Brake squeal, how to stop it!
Discussion
The front brakes on the Mexico squeal awfully every time I pull up. They work nicely pulling the car up straight but as the speed drops off, they start to squeal and it's starting to get really annoying. The brakes feel strong but seam to 'grab' as the speed diminishes.
They are 3 pot Girling callipers with ventilated disks, callipers have been refurbished and the pads and disks are new. I've pulled them apart a couple of times now, re-assembled with copper grease etc, all the usual stuff but without any real change. The setup is standard 1960s large GT, used on Aston Martin and Jags so this should be a fairly normal issue, so has anybody got any suggestions on what to try next?
Paul
They are 3 pot Girling callipers with ventilated disks, callipers have been refurbished and the pads and disks are new. I've pulled them apart a couple of times now, re-assembled with copper grease etc, all the usual stuff but without any real change. The setup is standard 1960s large GT, used on Aston Martin and Jags so this should be a fairly normal issue, so has anybody got any suggestions on what to try next?
Paul
Not au fait with the girlings but squeal is the pad moving about (only very slightly), typically damped with copperslip on the back between piston and pad.
That however assumes all is reasonably well with the setup.
Firstly are you sure you're not missing any shims (often removed with after-market pads and not replaced) or clips to stop the pads moving around.
With the brakes off you should not be able to move the pads about at all, if you can then investigate why.
If that then fails then you can get some special dampening paste (eg http://www.motoelectrical.co.uk/crc-shop/crc-disc-... ) which dries as a hard rubber back on the pads to prevent the noise.
You might also want to consider trying other pads as it might just be those pads that do it.
That however assumes all is reasonably well with the setup.
Firstly are you sure you're not missing any shims (often removed with after-market pads and not replaced) or clips to stop the pads moving around.
With the brakes off you should not be able to move the pads about at all, if you can then investigate why.
If that then fails then you can get some special dampening paste (eg http://www.motoelectrical.co.uk/crc-shop/crc-disc-... ) which dries as a hard rubber back on the pads to prevent the noise.
You might also want to consider trying other pads as it might just be those pads that do it.
esso said:
If they are Mintex pads,bin them.Use EBC then you shouldn't have a problem.
No, don't bin them if Mintex. Brake pad squeal is nearly always down to poor fitment by the installer. Mintex have been around far too long and know how to ensure squeal free operation. Ensure caliper is spotlessly clean with proper free movement of pistons, install pads with either copperslip or ideally Ceratec paste, if possible fit new shims, clean, grease and adjust sliders correctly. Plus, before fitting make sure the brake disc surface is spotlessly clean/both sides as any contamination will go straight on to the new pads. For best results de-glaze with 600/800 and clean with methylated spirit, allow to dry and install calipers. Once tightened re-check pads for any movement and adjust if necessary.The remedy for stopping brakes squeeling worked when a mechanic many years ago.
Remove the pads and, I was told, the problem is caused by the acute angle, 90 degrees, that the pad is to the disc. Get a file and file that square edge down so that this angle is reduced to about 45 degrees. You only need to take a small amount off, and NO it won't make any difference at all to the braking ability of the vehicle. You should do this to all 4 pads, (that's 8 surfaces), for some unknown reason it often cures the squeek permanently, even though, logically, it shouldn't.
Another trick I learned, back in the good old days. If your car pulls slightly to the left or the right, and you've checked all the front geometry, and found nothing wrong. If you just swap the front wheels over - it often cures the problem. Sorry, but I never found out WHY it worked - but it did.
Remove the pads and, I was told, the problem is caused by the acute angle, 90 degrees, that the pad is to the disc. Get a file and file that square edge down so that this angle is reduced to about 45 degrees. You only need to take a small amount off, and NO it won't make any difference at all to the braking ability of the vehicle. You should do this to all 4 pads, (that's 8 surfaces), for some unknown reason it often cures the squeek permanently, even though, logically, it shouldn't.
Another trick I learned, back in the good old days. If your car pulls slightly to the left or the right, and you've checked all the front geometry, and found nothing wrong. If you just swap the front wheels over - it often cures the problem. Sorry, but I never found out WHY it worked - but it did.
v8250 said:
esso said:
If they are Mintex pads,bin them.Use EBC then you shouldn't have a problem.
No, don't bin them if Mintex. Brake pad squeal is nearly always down to poor fitment by the installer. Mintex have been around far too long and know how to ensure squeal free operation. Ensure caliper is spotlessly clean with proper free movement of pistons, install pads with either copperslip or ideally Ceratec paste, if possible fit new shims, clean, grease and adjust sliders correctly. Plus, before fitting make sure the brake disc surface is spotlessly clean/both sides as any contamination will go straight on to the new pads. For best results de-glaze with 600/800 and clean with methylated spirit, allow to dry and install calipers. Once tightened re-check pads for any movement and adjust if necessary.Several years ago I had a much modified V12 E Type with uprated brakes from AP (I think).
