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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #1
Had an issue tonight with my brakes failing and pedal going to the floor.

Car is an 00 RS with full 05 STI swap and Goodrich steel braided lines.

It seems like the RS proportioning valve is leaking when the fluids get hot and then it failed.

They don't make the RS valves anymore according to my dealer, but I could get the 05-06 STI one

Will it fit the RS hard lines?

Any other suggestions?

In Seattle and trying to drive to Colorado next week.

TYIA!

82709
82710
 

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95 L, 96 OUTBACK
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2,889 Posts

I would get an adjustable one at this point. I would also buy 1/8NPT to -3AN fittings and reflare the tubing to us AN fitting were needed.

I just installed AN fitting from directly flaring the OEM brake pipe on my brothers 96 outback. If you look up the standard subaru uses 3/16 lines but 10mx1.0 inverted flare nuts. An fittings are MUCH nicer to work with plus you dont have to double flare the stupid things.

You can still get an OEM valve from another model that might be close. You will probably still need to replumb but I would bet not by much.
 

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1999 2.5RS
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355 Posts
If by full swap you mean front and rear brembos, ABS pump as well, then you should just use the STI "valve" (I recall that it's just a passthrough block to connect the lines).
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #5
If by full swap you mean front and rear brembos, ABS pump as well, then you should just use the STI "valve" (I recall that it's just a passthrough block to connect the lines).
I have the '05 STI Union block, that I could put in there, currently the RS shell is running the RS ABS pump and hard lines but I could swap to the STI pump
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #6
We used to have a great community forum for our beloved first generation Subaru Impreza. A place where people could come together and share information, how-to's, and just general subaru love. Since Vertical Scope took over the site, it is riddled with misinformation and scam/spam posts that the owners do not clean up, leaving the site in shambles. Vertical Scope ruined rs25.com - RIP RS25 10/25/2019
What?
 

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1999 2.5RS
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I have the '05 STI Union block, that I could put in there, currently the RS shell is running the RS ABS pump and hard lines but I could swap to the STI pump
Since this is brake related take everything on at your own risk, however I HAVE done a full swap (Master, front and rear calipers, that union, ABS) and it worked just fine.
Test the bias on a closed road without traffic ! ;)
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #8
Since this is brake related take everything on at your own risk, however I HAVE done a full swap (Master, front and rear calipers, that union, ABS) and it worked just fine.
Test the bias on a closed road without traffic ! ;)
I'll be sure I conduct all my tests safely somewhere in Mexico ;)

Right now I have a full driveline swap in there, EJ257, functional DCCD with a spider controller, iwire harness merge, 5x114.3 hubs, Brembos, 17" STI BBS and Goodrich stainless steel lines.

My only issue has been the brakes locking once it was swapped over to the 5x114.3 setup with the brembos front and rear.

I think my plan of attack right now is to check the RS master cylinder which is still in there, see if it's having an issue, if so replace it with the STI one.

Replace the RS proportioning valve with the 05 Union block.

Button all that up, then flush drain refill and bleed the system To make sure there's no air or contaminants in there somewhere from all the swapping around.

Test that out.

If I'm still having issues then I'll swap to the STI ABS pump as that's the last component, and then maybe swap to an aftermarket proportioning valve if I need to due to brake bias.

The reason I didn't put the ABS pump in is because I know it has EBD and a bunch of other stuff that the RS doesn't have the sensors to manage and I didn't know how that would work...

Right now it's just frustrating because I'm so close to getting this thing buttoned up and ready to go and the damn brakes are the only thing holding me back.

(No pun intended ?)
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #10
Quarantined and laid off so been back to the RSTI.

Swapped the RS proportioning valve out and 05 STI one in.

Sealed it up and bled and still locking up.

Pulled the MC and inspected and looks like it was the cause.

Is there a better MC for full Brembos than the RS MC that will bolt up?

Looking at the 05 STI MC looks like the ports are in different places.

