Is a brake master cylinder bigger on a sti 4pot brakes than a WRX?
#1
Scooby Regular
Thread Starter
iTrader: (1)
Join Date: Jan 2010
Posts: 147
Likes: 0
Received 0 Likes
on
0 Posts
Is a brake master cylinder bigger on a sti 4pot brakes than a WRX?
Hi i had a bit of a bump about two years ago and we had a bit of a problem with the brakes were the pedal would drop to the floor and when pumped the brakes would firm up again.
This was solved as there was a hair line crack on the disc..so the fronts were changed....the first thing we did was change the brake master cylinder but the code on it was different...the brakes ave never been the same so we thought it was the front calipers so refurbs them and added braided hoses and motul fluid...got all the air out but still *crap...
when i drive the car and i brake the brake pedal pressure is there and when pumped straight away the pedal goes firmer. i have reason to believe that the brake master cylinder may be smaller that that of a sti.
could anyone please assist. thanks
This was solved as there was a hair line crack on the disc..so the fronts were changed....the first thing we did was change the brake master cylinder but the code on it was different...the brakes ave never been the same so we thought it was the front calipers so refurbs them and added braided hoses and motul fluid...got all the air out but still *crap...
when i drive the car and i brake the brake pedal pressure is there and when pumped straight away the pedal goes firmer. i have reason to believe that the brake master cylinder may be smaller that that of a sti.
could anyone please assist. thanks
#3
Scooby Regular
Thread Starter
iTrader: (1)
Join Date: Jan 2010
Posts: 147
Likes: 0
Received 0 Likes
on
0 Posts
cheers dazza for the reply, my brakes are crap at the moment. do you know or if anyone else if the kevlar pads need warming up before they work properly?
really need to know because i can stick the old master cylinder back on.
really need to know because i can stick the old master cylinder back on.
#4
Scooby Senior
iTrader: (3)
Join Date: Jun 2006
Location: Slowly rebuilding the kit of bits into a car...
Posts: 14,333
Likes: 0
Received 0 Likes
on
0 Posts
I would expect that a 2 pot master cylinder will be different to a four pot item, as it has to move more fluid...
IMHO
dunx
P.S. For a 2 pot to Brembo swap, it would be very likely to need a Newage master cylinder.
IMHO
dunx
P.S. For a 2 pot to Brembo swap, it would be very likely to need a Newage master cylinder.
Trending Topics
#8
Scooby Regular
iTrader: (6)
Join Date: Dec 2005
Location: Nr Grimsby
Posts: 2,641
Likes: 0
Received 0 Likes
on
0 Posts
Yes there is a difference, as std an early 2 pot cars has a 25mm cylinder fitted, later 4 pot cars have the bigger 27.##mm version.
I did the change on mine (fitted an STI8 cylinder)
By fitting it you increase braking feel no end. A must IMHO.
I did the change on mine (fitted an STI8 cylinder)
By fitting it you increase braking feel no end. A must IMHO.
#14
Scooby Regular
Thread Starter
iTrader: (1)
Join Date: Jan 2010
Posts: 147
Likes: 0
Received 0 Likes
on
0 Posts
Hi guys just thought id update on the progress.
The sti comes with a larger master cylinder as i have recently found out.
On the sti master cylinder just below the front of it it is marked as: -
1 1/16.
I think on the wrx it is just one but you can find out but looking at it with a mirror just underneath the front.
dexster81 you just need to add on the sti master cylinder as servo doesnt need changing.
Could anyone on here who has a turbo 2000 or a wrx classic confirm the master cylinder size by looking underneath the front with a mirror would be interesting to see if its smaller and confirm.
thanks guys for the replies.
The sti comes with a larger master cylinder as i have recently found out.
On the sti master cylinder just below the front of it it is marked as: -
1 1/16.
I think on the wrx it is just one but you can find out but looking at it with a mirror just underneath the front.
dexster81 you just need to add on the sti master cylinder as servo doesnt need changing.
Could anyone on here who has a turbo 2000 or a wrx classic confirm the master cylinder size by looking underneath the front with a mirror would be interesting to see if its smaller and confirm.
thanks guys for the replies.
