair on my car I did brake caliper rebuilds at the rear as one of them was leaking. However, now when I brake lightly I am getting a noise from the drivers side rear area.
It's not the usual squeal from a brake pad though: this one sounds just slightly higher than a foghorn! If I push the pedal harder the noise goes away; if I take my foot off the noise goes away. Have tried swapping the inner and outer pads, have covered the area with brake cleaner and have regreased the 2 sleeves on the caliper but nothing has helped. Might be my imagination but the noise seems to be more frequent if I brake while I am turning.
Brakes feel fine and I'm not leaking fluid or anything. Should I just live with the noise and be happy my car is running at all(!) or should I look more into it, maybe getting the almost new rotor resurfaced?
Brake noise, but not the usual squeal
1993 Suzuki Alto Works RS-X
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Did you by chance remove the anti rattle shims? they are a thin peice of metal that goes between the back of the pad & the piston. If the shim has been lost there is an anti rattle preparation available - it comes in a bottle or tube & dries to a soft gel/foam. also make sure there is a short taper on the leading edge of the pad.
So many delays to getting my MB back in order with 993cc & 5 speed transaxle... neighbor issue gone, donor shell up on rotisserie, new sheds on the way.... another project also..
I have found 'rattle' shims do bugger all on disc brakes....
by the sounds of it being worse around corners I would say your wheel bearings have got a slight amount of play in them and need replacing.
I found a good test if to quickly press the brake pedal twice and if the second time the pedal is MUCH firmer and the noise stops it's wheel bearings.
The other option is that after your brake rebuild you have trapped a small amount of air in the calliper that can't escape from conventional bleeding of the brakes (ie. pushing the pedal and topping up the reservoir). This small amount of air means the calliper piston cannot push with an even amount of force on it's surface area so it skews off centre and then the pad doesn't meet the disc flat and allows all sorts of noises/rubbing....
To fix take the calliper off and put a length of clear tube over the bleed nipple with it facing vertical (so that the trapped air will come out first), open the nipple and push the brake piston into the calliper body until it's all the way (make sure it it all the way...sometimes it requires some force to get it started, but don't use excessive force. I use a spanner over the face of the piston and only use my fingers as levers....NO tools!!!).
Close the nipple push the brake pedal until brake piston is halfway out (careful not to let it out all the way!!!!) and repeat it for a second time just to make sure all the air is out. Top up your brake fluid and way you go...
by the sounds of it being worse around corners I would say your wheel bearings have got a slight amount of play in them and need replacing.
I found a good test if to quickly press the brake pedal twice and if the second time the pedal is MUCH firmer and the noise stops it's wheel bearings.
The other option is that after your brake rebuild you have trapped a small amount of air in the calliper that can't escape from conventional bleeding of the brakes (ie. pushing the pedal and topping up the reservoir). This small amount of air means the calliper piston cannot push with an even amount of force on it's surface area so it skews off centre and then the pad doesn't meet the disc flat and allows all sorts of noises/rubbing....
To fix take the calliper off and put a length of clear tube over the bleed nipple with it facing vertical (so that the trapped air will come out first), open the nipple and push the brake piston into the calliper body until it's all the way (make sure it it all the way...sometimes it requires some force to get it started, but don't use excessive force. I use a spanner over the face of the piston and only use my fingers as levers....NO tools!!!).
Close the nipple push the brake pedal until brake piston is halfway out (careful not to let it out all the way!!!!) and repeat it for a second time just to make sure all the air is out. Top up your brake fluid and way you go...
Could be the latter as there was no noise before I did the rebuild and as soon as I'd done it there was noise.ike849 wrote:I have found 'rattle' shims do bugger all on disc brakes....
by the sounds of it being worse around corners I would say your wheel bearings have got a slight amount of play in them and need replacing.
I found a good test if to quickly press the brake pedal twice and if the second time the pedal is MUCH firmer and the noise stops it's wheel bearings.
The other option is that after your brake rebuild you have trapped a small amount of air in the calliper that can't escape from conventional bleeding of the brakes (ie. pushing the pedal and topping up the reservoir). This small amount of air means the calliper piston cannot push with an even amount of force on it's surface area so it skews off centre and then the pad doesn't meet the disc flat and allows all sorts of noises/rubbing....
To fix take the calliper off and put a length of clear tube over the bleed nipple with it facing vertical (so that the trapped air will come out first), open the nipple and push the brake piston into the calliper body until it's all the way (make sure it it all the way...sometimes it requires some force to get it started, but don't use excessive force. I use a spanner over the face of the piston and only use my fingers as levers....NO tools!!!).
