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My wife’s 10 year old RAV4 (2005 model) had been suffering from the classic ‘spongy brakes’ syndrome: With the ignition off, the brake pedal would feel solid, and the same after the ignition key was turned to the first position. However, the very instant the engine was started, the brake pedal would sink halfway to the floor, and give the feeling that the system had air in it; pumping the pedal would bring it back to the top, but only for a few seconds.

After finding a one-liner solution on another blog, I decided to re-post the fix, the simple work I did, and confirm that it had worked. The brakes are now 100% solid and efficient again! My wife is very impressed!

The problem had been going on for several months, and even after a couple of visits to the local garage, the problem persisted.

Getting straight to the point, the problem is caused by corrosion of the calliper pins. These are relatively easily removed, cleaned and replaced.

If, like myself, you’re happy to change the front pads, and feel competent to undertake this task, then just the one further step is required; that being to remove any rusted and obstinate calliper pins. There are two on each side, and in my case, it was the lower one on both sides which had seized.

Important, don’t forget to crack open the top of your brake fluid reservoir before starting, and to place an old towel etc., underneath to catch any fluid which may overspill during pushing the pistons back in.

My wife’s RAV4 has the ‘floating calliper’ design … something fairly ordinary, but something which I’d failed to appreciate. The calliper component which you remove to change the pads actually ‘floats’ on greased moving pins. You may not realise this at first … I didn’t. These pins aren’t visible or totally obvious, but once the two small calliper securing bolts (two on each side) have been removed and the initial calliper part removed allowing you full access to change the pads for example, you’ll notice there are two hex bolt-heads remaining. These are the pins! Each head has a threaded hole in it, which you can only see by sticking your head right into the wheel-well and looking back at the inside aspect of the brake assembly. The smaller bolts (already removed) had been screwed into this larger threaded bolt-head (the floating pins).

In my case, the top pins on either side were sliding fine, and by using a 17mm ring spanner and wiggling them clockwise/anti-clockwise, I was able to pull them out, just for a practice run. They’re a good tight fit, should be laced in grease, and offer some suction resistance when removing and replacing. The little rubber seals are no problem, just make sure they’re reseated properly.

The lower pins however, were seized solid! To remove these, I had to spray WD40 under the rubber seals, then wiggle them back and fro with that 17mm ring spanner. I had to repeat this process for a good 20 minutes on each pin to remove them. In fact, on one side, I had to ask my wife to do the wiggle :) whilst I gently tapped (with hammer and screw driver) the seized pin out from its location.

Once out, I cleaned each pin’s surface rust away by a bit of gentle filing, re-greased the pin shafts, and re-inserted them back into their holes. They will go in fairly easily, although I did have to wiggle and push again with that 17mm ring spanner.

And that’s it! All that remains is the normal re-assembly of the rest of the brake components … y’know, filing down lugs, copper-slip here and there, faffing with shims etc. :-(

Just to add, in my case, the inside brake pads (piston side) were completely worn almost to the metal, whilst the outside pads still virtually retained their original thickness! This is the result of the floating calliper not actually floating, because of seized pins! It’s a clever design which allows the single piston to both push the inner pad onto the disk, whilst pulling the outside pad onto the disk with equal force. It only works of course if those pins aren’t seized.

Hope this helps.
 
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