Let's Start

Before jacking up the car, it is advisable to loosen the axle nuts with a 32mm socket and breaker bar. Do this with the tires on the ground and the handbrake fully applied - it will give you a much bigger mechanical advantage than when the car is up on jackstands.
Jack up the rear of the car. Use a block of wood to prevent slippage. Rest the car on two jack stands. Remove the wheels. The descriptions from this point onwards will apply only to the right side - repeat as necessary when doing the left side:

If you forgot to loosen the axle nuts and have a helper, have him/her stand on the brake pedal while you loosen/remove the nut.

Remove the brake drum. If it is stuck, insert a M8x1.25 hardened bolt into one of the holes and turn with a wrench to pull the drum out. The drum will only get stuck on high-mileage cars where the drum shoes has worn a wide groove into the drum surface, resulting in a lip in the drum that catches the drum shoes.

Remove the rubber drum brake hose from the drum brake line at the strut tabs to the chassis (not shown). The rubber hose is attached to a rigid brake line out of the drum brake assembly. Be prepared to have a catch pan for the brake fluid spills (it was too late in this picture). Pinch off the brake hose or temporarily tie the brake hose so that it is up and out of the way.

Remove all the bolts securing the parking brake cable to the underside of the car. (Unfortunately, it was impossible to take pictures of the underside of the car, so you'll have to bear with line drawings.) It's probably very dirty under there, so please wear eye protection.
Go to the interior of the car, and remove the plastic center console. Remove or peel back the plastic parking brake skirt from the parking brake lever (not shown). Remove the rear seat.

Peel back the carpeting to expose the equalizer cover. You may need to remove some interior panels to get access to removing parts of the carpeting. You may also need to remove the driver's and passenger's seats to be able to peel back the carpeting.

Remove the two nuts that bolt the cable clamp to the floor.
Loosen the parking brake cable locknut and adjuster nut at the parking brake assembly. Using the extra slack from the loosened/disconnected cable, remove the parking brake cables from both sides of the equalizer. A pair of pliers will come in handy here.

Push the parking brake cables, including the rubber boot, through the holes in the tunnel floor. Fish them out towards the knuckles under the car.

Remove the strut-to-knuckle nuts and bolts. Leave one bolt in until the knuckle is ready to be removed entirely (a few steps from now).

Remove the ABS sensor from the drum assembly, if applicable. The existing ABS sensor can be reused with the disc assembly. If there are metallic particles stuck on the magnectic pickup, now is a good time to clean them off. The picture shows the sensor sitting on top of the parking brake cable, which is on top of the trailing link.

Remove the trailing link nut and bolt (not shown). This is the nut and bolt on the knuckle assembly that is lowest to the ground.

Remove the control arm-to-knuckle nut and bolt. This is the very long bolt that connects the two control arms to the knuckle. Be prepared with some lubricating spray and a lot of wrenching to pull the bolt out.

Remove the last strut bolt (from a few steps ago). Remove the knuckle, along with the parking brake cables. Gently tap the axle with a rubber mallet as you slowly pull the knuckle away from the control arms, strut, trailing link, and axle half-shaft. The axle half-shaft will slide in and out of the center differential as well, so make sure that you don't pull the axle all the way out of the center differential. You may need to use a suitable drift or punch to push the axle the rest of the way out of the wheel hub.

I used a block of wood to rest the knuckle assembly while removing it - it's heavy!

Install the new (or used) brake hose. You may also use stainless steel lines such as those from Goodrich instead of the OEM ones I have chosen.

If you haven't already, preassemble the disc knuckle with the parking brake cable (not shown). Don't forget to reinstall the retaining clip that secures the parking brake cable to the knuckle.

The caliper and brake pads may be preassembled or left off for now, although it is wise to check the fit beforehand. Once fit looks good, leave the calipers off the knuckle.

Insert axle (half-shaft) into the disc hub (not shown). This is simply the reverse of the knuckle removal procedure. Apply grease where necessary. Again, a block of wood helps to hold the knuckle upright during this step.

Reinstall the control arm-rod-to-knuckle, trailing link-to-knuckle, and strut-to-knuckle nuts and bolts, in that order. You do not need to worry about alignment, as alignment is done at the other end of the control arms. The torque specs should be about 100 ft·lbs for the strut bolts, 100 ft·lbs for the control arm, and 80 ft·lbs for the trailing link nuts. Install the ABS sensor into the disc knuckle, if applicable.
Install the parking brake cable to the underside of the car, reusing the same bolts and locations as for the drum brake cable. Bring the cable into the parking brake area through the holes in the tunnel floor, and attach the cables to the equalizer. Seat the rubber boot to seal up the tunnel floor holes. Reinstall the cable clamp bolts. Note: if you have a Legacy parking brake cable, it may be too long, and you may need to loop the extra length somewhere under the car.

Attach the new brake hose banjo bolt to the caliper. Note that the OEM brake hose has a specific orientation for each side of the car, but I don't remember if the Goodrich lines are this way or not.

Test-fit the rotor disc. It's probably a good idea to turn the rotors if they have high miles on them, appear warped, or are grooved. I got mine turned for $48 at the local Subaru service department, and they did a great job. I later bought a pair of brand new rear rotors from Double Discount Auto for just $30! The industry code for non-vented rear rotors is 470.

Check the parking brake cable adjustment. You may need to turn the parking brake adjustment wheel if it's too loose or the rotor won't go in easily. Some trial and error may be required to get the parking brake pads adjusted properly.

Install the calipers and brake pads.

Reinstall the 32mm axle nut. Hand-tighten for now.

Reinstall the parking brake cable to the parking brake lever. Replace the carpeting inside the car, and reinstall the seats. Adjust the parking brake using the adjustment nut and locknut. You should be able to count 7-8 clicks until the parking brake is fully applied. Reinstall the parking brake lever skirt, followed by the center console.

If the caliper sliders are frozen or rusted, pry the caliper off the slider, clean thoroughly with brake cleaner and a cleaning pad such as scotch-brite, and re-grease with a high-temp grease. If the boots and/or seals are cracked or punctured, replace as necessary from items in the Subaru disc brake seal kit.

Replace with new brake pads if necessary. For most pre-1999 models, the industry rear brake pad code is 471. For 1999 and later models, the brake pad code is 770.

Bleed the brakes and top off with new brake fluid.

Reinstall the wheels and lower the car so that you can tighten the axle nut to no more than about 135 ft·lbs. However, if you have a helper, you can get him/her to stand on the brakes while you torque the axle nut, and not have to wait until the car is on the ground. (If you have 2.5RS wheels, the fixed center cap doesn't seem to allow access to the axle nut anyways.)

Drive carefully while the pads bed in.

I noticed that the rear rotors don't get used a lot under light braking, as normal driving barely clears away surface rust on the disc rotors. The brake proportioning valve must have a bias towards the front brakes. However, the rear discs do see a fair bit of duty when the brakes are applied heavily, and that's when this upgrade is valuable. I have also upgrade the 1-pot front calipers to 2-pot calipers, and this combination consumes rear brake pads about twice as fast as front brake pads.

I've also noticed that the parking brake is a fair bit sloppier than the old drum setup, since the rear discs utilize a separate inner drum parking brake. This is a small detail, and does not necessarily indicate a problem with the parking brakes. My guess is that the geometry of the smaller inner drum provides less mechanical advantage than the full-size drum setup.

Standard disclaimer: This information is being provided as an educational and informational service for the Subaru community. I do not make any warranties, but I will be happy to help with questions about these modifications. Please proceed at your own risk!

 

how do you remove the abs sensor? mine wont budge

 

It has been many years, so I'm going by memory...

The ABS sensor has a teardrop-shaped flange, with the sensor at the wide end and a mounting screw hole at the narrow end. You just remove the screw and it should come out of the knuckle assembly.

If it won't move, then it has probably rusted and you will need to tap it loose with a hammer and/or punch. If it still won't budge or it gets damaged, you can buy a replacement from Ebay or the classifieds - they are pretty much universal for all GC through GR Imprezas. I found this photo from an Ebay listing, with a black zip tie through the mounting holes:
02 subaru wrx impreza OEM rear ABS sensor sensors : eBay Motors (item 120624466815 end time Nov-20-10 10:02:00 PST)
(I'll update the photo later if the Ebay link expires.)

Hope this helps,

-Wayne

P.S. Sorry for the lousy photos - they were 640x480 still frames captured off an 8mm analog video camcorder. The front-facing camera in my new cell phone takes better pictures than that.

 

good writeup. I would imagine it's probably easier for FWD

 

Nice !!!

 

Does anyone know what are the rear brakes that will be a direct boit on?(modles and years)
And if your car came abs-less could I still use brakes with abs just not have any place to plug in the sensor?
Thanks!

 

Pretty much any 1991-2004 Legacy/Outback and 1993-2007 Impreza (and Forester) with rear disc brakes should work. The newer models may also work, but I have yet to see it in person to confirm. What year is your car that you want to do the conversion on?

The only thing to note is the brake pads and calipers are different among the years. One changeover happened in 1999 for the Impreza and 2000 for the Legacy. I don't know if there has been another change since then. This only affects you when you have to change brake pads such as for track days.

You will just have a hole where the ABS sensor goes in.

-Wayne

 

Pretty much anything that uses a 5X100 hub will work in the Impreza line.

Yes I have abs hubs on my L, you just cut off the abs sensor and if you want you can remove the tone ring, I left mine on though.

 

Thanks guys well the car I'm doing the swap on is a 96L I'm thinking of going to the junkyard soon and they have 91,92,93 legacy and a 2005 forester. What would be the best choice for an over all (pads,rotors,performance) pick

 

02-03 wrx components are the best to use. The brake parts can be found for cheap and pads/rotors are much less than later years.

 

Forrester. newer is prob. bigger and better. Unless you get turbo legacy rear "vented" disk.

 

+1 million rep points to Josh

He helped me with my L to WRX conversion, great write up Josh!

Edit: That works too Josh, haha

 

Thank wac

I just copied and pasted it from his site

 

Did this and it helped a lot, but now the abs system is disabled (abs light on). i was careful not to damage the sensors and reused them. Anybody else have this happen?

 

I couldn't get my bad sensors out at all, out of either sets of hubs. So I cut 'em off and spliced the old wires to the sensors on the disc hubs. No abs light unless I hit a bad pot hole, but every time I get back in the car the light is off again.

 

I've heard people talk about re-using their original e-brake lines. Does anyone have more information on how to do this?

 

i've heard people talk about re-using their original e-brake lines. does anyone have more information on how to do this?

This may be to late for you, but I used my original e-brake lines. The doner disks and knuckles came from a 97 legacy. the e-brake inlet nub on the strut side of the backing plate for the 97 legacy uses a C-clamp that holds the e-brake casing in the nub. the 99 obs e-brake casing was to thick to fit in the nub.
Result, not enough slack in the line to fit the disk over the e-brake shoes.
Solution, I used a dremel to cut down the inlet nub down to the bottom of c-clamp holes. Worked great.

Not saying this is the only way or even the best way. This is what I did and it worked for me.

 

Yes I know its kind of an old thread but will the rs rear discs work with a 15" rim. I have raceline rl-7's i should be ok right?

This is on my 97 L

 

This write up gpt me through my conversion today!! Awesome job on the write up! One question... what's the name of the bolt that's on the rear caliper where the brake line bolts in?? the one with the holes in it to allow brake fluid through?? I'm missing one and plan on running to a parts store tomorrow to find one. Also would that be something I can find at advance, auto zone or orielys?? I don't really want to have to go through the stealership for one!

 

this write up gpt me through my conversion today!! awesome job on the write up! one question.. whats the name of the bolt thats on the rear caliper where the brake line bolts in?? the one with the holes in it to allow brake fluid through?? im missing one and plan on running to a parts store tomorrow to find one. Also would that be something i can find at advance, auto zone or orielys?? i dont really want to have to go through the stealership for one!

Banjo Bolt


and +1

I just did this a few days ago with the help of John2.5RS' help and garage space. Thanks SUBEWGN for the parts!

 

I'll check with the auto parts store tomorrow to see if they got one. If not I'll PM you for one before I go to the dealership and pay out the ace for one! Thanks supers!

 

Ok so I was able to get a banjo bolt off the parts car I have!! BUT! I think my caliper is seized up... kinda I'm able to press the brakes and the piston comes out but it wont go back in and the brakes just stay locked any suggestions?

And its not the slider bolts cause those are nice and lubed up!

 

I can't stop my brakes are Fed

 

So I did this swap and my brakes are spongy should I bleed all my brakes fronts and back bled only the backs and also why dot4 i have a dot 3 car 99 obs

 

Yes you need to bleed both front and back.

 

To do this correctly you need the larger bore 4 wheel disc master cylinder and the 4 wheel disc proportioning valve. Otherwise you will have excessive pedal travel and incorrect brake bias. Calipers need more fluid volume than wheel cylinders.

 

All I did was the rear disc change and new fluid. Pedal travel is less (than what it was with drums) and bias didn't change very much (granted i used a 95LX rear disc).

 

I am converting them right now Little tips and such so far...

-'06 STI OEM brake lines work, E-brake and all The seal is perfect in the hub.

-Jamie

*Note*

I have the complete hub assembly out of an '04 WRX.

 

can i put the rear discs from a legacy 93-97 to a FWD impreza '99?

 

Doesnt matter, the prop valve still thinks you have drums, and is sending more pressure to the rear. This has been covered many times over, we arent saying it just to mess with your head, were saying it because this is a known fact.

This is directly from the service manuals, highlighted thanks to Pakin.

 

The SVX Proportioning Valve appears to be the correct ratio for those without ABS (ME!). I read the whole thread and didn't really see a confirmation so just felt like putting this here as I'll be doing this as well.

Hope this helps.

EDIT: The service manual was for a 1992 SVX.

Double EDIT: Just realized that the SVX (with rear discs) and the Impreza (with rear drums) have the same amount of bias in their proportional valve. I was looking at the wrong numbers. Weird... Guess the SVX Valve is no good.

 

I was curious... i upgraded the front brakes on my 98 obs to legacy 2 pots and rotors (off a 98 gt i think?) and still have my original front rotors and calipers.

Is it possible (once i find serviceable rear awd knuckles) i could utilize my old front brakes & rotors on the rears? with changing out the brake lines and ebrake cable of course

 

I just removed the rear knuckles with half axles all together from a 99 Legacy I believe. Now the question is will this be able to install into a 99 impreza L with the half axle all together.