More cost effective Brake upgrades ??

[Topless]

Remember that stopping distance is mostly a factor of weight and tire grip, not brake components. Base Boxster brakes are some of the best in the business with a stopping distance similar to a Ferrari Marinello. If your car does not stop on a dime, there is something terribly wrong with your brakes (contaminated brake fluid, bad master cylinder, bad wheel caliper. bad brake booster, etc.)

Get your brakes checked by a qualified tech. After having your brake system thoroughly serviced, switching to a more aggressive bite will give you quicker braking response with less pedal effort. Pagid black, Performance friction 03, Raybestos ST-43 are a few good choices with a lot of bite. These pads will easily overpower a set of stock street tires on the front. Maybe just better tires is your answer.

[insite]

topless is right. the difference w/ the brake upgrades is not the stopping distance. it's how many times in rapid succession you can panic stop without boiling the fluid, fading the pads or causing a fire.......

with cars like the cayenne, even a single panic stop from 100mph could cause fade problems if it had the brakes of, oh, a boxster...... weight is a concern.

with a tiny car like the box & only street driving, you will, as i said, see a net performance LOSS due to the added unsprung weight if you put cayenne brakes on your car. now if you want them because they look cool, well that's a different issue.

[Roy_Josef]

I seem to remember someone saying that when you put Box 'S'/996 front brakes on you can take your 'old' front calipers and rotors and put them on the rear. (Front left to right rear, Front right to left rear) Any truth to this?

[shlim8]

Hmmm, thanks for all the inputs.

I've currently got pretty new Michelin PS3 upfront and PS2 behind (both less than 8k km).... Made the mistake of changing the front to PS3 then realized that they don't make PS3 of the right size for the rears. The fronts are not N specs. But I presume this shouldn't be the cause of my problem ?

Oh, my front calipers were rebuilt afew months ago (one side sticking).

Does the ABS system on the Box come on to prevent ALL wheel locks ?? I did lock my front wheels once or twice and the ABS didn't come on.. No ABS warning light on at the moment. I've never felt the ABS coming on before at all (I presume there would be juddering feeling from the brake pedal ?).

Maybe I need to have that looked at first. Maybe a faulty ABS sensor ??

[insite]

Originally Posted by Roy_Josef

I seem to remember someone saying that when you put Box 'S'/996 front brakes on you can take your 'old' front calipers and rotors and put them on the rear. (Front left to right rear, Front right to left rear) Any truth to this?

you CAN do this, but DON'T! the brake system is designed to have smaller caliper pistons in back than up front. the pistons on the boxster front are the same size as the boxster s front. this means that by putting the front calipers on the back, you change the brake bias.....a lot.

since the car dives when you brake, roughly 70% of the car's weight is over the front tires during a heavy stop. this means that about 70% of the car's braking power is designed into the front brake system. if the rear brakes are too big, the rears will lock up well before the fronts (particularly if braking in corners). the potential for spins is very real. just ask pedro.

[ekam]

Well first of all that's called trail braking. As a novice you're not supposed to have your foot on the brake when you enter the corner anyway. It's an advanced driving technique and definitely not for someone who's not experienced.

That being said, I'm going to do the swap, but don't to what I do. It's bad for you.

[insite]

it's not called trail braking on the street. how about a panic stop in wet weather on a slight bend? the bias is too heavily rear for street OR track. if you do this, it's not a matter of if, but WHEN you will spin (street or track). a brake system is supposed to be balanced. moving the fronts to the back is a dumb idea.

Originally Posted by ekam

Well first of all that's called trail braking. As a novice you're not supposed to have your foot on the brake when you enter the corner anyway. It's an advanced driving technique and definitely not for someone who's not experienced.

That being said, I'm going to do the swap, but don't to what I do. It's bad for you.

[Topless]

Shlim8,

Sounds like you indeed have brake issues. Take your car out to a barren road and do a few full simulated panic stops from 50-0. Your car should go into ABS judder every time with no wheel lock up. If it does not you need some brake work. My car is really set up for track rubber and I get used to threshold braking and very high braking forces. When driving on the street with stock 205mm PS2 tires I get into ABS a lot.

[Roy_Josef]

How about a brake bias valve off another car? We used to do this (a lot!) right or wrong back in the day for both the 914 and the 944.

Originally Posted by insite

you CAN do this, but DON'T! the brake system is designed to have smaller caliper pistons in back than up front. the pistons on the boxster front are the same size as the boxster s front. this means that by putting the front calipers on the back, you change the brake bias.....a lot.

since the car dives when you brake, roughly 70% of the car's weight is over the front tires during a heavy stop. this means that about 70% of the car's braking power is designed into the front brake system. if the rear brakes are too big, the rears will lock up well before the fronts (particularly if braking in corners). the potential for spins is very real. just ask pedro.

[insite]

Originally Posted by Roy_Josef

How about a brake bias valve off another car? We used to do this (a lot!) right or wrong back in the day for both the 914 and the 944.

this is actually okay. rather than use one from another car, you can replace the proportioning valve with an adjustable one. they allow 'full force' to the fronts & let you limit pressure to the rear until appropriate bias is achieved.

just be sure you know what you're doing first. rear-bias settings that seem fine in a straight line on dry pavement may be to aggressive for wet weather & curves.

[Roy_Josef]

Thanks, good to know! I have all the bits necessary to do this and was thinking of doing it when I have everything apart to install my coil overs when warmer weather finally arrives. Any suggestions on a 'perfect fit' bias valve? I remember when we did 'Medium Red' brakes from the 944 Turbo 'S' on the regular 944 we would use the 928 S4 bias valve and when we did did the BMW 320i front brakes on the 914 we would completely take out the factory bias valve and install a VW 'Tee' bias valve fitting instead. Does nothing with a Porsche part number on it work?

Originally Posted by insite

this is actually okay. rather than use one from another car, you can replace the proportioning valve with an adjustable one. they allow 'full force' to the fronts & let you limit pressure to the rear until appropriate bias is achieved.

just be sure you know what you're doing first. rear-bias settings that seem fine in a straight line on dry pavement may be to aggressive for wet weather & curves.