Brake Caliper Slide Pin Cleaning and Lubrication

Thanks for the write-up. Sounds like you could check your rears every 30k miles or 2 years and fronts every 60k or 4 years and be good to go.

 

Yeah, Den, Thanks for the great report.
I'm at 122K, second owner, and I'm way past due for this important servicing.
Your report is the kick in the pants I need to get out there,, but not this weekend....

You brought up some important steps. I suspect once the LV battery is disconnected the car should be dead, but not touching the driver's door is still a good idea.
I plan on using a light silicone grease on the sliders and the high-temp brake grease ( in little ketchup packs at the counter of parts stores) on where the pads touch the caliper and where they touch the caliper carrier. Very little, just the lightest coat. A light, small wire brush across the those contact points just to knock the dust off and then the grease, mainly as a corrosion preventative.

What grease did you use on the sliders? I think the high-temp brake grease is too thick.
Plus the sliders don't get that hot and they don't carry any of the braking forces. They just keep the caliper in position on the pads. The pads transfer the braking forces to the caliper carrier.

Thanks again !!

 

I wonder if you do need to push back one or more of the pistons (or do it inadvertently when swinging the caliper back into position), would pumping the brakes a few times prior to hooking up the 12 volt help avoid codes? Or not? I've heard that it's any amount of excess travel of the piston that's causing the car's computer to freak out.

And if it does freak out, is there any low tech recourse? Someone here was talking about hooking up a paper clip jumper between two plug pins, if I'm not mistaken.

And just to second Bill: what's your choice of grease for the pins?

 

Here's that paper clip jumper post, albeit for second gen.:

Bleeding 05 Prius brakes the old fashion way | PriusChat

Looks interesting, item's 12 & 13 are front and rear brake service guides:

2010-2013 Toyota Prius Hybrid Hatchback Common Problems, Repair Guides, & Vehicle Maintenance DIY Instructions

^ There's vague mention of "two blue relays", the jumper fix for dismissing warning lights, and lots of disclaimers, in the front brake guide (#12) above.

 

Thinking about, the 12V battery is maintained by the traction battery, so just disconnecting it may not help. You may also have to remove the orange emergency fuse for the big battery.

 

There have also been earlier posts with the same problem. How often it is needed could also be climate related. Places with real winters and salted roads probably need the service more often than most of Northern California, for instance, does.

 

The Canadian Schedule calls for a visual inspection every 12 mo, and a more in-depth "service" every 24 mo. I called our nearby Toyota Service department and the 2nd anniversary, asked about brake service, and they just kinda brushed me off, saying it's not needed. (Another "sealed" unit? )

That was about 6 months back. Thinking maybe I should persist. OTOH, if they're so reluctant to take it on, maybe they're not the best candidates.

It's really rock/hard place, with the electronics: I'm comfortable changing pads, but not so enthused with possibility of ejected pistons, warning lights and so on.

 

I put the whole car up on jackstands yesterday, and for both front and rear, pulled off the calipers, removed and disassembled the pads/shims, then cleaned and reassembled with thin layer of anti-seize compound on all contacting faces. What was on the pads when I opened them up was a very small dab or two of what looked similar to the sil-glyde grease.

I also popped out the caliper pins and relubed with sil-Glyde (mentioned above). They were by no means dry, but looked like they could use a little. The rear brake pins looked darker in appearance, like maybe they were heating a bit, not sure. Also, the front pins are two different lengths.

The car has just over 43000 km's, and here's the numbers I got for pad thickness:

front left outer:7.9
front left inner:7.7
front right outer:7.9
front right inner:7.5
rear left outer:7.7
rear left inner:7.1
rear right outer:7.2
rear right inner:6.4 (quarter sized fragment flaked off at center slot edge)

(new front pads are 10 mm, near rears 9.5, min is 1 mm for both, though I'd replace them if 3mm or less)

The torque value for caliper mounting bolts (screw into the caliper slide pins) is 25 foot pounds, front and rear. You need a slim 17 mm open end wrench to restrain the pin while loosening or tightening these bolts. I had a thicker wrench, too thick, but browsing Princess Auto I found one, just a bit slimmer, that worked fine. It's thickness is around 6 mm. the older wrench was 8 mm, and that was just too thick.