Nothing we did would stop them squealing and so we tried changing the pads, the third set finally did it and they were perfect.
Sorry I can't recall which pads we used, but the point is, changing the pads may be the only solution.
Nothing we did would stop them squealing and so we tried changing the pads, the third set finally did it and they were perfect.
Sorry I can't recall which pads we used, but the point is, changing the pads may be the only solution.
I used to have a set of 3 piston Girlings on an Austin 1800S (don't laugh!) and these worked perfectly quietly.
One other thought - have you had the wheels repainted and, if so, is there any paint at all on the surface where the wheel mates to the disk? If there is, this can cause vibration problems when braking and brake squeal. Remove the paint with abrasive paper.
One other thought - have you had the wheels repainted and, if so, is there any paint at all on the surface where the wheel mates to the disk? If there is, this can cause vibration problems when braking and brake squeal. Remove the paint with abrasive paper.
mph said:
Other than the squealing brakes how are you finding the Mexico ?
Smooth... It goes better with speed and doesn't like to trundle on twisty roads but the more I drive it, the more confidence I have in the handling. It has a slight misfire at the moment which is on the ignition side, fluffing in time to bouncing needle on the Rev counter so that needs looking at. There is also a whine from the gearbox, and even though changes are beautifully slick, I may drop it out for a refurb over winter. Hill starts are a bit of a bugger too as the handbrake is so far away!Despite these minor issues, we drove back from Whitby on Sunday, 3 up at 150kph ish and it was just effortless, I'm loving it.
esso said:
Mintex pads were fitted to my TVR professionally, both front and rear squealed badly and nothing I did stopped it, they were too hard for road use. They were changed for EBC red-stuff and the problem was immediately resolved....and the discs were brand new.
Ah, so it wasn't Mintex per se, it was the brake material that was too hard for road use and most likely needed to warm up before the squealing stopped; this is a common issue with upgraded pads. Interestingly, Mintex have an amazing selection of pad material mixes readily available for fast road use...one can use their online BrakeBook facility and then discuss further with them the pad characteristics. Brake squeal is notorious on Carbotech pads fitted to Evos, which is where I'm at. People have already mentioned chamfering the edge of the pads, which I did, I also opened out the slot in the middle of the pads to a V shape, and treated the back of the pads with an anti-squeal spray. So far, so good.
There are two types of squeal.
Do the brakes only squeal on light applications, but disappear on hard braking?
Or do they squeal regardless of pedal pressure.
The first case is the most common. When braking there is a high frequency vibration, which causes the piston(s) to rotate against the back of the pad. Hence why coating with copperslip or fitting anti squeal backing usually does the trick. Look for a very bright witness mark in the form of a ring on the back of the pad.
The second case is often material or disc related. It is incredibly rare for pad material to be at fault - only if there is some incompatability with the disc.
No brakes should squeal - there is always a reason/cure.
Do the brakes only squeal on light applications, but disappear on hard braking?
Or do they squeal regardless of pedal pressure.
The first case is the most common. When braking there is a high frequency vibration, which causes the piston(s) to rotate against the back of the pad. Hence why coating with copperslip or fitting anti squeal backing usually does the trick. Look for a very bright witness mark in the form of a ring on the back of the pad.
The second case is often material or disc related. It is incredibly rare for pad material to be at fault - only if there is some incompatability with the disc.
No brakes should squeal - there is always a reason/cure.
V8 FOU said:
There are two types of squeal.
Do the brakes only squeal on light applications, but disappear on hard braking?
Or do they squeal regardless of pedal pressure.
The first case is the most common. When braking there is a high frequency vibration, which causes the piston(s) to rotate against the back of the pad. Hence why coating with copperslip or fitting anti squeal backing usually does the trick. Look for a very bright witness mark in the form of a ring on the back of the pad.
The second case is often material or disc related. It is incredibly rare for pad material to be at fault - only if there is some incompatability with the disc.
No brakes should squeal - there is always a reason/cure.
It's the former, they're quiet when they're being properly used but squeal like a banshee at slow speeds. They are well greased at the back with copper-slip, but there are no shims present. Do the brakes only squeal on light applications, but disappear on hard braking?
Or do they squeal regardless of pedal pressure.
The first case is the most common. When braking there is a high frequency vibration, which causes the piston(s) to rotate against the back of the pad. Hence why coating with copperslip or fitting anti squeal backing usually does the trick. Look for a very bright witness mark in the form of a ring on the back of the pad.
The second case is often material or disc related. It is incredibly rare for pad material to be at fault - only if there is some incompatability with the disc.
No brakes should squeal - there is always a reason/cure.
Cheers for the guidance.
I've posted this before but it's always worth a chuckle. On one of our tours one person had great problems with brake squeal on his E-type. Being an intelligent university professor he thought about it and worked out how to fix the problem. Luckily we caught him just before he greased the discs. 
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