brake bias valve

[Albert]

did eny of You have any problems after instaling big brake kit in fornt ? form the theory rear should brake with less power ... and that could couse instability of the car ...

did eny of You use diferent brake bias valve or made some modifications to it ?

[Lloyd]

Has anyone worked out how to adjust the brake bias?

I would really like to increase bias to the rear. Perhaps just 2-3% to start with test etc. I'm am well aware of the risks in going too far too fast!

[Rusty]

I think you have to remove the ABS as this is what controls it normally. I guess you could remap the ABS ecu tho

[s2driveruk]

no obvious issues moving to the standard 996/323mm front setup in terms of stability...

[Lloyd]

Well. Here's my reasoning......

I'm running GT3 Monoblock's on the front along with Pagid RS29's and 322 x 32 discs.

Terrific setup. Works great - I'm now on my second set. But..... I do feel that the car overall would benefit from a little more rear brake bias. Clearly, I've now got far more brake torque upfront than factory and I believe a little more rear bias would help optimise the new front brake setup.

I would expect the nose to dip a bit less at the front and overall feel more well balanced. I'm not looking to go so far that the rear of the car really starts to snap out on trail braking but just a 'bit' more....

Anyone know anything about the ABS ECU? I'm totally clueless where to start. Was hoping there was a bias valve somewhere..

[goodall]

the standard system used a fixed ratio bias valve, part 13, located under the master cylinder
the system is longitudinally split rather than diagonally, which means the front circuit pressure is used to restrict rear pressure, ie in event total front brake failure due to a leak the rears get full pressure

other option is break in gear, that way torsion diff will balance the breaks, i think....

[ifa]

ABS dont have enough time to react if rears locks first. Corner braking especially in slippery condition may lead to some unwanted behavior.

Modifying abs unit isnt solution for this problem.

Adjustable brake pressure regulator or keeping brakes enough front biassed.

[Rusty]

S2/RS2 doesn't have vacuum, it has hydraulic assist so is a different setup to the picture.

[goodall]

S2/RS2 doesn't have vacuum, it has hydraulic assist so is a different setup to the picture.

ah this is true, but i thought was under the master cylinder in a ur so assumed be same for s2, for which i couldn't find a diagram for so used the one for a 80/90 id been looking at perviously

however i did go look again, and

part 8, mounted in front abs controller seems, which still disproves the abs does the biasing

i still actually dont get use the bias valve if linear, why didnt just use smaller diameter rear calipers.... or better bigger fronts as oem

[newsh]

Just below the master cyl on my 3B

[4WheelDrifter]

The stock bias valve is under the master cylinder on 3Bs, as Newsh shows, and by the ABS unit on ABYs.
I believe ESP controls bias, but not ABS.

[ifa]

S2 and RS2 have different regulators. I think rs2 one lowers rear pressure because bigger discs. That could be oem solution for big rear brakes.

Just my toughts about differences.

[Jamo]

S2 and RS2 have different regulators. I think rs2 one lowers rear pressure because bigger discs. That could be oem solution for big rear brakes.

Just my toughts about differences.

Do we know for sure the rs2 one lowers the rear bias over the s2?

[Dirtylouie]

Does anybody know what happens if i ditch the subject? i have hydraulic hb + tilton valve installed. Do i realy need bias valve with this setup? What if i connect main cylinder to ABS directly?