|Refreshing Sliders and Boots on Toyota 'Floating' Calipers
Description Replacing and regreasing the slidey bits on brakes found on a variety of Toyota vehicles
Author toxo Date Tue Dec 06, 2011 9:44 pm Type Picture How-To
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|Lots of Toyotas and Lexi have a floating caliper arrangement (at least on the rear if not on the front). This is where the brake pads sit in a 'carrier' which is bolted to the hub, and the caliper 'floats' on 2 greased slider pins. This is a nice cheap way of making effective brakes that only have pistons on one side of the caliper.
How they work:
The pistons are on the inside of the brake disc, and as they push the inner brake pad out towards the outside of the car, the entire caliper slides towards the inside of the car, thus pressing on the outer brake pad. Simples!
The slider pins sit in their own little greased up hole (hurr hurr hurr) with a rubber boot that concertinas in and out when the slider moves. This keeps the dirt and water out, and the grease in. But we know what happens to rubber boots, they break! As soon as there's a hole in the boot, water can get in and wash all the grease out. Then the slider corrodes and jams in the carrier. Dirt can get in and jam the slider, the tolerance between the slider and the carrier is pretty thin. Either problem results in the caliper being unable to slide from side to side, and means either a) your brakes are only operating the inside pad, reducing their effectiveness, or b) your caliper is stuck in the 'on' position so your outside brake pad is always on. b is the most common problem - if after you stop you feel your wheels and one is a lot hotter than the others, chances are you have a jammed slider.* This wears down the outside pad really fast, welds brake material to your wheels, etc etc.
* This can also be caused by jammed pistons but I'm not going to cover that here.
Really, you should check your calipers are free often, and that your boots are solid. Realistically none of us are going to check that often enough, so the first we know about it is brakes on fire, uneven pad wear, a smell of brakes all the time, etc. So here's how to rebuild your brake carrier, once it's already up the creek.
As per usual, if you balls it up, it's not my fault!
I'm not gonna post photos of these early stages as it's pretty different per car, and whether you're doing the front or rear. You may find some bolt sizes differ depending on model.
Get the corner in question up in the air, and take your wheel off. Stick 2 of the wheelnuts back on to hold the disc in place.
On the back of the caliper are 2 14mm bolts, one at the top and one at the bottom. Undo these and you should be able to lift the caliper away from the disc. You don't want to stress the brake line, so fix the caliper up out of the way somewhere (I usually cable tie them to the suspension spring). If you find that either of these 14mm bolts spins, the top of the slider has a 17mm hex head, so you can use a 17mm spanner to hold it still.
On the back of the hub should be 2 17mm bolts. These are done up 'wheel-nut-tight' and fix the carrier (with the brake pads in) to the hub. Undo these and you should be able to remove the carrier. Depending on the model of car, you may need to disconnect a pad wear sensor at this point.
You should have removed something that looks a bit like this:
Generally speaking, you should have the 2 springs in the top to keep the pads separate (that look like paperclips bent into a V shape), 2 brake pads which should each have 2 shims each on the back (4 shims in total), and 2 clips per pad holding them into the carrier (4 clips in total). Each part plays an important role, so if you're missing one you should fit it.
I took these photos while fitting a new shiny carrier so some of them may look a little odd.
For each carrier you are rebuilding, you will need:
1 top slider (same width all the way down) This one goes furthest away from the ground when the carrier is installed on the car.
1 bottom slider (has cutout section at thin end) This one goes nearest the ground, when the carrier is installed on the car.
1 bottom slider bush
If you're being cheap you can reuse any of those parts that you remove, as long as they look OK - boots shouldn't have holes in them, sliders shouldn't be corroded (or bent!!). I generally replace the lot for peace of mind, you don't want to have to do this twice for the sake of saving £15!
First step is to remove the brake pads and the V shaped springs. The shims on the back of the pads shouldn't come off but it's no big deal if they do. You may find that 1 pad has a metal spring thing attached to the back of it, make a note of whether it came from the inside or outside of the carrier - it will need to go back on the same side.
