2017 gs300h rear disc replacement with auto hand brake

[IMC1]

Hi, I want to replace the rear discs on my 2017 GS premier. It's got an auto handbrake that prevents the discs from being removed. Does anyone know how to release this and also back off the shoes to allow the discs to be removed?

 

   

[steve2006]

Hi Ian and welcome to the LOC.

Lexus would use Techstream the official Toyota diagnostic software to release the electronic handbrake.

If you can release the handbrake then disconnect the 12 volt Battery then keep pressing the brake pedal until it goes hard to fully discharge the accumulator and also for additional safety take the key fob out of range of the car the disc and pad change is conventional.

Remove the disc calliper and support bracket and tie up out of the way to avoid stretching the hose.

To allow the parking brake shoes to pull away from the drum there is normally a rubber bung in the section where the wheel studs come through. Remove the bung then turn the drum until you can see the knurled adjuster (see picture, A is the knurled section)through the hole (torch helps). Flick  the adjuster with a screwdriver to slacken off the shoes ( I can’t remember which way to turn it but if you go the wrong way the drum will lock so then go the opposite way).

Remove the drum to hub fixing screws and the disc/drum should then slide off.

Thoroughly clean the hub to disc mating surface and fit the new disc.

Turn the adjuster the opposite way to push the shoes towards the drum until the drum locks then back off a little until it turns freely.

Reassemble the callipers.

I would suggest opening the calliper bleed nipple when pushing the pistons back to avoid back flowing the brake fluid through the seals then  lose them back up.

The hydraulic brake system used an accumulator not a conventional servo so avoid getting any air into the brake lines or this is a techstream only job for brake bleeding.

Reconnect the Battery, start the car and press the brakes to bring the new pads out to the disc.

This link provides more info including torque settings including a mention that the ISF has a similar set up with YouTube videos available.

[Legendliving]

Just checking that you have found the handbrake release mechanism and the long pointy thing to insert into the screwdriver once you’ve removed the little plug in the boot?  Looked it up in the pdf of the manual on pages 618 and 619. As I’m a take it in under warranty for everything sort of driver I’ve no idea whether that helps in your situation!

[IMC1]

Great, thanks. I'll have a look. Regards, Ian