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MG MGB GT V8 Factory Originals Technical - Princess Calipers

Hello again
Can anyone tell me which princess four pots are the right ones on the V8 disc? Are they single line or do they have to be modified internally as I have heard in some cases? Thanks

Stainzy
Stainzy

They are double line. I had mine modded by the people who made up the spacers for me - Hi Spec Motor Sport 01-474-707733 ask for Geoff. I sent them a stub axle as a pattern and they did the whole kit discs and calipers for me for 250 quid!
robert pulleyblank

There is a Low Tech solution and it only costs a few quid.
You will need:
two 5"lengths of brake pipe with metric male nipples on each end
two short lengths of brake pipe with a female metric union on one end and amale imperial union on the other end.
two princess brake hoses
set of bolt spacers (any V8 conversion specialist sells them for £4)

Bolt the calipers on using shims on the bolts (or late GT6 bolts)
Unscrew the top lh bleed nipple. screw in one end of the 5" pipe.
Screw the other end into the top brake hose hole.
Screw the Brake hose into the other hole.
Secure the other end and atttatch the female ned of the short pipe to the brake hose.
Screw the other end to your existing brake pipe.
Job done
peter may

Thanks very much for help Peter, can't tell you how much it's appreciated. Now for the rude question, I don't suppose anyone out there in the UK has a cheap pair of princess calipers lying around or can tell me the best way to get them? Regards,

Stainzy
Stainzy

You could try scrappies, remember that SD1 Rover calipers are the same. If you have any problems fitting your calipers E mail me.
philip may

Sorry Phillip Princess (and Ambassador) calipers are different to SD1 4 pots.

The Princess uses a 38mm dia piston, with the Rover using a 41mm diameter. Range Rovers, some Sherpa vans and Transits use the same base caliper as the Rover with RV8, and some post 1994 Morgans using the same basic caliper as the Princess.

The same issue applies to the twin pot SD1 caliper compared to the MGB. Here the MGB has a 54mm dia piston and the SD1 57mm.

For the purpose of comparison the surface area of the Princess 4 pot equates very closely to the MGB so that when fitted to the MGB brake pedal travell will be almost the same. However use of either the Rover 2 or 4 pot will see a longer pedal travel which will not be to everybodies ideal.

For comparison the usual MGB master cyl bore size was 19mm, except for the later (post '78) twin circuit direct acting servo type which had 20.6mm. The later cylinder works better with the Rover calipers as it displaces more fluid per mm of piston travel. For information the Rover master bore size is 22.2mm so you can see the effect this would have with the 19mm single circuit MGB master.

As to supply of Princess calipers there obviously was a stock clearance a few months ago from someones shelves (AP?) as a large quantity of new (old stock) items appeared. These were snapped up as I think the prices were as low as £60 per pair in some places!! However recently at a couple of shows I have seen pairs of these appearing at not much more. Might be worth trying some local motor factors to see if they hold any.

Alternatively it may be worth speaking to Hi Spec Motorsport in Dartford, Kent. I have Princess calipers on my V8 (with a simple crossover connection pipe to turn the twin feed to a single) and when I wnet looking I raided several pairs from scrapyards. Then I found that for virtually the same money as the parts to recon, Hi Spec would supply me with a pair done to a superb condition also with a bridge spacer to suit the vented disc I am using.

The standard Princess casliper would not need any spacing for the V8 1/2" thick disc as it bolts straight on with the Triumph shouldered bolt. As an additional feature you can add a brake pad wear sensor if you desire. These are found on the pads that are for the Ambassador, Princess ones don't have them, otherwise they are the same.

Note that this caliper is much sought after by the modified Ford brigade for big brake conversions. This has led to a shortage of calipers in breakers yards.

Rog
Roger Parker

with all this discussion of brakes, we offer a very good - and inexpensive - upgrade. we supply kevlar lined rear shoes and front calipers that accept xj6/xkev12 jag pads. these pads have approximately
23 - 25% more pad area than the stock mgb. since the calipers are modidfied originals, there is no
need to change wheels, hubs, rotors, etc. these components, large front brakes combined with the
kevlar shoes provides excellent stopping power with a minimal investment. kevlar is avialabel for pads or shoes and is a drum/rotor friendly compound that needs no warmup.
Ted Schumacher

ted
how much for the rear brake shoes? and how much for the modified front calipers? It's my understanding you use the stock calipers modified to accomadate the larger xj6 pad. My experience with using a 83 compound performance friction pad on an s-10 pickup is a dramatic increase in friction (lighter pedal) and much better hi load stopping with virtually no fade even towing a large trailer. They wear longer too. Isn't just installing hi performance pads enough all in itself to provide more than adequate braking. After all it is a pretty little car with big rotors.
Barry
Barry Parkinson

This thread was discussed between 04/05/2000 and 29/05/2000

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