MG ZS rear caliper sticking

[Daston]

Hey guys,

I just used the MG for the first time since the epic rain of the weekend. Drove 8 miles to visit my Mum and didn't notice a problem, however when I got home I could smell that great burning smell of hot brakes. A quick check and the rear near side wheel was rather warm to the touch.

Other than that I didn't notice anything wrong in the way the car drove so I wonder if its just a bit of corrosion that has caused the caliper to stick enough for the pad to make contact with the disc.

I plan on jacking the rear up and seeing if I can rotate the wheel by hand but other than that not sure where to go from there. Would a rubber mallet be enough to loosen it up or should I be looking at stripping the caliper down?

[Mr2Mike]

It's probably just the sliders that are sticking. Quite common, and easy to fix:

1) Undo the two bolts the hold the caliper to the carrier
2) Lift off the caliper and extract the slider pins. Make sure you don't tear the rubber bellows that seal them. If already damaged, get some new ones.
3) Thoroughly clean any old grease from both the holes in the caliper and the pins and remove any corrosion on the pins.
4) Lubricate with some silicone grease and reassemble.

[Daston]

Yeah that makes sense, will get it up in the air when I get home and have a butchers

[Daston]

Cheers dude, looks to have done the trick!

[Daston]

Well cleaned up the slider pins etc, with the car in the air the wheel spun freely but as soon as you apply the Brakes for the first time you can then feel them stick.

Just got into work (only 2 miles if town driving) and you can smell the caliper is sticking.

Time to pull the piston out? Or just easier to replace the whole thing? New ones are only £30

[Mr2Mike]

Could be the piston sticking due to corrosion, or it could be the handbrake mechanism sticking. The handbrake mechanisms within rear calipers can wear so they won't return properly when the handbrake is released (my Civic is doing this at the moment). Pumping the brake pedal hard will often release it in this case.

I'm assuming the handbrake cable itself is ok; if you disconnect it from the caliper you should be able to move the inner cable in and out quite freely.

If it's the caliper then for £30 I'd be tempted to get a refurbed one.

[Daston]

Mr2Mike said:

Could be the piston sticking due to corrosion, or it could be the handbrake mechanism sticking. The handbrake mechanisms within rear calipers can wear so they won't return properly when the handbrake is released (my Civic is doing this at the moment). Pumping the brake pedal hard will often release it in this case.

I'm assuming the handbrake cable itself is ok; if you disconnect it from the caliper you should be able to move the inner cable in and out quite freely.

If it's the caliper then for £30 I'd be tempted to get a refurbed one.

Thought I would follow up with where I am on this issue. Car isn't a daily driver so really only been spending some time here and there on it.

I disconnected the caliper over the weekend, the handbrake mechanism moves freely as does the cable however the wheel was still stuck solid. I took the pads out and rechecked the sliders which were moving freely.

Annoyingly the company I ordered the caliper off of contacted me to say its £120 as the brakes on the V6 model are larger

With this in mind I have ordered a new seal kit and caliper piston and plan on stripping the caliper down over the evening s this week and cleaning it all out.

One thing I can't work out is how the handbrake works, I understand the cable pulls a leaver but how is this reflected inside the caliper? Is there a mechanism that stops the piston from going back? If so can this fail even though the leaver on the top of the caliper moves freely?