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MG MGA - Brake noise

Disc brakes, Mintex 1144 pads from Bob West. About 3,000 miles on them. Previous green stuff pads did not seem to do much stopping so switched to Mintex. Much better. But recently they have developed a vibration at low speed, low pressure application. Highly embarassing on the high street.
So far I have checked all the caliper mounting for tightness and chamfered the edges of the pads.
What else could be wrong?
Other info - the discs have about 5,000 miles on them. I bought them new years ago during restoration. They developed a thin film of rust during these years, but seemed to scrub off OK with the first set of pads.
Art Pearse

Art,
Did you de-glaze the discs after the Green Stuff? I know it was 3000 miles ago but your Mintex could have "contaminated" with the green stuff rubbish. De-glaze the discs and the pads. Apply copper slip to the backs of the pads and all contact surfaces between pad backing and calliper.
Allan Reeling

Allan, no I did not deglaze. What's the best way to do this?
Art Pearse

Art
I did exactly what you did and swap a new set of Greenstuff pads with only a few hundred miles on them for a set of Mintex 1144 pads.
They were a vast improvement and the brakes are now superb.
They do tend to squeal though, especially when lightly operated and I cured this by fitting a set of thin self-adhesive shims.
(Available from Mintex or on ebay)

I am now on my 2nd set of Mintex pads but they were fitted in a hurry and I haven't gotten around to fitting the shims yet.

But I will never go back to using Greenstuff.

Cheers
Colyn
Colyn Firth

Art, Just 120 grit, abrasive, a bit of roughness helps to bed in new pads.
Allan Reeling

I was looking on the Mintex web site for the backing pads. They do not list MGA pads at all, just MGB and C
Art Pearse

The Mintex self-adhesive shims come in one size Art and you just use scissors to cut them down to fit the MGAS pad backplate.

Because you have used your pads for a few miles it should be a little easier to fit the shims as there will be more space for them.
Cheers
Colyn
Colyn Firth

I think what Art means is that Mintex doesn't list a brake pad at all for the MGA. I believe Bob had some made as a special batch, they don't seem to be a catalogue item from Mintex.
Dominic Clancy

Sorry Dominic, I thought that from Arts first post he had already fitted a set of M1144 pads and that it was just the shims that he was looking for.

After I fitted the 1st set of Mintex pads I then decided to go the "whole hog" and fit a pair of matching Mintex M1144 rear shoes as well so that there was a perfect balance between front and rear brakes. (rather than having different brake lining materials at the front and rear).
I fitted a pair of new rear brake drums at the same time so that the brakes would be as good as possible.

When I fitted these I immediately noticed a significant improvement in the feel of the brake pedal, which became so much firmer.
Cheers
Colyn
Colyn Firth

As Colyn has fitted them to rear drums are they a good idea for all round usage on a drum braked car? Are the shoes a Mintex standard item?

Paul
Paul Dean

I’ve been using Greenstuff on my roadster front discs

for a few years now, no problem on the road and same on the track - Phillip Island and Sandown raceways, Europe & UK tour, they outbrake my ability!
I have recently installed Redstuff on my competition coupe rear brakes (Dunlop calipers, 10” discs, brake bias control) - will be testing at Winton in 3 weeks, don’t expect any problems as my car is overbraked on the rear.
Mike
Mike Ellsmore

Paul,
I think that Bob West is probably only source of the Mintex 1144 pads and shoes for an MGA, I think he gets them specially re-lined.

Mike, the difference I noticed between Greenstuff pads and the Mintex 1144 was that there was much more instant "bite" with the Mintex than there was with the Greenstuff.
They also have a very "progressive" feel in that the braking effect seems to increase even though you are keeping a constant pressure on the pedal. This does give you a lot of confidence in your brakes.
The Greenstuff pads had a very "dead" feel to them in comparison.

I have swapped between both types of pad over the last few years and have driven both types very hard over the French Alps and on balance, I much prefer the Mintex.

These things tend to be very subjective and I suppose that the only real way to compare the two types is on a rolling road brake testing machine.

Cheers
Colyn
Colyn Firth

Just to clarify things - I got my Mintex pads from Bob West. They did not come with backing shims, and I doubt I could have installed them as there is not enough room with new pads.
As for the noise, It is not your typical high frequency squeal. It is a hard, harsh vibration, low frequency, as if something is loose.
It is only on the RHS
I am beginning to think it may be that one or more pads is a loose fit in the caliper and is vibrating up and down or back and forth. It could only do this if the caliper piston was not pushing, so I may have a tight piston. So I'm going to remove the caliper and push beck the pistons and start over.
There is also a pulsating feel when the brakes are on hard and quiet, so maybe new discs are in order.
Art
Art Pearse

Art
I decided to fit new discs (Rotors) when I fitted the pads as my old discs had become very slightly grooved and I wanted the maximum friction surface on the new pads.

New discs are currently £34.20 a pair here in the UK from Moss.

Cheers
Colyn
Colyn Firth

Colyn, yes I noticed the price had come way down They are USD 25.00 each here
Anyway good news. I finally decided to deglaze the disc on the RHS which was the trouble side. I used first 100 grit paper by hand, then switched to the rotary nylon pain removing disc on a drill. Got to a nice matt finish and cleaned it all with thinners.
On test run, first braking it pulled to the left quite badly, but after a few applications all came straight again, and NO VIBRATION!
Now I know what to do if it recurs!
Thanks to Allan Reeling for that advice, which I had ignored.
Art Pearse

This thread was discussed between 05/07/2018 and 14/07/2018

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