AMX drum brake question

Drum brake AMX's of curse existed.  I can not with out looking things up tell exactly what should be on it but then again that is what TSM's are for and my recommendation to you would be to make that your next purchase so that you have some form of reference material to tell you what should be on it vs what you found.
The car is OLD, no surprise and it is possible some where in the past a set of different drum brakes did indeed get bolted on to the thing because the were available and probably CHEAP and they made it stop.
Usually the 6 cylinder cars had smaller brakes than the V8's did but if you unbolted things far enough it was a complete swap over to change them.
As to what belongs on the car I will look in my 1970 manual to see what they had.
But
as to your AMBO disc brakes?
Yup they will fit , so will Hornet,  Concord, Javelin, Matador and Spirit.  And it is the Spirit ones I have sitting on my shelf to put on my 1970 Javelin if I get backed into a corner but for the most part at the moment I do not have to.
The rule of thumb that has been pretty much the test of time behind it, is to unbolt everything on the front of your car back to the steering knuckle, the last thing to be removed is the spindle.  And do the same to the AMBO and carry them over to the AMX and Bolt them in just as they came off of the AMBO
With one possible exception.  Again something I would have to look up.
The caliper may not fit correctly due to interferrance with the trunnion suspension and IF that happens and the operative word is IF, the caliper if I am not mistaken is on the rear side (the side point towards the back of the car) of the steering knuckle.  And the bleeder screw is located toward the top of the Caliper.
What is done if they interferre is to move the caliper to the front side of the Steering knuckle, but if you do that the bleeder screw is not at the top but at the bottom.  To solve that, take the right front caliper from the rear mounting position and mount the caliper on the left front steering knuckle to face the front of the car, Mounting it this way will have the bleeder screw again at the top, which is where it wants to be when bleeding the brakes.
This is quite doable but will require you of course to take the mounting brackets for the right front and mount them on the left front correctly.
This has been done multiple times in the past and it works. 
Be advised though that those brakes are also getting hard to buy parts for, so take that into consideration.
There are now aftermarket brake conversions available for the car with different costs and of course quality. They are your choice.
My choice is to find 1980 or so Spirit or Concord disc brakes and to the same thing, but they too are getting hard to find parts for too.
However my Hornet (both of them) have brakes similar to your AMBO and I am not changing them as does my Javelin still have the OEM brakes supplied in 1970 and I am not changing them either.
To help hook up the rubber brake line to your now relocated disc brakes if needed a brake hose from a middle 70's Ford Bronco I believe is long enough to fit and you may need "Banjo" brake line fittings to deal with tight clearances.
All these parts are available at auto parts houses.
Now you have a whole bunch of choices to make.
My 1970 TSM says the 6 cylinder front brakes were dual servo 9 inch drum
The V8 front brakes were 10 inch dual Servo Drums.
The point.
It stopped when you bought it.
So start with it stops.
Repairing what is on it will stop the car.
You can spend $1000.00's of dollars changing things,  and the car will still stop.
The ball is in your court.
At freeway speeds the rules are the same.  At 70 mph you need to stop the car.  How it gets stopped really makes no difference but the amount of money spent doing it is a big difference.
It is advisable to deal with a replacement master cylinder when moving over to disc brakes, but and it is a big but, it has been done with out doing a master cylinder change as has an adjustable proportioning valve been used or not.
My recommendation?  I don't have one, I'd find out what it needs as I go along down the line and deal with it when I get to it.

Sounds like you've got something odd going on. AMX's did not come with sixes and did not come with 9" drum brakes. Someone had to have done a swap over time, probably because they didn't have the correct from drums for the 10", and had some 9 inchers lying around. DO NOT rebuild the 9" brakes...they won't stop the car adequately. Get the proper 10" or discs on there.

As said the Ambo setup from the 4 bolts out will swap. Only thing might be steering stops between the 2 but is not a big deal to deal with. If you do use the Ambo setup and the AMX has power brakes just swap the master over. If not you might be able to swap the whole power assy. Over to the AMX, that is if you want power breaks.

As for aftermarket front disc you can go from mild to wild. Scarebird https://scarebird.com/index.php?route=product/category&path=95
Is a bracket kit and you buy the other makes parts to finish off the brakes – mild.
Then you have Wilwood & the other that starts with A***** forget the name now – wild.
There are disc kits for the rear also if you want to go that way too.

I am not 100% sure you but may be able to take the Ambo front cross member and use it in the AMX and not have to deal with whatever was mickey mouse to fit any motor in the car other than a AMC v8 motor as the AMC 6 uses a different cross member for all cars.

If you want to go with a stick trany there are different ways to do this. A lot depends on the parts you have now and what you will need and if you think it is worth going thru all the work to find parts & do the swap. Because it sounds like you are not keeping it stock you might look into a 5 or 6 sp that has overdrive, search for T5 for this swap on here.

BTW I have done 2 disc swaps on my 70 Javelins using 76 Gremlin parts (drag car) and 83 Concord spindle/caliper parts on the street car as it had 4 piston disc.
I also did the T5 swap from a T10 on the street car too.
Good luck on your project
Dave ----

A Rebel cross member should fit fine. Ambo has the wheel stretch and will bolt to the car but put the engine into the firewall. if your cross member is seriously hacked you can use the Ambo's and reposition the mount brackets, but that would be a bit of work to sort out.

Since you are already into redoing the front drums, look into drilling them.
tomj did his. I forget his new url? anyone?

With the drums drilled when you get into water or even as they wear and build dust the centrifugal force throws the water out fast. Tom was very happy with his. There's a company in Ca. that will do it for you.

As a side note, tomj just did a weight comparison and the drilled 9X2 1/2" drum setup weighs 10lbs less per side than the scarebird discs and that is unsprung weight. stock, I'd be real careful, The 9 x 2"s on the Americans I have had over the years faded big time, real fast with spirited driving.

John,

The Javelin and AMX 68-69 are b@$t3rd children.
They use the wide crossmember with the narrow/small body trunions.

Why? I have no idea?