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MG MGB Technical - Screeching brakes

Just put a new pair of calipers on the roadster. The discs and pads are good, cleaned everything and copper slipped the back of the pads but it has now developed a squeal every time the brakes are applied, any suggestions as to why.
Trevor Harvey

Did you fit anti-squeal shims/pads too.

Sometimes you just get brake squeal, with use of the car and brakes it can just go away, sometimes after not much use sometimes after lots (and lots) of use.
Nigel Atkins

It did not have shims on before the new calipers and never screeched then so can’t understand why it does now..
Trevor Harvey

Not found any for sale for the MGB. Are these normally fitted to the MGB?
Trevor Harvey

Same happened to me after fitting new calipers.I bought some 3M anti squeal self adhesive shims. Cut them to size and stuck them where the pads slide in the calipers. Ok for last 18 months but time will tell. A cheap fix and I hope it lasts.
Craig M Harvey

I had a B that had a very loud and annoying front brake squeal after fitting new parts, various remedies and combination of remedies were tried to no avail. Then at some point it just went away, I assume the parts just wore passed the point of squeal. I was happy to accept it rather than question it and soon forgot about it and it never returned.

You could try adding shims with or without copper grease, or new pads, with or without copper grease and/or shims - or see how it goes as you are.
Nigel Atkins

Are the cutouts properly aligned in the new calipers?
Chris at Octarine Services

Tried all sort when new calipers and pads started screeching, the only thing that worked - well, I stopped trying things when it did - was self-adhesive pads as mentioned by Craig. Just stuck to the back didn't work, but it seemed to me that the pads had a lot of sideways slop in the calipers, and I had enough space to stick strips down each side from left-overs, and finally silence. That was back in 2014, and still good.
paulh4

Trevor, just to be clearer, by shims I meant the self-adhesive type Craig mentioned, and by pads I meant brake pads, I can't remember the B having the metal type shims.

Even replacing worn/bent/broken brake pad retaining clips could help (by themselves or in combination or permutation of other changes).
Nigel Atkins

As Chris pointed out the piston cutout orientation seems important.
A good many years ago I put new pads in a midget.............squealed like mad to the point where I replaced them with the original brand........sqealing stopped. One set was Ferodo and one Mintex but can't remember the noisy set.
Allan Reeling

The cut-out situation is odd, last time I looked Midget have them facing up or down and MGA outwards.

My V8 pads came with metal shims on the back (Image 1) but the roadster didn't. May depend on manufacturer, e.g. for the ZS MG/Rover pads came with springs, shims and sliding pin bolts whereas others were bare pads.

The V8 shims have cut-outs as well, and with the piston cut-out positioned facing the stub-axle you end up with one quarter having both piston and shim cut-outs in line, one with neither in line, and two with one cut-out either piston or shim.

Looking at the witness marks on the back of old roadster pads (Image 2) the piston would go off the pad on the side nearest the stub-axle, but with the cut-out in that position they don't, so presumably the pressure is 'square-on' rather than pushing that inner edge in harder.






paulh4

If the pistons are slightly out of position as Chris suggested, is it possible to realign them without removing then from the calipers as in the past I damaged the seals On an old pair when reassembling them.
Nigel, Not familiar with the self adhesive shims, can you remember where these were purchased thanks.
Trevor Harvey

Alternatively, look for Permatex Anti-squeal. Comes in a spray can and is sprayed on the backside of the brake pads. It forms a sticky layer, like the self adhesive shims.
C.Boerop Kees

Trevor, you can get the self adhesive anti squeal pads from MGOC spares, see this link

https://www.mgocspares.co.uk/acatalog/MGOC_SPARES_DISCS__MGB__49.html#l17

To be honest, I've used them in the past with not much success as the piston cuts through them and leaves witness marks on the pads. So I used copper grease instead and put a smear of copper grease on the top lugs of the pads as well. This seemed to cure the squeal after a few hundred miles - bedding in I guess.

If the pistons are out of position, then you may be able to reposition them by slightly pushing them out and then use water pump pliers wrapped in a rag to turn them.

