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MG Midget and Sprite Technical - Squealing brakes

Not on a Spridget, but someone will know.
Fitted new pads and discs on the Fiat and at light brake pressure they are squealing badly.
They don't use anti squeal shims so I will try chamfering the edge of the pads. But is it the leading edge, or the trailing edge that one does this to?
GuyW

I always though copper grease was the cure for squeaking brakes.
James Paul

Well I've done it now, though not yet tested.
I found that the pads were already chamfered at leading and trailing edges, but not on the inner curved edge next to the hub, where they might have been picking up dust. The only other thing I did do, as James mentions, is to add more copper ease to the backs of the pads. We shall see!
GuyW

On my MGB V8 conversion the front brakes (4-pots using large Volvo pads) squealed horribly at low speed. I bought some 3M anti-squeal pads and stuck them on the back of the pads and so far they are quiet.
Mike Howlett

Thanks Mike. Another option if the copper ease doesn't work. I hadn't heard of that 3M stuff.
GuyW

It's a Fiat so has auditable warning to let you know the pads are at least touching the discs.

Just for info when I fitted some Pagid discs and pads to my wife's current car it had not to use copper grease on modern cars but copper-free grease for metal to metal and another grease for the pins in rubber boots.

Delphi doesn't recommend copper grease either. - https://www.autotorque.news/the-aftermarket/technical-talk/delphi-does-not-recommend-the-use-of-copper-grease/

Below, from about 20 + years ago, a proper sized Fiat family car, lowered, and on BMW !! favoured dampers and springs, and with sports exhaust obviously.



Nigel Atkins

This the stuff Guy. https://www.ebay.co.uk/itm/274644968043
Mike Howlett

I and/or a mate have used that sort of stuff (comes in the brake pad kit sometimes IIRC) and it seems to have worked but IIRC I once tried it on some very noisy pads on my B and IIRC it didn't work, but the noise just went away by itself after a fair bit of car use and mileage (certainly for average MGB use).
Nigel Atkins

Well, for now it is sorted. Will have to see how long that lasts.
GuyW

Reactivating this thread as although I thought my squealing brakes were cured - they still squeal! I have R & R'd the front pads repeatedly and each time the squealing returns after a very short period of time. I had replaced disks and pads (I think they were Pagid ones) and have tried:
Thorough cleaning of all pad to caliper surfaces
Chamfering all edges of the pads
Use of copperease on the pad backs where they contact the caliper pistons
Use of copperease on the 'ears' of the pads where they locate in the calipers.
I tried the suggested 3M backing pads. They worked best, but only for a while and the annoying noise is back again!

Any more suggestions?I
The only thing I can think of is to try buying another set of new pads of a different brand.
GuyW

No more ideas?
GuyW

You've tried everything I'd have suggested Guy; the only thing I can think of is did you get new retainers with the new pads? If you did and you fitted them how about changing them for the old ones? You can tell the barrel's base is being scraped here😧
Jeremy MkIII

I am not familiar with Fiat brakes. Do they have the usual single pot and sliding caliper? I had a an issue with my wife's VW UP! and found the sliding pins needed relubing with hi temp silicon brake grease (not copperslip) It is made by Pagid and designed for modern braking systems.
Bob Beaumont

No Jeremy, these dont have those wire retainers. There are little stainless steel inserts tgat slot into the notch in the caliper castings, into which the lugs on the brake pads then fit. An obvious possibility for a high frequency vibration there, but they are well doused with copperease.