TYIA
83163
83164
 

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I would recommend running the matching STi master cylinder with the Brembo brakes. And yeah, you’ll probably have to bend some lines or make some new ones. Or look at chasebays.com and delete the power brakes and ABS altogether
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #12
I would recommend running the matching STi master cylinder with the Brembo brakes. And yeah, you’ll probably have to bend some lines or make some new ones. Or look at chasebays.com and delete the power brakes and ABS altogether
I'd have to run the STI brake booster, possibly the ABS pump and new lines to make the MC work.

So I've got an RS MC coming

But if that doesn't fix it then yeah I'll pull everything and run the full STI setup with new lines since the RS hard lines won't match
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #14
I might.

If it ends up becoming a strictly track car then I definitely will, but as a DD I kind of want the ABS for the snow here in Colorado
 

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I actually live in CO too. Western Slope now, but spent some years on the front range and still travel a lot with our Subies. Honestly, I trust my older non-ABS car in the snow more than I do my slightly less old one. My 95 Legacy with brand new all season tires was more predictable than my 01 Forester with snow tires.

Now the Forester has more traction overall, but I knew exactly how the Legacy would react. And I feel I had more control of it once it started to slide vs the slow and indecisive ABS on the Forester. The Forester is getting an ABS delete later this year from Chase Bays
 

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2000 2.5Rs
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Hello and good afternoon. I'm having this EXACT same issue with my 00>06 RSTI.

Current parts list:
Full 06 drivetrain with Brembos
RS proportion valve
06 STI MC and brake booster
RS ABS pump and hard lines
iWire merge w/STI cluster

I've bled the brakes in the crossing procedure and I even wired up the diagnostic port under the dash and cycled the ABS pump. My brakes pedal hits the floor and I can't build pressure. I'm at the point where I'm coming to start replacing the whole system because I simply can't figure this out. Thoughts? I don't want to hijack this thread but rather work together to sort it out for both of us. Thanks.
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #17 (Edited)
No worries on hijacking, may as well keep it in one place for others, though it doesn't seem like we're having the exact same problem, because my brakes were locking and would not release, it's not that they wouldn't build pressure.

My original build:
05 full STI swap w/Brembos
RS proportioning valve
RS Master Cylinder
RS lines
RS Brake Booster
RS ABS pump
iWire harness merge w/Spiider DCCD controller and JDM v6 STI gauge cluster

Actions taken:
Replaced MC with new OEM RS
Rebuilt all 4 Brembo calipers
Replaced ABS pump with WRX
Replaced old SS lines with new
Cycled ABS pump with SSM
Bled the shit out of them.

Brakes would still lock.

Removed check valve and replaced it and vac line with new

Still locked.

Solution: replaced RS brake booster with WRX brake booster and WRX MC

Determined RS brake booster was collapsing under boost load, and The diaphragm would get sucked to the wall of the booster, and then not release because the check valve would keep it from losing pressure.

The RS Booster is vacuum assisted, but not designed for the kind of boost / vac and STI can pull over the stock NA 2.5.

I replaced the RS brake booster with a WRX booster (tight fit but you can make it work) and that solved my issue.

For you--are you seeing any signs of leakage?

When your pedal goes to the floor, are you pushing fluid out somewhere else?


Hello and good afternoon. I'm having this EXACT same issue with my 00>06 RSTI.

Current parts list:
Full 06 drivetrain with Brembos
RS proportion valve
06 STI MC and brake booster
RS ABS pump and hard lines
iWire merge w/STI cluster

I've bled the brakes in the crossing procedure and I even wired up the diagnostic port under the dash and cycled the ABS pump. My brakes pedal hits the floor and I can't build pressure. I'm at the point where I'm coming to start replacing the whole system because I simply can't figure this out. Thoughts? I don't want to hijack this thread but rather work together to sort it out for both of us. Thanks.
 

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2000 2.5Rs
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True not the exact issue. No signs of leakage. I actually got to the shop and found out I didn't swap the master cylinder but I thought I did. I'm going to try and swap that and hopefully that fixes it.
 

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00RSTi, 06 GD STI, 09 GR STI
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Discussion Starter #19
If you can, I would swap the booster and master together with known good ones.

True not the exact issue. No signs of leakage. I actually got to the shop and found out I didn't swap the master cylinder but I thought I did. I'm going to try and swap that and hopefully that fixes it.
 
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