STI Master Cyl. and Brake Booster SWAP SUMMARY for LGT

Slotted rotors will not help pedal feel, they're only there to keep the brake pads from being glazed, and offer a minimal amount of fade resistance, if any. Less metal = less thermal capacity in the rotor = more heat in the brake fluid. However more surface area = more area for heat to escape.

And by "more surface area" you mean - more contiguous, uninterrupted, contact area.

And by "more surface area" you mean - more contiguous, uninterrupted, contact area.

 

False. The slots in the slotted rotors add more surface area for heat to escape vs. a traditional blank rotor

That wasn't a statement... . It was intended as a question, obviously sans "?"

I think most people, like me just want to be like race car. Race car has cool rotors, I must has cool rotors too.

Car started showing signs of a failing MC so I decided I might as well upgrade. Parts ordered, but probably won't get around to doing the swap till July.

I just ordered a 2011 STI master cyl and brake booster with hose. I am swapping an STI intake manifold also so I'm going to use the hose it comes with. I don't see any reason not to use the 2011 STI one...

The 2011 STI booster seems to be similar to the legacy and the WRX

 

I wanted the Bosch booster so I looked around until I found a good older one.

 

Let us know how it works out

I'm hoping the biggest difference will be from going 15/16" bore to 1-1/16" bore. I may track down a larger volume reservoir also.

My car is going to be a 2011 STI at its heart just about.. lol

well that's a fail.. the 08+ WRX and STI are 15/16" for the MC bore like the LGT. Sure enough, the booster and MC I Just got is marked 15/16". So, I might see if I can source an aftermarket MC and reservoir to use with the newer booster.

Get a hold of these guys if you want an older STI one.

 

http://y2kimports.com

Ok thanks for the lead. 2007 STI one should be on its way.. sigh.

I posted somewhere in this thread the numbers to look for as well as Bosch on the sticker....

just got mine off of my front stoop! stamped 1 1/16. it will be installed on wednesday. i'll let you know...

I did mine last week and it was painless. The brakes are so much more firm now. I then took my car to the track and it never ran out of brakes.

 

I purchased my STI brake master cylinder booster from ebay. It was delivered from Canada. I could not use it because the tube is on the right side of the cylinder. Is this a Canada thing?? It was advertised as a "JDM Subaru WRX STI Brake Master Cylinder Booster 04-07". Here is the photo:

 

http://i227.photobucket.com/albums/dd236/greg992/B9wg5QEGkKGrHqJlcEyjCGBBM6t8GQw_3_zps11d84e29.jpg

 

As you can see, the tube is located on the right of the cylinder:

 

http://i227.photobucket.com/albums/dd236/greg992/IMG_20130725_192148_464_zpse9920662.jpg

 

This is my LGT cylinder. It is not the same.

 

http://i227.photobucket.com/albums/dd236/greg992/IMG_20130725_192207_663_zpsb59b1b1c.jpg

 

Can someone tell from the numbers which cylinder this is?

 

http://i227.photobucket.com/albums/dd236/greg992/IMG_20130725_192229_528_zpsf50beb2f.jpg

 

http://i227.photobucket.com/albums/dd236/greg992/IMG_20130725_192415_462_zps22857ded.jpg

 

If it is not an 04-07 STI cylinder as advertised, I could likely send it back. If not I guess I'm stuck with it. Please let me know your thoughts. Very disappointing!

 

Thanks, All.

Edited July 26, 2013 by damascus

Those look like they were made for right hand drive cars which is why the tube is on the right. If the booster still fits in the car and the hard lines will match up with the master cylinder, the. you could modify a vacuum hose to each that tube.

You also still need to source the "pill" that's found in the sti vaccuum hose line and fit it into your line.

Yep JDM = right hand drive so booster would be on the opposite side of car and tube would be on inside closee to manifold

 

The ideal STI master cylinder set up is the 05-07 (?) Bosch unit with the numbers I posted in another post somewhere.

