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Drum to Disc Brake Conversion


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My friend has a 97 Outback sport with rear drum brakes. He wants to convert it to disc. What all is involved?

 

I am assuming I can just take calipers and caliper brackets from a legacy or impreza at a junk yard and then buy the proper pads and rotors?

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You'll need the brake hoses as well, along with all related mounting brackets and the E-Brake hardware. The E-Brake on Subaru cars with rear discs is a small drum brake that uses the inner surface of the disk as the brake.

 

Your best bet is to go to a junkyard and pull off the rear knuckles with everything attached then just swap them over in one piece. Good luck getting the lower control rod bolt off though, they tend to seize inside the bushings for the control rods and refuse to budge. Cutting them with a Sawzall and replacing them is your best bet. Usually the only place to get new lower control rod (Or control arm) bolts is through the dealership for $15-20 a piece.

 

I've never done this on the Legacy, but I did a similar job on a Hyundai and it was a pain. I wound up just dropping the entire rear suspension from the struts down. Crossmember, knuckles, brakes and all. A Subaru will be more complicated to do though because of the rear drivetrain, so just make sure you have a Sawzall handy before you start. Its easier than you think to do a swap like this if you have the entire knuckles ready to drop in. After you swap the knuckles and get new bolts (If you even need new bolts) you can just buy new rotors and pads and be on your way. The E-Brake shoes generally last a long, long time.

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I am going to be doing this to a 95 Legacy I am buying on Monday. I did the same swap in my wife's OBS a little over a year ago. The biggest problem we had was not having all of the parts we needed. Other than that it is pretty simple. If you can get the e-brake cables from the car that the rear discs are from it makes it easier.
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the legacy conversion is waay easier than the hyundai sounds to be, it took two of us a couple hours to do.. one sec...

 

 

syyyyyuuppp: http://legacygt.com/forums/showthread.php/diy-rear-drum-disc-conversion-143569.html

 

 

I know it's not supposed to be that hard to do, and I could've done it without replacing all that.

 

The problem was that my impact wrench was just twisting the heads off seized bolts left and right. Before I knew it, I had a fist full of broken bolts in my hand. I tried an acetylene torch to get the stubborn, broken bolts out of the knuckle but it just wasn't going to happen. I just went back to the junkyard, bought the rest of the rear suspension, dropped my suspension and threw the new one on in one piece. Trailing arm, crossmember, knuckles, brakes and all. Bingo. I fought with a torch, a hammer, an air chisel, a Sawzall, and an angle grinder for about 2 days. After I bought the whole rear suspension assembly I had the car back together and on the road in 2 hours for about $150. It was just the cheapest, easiest course of action at that point.

 

 

And I like the writeup thread you posted. That kind of quality needs to be stickied.

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You will need the knuckles too. The drum brake and disc brake knuckles are different. You will need rotors and pads too ;) When I did the swap the pads and rotors were bad but I didn't check before I installed them and had to replace them 3 months after the swap. It would have been a lot easier to do it at the time of the swap.
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I am going to try to explain it but I am having trouble thinking of a good way to do it. The knuckle is the part that attaches to the struts, in the knuckle is the hub which also has the wheel studs. I tried searching for a good picture that shows it but didn't see any with a quick google image search. If that made sense then awesome :) and if not, well hopefully someone can explain it better.
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We got the calipers. But we ran into a problem. The struts. I brought all the tools along the DIY said nothing about a 19mm? Which I believe is what the bolts that hold the hub/strut together are? Correct me if I am wrong.

 

So we called it a day.

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Yeah I got that off. Well we got the rear right assembly off without any problem with the emergency brake cable attached :)

 

Problem now is that the rear right at the junkyard all the bolts came off find but for the life of us we CANNOT get the damn axle out of the hub. Tried for over an hour? Any help ?

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Well he bought brembo rotors not knowing that he had rear drum. So he has the rotors and Hawk HPS pads waiting.

 

And the knuckle is what part? :( Excuse my ignorance.

 

 

I'm probably too late, but here goes anyway...

 

Its the part the strut bolts to on the top.

It has the CV shaft going through the middle of it.

Its also the part the caliper bracket bolts too.

Its the part the trailing arm bolts to on the bottom.

 

 

To remove it, there should be a bolt on the bottom that holds the knuckle to the control arms. There should be another bolt holding the jnuckle to the trailing arm. There will be two bolts that hold it to the strut. There will be one bolt holding the CV shaft in place. You will also need to remove the E-Brake cable and the brake line.

 

If I forgot something, feel free to correct me.

 

 

 

Once you have this critical piece, you can install it as one large chunk and simply replace the pads and rotors. Makes life way easier than trying to swap individual parts in and out trying to assemble a complete system.

 

%5Bimg%5Dhttp%3A//i338.photobucket.com/albums/n415/Wargrimes88/130_0511_07zSubaru_WRXSuspension.jpg[/img]

 

Yeah I got that off. Well we got the rear right assembly off without any problem with the emergency brake cable attached :)

 

Problem now is that the rear right at the junkyard all the bolts came off find but for the life of us we CANNOT get the damn axle out of the hub. Tried for over an hour? Any help ?

 

Is it just an issue of working the knuckle in the right direction to slide the CV shaft out of the hub? If so, remove as many parts as you can and twist the knuckle till the shaft comes out. the trailing arm by nature of design will prevent the knuckle from twisting. If its just an issue of getting the shaft to let go of the knuckle, try a bigger hammer. The shaft is still installed on the rear differential, so it won't want to move to much. It is designed to compress and extend with suspension movement, but not much. Once you have as many bolts removed as possible, try hitting it with a hammer. If the shaft is stuck on the spline in the hub try some PB Blaster to break it free.

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Yeah I have the big chunk with the E Brake cable attached. My only issue right now is getting the axle out of the other and we will have all the parts! Other then the brake lines. I had a question about that.

 

When you say the brake lines you just mean the rubber hose that is in the back of the car right? I dont need to take a whole assembly out do I?

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Yeah we disconnected everything. Started to hammer on it. I will try a bigger hammer next time around. He is moving into a place soon so the conversion will have to wait a week or so but no harm in gettin the parts ready to go.
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