Originally Posted by streckfu's

Is there any advantage to using this with stock brakes? I know it's virtually esential with the bigger brakes but I was thinking that this could be useful since I don't have ABS.....

Originally Posted by Kurt R

It will give you more rear brake - proportionally. This could be a good thing or could be a bad thing, depending on conditions..... Lawyers like less rear brake. If you hit something head on it is your fault. If you spin and hit something you can blame the car, not your ability.

Originally Posted by streckfu's

I've heard that it improves overall braking by allowing the rears to work a little more which also slows front end lock-up. Is that a fair assesment?

Originally Posted by Kurt R

That's it - the rears work more, so overall braking is improved. Less chance of front lockup at a given brake pressure, but a greater chance of rear lockup. With this valve braking in a straight line you will still lock the fronts first, but the rears will be doing more work.

Originally Posted by sh944

Yes, it is. In my opinion, the proportioning valve, a set of Pagid Orange pads and a set of 968 cooling vents will get most drivers all the braking power they would need. If you have substantial power increases on your car, you might think about the bigger calipers, but I dislike them due to weight considerations.

Regards,

Originally Posted by streckfu's

I know I don't need bigger calipers. I just want the most from what I have.

What started this process was an ealier thread about ABS. I don't have ABS to prevent lock-up and from what I've learned, the 5/33 would improve the braking and slow the front lock in a panic stop scenario.

Also, can the bias valve be changed w/o bleeding the brakes or losing fluid?

Originally Posted by sh944

You should flush the brakes at least annually on these car, in my opinion, so its an excellent excuse to take care of some maintenance at the same time. Yes, you will lose fluid.

Regards,

Originally Posted by streckfu's

So this is a good upgrade with stock calipers?

Originally Posted by tjbreen

Before I put in the 5/33 in my non-abs car the rears wouldn't even get warm. Now they do. With the valve, I have tried locking the rears before the fronts and it has never happened, even on wet roads.

Originally Posted by mmmbeer

Actually, wet roads are where you normally won't get rear lockup. The better overall grip the less rear brake bias is needed.

The reason why OEM is so far from optimal is because rear lockup can be a very bad thing. How the brake bias is supposed to be set to get optimal balance vary greatly depending on alot of factors. But mainly road conditions. The factory setting is ment to be fool proof even with the wrong tyres or wrong air pressure etc on the best gripping asphalt in the world. Even then it has a bit of safety margin. In the rain or specially on snow, you will need ALOT more rear braking balance to stop efficiently. This is one more reason ABS will stop your car faster in daily driving, it gets the right balance instantly in "all" conditions.

Get a adjustable valve and you will be able to fine tune it just the way you want. Even change it depending on road conditions or mechanical changes on your car.

Regards:
Eirik Kvello-Aune
www.944968.com

Originally Posted by mattipuh

I got rear (and front) lockup after replacing bias valve with 5/33 on track. on street the brakes felt superb with new bias valve. some way I think there's air left in Abs unit, which makes in work strangely... what is your opinion?
Would love to keep 5/33, because car handling (if it wouldn't lockup) would be almost perfect in braking now.

rear disc felt almost hotter than fronts (of course rear disc is much smaller than front at the moment), so they're definitely working now aswell.

p.s. car has 996TT 330x34 fronts and OEM rear brakes.

Originally Posted by Oddjob

More

Originally Posted by Eric_Oz_S2

Incorrect - the 5/18 sends less pressure to the rear. 5/18 means 50% reduction in pressure when over 18bar to rear.

Originally Posted by carreracoupe997

I know the 5 means 50% and 18 means 18 bar, but is at a 50% reduction in the original brake pressure or 50% of the original brake pressure less the 18 bar?

Originally Posted by Eric_Oz_S2

.....and beyond 18 bar each additional bar is reduced by 50% (technically it is actually 46%)....