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Discussion Starter #1
Hi all,

I am looking to change out the brakes on my 2000 Subaru Outback [150,000 miles] myself for the first time. I've already purchased all of the appropriate parts required and plan on doing this today. I've done the research and know how I am going to go about it, however I do have a couple of questions. Specifically, I am a bit confused about appropriate treatment of the rotors. I've gotten varying answers on how to treat your rotors if they do not need to be replaced. Some people have told me move front rotors to back and vice versa, some people have told me that I am supposed to "turn" them but I'm not exactly quite sure what that means. Some people have said that you have to machine them every time you change your brake pads... at this point I have no idea. I've purchased new rotors for if they do need replacing, but if they do NOT need to be replaced, what should I be doing?

Thanks all
 

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Turning a rotor means bolting the rotor onto a lathe and removing metal from both faces to create a new, perfectly flat surface for the new pads to bite onto.

If you've already spent money on new rotors, why not just install them and get the benefit of all new brakes? If the take-offs are not totally wrecked you can hang onto them as a spare. Doubt I'd bother, they're cheap enough...
 

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For a beater car or a 4x4 that sees lots of dirt and mud, I would just measure the rotor thicknesses to see if they are within the limit (the number is cast into the iron). Then install the pads, grease the caliper pins, bleed the system and be happy. A daily driver requires more work to keep it safe and reliable.

If your used rotors are in great shape with lots of life left, then get them turned at a machine shop or auto parts store, and return the new rotors for your money back.

For a good car, one you expect to put a lot more miles on, then I suggest new rotors all around. If the calipers and pistons are badly rusted, install rebuilt ones. Once you have new calipers and rotors in place, you can expect many more years of trouble free driving. It's disheartening to skimp on a brake job to save a few dollars now, only to have to do more repairs a year later (for a frozen caliper, for example).

Don't forget the emergency brakes! You will most likely need to at least clean them up really well. With thirteen years and 150K miles on them, I expect they are pretty much trashed, so you will need new shoes, springs and hardware. And check the cables to make sure they are in good condition and move freely.

ALWAYS bleed the brakes after installing new parts. It's not a good idea to force old contaminated fluid back up into sensitive hydraulic parts like the ABS unit and master cylinder.

Good luck. Brake jobs are time consuming and messy, but rewarding when you do them right and the car stops sooooo fine.

One hint to make the job less messy: pull the rear rotors off and thoroughly douse the e-brake shoes and inside of the drums with water. Blow dry with compressed air if you have it, or just wipe them down with a clean rag. This gets almost all of the nasty fibrous carbony junk off, saving your lungs and hands.

John Davies
Spokane WA USA
 

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So I now think I am going to go ahead and replace all of the rotors. Now I am curious about how to "bleed the brakes." What does this mean, and how would I do it? Do I need to go buy new brake fluid, flush the whole system and pour in new fluid, or is that referring to something else? If so, I'd like to know exactly how to do that. If not, I'd like to know what it does mean.
Thanks for the help so far.
 

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You'll need new fluid to bleed the system, yes. It also helps to have a brand new cheap turkey baster for use in adding the fluid carefully to the reservoir. Brand new so there isn't any residual contamination inside it, and cheap because you'll toss it out afterwards.

If you have not bled brakes before, I strongly recommend that you get someone who has done it before to help you the first time. It is commonly done as a 2-person job anyway. It can be done by a lone mechanic, but you'll need more for tools, such as a hand powered vacuum pump, tubing & catch jar. Complete kits are usually under $50.

Bleeding the system is done to remove air, water, dirt, and old contaminated fluid from the system to prevent damage to the hydraulic parts. You basically open a drain (bleeder screw) on each caliper, one at a time, and pump (or pull) the old fluid out while adding small amounts of new fluid to the master cylinder reservoir. Many more detailed guides to be had in the service books and on the internet.

