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Can I adjust my Brake Porportioning?

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Does anyone know how to get my rear brakes to do more of the work? (I would love 55% front, 45% rear)

It seems my front brakes are doing all the work.

Just before my ABS kicks in, my fronts lock up and I'm just not feeling any rear stopping power.

I've searched without luck to find any info on adjusting the front to rear proportioning.

All pads and rotor are in good working.

Thanks in advance for your input.


2000 986 2.7 84k

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  • Moderators

You need a brake test bench to check the brake power balance between the front and rear brakes. Under normal driving conditions you cant feel the rear brakes working.

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Thanks for the input RFM. Under normal driving conditions your right, I can't feel the rear brakes working and the car stops fine...

Under hard braking, the fronts lock up, on and off (the ABS is working fine). The rears never lock or even "grab". The truth is, I think the car is working fine(the rear rotors show that they are indeed working) but I would prefer more stopping power from the rear.

From my 928S4 days, I remember that there was a way to adjust the proportion... because people had the same complaint about 928's especially for track use. I can't remember how they did it...I'll do some searching.

My question is: Is it possible to increase the rear braking proportion on a Boxster, and if so how?

If someone can answer this question, it will greatly benefit all of us because I've owned 3 Boxster's so far, and they've all suffered from the same thing... and with those big fat rear tires doing much more of the braking, brake efficiency and stopping power would be incredible (like my A6).

Thanks again. Zebswiss

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Here is something I found on Ebay that might fit the bill... I wonder if there would be any complications with ABS?

I Searched for: Adjustible PROPORTIONING VALVE

On Sale Now...only 29.95

Ships to you Priority Mail w/tracking, only 5.95 ...FAST!!!

This is a new universal adjustible Proportioning Valve, manufactured from billet aluminum with a knurled knob for adjustment. This can mount vertically or horizontally.

This PROPORTIONING VALVE comes new in the package w/instructions.

Note: Availabe w/CHROMED FINISH for 8.00 more, Just Ask!

The purpose of a proportioning valve is to control the pressure to the rear brakes to prevent premature lock- up. It is fully adjustible for fine tuning, and can be installed with Disc or Drum brakes, on street rods, race cars, classic cars & trucks, 2WD & 4WD.

(NOTE..... If you have a 67-75 Bronco, I offer a complete Proportioning Valve Kit, w/hoses & mounting bracket, in my ebay Store).

You install this valve on the brake line that goes to the rear brakes. It connects to standard 3/16" brake lines and it has a knurled knob with fine threads which allows you to be extremely precise in your adjustments.

Pressure Range is 100-1000 psi. It is 4" long and 1-5/8" wide.

This Proportioning Valve will work on most any type of brake conversion, front disc, 4 wheel disc & drum brake cars or trucks. It cost less than a factory valve and is easy to install.



Anyone have any experience with anything similar to this? Thanks again! Zeb

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I think you will still be fighting the ABS. If you change the brake balance you will need to change the ABS.

I would try the racing version of the ABS first. As I recall the one that the race prep shops sell does not turn on ABS until two wheels lock (it only takes one wheel lock on the standard version).

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