In this thread, I'll be detailing the removal and replacement of the front and rear brake rotors along with a front caliper rebuild.
Now, the front axles of these vehicles share the same design as the 123 and the 116 (so this thread will aid 123 and 116 owners as well!) For those who are unaware of what that means, the rotor itself is bolted to the wheel hub. Consequently, in order to remove the rotor, you must remove the wheel hub from the spindle. This also means your wheel bearings will be coming out. I recommend REPLACING them, especially if you've never done them before, but this will all be detailed further down.
Without any further delays, let's get started!
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*Now, I'm going to assume anyone reading this thread is competent enough to secure their vehicle and remove their wheels to access the brakes, so I won't be going over those steps. I will be starting from having already removed the wheel.*
Step 1 - Remove the pads from the caliper (if you can):
*The reason why I say "if you can" in this step, is that my front left pads were the least worn of all! (This is why I'm doing this job to begin with) The rotors however, all have a nice lip, so they're pretty well worn, and I couldn't remove my pads without getting the caliper off (which I will cover how I got around that in this step).*
Alright, let's get those pads loose! Grab yourself a hammer, and 1/8" pin punch!:
The pins are fairly easy to spot, just gently tap them in as far as your punch will allow:
Once you've got them as far in as you can, you can continue to gently tap the pad retaining pins until they fall out or you can pull them out by hand once they've cleared that leaf spring:
Once the pins are out, use a pair of needle nose pliers to disconnect the pad wear sensors:
Now you can remove the leaf spring, but you'll likely end up snapping a portion of the sensor (immaterial as these should be replaced with new ones anyway!):
Now, at this point you may be able to pull your pads out, especially if they're very worn down, or you didn't depressed the brakes when you parked the car for this job meaning the pistons aren't fully engaged. As you can see in the photo below, mine were still very meaty, but the significant lip in the rotor still meant that although my pads were loose, they wouldn't clear the lip until I further compressed the pistons.
Here's where you'll start and determine if you need to compress or not:
To compress the pads, you can use a pad-spreader (if you've invested in one), channel locks, vise grips, or C-Clamps. I went with a small c-clamp and CAREFULLY and SLOWLY compressed in each of the two exposed corners for each pad:
It's usually after this step where you can pull out your pads and claim victory, but I couldn't; I needed the extra play of a loose caliper to get it all free.
So, let's move on to removing the caliper!
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Step 2 - Remove the two (2) 19mm bolts that hold the caliper in place:
This is pretty easy. Depending on when you've last done your pads, you may need to use a breaker bar to break them loose (they may have blue Loctite on them, mine did).
There are several 19mm bolts, so I've circled the ones you will be removing to avoid any confusion!
With those bolts out, you should be able to pull the caliper right off and set it aside:
I'm going to take it a step further and rebuild my fronts as the piston seals are rather crusty. If a rebuild thread is requested, I will do it in a separate thread all together. I may incorporate it into this thread (along with steps for bleeding the system), but we'll see.
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Step 3 - Get that rotor off!
Here's where things get a little bit more involved as you'll be pulling off the bearing dust cap to get to the axle nut at the end of the spindle.
Apparently there are special tools you can use, but I just use different flathead screwdrivers to GENTLY tap a gap between the cap and the hub itself.
Here's what I used (it's hard to tell from the angle I took the photo, left to right it's thinnest to thickest):
Start with the thinnest and gently tap, rotating the hub around to ensure the gap is staying even and in fact getting larger:
After going through the motions a few times with your various drivers, you'll graduate to the largest one:
At this point, the gap has gotten large enough that the cap is no longer as snug as it was, and you can reposition the driver to that front lip on the cap and begin gently tapping from there.
This shot was taken after I had already tapped it out carefully:
As soon as I removed the driver, the cap fell off into my hand:
Now you can see greasy mess that hides underneath!
Take a rag and wipe away the grease to expose the axle nut:
After you clean things up, before loosening the bolt to loosen the retaining nut, use a set of needle nose pliers to pull out the anti-static spring at the very front.
I took this picture AFTER the fact because one side didn't have one at all, and the other side was broken off and just left in there!! (Gotta love "independent" work):
The actual part looks like this:
Now use a 5mm hex bit to loosen the bolt that keeps the axle nut in place:
Once it's loose enough, simple twist off the nut counter-clockwise!
Action shot:
*Important Note* - here's where you must be VERY careful if you plan to reuse your bearings if they are still serviceable. Once that nut is off, the outer bearing will likely slide right off; if that hits the hard ground, forget about reusing it. Be ready to catch it!
Here's what your outer wheel bearing looks like:
When you reach this point, the whole hub/rotor assembly will slide off with incredible ease, be sure not to let this drop either, or you risk damaging the hub! Damage to the rotor is immaterial as it's being replaced, but I'd still avoid dropping the whole assembly on the rotor side as well.
