I import prepare and sell classic stangs in the UK
This statement is 100% true
There isn't a lot of advantage to rear disc brakes. In fact they seem to have perpetually an issue with keeping the Parking brake operable. With automatic transmission cars, that doesn't matter much because most of that is handled by the transmission.
We pull them off and replace with factory drums
The lincoln axled car we did, we had to replace the whole axle assembly due to zero parking brake ability even after installing brand new disk brakes on the axle
There is no question that the Versalles parking brake mechanism is touchy to say the least. Internally it works with three ball bearing balls that go up an inclined ramp. There is no "muscle" necessary for it to work. Just a 90 degree lever movement, cable actuated.
Its actually an interesting idea. As the balls of up the ramp they exert more pressure on the piston to squeeze the pad.
The piston is self adjusting for pad wear.
Mine works but won't hold on a steep hill. The piston needs more pressure exerted on it.
As I said, I think there is a solution which is using a larger diameter ball in the assembly.
There were no manual transmission Versalles made. With an automatic transmission, you don't even need a parking brake.
I've never come across a technical service bulletin on the subject, but that would help. What I was doing with that system 25 years ago, there was no one to help. I was on my own. I wouldn't be surprised if the "factory fix" was to install the three larger diameter balls on each side.
Those are located in a location where there is no brake fluid and that assembly has accessibility. Mechanics, me included, have difficulty because as far as I know, this is a unique system limited to the Ford Granda/Versalles rear discs. Yes they are listed as a Granada option.
The biggest draw back to them is that hardware parts are no longer serviced for them, So if you are missing one of the actuating levers for instance, you are out of luck.
I would say that I have a similar issue with my Audi TT parking brake. On a steep hill it won't hold. That one is a simple cable operated mechanical device with an adjustment clamp to tighten to make it hold.
An adjustment to that will hold it for a week or so then the same results.
My Taurus SHO, with rear discs, manual transmission, never had a parking brake issue and it was constantly parked on a hill.
My two Contour SVT's, same. No issue.
It depends on the scenario of combinations INCLUDING the composition of the pads themselves. Original Ford pads hold. Aftermarkets? Eh?
Rear drums aren't exactly innocent in this regards either. Just easier to adjust, but once you have them set, there is less problem.
The Corvette rear brake system is probably the best but derived at from the manufacturers school of hard knocks.
The question is, is it worth the efforts to install rear discs? Everyone needs to decide for themselves. Some folks love 'em.
"You pays your moneys and you's takes your chances!" It just the way it is, but rear discs simply put are not a simple bolt on. Just be aware of that.