Andy



Andy Robinson

To answer the original poster's question, it seems to be the interaction between the piston in the calliper and the brake pad that causes squealing, so I guess changing either can cause it to appear.

I installed Mintex MLB40-M1144 pads (V8 size) last month which are great at stopping but squeal appallingly from 20mph to 0mph. Copper grease had no effect. Mintex stick-on shims (3M branded), plus Ceratec grease, dealt with it for 100 miles but now the noise is back. The pistons are cutting through the shims to the metal of the pad (see photo).

My Plan B is to try metal shims sold by Rimmers under part no. GBP242SHIM.

Plan C will be beefier looking stick-on shims from Mintex sold as Britpart no. DA1141.

I don't want to go back to conventional pads because the M1144 are effective (and also expensive)!

Paul, do I recall that you got rid of a brake squeal once by swapping the brake pads side-to-side?



T H Brearley

Do you guys get CRC products over there-
They have CRC disc brake quiet, it's an orange solution that dries semi firm, just a good clean of the rear of the pads and apply a bead where the piston rubs - no more noise

https://crcindustries.com.au/products/crc-disc-brake-quiet-118ml-5016.html

If it's really noisy I've had luck with scribbling all over the braking surface of the pads with a grey (graphite) pencil, but be carefull first time out as stopping power will be down a tiddle till it all rubs in
willy
William Revit

Andy is quite right that the piston cuts through the self-adhesive pads, but what remains is still effective for me.

Like TH copper grease which I had always used previously stopped working, hence the the continued search. I did get CRC brake Quiet as my next weapon but haven't needed to use it yet.

Swapping between sides that TH asks about was for the rear shoes on the roadster, which only started squealing after years of use, and never came back.

Another oddity on the rear brakes on one side of one of the cars was jamming on when trying to go backwards, again after many years of use. Backing-off the adjuster one click solved that, and even though since then I've carried on assembling and adjusting the brakes as I always have it hasn't reoccurred ... so far.
paulh4

An update to my original question. The pads that were fitted last year were Mintex these appear more prone to squeeling as others mentioned the same problem after fitting these. I have fitted anti squealing pads and the noise has gone away but for how long only time will tell. Thanks for the advice.
Trevor Harvey

Trevor, thanks for reporting back - and all being well that's the end of the squeal.

I've not had squeal with my last and current Mintex pads but different type and different car.

You may have already done this but, in a recent Midget thread it was suggested that new disks should go with new pads as best practice, which it is and which I done on the last two changes at least but IIRC I didn't change the discs on the pads that squealed on the B as I reported in an earlier post - but it's so long ago I can't really remember.
Nigel Atkins

Another update:- all quiet on the brake front now that I'm using both metal and rubber shims on each pad with Ceratec grease.

Belt, braces and one hand holding the trousers up.
T H Brearley

If that fails you'll want belt, braces, chewing gum and a bit of string, we always had this as a kit on order but rarely in stock.
Nigel Atkins

Trevor you say that you have fitted metal as well as rubber shims. Where did you get the metal shims from, or did you make them yourself? Are your replacement callipers standard MGB or are they V8/RV8 ?

When I first had my MGB and overhauled the brakes I looked everywhere for metal shims for the front brakes and couldn't find any, just the stick on ones.

Andy
Andy Robinson

Shims included with some brands of pad, and springs and split-pins, these for the V8. Others are just bare pads. The 'A' and 'B' show how those pads are handed - an inner and an outer.

Circular shims from a particular Peugeot are said to help, similar to these from a ZS 180, but Googling has shown nothing remotely like those.







paulh4

I got the metal shims for my V8 pads (in standard callipers) from Rimmers - https://rimmerbros.com/Item--i-GBP242SHIM

T H Brearley

Thanks Trevor, I really didn't know that you could fit V8 pads into the standard MGB calliper. I had always assumed that the V8 pads would be larger as they have different part numbers.

Really handy to know as you can of course get metal shims for V8 brake pads.

Andy
Andy Robinson

A slightly larger swept area but the jaws are the same width. They are apparently a mix of MGB and Triumph 2.5 PI saloon components which may explain the handing.
paulh4

This thread was discussed between 10/07/2020 and 13/08/2020

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