Once you've removed the hub/rotor assembly, clean the spindle and inspect for any wear on the spindle:
Fortunately, unless you spent a lot of time driving on destroyed wheel bearings (though you'd have a lot more to worry about!) I don't think the spindle should be showing any signs of wear.
This is also a good time to remove the dust cover if you want to replace/repaint it. I will be repainting mine since I have the opportunity to do so.
Before proceeding any further, examine your bearings for rust, pitting, burn marks, scoring, cracks, etc.
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Step 4 - Divorce the wheel hub and rotor!:
Yes, it's sad that all good things must come to an end, but your wheel hub desires to be paired with a newer, younger brake rotor with a little bit more "substance to it" (these puns doing anything for y'all?).
The rotor is bolted to the hub by five (5) bolts with 10mm hex heads. These have blue Loctite on them, so be prepared to reapply during reassembly.
Now, there are several methods people have used to grab onto these to get them loose. Some folks have mounted the hub and rotor to a wheel, and then placed the wheel face down to access the bolts. I can't help but feel that with the torque required to break these loose, you'd end up slowly rotating the wheel on the ground and scratching/dirtying up your sidewall. I opted to clamp the rotor in the vice since it's off into the garbage afterward. You'll really want to tighten it down though.
Grab your breaker bar, an extension (if you need it) and your 10mm hex bit:
Once you've got all five (5) bolts out, you'll likely need to use long driver to finalize the divorce, as the hub is still being clingy with its old flame despite the desire for a new one.
Interestingly, the first one I did I had to use a driver to carefully work them apart. The second time (pictured here) the hub was already loose and free after removing two of the bolts, so it came apart super easy:
This is what it looks like when they've been split apart:
Now we can start the process of pressing out the old races and bearings, and rebuilding everything as needed for the reassembly with the new rotor!
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Step 5 - Removing old bearings and races and installing the new ones:
First, we need to remove the old seals for the inner bearing. To get the best leverage, I secured the hub to a wheel with three bolts until they were hand tight (you don't need more than this):
Next, you'll want to use a seal remover (I have a generic "OEM" one from AutoZone that did the job) to pop the inner bearing seal out like this:
Claim victory, clean it off to be nice to Mother Nature, and chuck it in the garbage:
Examine the bearing if you plan to reuse it, if not, do exactly what you did with the seal and chuck it in the garbage:
Take this opportunity to clean out the hub with a rag while it's still bolted to the wheel:
Now, the front axles of these vehicles share the same design as the 123 and the 116 (so this thread will aid 123 and 116 owners as well!) For those who are unaware of what that means, the rotor itself is bolted to the wheel hub. Consequently, in order to remove the rotor, you must remove the wheel hub from the spindle. This also means your wheel bearings will be coming out. I recommend REPLACING them, especially if you've never done them before, but this will all be detailed further down.
Without any further delays, let's get started!
As always, ensure your vehicle is completely and utterly secure before getting underneath to avoid injury or death. Use only quality ramps, jacks, etc., when attempting to support your vehicle.
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Front Rotor, Wheel Bearing Replacement, Pad Replacement (Front Brakes)
*Now, I'm going to assume anyone reading this thread is competent enough to secure their vehicle and remove their wheels to access the brakes, so I won't be going over those steps. I will be starting from having already removed the wheel.*
Step 1 - Remove the pads from the caliper (if you can):
*The reason why I say "if you can" in this step, is that my front left pads were the least worn of all! (This is why I'm doing this job to begin with) The rotors however, all have a nice lip, so they're pretty well worn, and I couldn't remove my pads without getting the caliper off (which I will cover how I got around that in this step).*
Alright, let's get those pads loose! Grab yourself a hammer, and 1/8" pin punch!:
The pins are fairly easy to spot, just gently tap them in as far as your punch will allow:
Once you've got them as far in as you can, you can continue to gently tap the pad retaining pins until they fall out or you can pull them out by hand once they've cleared that leaf spring:
Once the pins are out, use a pair of needle nose pliers to disconnect the pad wear sensors:
Now you can remove the leaf spring, but you'll likely end up snapping a portion of the sensor (immaterial as these should be replaced with new ones anyway!):
Now, at this point you may be able to pull your pads out, especially if they're very worn down, or you didn't depressed the brakes when you parked the car for this job meaning the pistons aren't fully engaged. As you can see in the photo below, mine were still very meaty, but the significant lip in the rotor still meant that although my pads were loose, they wouldn't clear the lip until I further compressed the pistons.
Here's where you'll start and determine if you need to compress or not:
To compress the pads, you can use a pad-spreader (if you've invested in one), channel locks, vise grips, or C-Clamps. I went with a small c-clamp and CAREFULLY and SLOWLY compressed in each of the two exposed corners for each pad:
It's usually after this step where you can pull out your pads and claim victory, but I couldn't; I needed the extra play of a loose caliper to get it all free.
So, let's move on to removing the caliper!
