Installing DBA 2657 rotors in the rear

[fletch]

Here is my experience in mounting the DBA 2657 rotors to the rear hubs. The purpose of which is to create a near "square" brake setup to match the weight distribution to the 818 while also retaining the Subaru parking brakes.

Items required:
Subaru rear wheel housings & hubs
Forester XT rear backing plates - I'm using DORMAN P/N MTM 924-375 from RockAuto
Forester XT front calipers, brackets, & bolts
Rear bearings & seals
DBA 2657 rotors
Angle grinder
Drill & dremel or milling machine

This post was very helpful in sorting out a variety of compatibility issues. https://forums.nasioc.com/forums/sho....php?t=1265631


The steps are generally this:
1) Disassemble donor rear housing. Press out the hubs to remove the rear backing plates. I had parts from an 05 Forester XT and could have used the backing plates, but I made two mistakes which I'll point out below. So, if you've got OEM plates feel free to use them. If not, buy the DORMAN parts. Note: The important part here is the spacing of the holes for the caliper carrier.
New_BP.JPG

2) Modify the backing plates and caliper carriers to fit one another. The backing plates need to have the dust shields removed and holes widened/relocated for the caliper bolts. Work to make the holes equidistant from the center of the inner circle. They also need some trimming of the parking break carrier area. <--- This is where I made one of my errors with the OEM plates. **** The six "lands" on the parking brake support area need to be preserved in their entirety. Don't trim them at all. They need to be in place to support the parking brake shoes through their full range of motion. You can see the lands in the 4th picture below. ****
The caliper carriers need to have some material cut out of the back side. The caliper bolts will also need some sort of spacers to keep them from poking through the carriers into the rotors. I used various drill sizes working up to 1/2" for the holes. The "snowman" hole was a real pain, but I made do with a variety of dremel bits and a dose of patience. In the third picture, note the material removed from the bottom edge of the caliper carrier.
Prepped_BP.JPG
Brkt_Mod1.JPG
Brkt_Mod2.JPG
ParkBrake.JPG

3) Once you've got a good fit between the backing plate and the carrier, press the hubs & bearings together.
Caliper_Install1.JPG
CaliperInstall2.JPG

4) The rotor hats will need to have ~1/4" of radius removed from them in order to clear the caliper carriers. So, make friends with a machinist. This step along could cost more than all the rest.
RotorInstall.JPG

I've gotten this far and found I've got a small clearance problem between the rear face of the rotor and the caliper carrier. There is a small interference so I'll need to grind a small amount from the inner face of the carrier to allow the rotor to spin freely.

More to come...

Oh yeah, my second mistake. I don't have any idea how I did this, but I ended up warping one of the OEM backing plates. When I bolted it to the wheel housing I discovered it was potato-chipped such that the plane of the caliper bolt holes was not coplanar with the hub surface. Again, I don't know how I managed to do this, but I clearly wasn't going to use a crooked backing plate.