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-   XK / XKR ( X150 ) (https://www.jaguarforums.com/forum/xk-xkr-x150-33/)
-   -   Took a look at rear brake calipers (https://www.jaguarforums.com/forum/xk-xkr-x150-33/took-look-rear-brake-calipers-120766/)

jagtoes 06-27-2014 02:55 PM

Took a look at rear brake calipers
 
So once again as my car is on the lift I had a chance to look at the rear brake calipers. 2012 XKR with big brake package not Alcon. As I mentioned in the past I was curious as to how the rear E-Brake system works and as someone mentioned there are cables involved. So looking at the calipers I see where there is a cable/pulley system which is operated by an electric motor. This is way different from my kids Audi A4 which has an e-motor built into the caliper. So looking at this set up it appears that you can remove the caliper and unhook the cable and then just wind the pistons back into the caliper and replace the pads. I don't know if there would need to be a re calibration of the E-brake but when the time comes to replace pads I'll search it out. Just an FYI here.

8bit 06-27-2014 05:29 PM

My car is a 2008 4.2 XKR but I don't believe there are significant differences in the e-brake setup. I changed my rear discs and pads last year, no need for recalibration but I did park up in P with the e-brake off before I started working on it.

You are quite right though, it's just cables operated by an electric motor, from under the car you can pull on the cables and operate them manually (useful for testing), there's no need to disconnect the cables before changing pads and discs though.

JeremyB 06-29-2014 03:54 PM

8bit - a quick question.
I'm planning on changing my pads for low-dust Akebonos.
The shop manual mentions the need for a special 'retractor' tool to retract the rear pistons back into the calipers in a helical manner.
Did you find it necessary ???

Jeremy

8bit 06-30-2014 01:02 PM

Yes, I used a Laser Tools brake caliper rewind tool (Google it for US resellers) and a Laser 4342 piston adapter which fits the dimples in the face of the piston. Laser Tools are a UK firm, I imagine you'll find them in the US somewhere.

Incidentally I installed EBC Red Stuff pads at the rear and found a slight improvement in braking performance and a large reduction in dust generation. I've never heard of Akebono before but EBC are one of the biggest names in the business. Might be worth thinking about, the EBC part number for the standard (i.e. non Alcon) XKR rear pads is
DP31749C, I'd advise checking with them for the XK.

GGG 06-30-2014 01:47 PM

1 Attachment(s)
The pistons don't push straight back into the caliper. They have to be rotated.

The piston has two indentations. The two pins (arrowed in red) on the rewind tool engage with these.

Attachment 89668

As the tool is tightened, the piston turns and retracts into the caliper body.

Graham

axr6 06-30-2014 03:17 PM


Originally Posted by JeremyB (Post 1005262)
8bit - a quick question.
I'm planning on changing my pads for low-dust Akebonos.
The shop manual mentions the need for a special 'retractor' tool to retract the rear pistons back into the calipers in a helical manner.
Did you find it necessary ???

Jeremy

I had done a good number of rear brakes with that kind of calipers. Always forget to purchase the retractor tool and used successfully needle nose pliers to simply turn the pistons to retract.

8bit 06-30-2014 05:22 PM


Originally Posted by axr6 (Post 1005921)
I had done a good number of rear brakes with that kind of calipers. Always forget to purchase the retractor tool and used successfully needle nose pliers to simply turn the pistons to retract.

That may work but the correct tool for the job is always better, and gives an excuse to buy new tools :) I found the Jaguar pistons a little tighter than others I've done myself even with the wind-back tool, plus the caliper can move about a bit even if you put it back onto the carrier with the disc off to wind in the piston which gives more opportunity for the pliers to slip out and (ask me how I know this) stab yourself in the hand...


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