JasonSMassey

It appears that my S500 has 2 bolts inside a rubber boot on the rear calipers. I cannot see inside there to see what size is needed. Based on the front calipers and other threads, I'm guessing these are Torx. However, my set of torx are designed for 3/8" ratchet and the are too short fit inside the rubber boot.

Am I correct these are Torx inside there, and does anyone know the size? Is there a known tool that fits correctly, preferably with a 1/2" or 3/8" drive?

silverjimm

Are you changing brake pads? or trying to take the caliper off?

JasonSMassey

Chaning pads at the moment. Sensor came on and the rear pads are very thin. Rotors are on order so I will change those when they arrive (no local sources) at the moment.

I see the caliber housing is mounted with a pair of what appear to be 18mm bolts. I say it appears to be 18mm because I have everything but 18mm at the moment.

If I can remove the entire assembly, I'll go with that option. It's very tight in there, so I'm not sure if my Air ratchet will fit. A regular ratchet would be tight as well, and I'm not sure if there's enough room to get a break bar inside the wheel well.

Would be nice to know if there's a specific tool that would work.

silverjimm

To remove the caliper, yes the 2 18mm bolts will need to be removed.. As for as the pads, you just need to pop out the guide pin that runs through the top of the brake pads. no other bolts need to be removed.

rufusjack

Are these 18 mm bolts standard meaning lefty-loosy? I am trying to get a caliper off and I cannot get the bolts to budge.

Quadcammer

yes, they are standard, not reverse, thread.

these bolts have loctite on them.

get a good 18mm box wrench, and a mallet/dead blow hammer, etc, and hit the wrench until the bolts crack loose.

jnash

they are hard to get off. Soak them in penetrating oil for a while. Use a 6 sided hex socket and impact wrench if you can get there. There are some great 20V impact wrenches out there these days that match the same performance as air impact tools.

kraut56

I have never had much luck on these 18mm bolts with impact wrenches, but, six point 1/2 inch drive socket and a 24 inch breaker bar (sometimes with pipe extension) does the trick every time.

jnash

good to know - thanks

corkshoppe

why are you taking of the caliper for the pads? you don't need to.

rufusjack

1) taking the caliper off allows a good measure of the rotor. Not needed on the front as there is adequate room for measuring.
2) I was changing the strut and removal of the caliper allows more room to pull the old strut out.

Conchasjim

Does the same hold true for the front brake pads, as to removal. Just pull the pins? My brake service needed warning came on as well.

Quadcammer

so long as its not a 4matic, yes

Conchasjim

Yes, it is a 4matic. What's different in replacing the pads and sensors?

Quadcammer

eh, its a bit more involved, but far from difficult.

The RWD models have fixed calipers, we have floating calipers.

Lift car, remove wheel, support as you normally would.

Using a flathead screwdriver, pry the flat metal spring bar on the front of the caliper off.

Moving to the back of the caliper, locate the 2 slider pins (in a rubberized tube) and take the plastic caps off.

Using a torx socket (can't remember the size, maybe a t-40 or around there), loosen the slider pins.

Look at the space between the caliper and the pins and look for the shoulder on the slider pins where the thread ends. Using a screwdriver, gently push the pins towards the center of the car until they are free from the calipers. Remove the pins completely.

Wiggle/pry the caliper up off the rotor.

remove the outside pad.

Open brake fluid reservoir and suck out a bit of fluid.

With the inner pad still in place, compress the pistons using your hands or any number of readily available tools.

Install new pads using grease on all contact surfaces (obviously on the backs of the pads, not the face)

reinstall caliper, clean and lightly grease the slide pins and reinstall.

Put spring bar back in place

done.

seems complicated but its actually painfully simple.

Conchasjim

Thanks quadcammer! I'll give it a try. Sounds simple eenough.

Cid

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