If it didn't have Bosch and those numbers I wouldn't get it personally.

Just my opinion but that is what I did

Gentleman,

 

I figured I ought to throw in an update, since I have been the most vocal against this upgrade. You can read back a few pages to find my discontent, but I'll summarize it again, before offering my professional opinion:

 

I didn't feel the money for the booster and cylinder was worth the performance gain. In my experience, the pedal throw became too short, offered no improved "feel," and that the performance didn't actually improve.

 

What has changed?

 

I had Frank from Prolific Autosport in Upland, CA, take a look at my car a few weeks ago. He agreed that something felt off, most likely that the booster wasn't working. If you'll recall, I'm an automotive journalist/photographer. I've driven almost 300 cars in the past 18 months, and I'm on record saying my OBXT brakes are the worst feeling and performing brakes of any car I've ever driven.

 

Frank concluded that the booster and master cylinder were correctly installed, but not correctly adjusted. Something about a nipple, I don't remember.

 

Upon adjustment, there was an immediate difference in pedal feel. Instead of a stupid short throw, there was actually a decent amount of travel, still a lot less than stock. With the install before adjustment, there used to be no travel and no gradual easing into the brakes. Now there is an acceptable amount of travel, and better yet, the brakes respond to varying levels of pressure. This didn't used to be the case.

 

Around town, the brakes are easier to work with. They respond to light and hard pressure, and more importantly, to gradual and increasing pressure. This is the good news: they perform as they should have from the factory.

 

Unfortunately, this is still not great news: the performance still sucks.

 

I have LGT stoptech rotors and pads, SS lines, and the Grimmspeed MC brace. I still think the best bang for the buck is harder than OEM pads. I'll rescind my disdain for the STI MC/B upgrade as long as it can be done cheaply, and if you know how to adjust it. Otherwise, you'll fall into the trap of thinking little pedal travel is race car brakes, disguising the fact that nothing improved.

 

In all, I now think that the brakes are passable, if barely, and still toward the bottom of my list. It is an improvement in feel, but not much in performance.

 

- Jason

Who said this was a performance upgrade ? If your brake setup was the same before the mc/booster swap, the distance for the car to stop will still be the same after.

 

It's clearly just a mod to get rid of that squishy mushy pedal travel.

 

Had this upgrade now for 8 months and love it!

 

I guess this is just a user preference thing.

I can personally attest that STI booster/master improved brake feel. Of course I installed s/s lines, stoptech pads and new slotted rotors. Car stops on a dime now, there's no guessing if it will stop in time in panic stop.

Installed an 05 STI booster and master cylinder and drove around. The brake pedal itself feels amazing. When I hit the pedal hard though, the brakes feel weaker than they should be. Any suggestions on adjustment? We adjusted the rod toward the brake booster and it seemed to have improved it somewhat.

Maybe air in the system ?

Here is my take on this mod. I went in to change the pads and also replaced all 6 rubber lines with stainless steel braided hoses from Goodridge and figured if I have to bleed the whole system I'm going to throw on the STI booster and MC. The brake pedal feel is completely different. If it's for better or worse really lays in the users eyes. If you want a hard pedal this is the mod for you. If you care for your car to stop better, this does nothing for it. It feels like there is a wood block behind the brake pedal with not much travel even after adjusting the brakes.

The other reason I did this is, next time I do my brakes I'm going with a Wildwood front calipers and STI's bigger MC will push more fluid since Wildwoods have twice as many pistons. This will also take some of that wooden hard feeling out of the pedal too.

Am I glad I did it? Not really sure. It did not ruin anything just changed its feel and it did set me up for the next mod. If I was not going the way of calipers with more pistons, I would have preferred the old pedal feel.

I don't race or drive this car hard, but do know how I like my brakes. This is mainly from being a motorcycle track-day junkie. I can tell you how I prefer the lever to feel and brakes to work when I need to haul the bike down into the first corner from 180 MPH and trail brake through.