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Old 09-12-2010, 08:03 PM   #1
cueballsi
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Default sti master brake booster vs wrx brake booster

Iwaas wondering if it would be worth it to swap my 03 wrx brake booster for a sti brake boster. i already have the 1 1/16" master cylinder. are they the same????


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Old 11-19-2012, 01:26 PM   #2
paulpat
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Bump!

I need this answered!

I have an 02 WRX. 02 & 03 WRX's came with the 1 1/16" master cylinder. I got a 07 STi master brake cylinder and brake booster from a kit I bought. The STi one also has a 1 1/16" master cylinder.

So is there a difference in the brake boosters: 02 wrx to 07 sti? (they have the same master cylinder bore size though)
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Old 11-19-2012, 03:29 PM   #3
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Old 11-19-2012, 03:35 PM   #4
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FXT folks swear by upgrading the booster from an STi. Though the knowledge on that forum is pretty scare overall.

Externally, you can't tell a difference in function, and all you can do is go by part numbers which are different.


It's a pretty easy swap of a booster that you can do without having to bleed anything... So just swap em away and see if it makes a difference. Don't forget to pllay with the brake pedal engagement.
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Old 11-19-2012, 09:13 PM   #5
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didnt your 02 wrx already come with the 1 1/16 master?? Mine did.
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Old 11-19-2012, 11:00 PM   #6
teiva-boy
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Quote:
Originally Posted by scby rex View Post
didnt your 02 wrx already come with the 1 1/16 master?? Mine did.
Booster and Master Cylinder are two totally different things we're talking about here.
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Old 11-20-2012, 02:05 PM   #7
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Yeah thanks everyone. I was aware of the FXT forum that talks about it but they dont ever say that the brake booster is any different. They just say it feels better. I suspect because they adjust the brake pedal and flush fluids.

I called Turn in Concepts. Clint and Tony say that it is slightly different due to the different part numbers but could not confirm if it was different, e.g. diaphragm sizes might be 2% off or X% off from each other. They said it probably wasnt worth it if you want to get the car on the road quickly but install it if you have time because it was newer or in the event the old one craps out.

I called KNS Brakes but I believe Ken is out for vacation for a week. I hope he has a good one.


-paul
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Old 12-17-2012, 12:37 AM   #8
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Any word on whether or not the sti booster is superior to the wrx?
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Old 12-17-2012, 11:30 AM   #9
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It feels a little stiffer, less throw, with the sti brake booster and I know I still have bubbles in my lines from the ABS. I need to lock the wheels up then bleed again. But I also adjusted my brake ingaugement.

So the answer is still the same, there is a very small difference. I don't think anyother driver in my car could feel what I'm talking about. I bet a fluid flush and a brake engaugement adjustment could make the two boosters seem identical.

I still haven't asked KNS brakes yet
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Old 06-06-2013, 10:59 PM   #10
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Update:

I had a discussion with Jarharms and wanted to post the conversation with his permission.




I did not want to derail the OP's thread but when you said you did the STI booster upgrade to your existing 1 1/16" BMC, I got curious.
http://forums.nasioc.com/forums/show...6#post39938876

Did you notice a difference that you think the booster had a hand in? I'm still looking for a clear reason what the STI booster will do or not do.

Any suggestions based on your experience?
~Jamie
_________________________


Here is the break down:
02 wrx - had the bigger bmc
Got front Brembos
added lines, fluid, good pads, h6 mod, bmc brace, all goodies
blew transmission
07 sti swap


So stock brakes sucked but had good pedal feel. I got the front brembos and h6 with such and I felt much knockback. There was always a long throw with the brakes and then a knockback issue. I liked it but it required a different driving style.

My 5mt locked up and sounded like a rock tumbler so I bought a 07 sti swap package. This came with the brake booster. I started to look on the sites half way through the swap to see if the sti brake booster was worth it. The fxt guys said it was because they were in the same boat as the early wrx's with the 1 1/16 bmc. If you search I think you can find the exact thread. No one could say that there is a difference or why it felt better. In theory the early WRX's and sti's should have the same dual brake booster because the bmc are both 1 1/16, the only difference is the amount of fluid they should move (2pot/1pot vs 4pot/2pot brembos). That should not make a huge impact. However the part numbers are different for the 02 wrx brake booster and the 07 sti brake booster. Looking at the two, they are the same shape and size.

I called up TIC and they said the difference is small and depending if the car is apart they would put the sti brake booster in. I noted this in the thread that discussed the brake booster. The reason I went through this trouble is because if I did not have to swap it out then I could sell it for some cash to help with the 6mt.

So I ended up swapping it out because the fxt guys said it would make a difference with no proof.

It felt much better. The only thing that changed was the addition of rear brembos and the 6mt with a sti brake booster. I had relatively fresh fluid in both systems; pre 6mt and post 6mt. My pedal travel is about the same as the stock car but with better brakes now. The knock back is almost not noticeable or gone due to the 5x114.

Now 6 months later the travel is the same but it is not as rock hard as it was. I assume this is because my down hill aggressive driving one day and the fluid being a half of its life. It reminds me of the pre 6mt brakes but I cant really say it is that bad because it has been 6 months. Logic tells me it is way better but the loss in capacity and length of time is giving me a mind trick making the two the same. It is like asking you to describe a serious stomach pain 6 months ago and compare it to a bad case of ****s last week. Chances are you will think they felt the same.

So a STi brake booster will help, just like SS brake lines and a BMC upgrade and a BMC brace. But it is the same amount of help each other mod gives you. I think you know what I mean, more of an "it feels better, life is good" rather than a "OMG!!! BRAKES OF THE GODS!!!"

I say do it. Buy it and install. It will help.
Sorry for the long rant, I had a nice "brake" from homework. I hope it helps.

-paul
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Old 06-07-2013, 01:07 AM   #11
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well this was an interesting read

i've got stoptechs front/rear<st40 front and st22 rear>, tic mc brace and better fluid.. sounds like the booster isn't a worthy mod for me
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Old 06-07-2013, 01:45 PM   #12
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Quote:
Originally Posted by subaru3169 View Post
well this was an interesting read

i've got stoptechs front/rear<st40 front and st22 rear>, tic mc brace and better fluid.. sounds like the booster isn't a worthy mod for me
I think it is quite the opposite. It is a worthy mod. For the 100-200 I have seen it for, I would drop that cash in a heart beat. Ur system is lacking if you have upgraded calipers and no sti brake booster.
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Old 06-07-2013, 04:03 PM   #13
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but you said the guys previously have said it's only worth it if you already have stuff out/apart

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Old 06-07-2013, 04:41 PM   #14
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The larger master cylinder is worth it if you're still on a 1" unit. The booster is only worth it, if it came attached to the MC. I wouldn't go out of your way to buy it alone.
Especially if you haven't added an MC brace, SS lines, flushed your fluid, and adjusted your pedal free-play. (Let alone not on factory 2pot calipers)

Alone it's not worth it IMO. As part of a complete "system," it's improvements could be beneficial.
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Old 06-07-2013, 07:45 PM   #15
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Quote:
Originally Posted by teiva-boy View Post
The larger master cylinder is worth it if you're still on a 1" unit. The booster is only worth it, if it came attached to the MC. I wouldn't go out of your way to buy it alone.
Especially if you haven't added an MC brace, SS lines, flushed your fluid, and adjusted your pedal free-play. (Let alone not on factory 2pot calipers)

Alone it's not worth it IMO. As part of a complete "system," it's improvements could be beneficial.
This is a more elegant way to put it.

Me civil engineer. no know how to speach good.....
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