Im replacing the rear calliper boot on x150 and wondering whats the trick to get it to sit.
It slips off very easily plus there’s no grove that locks it in place.
Any tricks would be most welcome

 

If it's the same as my XK8 and many other cars these days, the groove which holds the boot in place is actually inside the cylinder bore rather than external and the piston itself holds the boot in place. The only way to refit the boot is to clamp off the flexible pipe (assuming the caliper is still on the car) and remove the piston completely, then fit the boot into the internal groove and then re-insert the piston through the boot and then bleed the brake.

It sounds easy but, in practice, it is very fiddly. The only way I've ever been able to do it properly and be 100% certain that the boot is correctly seated inside the bore, is to remove the caliper from the flexible line and do it on a bench / kitchen table. One of mine was not fitted properly by Jaguar from new at the factory and the piston corroded after a few years and I had to replace the piston, seal and boot. The fact that Jaguar themselves cannot always fit the boot correctly gives you some idea about how fiddly it can be.

Richard