2009 Avensis Tourer - binding rear brakes (a cry for help!)

[Chris775]

Hello all! 

I'm new here - thank you in advance for any advice that you might be able to offer...

I've had a 2009 Avensis 1.8 Valvematic tourer for nearly 3 years and would recommend one to anyone who needs a spacious, reliable and economical car. The only issue I've had with the car is binding rear brakes: a brief chronology below -

Late 2015 - first noticed build of brake dust on the rear alloys. Also noticed the wheels (driver's side in particular) got pretty warm after a trip - no appreciable heat from front wheels. Tried freeing off caliper by rewinding etc. to no avail.

Spring 2016 - As brakes at rear fairly worn (and thinking they could be binding as getting to near the end of their travel) I got Toyota to change the rear pads and discs. The problem persisted, so took car back to Toyota who checked it and said they'd free'd off the brake - next step would be changing caliper(s).

Summer 2016 - Took pads out and checked that they were moving freely, caliper guides sliding correctly, rewound calipers and tried to "work" the piston by rewinding repeatedly, but the problem is still there. The EPB appears to release ok - there's no apparent tension in it when off. The brakes bind slightly all the time (apart from maybe when first moving off / cold), you can notice the car doesn't roll as freely as it used to and you can hear the drag, especially if you have a window open.

In short, the binding is not extreme (wheels get very warm but not extremely hot) but is enough to drop 3mpg or so and is a bit of a pain - probably not good for the hub bearings in the long run either.

I'm tempted to take the pistons out the calipers to check for any corrosion / mechanical issues but have never done this on wind back calipers - would greatly appreciate any advice from someone who's attempted it or any other thoughts! Trying to avoid spending £330 per side to change the calipers :(

Many thanks

Chris

[Konrad C]

Hi Chris, you seem to have an idea of what to do. If you can remove the piston from the caliper to check for corrosion, then it is a matter to also check the seals, as well as the bore in caliper.

The following link to the brakes:- http://www.japan-parts.eu/toyota/eu/2009/avensis/zrt271r-awfepw/2_273560_041_410W/powertrain-chassis/4707_rear-disc-brake-caliper-dust-cover

Also the slide pins should be looked at. Much easier than dealing with the piston, since the pins can checked quickly.

Not actual the same brakes but this may help:

Recap, look at the slide pins if the pistons works fine.

Konrad

[TomdeGuerre]

Further to Konrad's post I would add that, if you believe the pistons are sticking in the caliper bore then winding them in and out may not be enough to free them, you'd be better to lubricate them. I've used a hypodermic syringe for years to do this, load it up with new brake fluid, insert the needle through the dust boot at the top and inject a little fluid which will then run round the piston. It's a matter of judgement how much to use but we're only talking about a few cc. Proper answer is to strip and overhaul or renew the calipers but at £330 per side that's a bit eye watering.

Also included a data sheet with some info FYI  Avensis EPB.pdf

[Chris775]

25 minutes ago, TomdeGuerre said:

Further to Konrad's post I would add that, if you believe the pistons are sticking in the caliper bore then winding them in and out may not be enough to free them, you'd be better to lubricate them. I've used a hypodermic syringe for years to do this, load it up with new brake fluid, insert the needle through the dust boot at the top and inject a little fluid which will then run round the piston. It's a matter of judgement how much to use but we're only talking about a few cc. Proper answer is to strip and overhaul or renew the calipers but at £330 per side that's a bit eye watering.

Also included a data sheet with some info FYI  Avensis EPB.pdf

Hi Konrad / Tom,

Many thanks for your suggestions - will look into these at the weekend and let you know how I get on. 

Cheers,

Chris

[Chris775]

I checked the sliders (all ok) and tried injecting fluid but I think the calipers were too far gone (on closer inspection both dust boots were damaged and probably had been for some time). In the end our local independent garage fitted reconditioned calipers on both sides at rear and now all sorted, for less than half the price it would have cost had I gone for (admittedly new) calipers via Toyota. Pleased to have a free running car at last! Thanks again for your advice.