I consider it to be the trickiest part of doing brakes because if you don't do it right, you can severely compromise your braking ability. In rare cases, you can even damage the master cylinder or ABS system, and that gets expensive. The work itself isn't very hard, but it really really helps to be introduced to it by someone who has done it before.

The procedure is nearly universal across different car makes, so it won't matter if you find someone who has never done Subarus.
 

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Discussion Starter #7
And is it absolutely necessary to do this every time or will I be able to get by with my old fluid? Basically, would I be a complete idiot to not do this, or is more of just a good preventative measure, that isn't of the utmost importance?
 

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I recall Subaru's recommendation as being 60k miles... I've always liked to do it based on time rather than mileage. Maybe every 4-5 years.

The brakes will work without a flush, and if there isn't any air in them now you can keep rolling. Do it a different weekend etc.
 

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The brakes will work without a flush, and if there isn't any air in them now you can keep rolling. Do it a different weekend etc.
Nope - that is a mistake!! You can indeed push the caliper pistons back into their bores to make room for the new pads, but this also pushes the old nasty fluid back up to the $en$itive parts of the brake system.

You can avoid this by cracking open the bleed screw at each caliper to let the old fluid escape there, but then you have introduced air into the system, so you have to bleed anyway.

Brake fluid becomes contaminated because the wheel areas are the wettest and nastiest area of your car. In rainy weather moisture can migrate right past the piston seals into the fluid, which is hygroscopic (water loving). From there the moisture creeps upwards toward your master cylinder, reservoir and other components.

If you live in the Mojave Desert and never drive through puddles, you could probably get away with never changing your fluid, but for those of us in the real world, we have to do it every three years or so, to keep the fluid clean enough to prevent long term damage from corrosion.

The moisture in the fluid also lowers the boiling point, so you will experience brake fade under severe brake use much sooner than if the fluid is fresh. This is why race cars get fresh fluid very often.

I don't recommend that any newby bleed his brakes without skilled help. If you do it wrong, your system will either be ineffective or completely inoperative. So you would have to get a tow to a shop to get the air removed. The pressure pot brake bleeders work MOST excellent, and you can do a thorough bleeding in 20 minutes or so, by yourself. With minimal mess.

The Motive Flow units are affordable and very efficient. Once you use one, you won't want to spend time crawling around under the car yelling to your kid: "pump, pump, hold .... release!" ... Universal Brake Bleeder 0250

Bleeder instructions: ... Power Bleeder Instructions

Brake systems are critical safety items and you should make sure you know what you are doing, or get someone who does to oversee your work!

John Davies
Spokane WA USA
 

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your questions should give you pause as to whether you should be doing this job on the part of your car that causes it to stop
 

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Consider offering pizza and a coupla beers to a relative or friend to come and assist you.

A lot may depend on if those 150K miles are mostly highway or mostly secondary roads.

But generally, I'm in the camp of not turning rotors. It rarely solves any uneven deposition problem for long ('warped' rotors) and new pads will 'wear-in' to any unevenness in the surface within the first 4 stops. If there is a large 'lip' on the perimeter or they are worn down to the minimum thickness, just put new ones on.

Also, never buy the cheapest pads for sale - they will be crap. Consider flushing the brake fluid if you're unsure when that was last done.
 

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Nope - that is a mistake!! You can indeed push the caliper pistons back into their bores to make room for the new pads, but this also pushes the old nasty fluid back up to the $en$itive parts of the brake system.
To put it in context, I agree that pushing gunk back up the lines is not a good idea, but I think it's a worse idea for a 1st timer to embark on a bleeding session on a Sunday night without assistance.
 

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To put it in context, I agree that pushing gunk back up the lines is not a good idea, but I think it's a worse idea for a 1st timer to embark on a bleeding session on a Sunday night without assistance.
Yes, I agree. And on a 150K mile car that most likely has had minimal (if any) brake system flushes in the past, it is probably too late anyway to preserve it....

John Davies
Spokane WA USA
 
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