Close the nipple push the brake pedal until brake piston is halfway out (careful not to let it out all the way!!!!) and repeat it for a second time just to make sure all the air is out. Top up your brake fluid and way you go...
Should note, this rear disc setup has the thing where you actually screw the piston into the caliper. Can I still follow this guide? Sorry for being dumb but I want to make sure.
1993 Suzuki Alto Works RS-X
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the latter certainly makes sense - you will also have a spongy pedal if there is air in the system.
I have seen anti rattle shims do some weird & wonderful things in my time.
some cars they do next to nothing others don't like being without. My experience is mostly vicarious through workshops that I have supplied parts & mates in the trade as well as my own maintenance - this doesn't make me any better than anyone else in my opinion - just wanting to show that I am not talking through you know what.
I have seen anti rattle shims do some weird & wonderful things in my time.
some cars they do next to nothing others don't like being without. My experience is mostly vicarious through workshops that I have supplied parts & mates in the trade as well as my own maintenance - this doesn't make me any better than anyone else in my opinion - just wanting to show that I am not talking through you know what.
So many delays to getting my MB back in order with 993cc & 5 speed transaxle... neighbor issue gone, donor shell up on rotisserie, new sheds on the way.... another project also..
Am just thinking it's not shims as the brakes worked without the shims for a time with no noise at all. Then as soon as I did this caliper rebuild I get the "foghorn" noise on light braking.
1993 Suzuki Alto Works RS-X
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Strange little update from my small trip out just now to get junk food for the night. To get from my apartment parking area to the road there is a small but steep kerbside. As I reversed out of it turning onto the road I heard the noise again, but my foot wasn't near the brake.
Thought it could be wheel bearing, but the noise doesn't sound like it's rotation-based. Usually it sounds like it's constant when the brakes have a little pressure on them. Suppose if there is air in the system the caliper might not be retracting as quickly, so when I set off it can stick and make a noise. Will try to check that tomorrow.
Thought it could be wheel bearing, but the noise doesn't sound like it's rotation-based. Usually it sounds like it's constant when the brakes have a little pressure on them. Suppose if there is air in the system the caliper might not be retracting as quickly, so when I set off it can stick and make a noise. Will try to check that tomorrow.
1993 Suzuki Alto Works RS-X
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gadj, I wasn't trying to offend you just that every car or bike i've owned they have been useless....
soldave same procedure for the screw in type pistons, in fact you should do that procedure every time you replace your brake fluid (1 to 2 years) just to make sure as much fluid as possible has been replaced!
air specifically won't effect the piston movement, but an off centre piston will jam and 'could' cause what your talking about....
a wheel bearing with play in it won't make a loud rotational noise, however a broken bearing will. The reason is that the whole assembly is on a slight angle which causes the problem gadj mentioned of a leading edge on the disc from the brake pads (ie. front of the pad touches before the rear of the pad).
Just had another thought, you said you swapped the pads around and it made no difference. You shouldn't do this without bedding them in again as the faces of the pads and the disc don't match which will cause vibration and noise also.
When ever I look at my brakes I always, get a metal file to ruff them up a bit on their face then clean them with brake cleaner to remove all brake dust.
Once on the car go through the bed in procedure again. you can't really bed in pads twice as bedding in does two things match the surface of the pads to the disc (which is what you want to do) and 'cook/bake/harden' the pad material from the manufacturing process (you can't do this twice)
I usually bed my brakes in by going for a normal 5mins drive to a stretch of road that has no traffic (important!!!) and is straight and at least a couple of km's long.
This warms the pads ready for the intense heat you are about to give them. I then follow a procedure like this;
(note you don't have to do exactly this as all you are trying to achieve is to get the pad and disc up to temp and wear away pad material to match the surfaces);
Procedure (all braking is done to almost a stop, don't come to a stop as you will be transferring a lot of heat directly onto one part of the disc...bad)
2x 50km/h medium braking
1x 100km/h medium braking
1x 100km/h hard braking (you should almost be breaking traction)
Drive for 30sec no brakes
2x 80km/h medium braking
2x 100km/h hard braking (you should almost be breaking traction)
Drive for 30sec no brakes
1x 80km/h medium braking
2x 100km/h hard braking (you should almost be breaking traction)
Normal driving for about 10mins to let the brakes cool down evenly
Park car WITHOUT the handbrake on for 2hours to let everything cool down completely.
The driving for 30sec with no brakes allows any loose brake material to clean away so that you get a perfect match between the surfaces. Don't leave this 'cleaning' period for more than that otherwise your pads will cool down which defeats the purpose.
