limenuke

I was wondering what the pedal travel for your s2ks feels like.

I just installed my stoptech st40 bbk and bled the lines and the pedal feel is essentially the same as before and after. I even paid a shop, after I bled it, to bleed it as well and the pedal feel is still the same. You could say that the system has now gone through two full bleeds (although when I installed my bbk, I did not bleed the rears. I assume my shop did).

The first 40-50% of pedal travel feels like very weak brake dragging w/ little resistance. The pedal resistance for the first 40% of the pedal travel is very low - I can basically press the pedal through this point of the travel with my hand.

The next 50-60% of pedal travel is very firm. I do not have sufficient strength to press this with my hand. The pedal resistance here feels great and gives me good stopping power.

My issue is this: I literally have have to press the pedal to the floor in order to brake hard enough to get my tires to lockup->ABS. Obviously, it doesn't hit the floor very easily as the pedal is very firm at this point, but it doesn't make me feel comfortable that I'm having to use 100% of my pedal travel to trigger lockup->ABS. As I've ridden motorcycles and bikes with hydraulic brakes, I can pretty confidently say that these brakes do not seem to feel "spongy". There is no sense that, during the firm braking zone, that there is too little resistance and I'm not getting a hard contact at the pads.

FYI, I'm on RS4 tires w/ stock Stoptech pads. I'm starting to think I may have to bleed the master cylinder or buy a new one - or just try other peoples' s2k brakes and see how they are. My local racing shop claims my pedal feels fine and that if I want more bite, I'll need better pads. This doesn't seem right to me - I have owned a number of BMWs with fairly decent tires and never have I ever had to press the pedal to the floor to cause the ABS to kick up. The pedals seemed engage the brakes earlier on the BMWs, so I wasn't wasting that 40-50% of beginning travel.

I've also tried the billman brake travel "fix" where you lodge a piece of wood against the brake pedal for 24 hours. This did not help at all for me.

noodels

Can not remember engaging ABS ever..

B serious

why not make sure the shop bled the rears? "I assume my shop did" just doesn't ooze with confidence.

Did they check the rear slide pins and pad ears? Maybe the rears slides or pads are seized.

You also may need an ABS bleed if your master cylinder has ever been run dry.

Did you bed in the pads?

limenuke

I brake pretty hard at autocross, and I also check my grip periodically (on empty streets), so I often end up setting off ABS with some hard braking. It does take quite a bit of effort to get ABS to go off in this car - but it's a feeling I think everyone should learn about in their own cars. The only way you know the threshold of grip is to cross the threshold.

If you want an excuse to try, just go and re-bed your pads, but brake HARD when you're doing your 60->20mph braking. Don't BABY the brakes there. If you're doing it right, you'll smell brakes by the third brake.

noodels

Forgot to say
AD08R Yokohama 225/255 +Ferodo 2500 pads.

limenuke

I'm on 255 square Hankook RS4 + . Stock ST40 street pads

ericmdub92

i was told to do 2 full bottles of brake fluid (motul rbf600) when bleeding the st40 brakes. while bleeding them it felt like i was wasting fluid, literally had clear streams of fluid being bled out of our bleeder tube (zero bubbles) but we persisted.

do all 4 corners, 2 person method, make sure the reservoir is always topped off w/ brake fluid

for reference: im on square 255 re71r and st40 street pads as well and i can definitely get my car to ABS w/o having to sink the pedal to 100%

s2000Junky

Make sure you are bleeding the calipers in the proper order ...and both sides of the st40 calipers, bleeding the outer bleeder first, then do the insides.

Charper732

I can't speak for the ST40s I have not owned them, but BBK's in general will require more pedal throw if the piston surface area is larger than the stock calipers. This is because it requires a higher volume of the brake fluid to move the pistons the same amount of distance. A larger master cylinder would of course solve this, but im not sure of anyone that makes one for our car that is still booster assisted. I have a brembo BBK with braided lines on my s2k but pedal is more progressive than what it is on my honda civic with stock everything.

But also to add, you could possibly still have air in the system. If you have ever had the master cylinder off, or sucked the resistor dry, odds are there is air in the abs unit/master clyinder. You need to bleed the master cylinder by its self. I believe there is a DIY write-up somewhere on the forum for that

nubbel

I get the same on mine (100% stock though)

Performed a gravity bleed on all fours around this time last year, didn't change a thing.

I've heard about Billman's 24h-pedal-press-fix but haven't tried it yet

If everyone here is getting better brake feel I might have to do another bleed...