#15
Scooby Regular
iTrader: (1)
Join Date: Mar 2009
Location: England
Posts: 195
Likes: 0
Received 0 Likes
on
0 Posts
On the UK 2000 MY97 Terzo it has a 1 so does that mean the STi brake servo will NOT fit
or is the 1 and the 1 1/16 just the size of the master cylinder and not the hole it is having to go in on the servo
or is the 1 and the 1 1/16 just the size of the master cylinder and not the hole it is having to go in on the servo
#18
Scooby Regular
Thread Starter
iTrader: (1)
Join Date: Jan 2010
Posts: 147
Likes: 0
Received 0 Likes
on
0 Posts
dexster81 that is great for getting that info for us fella, thank you.
This is all aspect answers our questions, firstly the master cylinder on a sti is larger in internal as 1 1/16, the wrx, turbo 2000 etc will have a smaller one that has 1 printed on it.
In my opinion all that needs changing is the mc and not the servo.
This thread is proof that we can work tgether to get a resolution which i think is great.
This is all aspect answers our questions, firstly the master cylinder on a sti is larger in internal as 1 1/16, the wrx, turbo 2000 etc will have a smaller one that has 1 printed on it.
In my opinion all that needs changing is the mc and not the servo.
This thread is proof that we can work tgether to get a resolution which i think is great.
#19
Scooby Regular
iTrader: (6)
Join Date: Dec 2005
Location: Nr Grimsby
Posts: 2,641
Likes: 0
Received 0 Likes
on
0 Posts
dexster81 that is great for getting that info for us fella, thank you.
This is all aspect answers our questions, firstly the master cylinder on a sti is larger in internal as 1 1/16, the wrx, turbo 2000 etc will have a smaller one that has 1 printed on it.
In my opinion all that needs changing is the mc and not the servo.
This thread is proof that we can work tgether to get a resolution which i think is great.
This is all aspect answers our questions, firstly the master cylinder on a sti is larger in internal as 1 1/16, the wrx, turbo 2000 etc will have a smaller one that has 1 printed on it.
In my opinion all that needs changing is the mc and not the servo.
This thread is proof that we can work tgether to get a resolution which i think is great.
#25
Scooby Regular
iTrader: (7)
Please have look on those threads
http://forums.nasioc.com/forums/showthread.php?t=958909
http://forums.nasioc.com/forums/show....php?t=2054265
http://forums.nasioc.com/forums/show....php?t=1456630
I'm pretty sure John Felstead covered this over here and 22b
https://www.scoobynet.com/scoobynet-...rt-brakes.html
http://bbs.22b.com/forums/showthread...-pot-330mm-kit
Hope this help
Thanks,Jura
#27
#29
Just checked my manuals (which are the US/Canada market but are often the same as EU)
The MY04 (which is MY03 to the EU market) has the same size master cylinder on the WRX and STI at 26.99mm
The MY06 (which is MY05 to the EU market) has the sizes I posted earlier.
Looking at the line pressures, either the brake pedal has a different ratio on the WRX and STI or the brake booster spec is slightly different.
At 66lb of pedal pressure the early Newage WRX has 1323psi line pressure, the STI has 1209psi line pressure.
The later spec Newage WRX has 1450psi, the STI has 1209psi line pressure, which ties in with the cylinder sizes being different.
Now if you are running the WRX 4 pot brake you are going to need a higher line pressure to achieve the same clamping rate at the pad as the STi Brembo 4 pot because the piston surface area is much smaller.
The MY04 (which is MY03 to the EU market) has the same size master cylinder on the WRX and STI at 26.99mm
The MY06 (which is MY05 to the EU market) has the sizes I posted earlier.
Looking at the line pressures, either the brake pedal has a different ratio on the WRX and STI or the brake booster spec is slightly different.
At 66lb of pedal pressure the early Newage WRX has 1323psi line pressure, the STI has 1209psi line pressure.
The later spec Newage WRX has 1450psi, the STI has 1209psi line pressure, which ties in with the cylinder sizes being different.
Now if you are running the WRX 4 pot brake you are going to need a higher line pressure to achieve the same clamping rate at the pad as the STi Brembo 4 pot because the piston surface area is much smaller.