Bob, yes a fairly standard single piston in the fixed part of the caliper, and then the other part slides. I had not thought of greasing the sliding pins, though I did clean them thoroughly. They are a bright chrome- like finish so maybe a smear of silicon brake grease there would help. I have some that came with some 'Big Red' brake parts for another car.
Good idea, and certainly worth a try.
GuyW

Guy
Apart from the stick on pads--could you fit some anti squeal pads from a different vehicle maybe.
As a last resort, I've had luck in the past by removing the pads and scribbling all over the working face of the pad with a black lead pencil--"WARNING" though, the first time you go down the road you'll have very limited braking power ,but it quickly returns to normal after a few stops---might be worth a try
William Revit

Not heard of that one Willie, but anything is worth a try.
It's a real hack vehicle just for shopping, trips to the tip and short journeys down our local really narrow lanes where anything decent quickly gets scuffed and scratched paintwork from the hedges. It's a low investment, low cost vehicle which I am happy to tolerate as long as it keeps going, but it's found a way to bug me with this brake squeal which keeps reappearing!
GuyW

Do your driving skills include rally car style left foot braking? I've used that in the past to bed in reluctant pads by driving on an open road with light pressure on the brake pedal until noises stop.

AdrianR

Guy

I was thinking the same as Adrian about the level and frequency of the use of the car including the nature and intensity of the braking. My regular car does not like sitting around for a week and gets a bit squeally in the brake dept. A decent run including some reasonably heavy braking - carefully done with no-one around so as not causing the inevitable too closely following aggressively driven Audi or SUV that is right up my a***e to join me in my passenger compartment - cleans off the discs and settles the pads a bit.

Either that or turn up the radio and as ever try to give everyone some space for appropriate braking distance even if this is an outmoded notion, along with looking to see if the way is clear, then signalling before manoeuvring!

Cheers
Mike
M Wood

This car gets daily use, short trips plus longer ones of anything up to about 30 miles. Beyond that we take the Volvo - which doesnt squeal though it had new rear discs and pads at the same time and from the same manufacturer.

Squealing doesnt happen on firm braking, its just that light braking at lower speeds in traffic and light 'check braking'.
I'm curious to know what actually generates the squeal noise? I presume its a high frequency vibration between two components somewhere but what, exactly?


And yes, I can still left foot and cadence brake from my rallying days (mini, welsh national championship night stage rallying c.1972/3)
GuyW

Light braking squeal, has to be vibration between the discs and pads Guy. Then as you push harder, the pads can't vibrate.

I've just read that,---

" New cars utilise harder braking materials to ensure they optimise stopping distances and have improved wear. However, when they are new and haven’t completed many miles they can often squeak from time to time because of how hard the metallic compound in the brake is."

Maybe all you need is a bit more time for the pads to bed in Guy.

My Sprite discs/pads squeal dependant on the weather. And the Capri did the same. Then I got some new old stock Mintex asbestos pads and put tbose in the Capri, and it never squeaked again.

I've never understood the copper ease behind the pads solution. I've tried it, and it's never worked for me.

On the rwa midget I had, I actually took the anti squeal shims out, and that *cured* the squealing. Work that out.

anamnesis

I think the copper ease is that it acts as a damper to the vibrating pad. But i wasnt sure if the vibration is between pad and disc, or between pad (dragged by disc) and the caliper.

But you are right about the weather conditions, particularly the humidity I think. Worst when its dry, dampened when it's, err, damp.
GuyW

Another follow up on my squealing Fiat brakes.
I had exhausted all of the known tricks to silence these brakes, and still they squealed!
I tried one last idea. Some pads have a slot across the middle, acting radially to the disk. I have never discovered what it is for but it gave me the idea. I removed the pads and cut narrow slots across each pad with an angle grinder and slitting disc. And so far at least it has worked! Something for the memory banks!
GuyW

I posted earlier in this thread that the 3M anti-squeal pads worked on my MGB V8, but since then the squeal has returned with a vengeance. It's quite deafening to someone standing near the car. Again it only happens with low speed gentle braking. It makes me want to roar up to traffic lights and stand the car on its nose. No squeal then.
Mike Howlett

Mike, I did try the 3M anti squeal backers too. They worked, for about 40 miles, then the squeal returned.
I shouldn't have posted that slotting the pads had cured it. Last night it began squealing again! Only a bit of a squeak so far but I'm not confident its not just practicing for a full chorous.
GuyW

This thread was discussed between 12/11/2022 and 05/09/2023

MG Midget and Sprite Technical index

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