I am doing some research on rear brake setups. So far I have gathered that to run the FHI 2 pot rear brakes from the 06-07 WRX on 04 STi hubs, you will require a fairly hard to get rotor. The rotor comes from the 2004 STi Spec C Gravel Edition. Which came w/ 16" steelies and the classic 4pot/2pot setup. The issue is that the STis have the 190mm e-brake while all of the cars running the R160 rear end use a 170mm e-brake. I came across a tid-bit over on the Legacy boards (http://bbs.legacycentral.org/viewtopic.php?p=298934&sid=4293cd20b3a550e5f1a5987f3d73ba63) That the 08+WRX share the 190mm e-brake with the STis. Thus I was wondering what is required to put the 2 pot rear brakes on the 08 WRXs. If it is just a caliper swap it might mean that the 08 WRX rotors could work for running 2 pot calipers on the 04 STi hubs. Making this swap much easier to get parts for. If you have any info on this please post it up. Thanks
NVM: It doesnt look like it will work out. I found the specs on the rotors from NASIOC (http://forums.nasioc.com/forums/showthread.php?t=1265631) 286x10mm 08-09 WRX rear rotor, which uses a 190mm parking brake and 1-pot sliding calipers. I'm not sure on the compatibility with other cars, but it seems to be the same caliper mounting as other 1-pots. 290x18mm (170mm parking brake) 290x18mm (190mm parking brake) This is a new rotor size for Subaru (in the US anyway). It uses either a 2-piston opposed caliper or a 1-pot slider. The 2-pot will not bolt up to other Subarus without something like the Kartboy brackets or having a new backing plate pressed onto the spindle. There are three versions of this rotor, one is for the regular 170mm parking brake, the others are for the sti 190mm parking brake in both 5x100 and 5x114.3 Applications: 05+ Legacy GT (1-pot) 06-07 WRX (2-pot) SVX (5x114.3) (only in JDM-land) Some older non-us spec-b Legacys and wrx/sti models
I'm a little confused on what you're trying to do here. You want to put the FHI 2-pots on a 08+ WRX in the rear? Why mention the 04 STI hubs? If you're only off by 4mm diameter, then why not just use the 290x18x190mm rotors with the FHI 2-pots? Won't those rotors clear the 2-pots mounted directly on the 08+ WRX rear hubs? It's only 2mm larger in radius? ~Dan
he wants to find rotors to run on an R180 diff with subaru 2 pot rear calipers. The wrx rotors that normally go with the 4/2pot set-up will not clear a 190mm R180 parking brake. As stated the Subaru Group N rear rotors or the DBA equivalent rotors are the only bolt-on rotor for this application that i know of (I have the same set-up on my rally car. STI R180 with Group N 2 pot rear brakes. I use the DBA rotor). Martin was exploring the possibility of using 08 wrx rotors instead of the group n rotors
^ Carl nailed it on the head. Essentially I was looking for a local and potentially cheaper method to run the FHI 2pot rear brakes on the 04 STi hubs which have the larger 190mm e-brake. Since the 08+ WRX has the same 190mm e-brake, if it is possible to swap the FHI 2pot rears directly onto the 08+ WRX than it would be possible to use the 08+ WRX rotors as an intermediary to run the FHI 2pots rears on an 04 STi.
Oh... Yeah, you can't use an 08 WRX rear rotor with the FHI rear 2-pots because the 2-pots are designed for a 16mm-18mm thick rotor. The 08 WRX rear rotor is 8.5mm-10mm thickness and the FHI 2-pots would over extend you'd blow out piston seals. The Subaru GroupN rear rotors were made to fit the 5x100 and 5x114.3 bolt pattern with the 190mm ebrake, for the FHI 2-pots and Alcon 4/6 pot. I've seen several rally teams using this configuration for gravel and street. So if I have this concept correct, you have 04 STi rear hubs and you want to use FHI 2-pots without buying the GroupN rotors. This equivocates to a 290x18x190mm brake rotor with 5x100 bolt pattern. This is the same as the 04 STi rear brake rotor. The magic is that the rear FHI 2-pots have the same bolt pattern as the rear Brembos. So in conclusion, the 08-09 WRX rear rotors will not work with FHI 2-pots (on any hub). And you'll need 04 STi rear brake rotors to work with the FHI 2-pots on a 04 STi hub w/R180 diff w/190mm (STi) ebrake. ~Dan
So I can just use the standard '04 STi rear brake rotor with the '06 WRX 2 pot rear brakes and it will all line up using the '04 STi rear hubs? This is essentially saying that the '04 STi rear brake rotor is the same dimensions as the Group N rear rotors. In which case what would be the purpose of even having the Group N rotors if the stock ones would work fine and all one would need to do is switch from the Brembo calipers to the FHI 2pot calipers? Edit: Aren't the STi Rear rotors 316x20x190? I which case they are slightly bigger than the 290x18x190 2 pot group n rotors?
Oh wait, no... (Whoever else reads this thread will be terribly confused). Sorry for the confusion! The 04 STi rear rotors are 316x20x190mm, which would not work with the FHI 2-pot. The 01 STi rear rotors are 290x18x190 and so are the GroupN rotors, which does work with the FHI 2-pots. Again, I meant the 01 STi rotors, not the 04 STi rotors as previously stated. ~Dan
^ Okay that makes sense. So anyway one looks at it they will need some JDM/Special parts to do this. The following seem to be the only options while keeping the 190mm e-brake. 01 STi rear rotors 04 STi Spec C Gravel rotors Group N 5x100 rotors DBA Group N style rotors If you ditch the 190mm/drum e-brake entirely and go to something else (ie Hydraulic) you could most likely fit the 06-07 WRX rear rotors.
I'm not even sure that would work. Ditching the ebrake setup entirely probably wouldn't work with 06-07 WRX rotors because the backing plate with the remaining drum parts will still be on the knuckle, interfering with the 170mm braking surface. I suppose you could remove the remaining drum parts from the knuckle, but that's usually not in compliance with rally guidelines/rules. Even in the WRC, cars must have a backing plate for the rear rotors [only]. Plus if you did that, that may be a point of no return for the car/budget. ~Dan
^I don't think he's too concerned with rally guidelines. also, the ziptie rally car only has a hydraulic ebrake. so AFAIK it's not really an issue. sweet post with detailed brake dimensions and links to detailed DBA drawings: http://www.ultimatesubaru.org/forum/showthread.php?t=85014 doesn't include specifics on non-usdm stuff. and isn't perfect on some models within the last few years. but still a pretty good list. also, with a quick look on the dba site ( www.dba.com.au ). it looks like 2001 is the only year STi that had those rotors. 99-00 had the 266s, 02+ had the 316s. but the 01 had the 290. I was always under the assumption that the 06-07s possibly had the 190mm ebrake, as they use the larger backing plate (which is why an adapter is needed to use a 2-pot with any other backing plate).
Bringing this back from the dead...I might be the last person on earth to discover this, but in case anyone else is trying to do this (and still doesn't know), an 06-07WRX rotor will not fit a 5x114 hub even if you get the bolt pattern drilled and remove all e-brake components. The inner diameter of the rotor won't fit over the outer diameter of the hub. Good thing they were only O'reilly rotors...looks like KNS is the answer these days.