Next thing is to try and get the sliders out. You should be able to pull healthy sliders free with your fingers. If they are jammed, you will need to free them up. Put the carrier in a vice. Get a 17mm socket, and use it on the slider until it turns freely. Try to pull the slider out again - if it doesn't work you'll need to use a hammer and punch to free it. If you have to resort to the punch route, rotate the slider frequently to aid in freeing it up. I've spent 20 minutes before on 1 slider!
Once the sliders are out, check the boots for damage. If there are any holes or if the rubber is starting to crack they need to go! You can remove them by using a hammer and a flat edge / chisel, positioned against the metal ring and pushing away from the carrier.
You should now have a carrier that looks a bit like the one on the right:
Now's a good time to degrease it and paint it, if you're that way inclined.
You will need to clean up the chambers that the sliders sit in. If the slider that came out was corroded, you'll need to get a cylindrical file down there to clean up the surface. If not, you can just clean out the old grease with a good degreaser and then get a pipe cleaner type wire brush down there. If the bottom slider didn't have the remains of the rubber bush on the end of it then you will be needing to get that out!!
When the carrier's clean, the reassembly starts!
You will need some lithium grease - LM2 or similar. You can get big pots of this for pennies at a motor factors or eBay. Whatever you do, DO NOT USE COPPER GREASE. Get a good size blob on the end of your finger and apply to both of the slider chambers:
Fit 1 of the boots inside a 19mm socket. You'll need to press the concertina'd edges inside the socket with something that isn't sharp (don't use a screwdriver). You shouldn't have any rubber protruding, the socket should press down onto the metal ring on the boot.
Present the socket with the boot, up to the carrier:
Tap the socket with a hammer, to press the boot into the carrier:
Check the boot to make sure that none of the rubber got pinched. If it's got a hole in, it's no good. Repeat with the other boot!
You need to pay attention here - the sliders are different top and bottom. The bottom one has this indentation at the end, which the small rubber bush fits in. This is because this slider has the weight of the caliper on it. So get it clear in your head which way up the carrier will be, when it's on the car.
Fit the bush to the lower slider pin:
Use your finger to apply a thin layer of grease to the top slider:
Push the greased slider into the boot and through into the carrier. Once it's all the way in the boot will slip over the lip near the top of the slider to seal it in. You should end up with this:
If the slider rises up out of the carrier, you've got too much grease in there and it's become airtight! Push it in and out a few times to force the excess grease (and air) out.
You should be able to easily rotate the slider, and pull it out to about here:
If you hear/feel metal on metal, or if the slider is too tight to move, go back and re-clean and re-grease the chamber. Remove the boot when doing this - you can reuse them if you tap them off gently.
Once they're right, push the slider back down and clean up the excess grease that came out.
Repeat with the bottom slider!
Refit your brake pads and springs. Pay a little attention to the small clips that hold the pads in place - there are 2 different kinds. The ones that go nearest the ground have 2 springy edges, to stop gravity moving the pads:
There should be 2 like this at the bottom end of the carrier, and 2 that only have one sprung edge at the top of the carrier. They fit with the curved/rounded edge of the spring facing outwards away from the disc.
Once it's all back together you should have something like this:
Fit it back to the car and do the other side!
Remember to torque your wheelnuts up once you're done. A general rule of thumb is to do the carrier bolts up as tight as you do you wheelnuts (generally about 85 ftlbs with Toyotas). The bolts that hold the calipers to the sliders I usually do up to about as tight as I can with a small socket (I know that's not very scientific!).
The part numbers above are correct for rev2+ MK2 MR2 front brakes and IS200 front brakes.
The procedure is the same (although probably with different part numbers) for at least:
IS300 front brakes
Altezza front brakes
LS400 rear brakes
Supra MKIV JDM / low spec front brakes