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MG MGB GT V8 Factory Originals Technical - In search of 4 pot brake calipers

In the past I have fitted V8 discs and Austin Princess calipers to my cars. As princesses seem to have disappeared form the scrap yards in my area, does anyone have any idea where else I could find a pair of these calipers? or perhaps suggest a more modern car that I could source suitable calipers from.
philip may

Lots of comments on this in the archive. One suggestion that has recently surfaced is that Volvo 240 front/rear calipers are about the same..... I've not tried it. Would need to look at piston area for hydraulic balance just the same as SD1/Princess/MGV8 calipers VS master cylinder, but there was a Dutch guy (sorry can't remember the name, check out recent posts) who says it works. I remember Car and Car Conversions about 4 years back fitted Volvo 240 rear calipers and Rover 216 GTI discs/rotors on the front of a MK1 Golf GTI. They had the same sort of problems, needed "sleeved" bolts as hub uprights had 8mm thread and hole in caliper was 12mm.

Someone very recently gave an address for brand new ones. Check the archive.
I have a single one spare if you like.
Marc Gander

Guys, the volvo 240 calipers fit.I had a pair of those at the front but i also changed the rotors too .I used Nissan 300zx rotors then had the Volvo 4 Pot calipers and they fitted fine.


Steve, do you know what year Volvo 240 the calipers came off of? TIA
Mario Funk

I'm trying (unsuccessfully at present ) to get parts for my princess calipers if anyone can help.
BUT...Friction Linings on the Granby Industrial Estate in Weymouth can supply new calipers for about 85 plus VAT.
I've just ordered some Peugeot 505/604 ventilaated discs from them for 70.50 including VAT.
So there's a source of new parts now what about pistons bridging pieces and seal?

I have a pair of 4-pot calipers removed recently from an Austin Ambassador (Princess replacement 82-83) 1.7HL with 90,000 on the clock. Before removal from the car, I checked their operation - fine. I had planned to use them on a project car which has been put on hold indefinitely. Good condition, anyone interested in these increasingly scarce items, please email me for details.

John McFeely

Four pots from Austin Princess can be bought from Schut in Soest. They could be in need of reconditioning. If Austin Ambassador callipers fit as well: they must be made new, because the Hindustan Ambassador is still alive and uses same components.
As for Volvo callipers: the year doesn't matter. Check out a Volvo dealer for the exact specs. They could need some machining, because the holes are around 4/5 mm farther apart, so I think it won't be a straight fit.
I still have to see if the Princess callipers fit within my original V8 wheels. Any info on that?

Frank de Groot

Hindustan Ambassador merely shares a name I believe, being based on a 1950's car not a 1970's vehicle
philip may


The Princess callipers centre on your V8 solid discs and will fit your wheels but you need sleeves for the bolts and metric to imperial hoses all available from your friend Dave Vale at V8 conversions but I guess you knew that.

The Hindustan Ambassador shares nothing with the Princess/Ambassador except the name; it is a totally different car.

Geoff King

Sorry for my mistake. Confusing, those names. Certainly because I imagine there is quite some British heritage running on other than British roads.

Frank de Groot

Mario, If i remember correctly its from one of those Volvo 240 series that came out in the mid 80's
Also i think they are vented as well
steve berno

It is true. All Volvo 240/260 models have vented discs. The smallest was 22 mm wide.

Frank de Groot

The Austin Ambassador was the final form of the 1970s introduced Austin Princess affectionately known then as the "Wedge". Anyone familiar with the Princess' side view profile will know why it was so called. A short production run during 1982/3-ish, the Ambassador like the Princess was a very spacious comfortable car by 1970/80s UK standards. In 1982, I had one as a company car and enjoyed driving it. My wife also liked it. Ambassador Production was discontinued with the introduction of the Montego.
John McFeely

Philip, the volvo caliper mounting is metric, which it's a bit larger/smaller ( Can't remember) than the B and a sleeve should be used after alongating the hole to fit the B. The mounting on the B is 3.5" The Volvo Caliper is also a dual line (fail safe system) and a conecting line must be built to conect the pistons and operate with a single brake line.
The volvo calipers are very heavy thus hindering the suspension of the B (unsprung weight)Which it was not design for a heavy caliper. The volvo caliper clamping force is not much greater than the B caliper, the only gain is the increase of braking pad surface thu this is a small increase. I have used the volvo pads on a B caliper.
This requires to cut some small amount of the pad.
This was achieved by using the B pad as a guide in a bend saw.
Hope this help you.
Bill G.
Bill Guzman

Try using Rover sd1 4-pot calipers.


I was surprised to see that when placed alongside each other, SD1 calipers are larger than Princess or Ambassador ones ..... both cars are reasonably large, but the SD1 variants were considerably heavier and often more powerful than the Princess, hence the need for more substantial brake calipers.

John McFeely

Do these work substantially better than the stock brakes? I'm reading about these esoteric parts and it only seems worth doing if there is substantially better performance. I've always had great luck on my GT V8 conversion with stock (twin-loop; non-servoed) brakes; I just use x-drilled rotors and greenstuff pads and that car stops on a dime. I was just wondering how much better it gets with the 4-pots.

For those undecided on MGB/Princess/SD1/Wilwood, I have a piston size/area comparison chart. Nothing new really...just all the info on the same page. Email if you'd like a copy.
Pete Green


Tried your email address but does not appear to work.

Can you email me a copy.



I put SD1 Vitesse calipers on my conversion, usind Peugeot disks, and sleeves on the MG bolts.

No fitting problems, except that you willhave to use spacers to clear standard wheels which catch on the bleed nipples, or use wheels with more offset, KN Minotaur 6"x15" fit well, but you will have to flare the rear wheel arches slightly if you use 195x65x15 tyres.
I'll be at Silverstone on the Sunday of the MGCC meeting, doing a parade lap, if you want to take a look at the setup.

Mike Barnfather
Michael barnfather

Still have a pair of SD1 4 pot callipers for 40 if anyone's interested?


Paul did you miss the underscore ?


What size are the 300 zx rotors? There are different sizes for different years/engine types; some with 270 mm disc. Interesting alternative to the Peugeot 604Ti/505Turbo?
As for weight: both Princess and Volvo calliper are cast iron and therefore pretty heavy. Does anybody know if it is possible to space out OE V8 callipers to fit thicker discs?

Frank de Groot

This thread was discussed between 20/05/2002 and 02/06/2002

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