looking to upgrade master cylinder

[rcravincase]

i looked around for baer and wilwood to see if they had a direct replacement for my car but found nothing. i have poor braking, but all new calipers, rotors, pads, and rubber lines all around. im sure the original master cylinder is bad (squirts up when applying brakes) which is causing me to have poor braking. i plan on keeping the stock 4 wheel disc for a while until they're worn out, or i upgrade to a 12 bolt and get a wilwood kit. i need some pointers on getting something that will bolt up to the stock booster

[astroracer]

I would suggest simply replacing the current master cylinder. If that is your problem it should greatly improve your braking. It could be the booster is bad also. You really need to get the problem figured out before you start throwing mismatched parts at and make things worse...
Mark

[a67]

... im sure the original master cylinder is bad (squirts up when applying brakes) ...

It is normal for the M/C to do this, nothing that points to it being bad.

The stock rear disk brakes on your car never worked correctly from the factory. Not enough line pressure (combo valve proportioning is wrong), and the parking brake needs to be used on a regular basis to keep the calipers adjusted.

Best thing to do for the stock brakes is to get some decent pads. Such as the Stoptech High Performance Street pads.

Other then pads & correcting the rear line pressure there is nothing that can be done to upgrade the stock brakes. The rotors are too small at 10.5" diameter.

Then when it is time to upgrade, need to look into set ups that use PBR calipers and larger rotors. There are the 1LE, C4 standard and HD set ups, C5, C6, along with the '98-'02 f-body brakes. Tons of info over on TGO about those upgrades. So much since the stock factory brakes on the 3rd gen f-body's (except 1LEs) are so bad.

Bob.

[rcravincase]

i already have an adjustable prop valve waiting to go in, i was aware of the poor rear brake bias when i bought the car, replaced the rear calipers, and it would still spin the tires when jacked up, in gear, and the brake to the floor. the booster is ok, its not leaking. even sitting for nearly a month i have two applications worth of vacuum left. a full brake application from 60 takes at least 300 feet to stop. again, nothing is seized. occasionally i can get the left front to lock

[a67]

i already have an adjustable prop valve waiting to go in, i was aware of the poor rear brake bias when i bought the car, replaced the rear calipers, and it would still spin the tires when jacked up, in gear, and the brake to the floor. the booster is ok, its not leaking. even sitting for nearly a month i have two applications worth of vacuum left. a full brake application from 60 takes at least 300 feet to stop. again, nothing is seized. occasionally i can get the left front to lock

Yes to the rears not being able to stop the axles from spinning at idle. That is a stock factory feature. Sounds like you have a handle on that. Gut the rear proportioning of the combo valve and use an adjustable inline to the rears.

What are you using for pads? They make a huge difference.

Bob.

[rcravincase]

im using mid grade napa pads all around. i did buy hawk pads for it before but they didnt fit the caliper correctly. i just did my state inspection on it the other day. the car sat for over 2 years after i blew up the 305. the front rotors are nicely cleaned up, but the rears barely have the rust knocked off the inside face of the rotor. i took them apart again just to make sure nothing was stuck and worked the parking brake lever to make sure the piston screw wasnt stuck.

[Skip Fix]

Other then pads & correcting the rear line pressure there is nothing that can be done to upgrade the stock brakes.

FWIW a friend just swapped out the ratchet rear calipers for just plain metric Malibu fronts and noticed a marked improvement in braking,you just loose the e brake capability. The ratchet calipers are a pain to get to work correctly.