A couple of cautions:

1. On advice I'd read, I disconnected and isolated the 12 volt negative lead. I also left a glove over the hatch latch mechanism, to prevent it closing, possibly being unopenable. Just for insurance I left the driver's door ajar.

On completion, when all the brakes were assembled and the car back on the ground, I pumped the brake pedal multiple times to build up pressure, then hooked up the 12 volt negative lead, and did a trial start, just a few seconds, then shut it down. There were no warning lights showing on the dash, woohoo! I hope this continues to be the case once we go for a drive today, knock-on-wood.

2. When I first reassembled the rear brakes, there seemed to be an inordinate amount of drag when turning the disk. Rereading the Repair Manual instruction this morning, I see it's saying to rotate the the rear caliper piston. This piston has a cross pattern on it's face: four high portions and four depressions.

The piston should be rotated so that the high cross is sort of in an x pattern, so that there's a depression at the apex, corresponding with pin on the back of the inside pad.

The Repair Manual describes this on a couple of pages, and I still don't think they've explained it clearly. They mention you can rotate it clockwise or counterclockwise, to bring the piston out or in. It's realy not that clear though, which direction to turn it.

Bottom line, lacking the special tool, I used a heavy duty pair of offset needle nose pliers, and rotated the piston clockwise, through around 45 degrees, to move the piston in slightly, and set the piston's depression in line with the pad's pin. Reassembled, the disk turns a lot smoother. I believe I've got it right: parking brake travel seems about the usual.

One thing I noticed after putting everything together: before hooking up the 12 volt I again did multiple depressions of the brake pedal. This time, I heard a clicking sound from the rear of the car, for maybe the first 1/2 dozen of those pushes. Then no more. Maybe this was sort of parking brake auto adjustment happening? Really not sure.

Here's a few pics:

Front right brake, caliper raised but not completely removed:



One of the front caliper slide pins:



Front brake pads disassembled (inside on right):



Rear right brake, with caliper disconnected and pulled away. Note the cross shape on face of piston. It's currently not in optimum position, needs 45 degree rotation:



Rear brake pads disassembled (inside on right):

 

Well done.

 

Since the goal is to stop the guide pins from seizing, couldn't you just remove one guide pin at a time, lub it and put it back ? Is there a reason you are removing the caliber ? Thanks.

 

Hi Den49,

Every week, I use a alloy wheel cleaner from wallmart to spray in my rims and hose off within 30 sec. Since you seem to know quite a bit about the Prius' brakes, I wonder if this cleaner has the potential to eat away at the vital grease and whatnot that is needed for the parts to work correctly?

I've had sticky sliding pins on my previous car and uneven rear brake wear on another car I owned a decade ago and those were expensive fixes! It would be nice if the prius would not fall into that state too

 

You could with the front. Pretty hard with the back due to park brake cable.

The caliper's are not that heavy tho, and more efficient to just pull them completely off.

 

What you are cleaning if its a degreaser is cleaning the rotors. If you want to lube the sliding pin, you just remove or lift the caliper out of the way. The sliding pin is what holds the caliper on the caliper bracket. You won't clean that grease out since its bolted onto the caliper bracket and tucked away by the sliding pin boot.

The sliding pin tend to seize up due to lack of grease after many miles of driving, that's what is causing the uneven brake pads wear. Most often or not, the inner pads wear out more than the other pads. I haven't checked my brakes yet, but I would assume the pads are good. I might lube the sliding pins later on.

 

Cleaner might have an effect on brake fluid hose and the various rubber boots, not sure.

Periodic inspection, and it is spec'd in maintenance, is needed. For pads and pins. Have to say tho it was very clean an new looking for 3 plus years. Otoh, low mileage, garage stored and fairly mild climate (not much salted roads).