Lever Bolt on hydraulic disk

I'm mounting a bracket for sat nav and I need a longer lever bolt.
It's a hydraulic disk and wondered if it's a special fit or if something longer is likely to exist.
The nut is on but I'd like more thread to be safe.
Cheers Simon
It's a hydraulic disk and wondered if it's a special fit or if something longer is likely to exist.
The nut is on but I'd like more thread to be safe.
Cheers Simon