--------------------------------------------------------------------------------------
Step 2 - Remove the two (2) 19mm bolts that hold the caliper in place:
This is pretty easy. Depending on when you've last done your pads, you may need to use a breaker bar to break them loose (they may have blue Loctite on them, mine did).
There are several 19mm bolts, so I've circled the ones you will be removing to avoid any confusion!
With those bolts out, you should be able to pull the caliper right off and set it aside:
I'm going to take it a step further and rebuild my fronts as the piston seals are rather crusty. If a rebuild thread is requested, I will do it in a separate thread all together. I may incorporate it into this thread (along with steps for bleeding the system), but we'll see.
--------------------------------------------------------------------------------------
Step 3 - Get that rotor off!
Here's where things get a little bit more involved as you'll be pulling off the bearing dust cap to get to the axle nut at the end of the spindle.
Apparently there are special tools you can use, but I just use different flathead screwdrivers to GENTLY tap a gap between the cap and the hub itself.
Here's what I used (it's hard to tell from the angle I took the photo, left to right it's thinnest to thickest):
Start with the thinnest and gently tap, rotating the hub around to ensure the gap is staying even and in fact getting larger:
After going through the motions a few times with your various drivers, you'll graduate to the largest one:
At this point, the gap has gotten large enough that the cap is no longer as snug as it was, and you can reposition the driver to that front lip on the cap and begin gently tapping from there.
This shot was taken after I had already tapped it out carefully:
As soon as I removed the driver, the cap fell off into my hand:
Now you can see greasy mess that hides underneath!
Take a rag and wipe away the grease to expose the axle nut:
After you clean things up, before loosening the bolt to loosen the retaining nut, use a set of needle nose pliers to pull out the anti-static spring at the very front.
I took this picture AFTER the fact because one side didn't have one at all, and the other side was broken off and just left in there!! (Gotta love "independent" work):
The actual part looks like this:
Now use a 5mm hex bit to loosen the bolt that keeps the axle nut in place:
Once it's loose enough, simple twist off the nut counter-clockwise!
Action shot:
*Important Note* - here's where you must be VERY careful if you plan to reuse your bearings if they are still serviceable. Once that nut is off, the outer bearing will likely slide right off; if that hits the hard ground, forget about reusing it. Be ready to catch it!
Here's what your outer wheel bearing looks like:
When you reach this point, the whole hub/rotor assembly will slide off with incredible ease, be sure not to let this drop either, or you risk damaging the hub! Damage to the rotor is immaterial as it's being replaced, but I'd still avoid dropping the whole assembly on the rotor side as well.
Once you've removed the hub/rotor assembly, clean the spindle and inspect for any wear on the spindle:
Fortunately, unless you spent a lot of time driving on destroyed wheel bearings (though you'd have a lot more to worry about!) I don't think the spindle should be showing any signs of wear.
This is also a good time to remove the dust cover if you want to replace/repaint it. I will be repainting mine since I have the opportunity to do so.
Before proceeding any further, examine your bearings for rust, pitting, burn marks, scoring, cracks, etc.
--------------------------------------------------------------------------------------
Step 4 - Divorce the wheel hub and rotor!:
Yes, it's sad that all good things must come to an end, but your wheel hub desires to be paired with a newer, younger brake rotor with a little bit more "substance to it" (these puns doing anything for y'all?).
The rotor is bolted to the hub by five (5) bolts with 10mm hex heads. These have blue Loctite on them, so be prepared to reapply during reassembly.
Now, there are several methods people have used to grab onto these to get them loose. Some folks have mounted the hub and rotor to a wheel, and then placed the wheel face down to access the bolts. I can't help but feel that with the torque required to break these loose, you'd end up slowly rotating the wheel on the ground and scratching/dirtying up your sidewall. I opted to clamp the rotor in the vice since it's off into the garbage afterward. You'll really want to tighten it down though.
Grab your breaker bar, an extension (if you need it) and your 10mm hex bit:
Once you've got all five (5) bolts out, you'll likely need to use long driver to finalize the divorce, as the hub is still being clingy with its old flame despite the desire for a new one.
Interestingly, the first one I did I had to use a driver to carefully work them apart. The second time (pictured here) the hub was already loose and free after removing two of the bolts, so it came apart super easy:
This is what it looks like when they've been split apart:
Now we can start the process of pressing out the old races and bearings, and rebuilding everything as needed for the reassembly with the new rotor!
--------------------------------------------------------------------------------------
Step 5 - Removing old bearings and races and installing the new ones:
First, we need to remove the old seals for the inner bearing. To get the best leverage, I secured the hub to a wheel with three bolts until they were hand tight (you don't need more than this):
Next, you'll want to use a seal remover (I have a generic "OEM" one from AutoZone that did the job) to pop the inner bearing seal out like this:
Claim victory, clean it off to be nice to Mother Nature, and chuck it in the garbage:
Examine the bearing if you plan to reuse it, if not, do exactly what you did with the seal and chuck it in the garbage:
Take this opportunity to clean out the hub with a rag while it's still bolted to the wheel: