HOW TO: Converting brakes from drums to disk on a spindle w/pics

[Ocard]

Hey everyone,

First let me start off by referring to Aarons DIY disclamer

The reader assumes all responsibility for any alterations and modifications made to their cars. DirtyImpreza.com or the author of the DIY thread you read are not liable for any damage to your car (or yourself) as a result of poorly documented instructions. The threads contained in this forum are for informational purposes only and should not be followed by people who are inexperienced when it comes to working on their cars. If you are not sure you know what you are doing, consult a qualified Subaru mechanic.

CN: We’re not responsible for any damages or injury sustained by following any of these DIY threads.

-A & The DirtyImpreza.com Staff (http://www.dirtyimpreza.com/forums/showthread.php?t=1079) I will not give torque specs cause different people give different info. The best suggestion I can give is to refer to your manual or maybe someone can pitch in their numbers as references.


Secondly, I will be converting FWD spindles from drums to disk and I know this may not be interesting to many because most of the people in the forum have AWD vehicles. I, on the other hand, am in the process of making a FWD rallyx car that will eventually become a group 2 rally car. But the logic applied in this DIY applies to both FWD and AWD spindles. I will be using pieces from both.

AWD people have a wide variety of spindles with disk breaks to choose from to easily convert from drum to disk by just completely swapping the whole spindle. There are many threads out there explaining how to do this.

This is one of them (http://www.rs25.com/forums/f105/t144728-diy-drum-disc-brake-conversion.html)
It is very detailed and explains steps very clearly.

The reason that lead to my DIY
This is what I my thought process was as I decided to make this conversion. Since I'm gonna be in Group 2, which is a 2wd open class with some motor restrictions, I figured why have drums when I could be running disk brakes??

The three ways I found to make this possible were:1. Use AWD rear disk spindles and use an axle stump


This is probably the cheapest method to do. People that do RWD conversions are familiar with this mod. The axle is taken apart at the boot and the stump is used to hold the bearing in place.

2. Find older legacy FWD rear disk spindles


These can be hard to come by but if you get lucky to have a source this can be an easy option

3. Get an FWD drum spindle and an AWD disk break spindle and piece them together


This works best if you happen to have both sets of spindles at your disposal.

My DIY is of the 3rd option
Since I had both a FWD rear drum spindle and my old AWD rear disk wrx spindles, I decided to try and see if this swap was even possible. I included loads of pics of practically the simplest of steps to make it as easy as possible for anyone wanting to try this,

so here we go:

we start off with the fwd rear drum spindle
https://lh5.googleusercontent.com/_ucjrOP1TcCo/Tda6nh_k8MI/AAAAAAAAAZg/T0-hUgpNwXs/s640/IMG_1470.JPG

take off the axle nut cover with a chisel or a flat head screw driver
https://lh4.googleusercontent.com/_ucjrOP1TcCo/Tda6o71eTTI/AAAAAAAAAZk/918T-NFZmT4/s640/IMG_1471.JPG

We need to loosen the axle nut. Since I was by myself I put my wheel back on and dropped the car so the wheel doesn't spin. If you have a friend to press the breaks you might not need to drop the car or put the wheel on.
note: after I took off the nut I realized that with the FWD spindle you dont need to drop the car since the axle stump doesn't rotate. just make sure your car is secure on jack stands
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6qBLbclI/AAAAAAAAAZo/c-POxTlI3Q4/s640/IMG_1473.JPG

remove axle nut
https://lh5.googleusercontent.com/_ucjrOP1TcCo/Tda6rLrWpuI/AAAAAAAAAZs/kIR6Ns5hcaI/s640/IMG_1474.JPG

Remove drum
https://lh4.googleusercontent.com/_ucjrOP1TcCo/Tda6saaYZyI/AAAAAAAAAZw/LbrYd9m792g/s640/IMG_1475.JPG

now use a hub puller to remove the hub. I rented one from my local parts store and my money is refunded when I bring the tool back. If your bearings are in bad shape, they might come apart as you pull the hub. this is as good as time as any to change your bearings
https://lh5.googleusercontent.com/_ucjrOP1TcCo/Tda6thMc-NI/AAAAAAAAAZ0/1QRSnMX_Y0Q/s640/IMG_1476.JPG

mine easily came off, make sure you don't lose the guide washer that goes between the axle nut and bearing. remove hub puller after it is off
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6uVxa2RI/AAAAAAAAAZ4/o47rY203hH8/s640/IMG_1477.JPG

This is what your drum assembly will look like. See the groove in the axle? that's where the guide washer goes when putting back together. Now We need to remove the 4 14mm bolts so we can remove the backing plate which holds the drum break assembly.
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6vCGX3tI/AAAAAAAAAZ8/JCB0sjRVh7o/s640/IMG_1478.JPG

like this
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6wBwvmpI/AAAAAAAAAaA/YJwvcKF8jUs/s640/IMG_1479.JPG

after bolts are removed, tap on the back side with a hammer or mallet to let it free
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6wzsMEfI/AAAAAAAAAaE/AjpAXWyyOS8/s640/IMG_1480.JPG

Here is my disk break backing plate from my AWD spindle that now we will be installing on the FWD spindle. The process is practically the same to disassemble the awd spindle except you will likely need a press to remove the hub and bearings in order to get to the backing plate.

https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6xlEJwsI/AAAAAAAAAaI/eykBYhJPctI/s640/IMG_1481.JPG

backing plate installed with the 4 14mm bolts. make sure you install on the correct side. The hand break line helps easily determine

https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6yRt2yvI/AAAAAAAAAaM/c8J6l7EcP9Q/s640/IMG_1483.JPG

slide hub back onto the axle stump with the guide washer
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6zKpTmwI/AAAAAAAAAaQ/ZJMgiGCE2G0/s640/IMG_1484.JPG

put new axle nut and punch it after correctly torqued
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda6zn4VBbI/AAAAAAAAAaU/f5wX_7CaZmg/s640/IMG_1485.JPG

put disk on these are some old ones i had laying around :oops:
https://lh6.googleusercontent.com/_ucjrOP1TcCo/Tda61M2PRII/AAAAAAAAAac/akEIcM0Xjo0/s640/IMG_1487.JPG

Install caliper with 2 14mm bolts in the back side. If you have an abs sensor put it back on
https://lh3.googleusercontent.com/_ucjrOP1TcCo/Tda611ItrgI/AAAAAAAAAag/kc-rsmedmg4/s640/IMG_1488.JPG

install brake line onto caliper
https://lh5.googleusercontent.com/_ucjrOP1TcCo/Tda63V2VuSI/AAAAAAAAAao/jje-mAZSREE/s640/IMG_1490.JPG

secure brake line away from rotating tire and out of the way, (zip ties are awesome :D) I got lazy but you should run through the brackets in the struts
https://lh3.googleusercontent.com/_ucjrOP1TcCo/Tda638ppnjI/AAAAAAAAAas/6Pf5Ty8wt6g/s512/IMG_1491.JPG

now bleed the brakes and you're done!
You now have FWD rear disk spindles, congrats! :rally-driver:

Please comment if you have any comments, concerns, correction and so on and so forth. Hope this info helps someone.

[kturner]

looks good.

brake bias needs to be changed to account for the disks in the back. I am not sure if you can just remove the junction block on the passenger strut tower or if the master cylinder has to be changed.

Interesting solution to a rear sway bar mount too. what keeps it from rotating?
did you reuse the ebrake cables? I needed to swap mine out for the swap.

[A1337STI]

Great Write up. Looks like i could do basically the same thing to convert a Drum knuckle to a disc knuckle (both awd)

[Ocard]

Great Write up. Looks like i could do basically the same thing to convert a Drum knuckle to a disc knuckle (both awd)

Why not just install the disk one instead of the drum one?? mix and match pieces?

[Ocard]

looks good.

brake bias needs to be changed to account for the disks in the back. I am not sure if you can just remove the junction block on the passenger strut tower or if the master cylinder has to be changed.

Interesting solution to a rear sway bar mount too. what keeps it from rotating?
did you reuse the ebrake cables? I needed to swap mine out for the swap.

sorry I forgot to respond :oops:

On the brake bias, to be honest I wouldn't know lol When I bought the car it came with all around disk breaks and was originally awd. So basically I just removed the diff and and did this here spindle swap. And to be honest I wouldn't know how to go about changing or removing the bias if it did have one but really good point. please let me know if you find out.

The rear sways also came with the car. the old owner said the car originally didn't come with sways. He installed a wrx sway with these aftermarket endlinks and mounts. The pressure from the later link and the spindle plus a bolt on the back side that practically pinches it keeps it from rotating

I just reused the hand brake lines that were in the disk break spindle cause they were in pretty good condition so why not i guess

[flyguyeddy]

so by the same theorey as what you did, i could just swap the drum backing plates on my awd spindles and reuse the drum spindles instead of tracking down a whole new spindle/hub assy. i already have backing plates from a 01 legacy, so it seems like i can do this.

[Ocard]

so by the same theorey as what you did, i could just swap the drum backing plates on my awd spindles and reuse the drum spindles instead of tracking down a whole new spindle/hub assy. i already have backing plates from a 01 legacy, so it seems like i can do this.

Yeah, I just actually did this again to swap back to awful spindles.
Using the fwd spindles was easier cause the bearing came off easily. With the awd spindles the bearing can come apart and you have to be careful when putting it back together and make sure to re grease. If you were thinking of replacing the bearings this would be a great time to do it.

It's a really straight forward swap once you see how its attached. Make sure to take your time and good luck :)

[acco205]

Any idea what the torque on those axle nuts its supposed to be? My car came with the swap already done but the drivers side has bad bearings. Cant even get that thing off with an impact gun!

Also I didnt think about the bias thing...that would explain the squirrely feeling under hard braking...