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MG MGB Technical - 4 Pot Calipers

About twenty years ago I fitted Princess 4 pot calipers with V8 unvented discs to my '72 Roadster. A popular conversion for a variety of cars. They've worked great with no problems. However now one of them occasionally seizes up, and I feel it's time they had an overhaul.

You can buy kits from sets of seals, to the complete works including stainless pistons. I've also seen for not much more than the overhaul bits brand new replacement replica calipers. Has anybody any experience of these, or know anybody who has?
Peter Allen

I can’t give you any recommendations for the replica calipers, but if it was me, I would be more inclined to overhaul the originals.
Dave O'Neill 2

About 25 years ago I fitted Princess 4 pot calipers to my V8. A popular ( and pretty cheap, then ) conversion.
I'm not sure the performance was a great deal different but they worked fine.

About 5 years ago I noticed that on a gentle stop I could feel the brakes coming on in two stages.
I can't off hand remember if it was the inner or outer pairs that were sluggish ( not actually seized ) but I guess it might be some heat difference that had affected them differently.

To get back to the original question, a kit including stainless pistons from Bigg Red has been fine. I don't have a Kit Part No. ( or prices then/now ) to hand.
( The kit included the seals between the caliper halves, but that's another discussion. I didn't find it neccessary to split the calipers. )

Additional points: the retaining clips suffer from age, heat, general muck etc, so it might be worth having some spares of those; remember it's the wider ones for MGB V8, Princess, MG RV8 etc.
I thought of getting clever and replacing the split pins by pins with holes for R-Clips. ( Easier pad changes between Mintex 1144 for bite on track days, and regular Mintex for no squeal on the way home ).
But the pins were a very tight fit in the caliper ( some metric size slightly up on the OE imperial ? ). The caliper holes could be eased, but then the pads were held too tight in the caliper. I suppose I could file a bit off the pad backing plate but that could get tedious with 8 places to file on each pad set.
So I just keep a stock of spare pins and don't re-use them too often.

Jim
J N Gibson

I have in the past considered converting my MGA to the Princess type 4-pot calipers as an upgrade, it is a fairly simple conversion, needing only a couple of spacers to make it fit. They are little hard to come by nowadays though.

But just before I went that route I was offered some Mintex M1144 brake pads to try out first on the original 2-pot calipers.

Like Jim has found, the Mintex M1144 pads are excellent, so much so that I use them all the time.

They don't seem to need warming up like full competition pad materials do and I also like the instant bite they give.
They also seem have a progressive quality where the deceleration appears to increase, even when you are not increasing the pedal pressure.

Certainly the best brake pad material that I have ever used on a road car.

They do tend to squeal a little when braking lightly but I cured this by fitting some thin anti-squeal shims on the back of the pads.
These are some kind of self adhesive rubberised material and they work very well, but they do work better when new and I usually replace them every couple of years.

Colyn
Colyn Firth

Thanks all for your comments.

Interesting the positive comments on the Mintex 1144. Not the cheapest thing in the world, but if they stop the car with alacrity.......

Colyn - where did you get your anti-squeal shims from?
Peter Allen

Hi Peter,

I got the anti-squeal shims from Ebay, the ones I bought come with an additional tube of anti-squeal solution that you are supposed to smear onto the back of the pad to further reduce the squeal effect.
To be honest, I have never needed to use this solution.

This is the link to the Ebay ad.

https://www.ebay.co.uk/itm/302879488070

Cheers
Colyn
Colyn Firth

I have this conversion on my competition MGA coupe with MGB cross member. Haven’t had any issues with them, believed they were sourced from Rover SD1. Details of this modification in Roger Parker’s book “Everyday modifications for your mgb gt and gtv8”
Mike

Mike Ellsmore

I've got Mintex 1144 pads in the 4-pot calipers on my BGT V8 with Hoyle front brake conversion. They work really well and only squeak occasionally when applying very light pressure, for example crawling in a traffic queue. They do make dust, but then in my experience decent pads always do, even Greenstuff which the makers claim are less dusty than others. Not true in my experience.
Mike Howlett

This thread was discussed between 09/05/2020 and 15/05/2020

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