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2000 2.5 RS Impreza 4 door
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Discussion Starter · #1 · (Edited)
I have done numerous upgrades to my brakes (better fluid, 4 pots, 2 pots, MCB, single stage brake booster, bigger MC) and nothing has gotten rid of the long pedal travel before engaging the brakes. So a few people recommended moving the unscrewing the fork that is connected to the brake pedal. What this does is move the pin that pushes the plunger on the MC a little closer so there is less free play between the pin and the plunger. I was on my last straw with the brakes if this didnt work I wouldnt do anything else.

This is the way I did it so I wouldnt have to unbolt the brake booster or re-bleed the brakes (both PITAs):
  • Unbolt the MC from the brake booster (you shouldnt have to unscrew the brake lines and re-bleed the brakes).
  • Get someone to press the so the pin sticks as far out of the MC as possible. Then I put a kind of thick rubber glove around the pin so as not to damage it and clamped a vice grip to it. I used a wire loom to hold the vice grip so it wouldnt move when the person let off of the brakes.
  • Remove the lower dash trim piece so you have room to work.
  • Now would be a good time to loosen the lock nut behind the fork. It shouldnt be that difficult with a 14mm open end wrench.
  • Disconnect the pivot pin holding the fork to the brake pedal. To do this you must remove a cotter pin and then then squeeze the white nylon barbed end and pull it through.
  • Remove the brake light switch which also acts like a stop for the brake pedal. It is connected to a bracket with two nuts on each side (both 14mm). This will let the pedal go up father so you can get the fork off of the brake pedal and rotate it.
  • Slip the rod with the fork off of brake pedal and unscrew it. The more you unscrew the sooner the brakes will engage but remember that the fork is father up the brake lever then the pedal part, so a 1/4" more unscrewed might mean the brakes engage 3/4" sooner.
  • You may want to test how the brakes feel before you put everything back on so I slipped the fork back on the brake pedal and put in a bolt though the hole the pivot pin was because its kind of a pain to get in and out. I put the brake light switch back on in roughly the same position as it was before. Then removed the vice grip, reinstalled the MC, turned the car on to see how it felt. Also make sure that there is enough pedal travel for the brake lights to come on before the brakes engage.
  • If you like the how much travel there is before the brake engages. Insert the pivot pin and cotter pin and put the dash back together.





Finally my brakes feel as sporty as the rest of my car. It sucks I didnt adjust them before I did all the brake upgrades because I never truly appreciated them because they still felt terrible. This was easily the most rewarding hour I have ever spent working on my car.

Just thought I would spread the word. :)
 

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2005 Legacy GT
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199 Posts
Doesn't this basically adjusts the pedal's height? I dont think it would give that instant jolt of an engagement similar to porsches' or audis'
-Steve
 

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2000 2.5 RS Impreza 4 door
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Discussion Starter · #3 ·
Nope, that would be adjusting the brake pedal switch/stopper. This adjusts when the brakes engage. If your happy with when your brakes engage no need to do this but mine where engaging with around 2" of pedal travel.
 

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99 WRB GC V9 Spec C RA recce
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990 Posts
I recomend going another route and adjusting the pin first that pushes the MC valve first, make sure it sits snug against it
if that is not enough, adjust the pedal by following poleboys directions (but this will technically always put some tension on the booster, though slightly, which is why I recomend doing the pin first)

I can elaborate on this more, as I have just done a tremendous research on RS/Leg/STI boosters and MC trying to perfect my brake setup :)
 

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I recomend going another route and adjusting the pin first that pushes the MC valve first, make sure it sits snug against it
if that is not enough, adjust the pedal by following poleboys directions (but this will technically always put some tension on the booster, though slightly, which is why I recomend doing the pin first)

I can elaborate on this more, as I have just done a tremendous research on RS/Leg/STI boosters and MC trying to perfect my brake setup :)
Please elaborate when you have time. :)
 

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99 WRB GC V9 Spec C RA recce
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poleboy, do you mind me hijacking your thread a little with this? :)
 

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2000 2.5 RS Impreza 4 door
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Discussion Starter · #8 ·
Go ahead Im interested as well. If the adjustment is located on the MC side of the booster than it would probably be a lot simpler. I dont see how my method would be any worse though...maybe more complicated?
 

