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Old 31st March 2021, 16:44   #1
Salisbury
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Default Brake squeal

I'm not much of a car guy. I can do the basic services and so on, but nothing too extensive.

I purchased an MG ZT last month. It's fine for the most part. But the brakes squeal very badly.

I thought maybe that it was due to not enough copper grease being applied to them upon its M.O.T., but I recently took it to my local garage, and had it looked at.

I drove the car away just fine, but the brakes still squeal just as loudly.

Any ideas on what the issue could be?
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Old 31st March 2021, 19:26   #2
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Front or back brakes ??
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Old 1st April 2021, 09:47   #3
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Brake squeal from discs/pads/callipers, front or rear, it makes no difference they both work exactly the same, can be caused by many things, the favourites being poor quality incompatible pad material, anti squeal shims being left out, or original rusted ones being re-fitted, pad material contaminated by oil, grease or brake fluid and lack of, though it shouldn't be necessary though it helps, grease, though many use Copaslip ceramic based one for the purpose is superior.


After the popular faults come glazed pads due to very light brake application, poor quality discs, general slight overall wear to pins, caliper sliders, pad retaining springs and pad seats on the calliper all insignificant on their own but can add up to allow excess movement and vibration, but this latter one is quite rare, but not unknown.


If you can determine if the front or rears only are affected, fronts are the normal culprit, then do the following to the ones affected, if all appear to be affected, then do just the fronts, test drive for a week or so to see any improvement, if so repeat on the rears.


The above is a generalisation of disc brakes, of which the 75 is similar.



Depending on the general condition, the best thing would be to clean and lubricate, where required, with a dedicated brake grease, the assemblies, checking that the anti squeal shims are actually fitted, bearing in mind many modern vehicles the 75 included, don't have separate loose shims of old, but have either a bonded one on the back of the pad or one that is clipped to the back of the pad if not then buy and fit some, they are quite cheap and see how you go on, if it still occurs then the next step would be to replace the pads, even though they may not be worn, with a good known quality set complete with new shims, it's surprising at how many folk ignore shims.


I'm intrigued when you said " not enough copper grease being applied to them upon its M.O.T., " what makes you think that Copaslip was used during an MOT ? during an MOT, nothing is removed or lubricated at all, it is simply an examination of all the relevant areas by various means, did the brakes squeal before the MOT and, or, after ? is there any paperwork with the car suggesting that the car has recently had work done on the brakes ?


One thing to try and it must be done with great care, is several full on emergency stops from a fair speed on a quiet road, empty car park, paying attention to everything around you and ensuring that in doing so you will not cause any danger to your self, others or property, doing this can temporarily remove pad glazing cause by continued light brake applications.
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Old 1st April 2021, 09:53   #4
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You could always whip the pads out and if glazed run over them with a dreadnought file - something I often do to the rear handbrake shoes.

If still squealing then a trick I learnt long ago was to cut a groove with a hacksaw in the brake material, you perhaps have seen some brake pads are made like this. It prevented squealing on my old Saabs. At your own risk of course.

Good luck
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Old 1st April 2021, 13:10   #5
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That happened to me and the culprit was cheap brake pads. I then fitted Bosch and the squeal went away.
I did note that the sides of the pads were at an 45 degree angle compared to the cheaper variety that were at 90 degrees.
I'm sure this has been mentioned before in other posts.
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Old 1st April 2021, 13:45   #6
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Quote:
Originally Posted by Salisbury View Post
I'm not much of a car guy. I can do the basic services and so on, but nothing too extensive.

I purchased an MG ZT last month. It's fine for the most part. But the brakes squeal very badly.

I thought maybe that it was due to not enough copper grease being applied to them upon its M.O.T., but I recently took it to my local garage, and had it looked at.

I drove the car away just fine, but the brakes still squeal just as loudly.

Any ideas on what the issue could be?
A lot of good advice herein, however and if you so wish, and in the lack of evidence of any recent service of note, take the car to a good garage and ask them to give you a price for a brake service, to include, disassembly, examining of the parts and replacing as required, if you can do it yourself then methodically carry out the work.
Does the handbrake hold the car well?.
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Old 1st April 2021, 20:30   #7
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Normally front pads and discs run hotter than the rear due to the fact they dissipate much more energy.--( 80% the front to 20% the rear .) this can affect whether they squeal or not.
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Old 2nd April 2021, 07:57   #8
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Quote:
Originally Posted by Salisbury View Post
... the brakes still squeal just as loudly. Any ideas on what the issue could be?
Clean and lubricate the sliding caliper Ben. It's the weak point with this design.

Simon
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