I have an 86 Runner that has a sticking front right brake caliper. Noticed that only the pistons on the outermost side are compressible. I would have thought the pistons on both sides would travel when pressure builds up in the caliper cylinders. Anyone know if the inner side pistons should expand/contract? I would have thought the pistons pushed from both sides since the caliper itself is bolted directly to the hub and would otherwise warp the rotor.

Aaron

 

They should push from both sides.

 

You are correct. All four pistons should move freely. You can take the caliper apart to rebuild it with a new seal kit, but if some of your pistons are sticking, you will likely find that those pistons have corrosion pitting on them, which means you'll need to buy replacement pistons also. Depending on how many pistons you need, you may be able to buy new remaned calipers for similar price (although I'm sure in the US, you guys can get pistons for $10-$15 a piece... up here, they were over $30 canadian each).

 

Thanks all. Might be simpler and cheaper to get remans from NAPA.

 

Bought the reman calipers from NAPA and all is good! Thanks.

 

YAY!!!

On our trucks the caliper is mounted and the pistons float. Many vehicles have only one set of pistons (or even one piston) and the caliper slides (a.k.a. "floating caliper") to bring the outer pad in to the disc.

 

yep yep, the pads "float" on the 2 pins spanning the gap in the caliper (the ones that hold the pads in)

be sure to replace those 2 pins too, although new calipers should come with them

 

And properly lube the pins with an appropriate anti-sieze lube.