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Modsterdomus
2000 STM RS Sedan 5spd
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i had considered this when i was working on my wrx pedals... but i got lazy so i never did it... would really decrease stopping distance by shortening the ammount of time it takes to get to the brake engagement point.

chris
 

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99 WRB GC V9 Spec C RA recce
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Here is the old and ugly (and shot! :lol:) RS booster



see the pin with thread? you adjust THAT to make full contact with MC piston
right now it's at maximum "out" position

now let's move on the different MCs



left to right:

STI 1 1/16" MC - RS 1" MC - L non-abs 4 port 15/16" MC



disregard the black part on RS MC, as it slides into the booster anyway

now, let's look from the top




see how I lined them up so they are identical in terms of how it connects to booster

now, let's take approximate measurements, starting with STI MC:




RS:




L:




notice RS measure different from STI/L... hard to see because it's not much, but believe me it's more than enough when you try to stop your car :lol:



Now let's put them on the RS booster with the pin extended OUT all the way:


STI:



RS:




aha! notice it doesn't sit properly because the pin is out TOO FAR for RS MC


L:




sits nice like the STI one... because I was running this setup for few weeks, 4 port L MC with RS booster, and I could NOT stop the car because RS booster's pin was too far from the MC valve


moral of the story - always measure MC and booster when changing those parts around, they might seem like a proper fit, but such invisible things can ruin your day


what I am running now? The ultimate combo - STI booster, STI Group N 4 port non-abs 1 1/16" MC, STI prop valve

so no abs and brembo power = me happy

for anyone on Brembos or 4/2 pots, I highly recomend using 1 1/16" MC, period.


Next step - hydroulic handbrake and STI GrN adjustable proportioning valve :devil:

kudos to karl for explaining this all to me!
 

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2000 2.5 RS Impreza 4 door
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Discussion Starter · #11 ·
Ahh okay so in the first pic you put a wrench on the hex cap end and adjust it?

You can do the same adjustments either way really. Because the first time I adjusted the fork I had the MC with a gap like that RS booster so I screwed it in more and I had brake engagement right where I wanted. But this way seems like it would be simpler as far as adjusting it, especially when it is not installed yet.
 

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99 WRB GC V9 Spec C RA recce
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as I said, I had to adjust both for the booster to work with that MC :)
it's also a bitch to adjust that pin on the front, it's a 2-man job
 

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2000 2.5 RS Impreza 4 door
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Discussion Starter · #13 ·
Ahh ok. Seems like it would be easy but doesnt everything until you actually do it? :( I cant believe I didnt see that when I was looking at it.

That should help some people though, thanks.
 

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2000 2.5 RS-T srp sedan
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2,732 Posts
great tip.

Wonder if it would affect the heel Toe a lill since it engages faster. More travel helps it get down to gas pedal height :p
 

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2000 2.5 RS Impreza 4 door
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Discussion Starter · #16 ·
So this is all that is needed to get rid of the soft pedal??
It doesnt not necessarily make the brakes firmer, it juts shortens the travel before the brakes engage. If you want a firmer brake pedal, bigger master cylinder and singe stage braker booster will be most helpful.

However, it does feel like it stiffens the brake pedal because the long travel kinda makes it seem like the brakes are squishy.
 

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SCC Magazine covered this a while back with a Forester that Coleman was working on for his dad.

I think you need to leave some play, because the brake fluid can expand and engage the brakes.

It was a while ago when I read the article.

-Cybin
 

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2005 Baja Turbo
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SCC Magazine covered this a while back with a Forester that Coleman was working on for his dad.

I think you need to leave some play, because the brake fluid can expand and engage the brakes.

It was a while ago when I read the article.

-Cybin
If this is the case, then your primary cup seal is sealing your vent port. You've got a problem at that point with the pedal actually pushing the piston in at all times. Adjust it out a little, and it should be fine.
 

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yep. you heard me.
‘18 E63s AMG wagon & 10 Subarus
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i run the stock 93 L FWD non-ABS brake booster with 4pot fronts and 1pot rears (from an OBS) and its a very firm stop. at least compared to the stock 1pot fronts (they are TERRIBLE, cant even lock up the tires on full hard braking in a straight line)... however there is quite a bit of travel before it engages so i may do just this mod :) thanks for the thread
 
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