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NG900 & OG9-3 Performance, Mods & Tuning Covers Tuning & Performance modifications for the NG900 (1994 to 1998) & OG9-3 (1999-2002) & '03 Convertible

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  #1  
Old 6th May 2011
Javimoros Javimoros is offline
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Default Brake Booster FAQ

Hi, I am a trying to improve my braking power without changing the calipers, which is what everyone is doing. I have another thing in my mind.

My thoughts go in the direction that if VAG group has an EXCELLENT OEM braking system, why my much better SAAB does not have it... because mine and yours are awful, except 308mm (12in.) Viggen system. And i think our handicap is brake booster. I am "studying" ( note the quotes, please ) several info over the internet just to understand how a bigger booster would affect to car's braking power.

As i have read, 9in. booster are used on small cars, and we DO HAVE 9in. booster, in the research work i have been reading, they calculate the impact of changing booster and Master Cylinder (MC) for bigger ones and the results are simply amazing.

They measure 3 scenarios, one with 9in Booster and stock MC (20.8 mm ), then everything the same except 10inch booster and bigger MC (22.20 mm ) and the third one is with 11inch booster and another MC even bigger 23.8mm.

Max loop brake pressure are:
( front loop/ rear loop)
95/60 bar for 9in.
125/125 bar for 10in.
145/145 bar for 11in.

But not only max pressure is improved, even response time to achieve good braking pressure is lowered.

Also brake pedal feel will change, it would depend on what kind of booster do you use, it can be hardened or softened ( really doubt you can soften saab brake feel )

My question is...Ok i have more brake pressure within the loop, which means that my pads and calipers are doing a lot more pressure on the rotor to brake, but...will all the joints popup with this improvement? or it is safe to do?
How can i know the max pressure can the system handle?

Because if it is safe to do, it is cheaper to buy a new booster ( 200 for a VAG one ) and MC ( 150 ) to improve front and rear brakes than buying a complete VIGGEN brake kit ( 400 front kit and 400 rear one ) and of course a lot more cheaper than buying a full set of 4 pot calipers ( 3000 front and rear kit ?? )

I have searched and no one has ever asked to do something similar, so i do not know if what i am purposing here is like trying to paste a pair of wings to a white horse and pretend i have a Pegasus.

Javi.
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  #2  
Old 6th May 2011
busaboy busaboy is offline
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Unless you are racing, why do you need more braking? The brakes on these cars are excellent!
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  #3  
Old 6th May 2011
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fromero fromero is offline
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J,
Go with the 95 Aero booster if that pleases you, although maybe you'll spend a lot of time and effort on something that is inherently not so bad.

Maybe cheaper to change driving habits, don't use the brakes so much, be water my friend. Have you seen Hamilton braking much?
;-)
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Old 6th May 2011
saabkid37 saabkid37 is offline
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Quote:
Originally Posted by busaboy View Post
Unless you are racing, why do you need more braking? The brakes on these cars are excellent!
lol are you kidding me?

my viggen feels like the brakes on a 92 geo metro after i drive my evo with STOCK brakes.
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  #5  
Old 6th May 2011
busaboy busaboy is offline
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lol!! Then you have a REAL problem!!
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  #6  
Old 6th May 2011
saabkid37 saabkid37 is offline
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trust me i dont. the vig brakes arent even stock. the bias is crap, and they just dont stop the car well.

i imagine a 900 is even worse.
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Old 6th May 2011
busaboy busaboy is offline
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Of course....I guess you're right......

I know my car just BARELY stops...I better replace the entire braking system.....
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  #8  
Old 7th May 2011
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For me it's a question of balance, I found that by changing the ineffective rear barkes by the 95 Aero's 300mm ventilated, was the best, the brake balance is better and increased brake efficiency.
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  #9  
Old 7th May 2011
Javimoros Javimoros is offline
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Ok, anyway, thanks to all for your comments, but what i am unable to know and thats the point of making this post, is to know if:

WILL THE SYSTEM SUPPORT THE OVERPRESSURE IF Y CHANGE MY PATHETIC OVERBOOST FOR ANOTHER ONE WITH MORE DIAMETER?? OR WILL THE JOINTS BLOW AWAY?

Thanks.

And i do not care if you think your car brakes very well and we are mad becouse we think our cars do not brake at all...and i think this is not a dicuss topic...
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  #10  
Old 7th May 2011
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Want to be heard, right?

As said, it's clear it will sustain pressure equal to the Viggen/Aero 95 size, of course this also means they may blow if not in good shape.
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  #11  
Old 7th May 2011
Javimoros Javimoros is offline
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Quote:
Originally Posted by fromero View Post
Want to be heard, right?

As said, it's clear it will sustain pressure equal to the Viggen/Aero 95 size, of course this also means they may blow if not in good shape.

I do not want any saab overboost, i do not want poor 9-5 aero brake stuff i would like to get audi, volkswagen for example overboost, so i need to know if adding some more PSIs to the braking system would blow it away, even if it is in good shape.
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  #12  
Old 7th May 2011
loveb loveb is offline
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When I first drove the 900 I thought the booster was broken with how spongy the pedals feel. I mean, they stop me well now with ebc yellows and slotted rotors but I wouldn't mind a little more pressure.

they did get a little better after i bled them out but yeah. I suppose they're alright lol
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  #13  
Old 7th May 2011
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mike saunders mike saunders is offline
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Javi,

You'll get better performance with bigger rotors and calipers. The 9-5 Aero rears will help greatly, as will changing to better pads in the front. You can also source a set of Viggen caliper carriers for far less than your quoted price.

Increasing brake booster pressure will likely change pedal engagement and feel...
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