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Master cylinder upgrade question..
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Old 07-28-2011, 03:39 PM   #1
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Default Master cylinder upgrade question..

Car: 99 obs, 5mt, abs

My question is.. just put 04 usdm wrx two pots up front, to replace my single pot l calipers. Try stop Fucking great when I step on the pedal, but I seem to have a soft pedal for the first half of travel, no fall off. System is bled correctly.

My question is, what direct bolt up master cylinder can I swap in to make up for extra oomph needed for the bigger brakes? and I do plan on converting the rears to disk, using the 04 usdm wrx single pots, so if we could keep in mind that I need to feed them too soon that would be great.

would the gc 2.5rs master be enough? Or the svx be ideal? I know the gc utilize a 2/1 configuration; but I can't seem to find the size difference between them and the 04's. Id like to not swap boosters, but if I have to I will.

Thankyou
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Old 07-28-2011, 03:56 PM   #2
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http://subarupartsforyou.com/cp_part...p?partid=11276



Also consider upgrading your brake bias valve for an RS one too


Have you done S/S lines?
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Old 07-28-2011, 04:15 PM   #3
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Nope, not yet. Further down the line but I figured the majority of my "swell" was in the now underpowered mastered. I was going to do the bias valve when I did the rears as well, but are you now saying that only if I went with the rs master? Ill probably go with the svx master. Thanks for the link! Can cross the part number with carquest and probably get a reman on the cheap.
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Old 07-28-2011, 04:21 PM   #4
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yeah thats why I love that site!

I believe the L and RS master are the same diameter so I dont think an RS would be an upgrade. I believe the SVX has the largest bore, I have seen all the numbers posted somewhere but I can find the thread. I think its L/RS 15/16, wrx 1", SVX 1 1/16"

I havent upgraded the bias and as a DD it didnt bother me, as a track car now I am going to swap it out.
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Old 07-28-2011, 04:23 PM   #5
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Ahhh ok, yeah with my beater down my car wont be seeing the track (parking lot) as I planned for it to; so I've got time to do so. I know what link your talking about but couldn't find the Fucking thing either lol what are your thoughts about my booster? Looks like the p/n is the same for the rs and l..
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Last edited by 1055; 07-28-2011 at 04:26 PM..
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Old 07-28-2011, 04:46 PM   #6
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hmmm may have to do this later on..
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Old 07-28-2011, 05:07 PM   #7
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Will the sti master not work? Its 1 1/16 or 1/8 and I thought I saw that others were using it.
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Old 07-28-2011, 05:48 PM   #8
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Quote:
Originally Posted by KOJAK-02-WRX View Post
Will the sti master not work? Its 1 1/16 or 1/8 and I thought I saw that others were using it.
Probably wouldn't be a direct bolt in. Im also pretty sure the sti booster is a two stage booster as well
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Old 07-28-2011, 06:50 PM   #9
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The RS, WRX, STI, SVX and all the foresters and legacys with 2/1 pot are all 1 1/16". There are different 1 1/16" masters that fit different boosters and different line configurations.

There was a 1" master for a few years on the legacy with the smaller 1/1 pot discs.

All the non abs drums cars are 15/16"

I have a few RS masters with boosters in my FS threads for $20 each. If your car is abs and has a 2 port master this would work.

If you don't have abs, the 4 port non abs master is the upgrade.
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Old 07-28-2011, 09:45 PM   #10
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I'm using a '94 SVX MS on my '98L, straight bolt up affair. I suffered the same issue after upgrading to the '06 WRX calipers and this did the trick. The '94 is non abs as is my '98L.
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