Alternative calipers

[David Witham]

Back along time ago I was a student at City of Birmingham Polytechnic. The Poly library used to take Autocar. Some time around about 1980 there was an article in Autocar about Bill Nicholson's MGB. One of the things I remember about the article is that he had fitted brake 3 pot calipers from an early XJ6.

Does anyone have experience of such a modification?

I know one of the issues with the now more common princess caliper modification is the bolt holes. The princess uses a slightly larger diameter bolt. Consequently, the holes have to be sleeved in some way. Perhaps the XJ6 caliper (also used on the Rover P6B) does not have this problem. Later the XJ6 when to a 4 pot design.

This question is largely a matter of interest. I don't have any plans to change my calipers in the short term.

[Not_Anumber]

I guess that may be best solved by locating the specs of the XJ calipers or going onto an XJ forum to ask someone to take a micrometer to the holes. It would be interesting if this was an upgrade path

[Issug987]

I upgraded my brakes, not because they were poor, they are not, they are perfectly OK, but I was finding that other drivers on the road had their brakes on all the way down hills causing me to use mine more then normal, so the 'upgrade ' was just to keep up with 21st century traffic.

I looked for some time and could not find a suitable direct replacement, so I ended up getting the Frontline conversion, fits the wheels , vented discs.

I did the rear conversion to discs too, turned some discs myself from a Rover 800, and had to get correct size caliper, so as not to over brake the rear axle.

It's not a simple job, as the brakes don't improve the stopping distance, just fade mostly.

[MGB281]

The area on the front calliper piston of a MGB are two times 2290sqmm, on a three pot XJ6 calliper they are 2290sqmm on the single piston and a combined 2268sqmm on the two smaller pistons. There is no advantage except for a bigger brake pad

The Jaguar callipers are also very heavy but there are several other options, the following link is to Charles Durning's solution; https://www.mgexp.com/journal/Charles-D ... kes.19263/
I am going for a different approach in that I will be using Mazda RX7 4 pot callipers, they have a slightly smaller piston area than the standard MGB ones but the pad size is much bigger and due to the alloy construction I can run 294mm brake discs with no weight penalty. I should also mention that I have changed the hubs to five studs with the same PCD as the MGC courtesy of Chevrolet.
Charles also came up with a rear disc conversion using Nissan callipers; https://www.mgexp.com/forum/mg-performa ... s.3607947/
Charles sent me a file for a laser cutter, so I have his axle brackets but at the moment am undecided as to which callipers to use, apart from the Nissan (same as some Renault) ones two other options are from the MGF & TF (Rover 800) and those from the MX5 NC. All three callipers are 38mm bore but you can use the 34mm callipers from a 1990's Almera or Primera if you are concerned about the rear being over braked. The MG callipers have the advantage in that they have clevis type hand brake levers, the Nissan and MX5 ones need modifying. Charles has run the 38mm rear callipers on a roadster with no lock up problems. There are free to use calculators for jobs like this,