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MG MGA - Squealing Brakes

I have been trying to identify the cause and solution for addressing LOUD squealing under braking and lighter squealing going around long RH bends. Informed ideas of where to look next are most welcome !

The car has standard MGA disc brakes up front. There is no squealing on using only the handbrake, which I would suggest rules out rear brakes. That the problem is also apparent under certain steering conditions also suggests a problem at the front of the car. The car brakes well and stops in a straight line when braked hard. No pulling to one side is apparent wench driving hands-free, or when braking. There seems to be no dragging when the car is allowed to roll downhill without engine running (so I can hear any rubbing). No clunks or knocks when driving or coasting.

New pads fitted cured the problem for a little bit (though the pads were a VERY tight fit between disc and calliper) but the issue is now returning and is also newly appearing in long RH curves. Pads were fitted with copper grease behind, and new pins and retaining pins.

Everything is tight, complete according to the factory setup, and correctly lubricated. All seals are OK. There is no play at the front wheel bearings on either side (rocking vertically and horizontally). There is no unusual sound from bearing or disc when the wheels are spun when jacked up (This has been checked with and without pads fitted). Discs are not scored and show no sign of warpage (measured carefully with a dial gauge and show about 0.1mm run out).

The problem appeared after replacing the rubbers on the swivel links, which had dissolved to goo. The hubs were not removed from the stub axle to do this, but brake callipers were unbolted and hung from the chassis to reduce the mass of the assembly. The old pads showed about 50% wear so were re-used. When the loud squealing started, the new pads were fitted, which brought temporary relief.

I expected to have a pair of new callipers to fit to this car, but the LH side supplied is out of spec (metric threads on the bleed nipples and insufficient clearance to fit the Mintex brake pads between the calliper and disc) so I am waiting for a correct replacement to be supplied by Leacy. I did check the pad thickness in another car and they went in immediately, and the supplied RH calliper is 2mm wider at the slot than the LH one. The new RH one looks like the original Lockeed ones on the car the new LH one obviously has a completely different manufacturer.

Anyone have any ideas?
dominic clancy

Hi Dominic
when you say there is no enough space to fit the Mintex pads, do you mean their actual brake pads or the anti squeal pads?

The Mintex 1144 pads I use are prone to squeal when you apply them lightly but are quiet when applied firmly.
I fitted the Mintex anti squeal shims which stopped the noise.

If there is no space for the shims, could you get some material milled off the pads to get them to fit? ( presuming that they are now asbestos free)
Colyn
Colyn Firth

I should have said that the squeal gets louder with harder braking. The pads on their own were a tight fit, no room for anything else but the copper grease
dominic clancy

Dominic

I had similar symptoms with my previous set of 'new' MGB calipers. For years I could not fully get rid of brake squeal. At its worst it was just as you describe, even down to the squeal when turning. I eventually gave up, bought a new set of calipers and the problem was solved. Never squealed since.

When I took the old calipers apart I found that the manufacturer/supplier/reconditioner had forced in the metal retaining rings, distorting the seals. It would seem that the pistons never fully returned to their at rest position after brake pedal release so there was always too much residual pad pressure on the discs, causing over heating and squeal. I would add that it was the same on both calipers, so it was not a one-off by the assembler.

The pictures show the story.

Steve


Steve Gyles

This stuff is magic:
http://mgaguru.com/mgtech/brakes/bt109.htm
http://www.amazon.com/CRC-Disc-Brake-Quiet-05016/dp/B000CINV88
http://www.oreillyauto.com/site/c/detail/PER0/80729.oap?ck=Search_80729_-1_1617&keyword=80729
Barney Gaylord

Did you resolve the problem Dominic?

Steve
Steve Gyles

No, still waiting for a set of identical matching callipers to renew both sides at the same time.
dominic clancy

This thread was discussed between 30/05/2016 and 14/06/2016

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