To be a litte more specific, but still being too lazy to link to the threads, I remember talk about S13 calipers and rotors on a 120Y strut, which is some pretty serious braking power - well above that offered by a set of girlocks on the Stanza strut - meaning maybe it's possible to get a whole lot of braking power out of a 120Y strut....which would mean top brakes and lower unsprung weight!

More think out aloud than actually presenting a well researched point....

the residual pressure check valve is it located at the bottom of the resovior? and you just remove it hey?

In SA you can put in a A14 without changing brakes but it is a good idea.

It all really comes down to what you want to spend.

get the brakes off a pintara or trx or whatever theyre called....
i got 4 of em on my ute and it pulls up a treat....

The disc brakes on the B310/ Sunny/ 210 were designed to handle a car of 1985 Lb [900 Kg Sunny Sport Wagon] but if used in a 1200 coupe that weighs 1520 Lb [691 Kg] then brake performance is improved substantially for that reason alone. The maximim legal speed here is usually 110Kph [68mph] so this brake setup should prove more than adequate in the majority of cases in an A series powered car. Fitting a Lancer power booster will further enhance brake performance if this is felt to be necessary.

Other cars with more powerfull engines & higher performance can still use the B310 strut, but with better brakes as these are not hard to adapt. Even the bigger, local Commodore caliper just bolts right on.

the stock sunny brakes are not very good if you live in a place where people like to drive 80mph. with average quality pads they smell really hot from 1 hard stop.

if you work it right you won't even be able to fit any groceries in the car. take the back seat out, make it so it holds about 1 6 pack as long as it can sit on the floor or the passenger seat. then it's a car for the pure enjoyment of driving nobody needing a ride anywhere ;)

Car performance is all a matter of balance. The harder it goes, the harder you need to be able to stop. This increased stoping power comes at a price, & that seems to be increased mass. It's hardly worth using the big Commodore calipers on the large Magna discs & mount them to 200B struts if you are running a near stock A14 in your grocery getter.
The braking performance would be supurb, but the vehicle performance just wouldn't warrant it.

Obviously the opposite situation of using a CA18DET with original drums in racetrack competition is more than just a little silly, but using a brake system that is right for the rest of the car is the way to go. so figure out what the car is to be used for & work with that.
IE. Road cars usually travel slower than race cars & ride quality is more important, so a lighter brake/suspension could be justified & I suspect that with an A15, the B310 [Sunny] struts & brakes would be needed for engineer certification. These struts will still take the 1200 shock inserts & springs, so it sounds like a good choice to me.
It's all a matter of balance.

I've got sunny struts on my 1200. (which look very simlar to 120y, but require 13" wheels?

I'm told the late model stanza are the best.

I guess it depends if you want to stop or if you care more about the unsprung weight.

God damn we are a helpful bunch, excellent post Dodgeman!

On the topic of 120Y struts - I have been starting to see a few people using these struts for brake upgrades rather than the Stanza struts.

As I imagine the 120Y strut would be a fair bit lighter - is definitely worth investigating further...

What year model is your ute?
If it is up to 1973, then the original engine will have the distributor above the oil pump & you will need to either modify the engine mounts to pick up the more forward placement of the towers on the crossmember or,.... find a crossmember from a 1974 or later ute & fit that instead.

If your ute is 1974 or later, you should have no trouble fitting the A15 into the engine bay as the crossmember will have the towers in the right place for these later engines.

An easy brake upgrade is to either use the complete strut assembly from a 1200 coupe, or get a pair of struts from a 120Y. Avoid the Australian assembled sedans from July 1976 as the disc brakes on these are completely different.

I recomend that you take the chance to slip a new pair of shock absorber inserts into the new struts while you can & if you want to lower the front a little, then some King springs should do the trick. Lastly, use the top piece from your 1200 suspension as these are different from the 120Y item & will leave your 1200 sitting a bit high. Use the 1200 ones to get the ride height right.
ALWAYS use a set of spring compressors when working on front springs as they can cause a lot of pain if you don't, so buy, rent or borrow some, but use them.

Now would be a good time to either overhaul or replace your master cylinder as the drum brake version will need to have the residual pressure check valve removed from the front brake circuit [but not the back] or a new 1200 coupe item will have that done already.