Paul,
Realty, you need to check the operation of the rear braking system, as a first step.
You have new callipers , so adjusted them up correctly first.
Check you haven’t a broken handbrake cable
( very likely if you have that much travel, on the lever.)
If you need new cable, change both, & get them from the same supplier/manufacturer. Often aftermarket ones may be slightly different lengths to the OME one’s.
This causes problems to a fellow member
The cables are ‘part’ hidden, behind the exhaust shield
These needs to come off if there are going to be changed.
Remember there’s a short cable from the lever, to the two cables that lean to the wheels. These cables are ‘handed’
In the car, if there’s any slack, to be taken up.
Pop the black cover on the top of the lever off.
You see a 10mm nut on the tread of the short cable , tighten this down, 10 mm deep drive socket required.
Test the operation of the hand brake, wheels off the ground, both wheels should hold on 3 clicks.
If you happy the cables are sound, try the last step.
Kit
Do I see a road trip coming up