When doing the bed in you may smell brake fluid or brake dust and sometimes you may get a puff of smoke coming off the pads (the smoke is usually from the resins in the pads cooking out), this is ok, just remember to keep moving otherwise all that heat will be put into one section of the disc which can make it warp. A good gauge of 'is everything ok' is the brake pedal, a small amount of loss in pedal power is ok, but a significant amount means you have either got a leak some where or your fluid is boiling....stop the bed in straight away and fix what's wrong then repeat the procedure.
If you are still concerned that something is wrong it won't hurt to stop quickly without the handbrake on and do a visual inspection of the rotors and callipers.
I like to replace my brake fluid after a bed in as it has most likely boiled (you can never prevent a tiny amount of moisture getting into the system) and it gives a very nice firm feel to the pedal again.
soldave same procedure for the screw in type pistons, in fact you should do that procedure every time you replace your brake fluid (1 to 2 years) just to make sure as much fluid as possible has been replaced!
air specifically won't effect the piston movement, but an off centre piston will jam and 'could' cause what your talking about....
a wheel bearing with play in it won't make a loud rotational noise, however a broken bearing will. The reason is that the whole assembly is on a slight angle which causes the problem gadj mentioned of a leading edge on the disc from the brake pads (ie. front of the pad touches before the rear of the pad).
Just had another thought, you said you swapped the pads around and it made no difference. You shouldn't do this without bedding them in again as the faces of the pads and the disc don't match which will cause vibration and noise also.When ever I look at my brakes I always, get a metal file to ruff them up a bit on their face then clean them with brake cleaner to remove all brake dust.
Once on the car go through the bed in procedure again. you can't really bed in pads twice as bedding in does two things match the surface of the pads to the disc (which is what you want to do) and 'cook/bake/harden' the pad material from the manufacturing process (you can't do this twice)
I usually bed my brakes in by going for a normal 5mins drive to a stretch of road that has no traffic (important!!!) and is straight and at least a couple of km's long.
This warms the pads ready for the intense heat you are about to give them. I then follow a procedure like this;
(note you don't have to do exactly this as all you are trying to achieve is to get the pad and disc up to temp and wear away pad material to match the surfaces);
Procedure (all braking is done to almost a stop, don't come to a stop as you will be transferring a lot of heat directly onto one part of the disc...bad)
2x 50km/h medium braking
1x 100km/h medium braking
1x 100km/h hard braking (you should almost be breaking traction)
Drive for 30sec no brakes
2x 80km/h medium braking
2x 100km/h hard braking (you should almost be breaking traction)
Drive for 30sec no brakes
1x 80km/h medium braking
2x 100km/h hard braking (you should almost be breaking traction)
Normal driving for about 10mins to let the brakes cool down evenly
Park car WITHOUT the handbrake on for 2hours to let everything cool down completely.
The driving for 30sec with no brakes allows any loose brake material to clean away so that you get a perfect match between the surfaces. Don't leave this 'cleaning' period for more than that otherwise your pads will cool down which defeats the purpose.
When doing the bed in you may smell brake fluid or brake dust and sometimes you may get a puff of smoke coming off the pads (the smoke is usually from the resins in the pads cooking out), this is ok, just remember to keep moving otherwise all that heat will be put into one section of the disc which can make it warp. A good gauge of 'is everything ok' is the brake pedal, a small amount of loss in pedal power is ok, but a significant amount means you have either got a leak some where or your fluid is boiling....stop the bed in straight away and fix what's wrong then repeat the procedure.
If you are still concerned that something is wrong it won't hurt to stop quickly without the handbrake on and do a visual inspection of the rotors and callipers.
I like to replace my brake fluid after a bed in as it has most likely boiled (you can never prevent a tiny amount of moisture getting into the system) and it gives a very nice firm feel to the pedal again.
Don't worry ike no offense taken or intended. I keep my ego in check.
We all have differing experiences & offering them up for others to learn from is a good thing.
Excellent advice on the bedding in procedure by the way!
We all have differing experiences & offering them up for others to learn from is a good thing.
Excellent advice on the bedding in procedure by the way!
So many delays to getting my MB back in order with 993cc & 5 speed transaxle... neighbor issue gone, donor shell up on rotisserie, new sheds on the way.... another project also..
Took the caliper off today, and did an alternative bleeding of the piston, as well as lubing everything up gratuitously with grease & WD-40. Only been for a couple of short drives but it sounds like the foghorn has gone, making my driving experience much less embarrassing!
1993 Suzuki Alto Works RS-X
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