Brake problem

[Glenn Briglio]

Went from no problem holding the car at 3000 rpm on line to pushing thru the beam. Four wheel wilwood disc brakes.Mopar master cylinder( don't know piston diameter).Checked the pressure at each wheel. 1000 lbs coming out of master going to front brakes. 1000 lbs at front wheels. 800 lbs at rear and it will go no higher no matter how much more pressue you build up. I didn't have an adapter to measure pressure coming out going to rears.Couldn't swap lines from front to rear on master (different sizes). 3/16 lines going to fronts and 1/4 going to rears.

[ss3011]

Refinish the rotors and install new pads !

[Glenn Briglio]

Originally Posted by ss3011

Refinish the rotors and install new pads !

First thing done at track........no difference

[nhramnl]

Have somebody watch the car to see if the wheels are turning or sliding. Also, go over everything you've changed recently that might affect the brakes ability to hold the car, including even things like engine and converter changes. Finally, don't hold me to this, but 1000psi (front) and 800psi (rear) doesn't sound like an overabundance of clamping force.

[Glenn Briglio]

Originally Posted by nhramnl

Have somebody watch the car to see if the wheels are turning or sliding. Also, go over everything you've changed recently that might affect the brakes ability to hold the car, including even things like engine and converter changes. Finally, don't hold me to this, but 1000psi (front) and 800psi (rear) doesn't sound like an overabundance of clamping force.

Nothing was changed. Front tires locked, rears are rotating and pushing car.The 1000 psi can go higher. The 800 at rears will not go higher no matter what pressure is coming out of master.

[ss3011]

Is it possible to bleed just the rear brakes and recheck the pressure ? Could be an air bubble .

[Glenn Briglio]

Originally Posted by ss3011

Is it possible to bleed just the rear brakes and recheck the pressure ? Could be an air bubble .

Could be an air bubble but have bled them 5 times. Nothing but a solid stream of fluid.

[kdanner]

Internal master cylinder leak only once the rear circuit gets to that pressure maybe?

[Myron Piatek]

Maybe internal degradation of any rubber lines you may have? I heard that they can bunch up and cause internal restriction or blockage as they age.

I've had some trouble with holding the car on the line with OEM disc/drums lately and this thread made me realize that the brake "T" assembly on the rear end housing is the only rubber hose I still have in the system. M/C has been changed and all the other lines are solid or braided.

I put a higher priority on the rear brakes because harnessing the torque there will accomplish more than at the front. The best front brakes still only have a pair of skinny front runners trying to hold the car and can easily slide.

[Glenn Briglio]

Originally Posted by Myron Piatek

Maybe internal degradation of any rubber lines you may have? I heard that they can bunch up and cause internal restriction or blockage as they age.

I've had some trouble with holding the car on the line with OEM disc/drums lately and this thread made me realize that the brake "T" assembly on the rear end housing is the only rubber hose I still have in the system. M/C has been changed and all the other lines are solid or braided.

I put a higher priority on the rear brakes because harnessing the torque there will accomplish more than at the front. The best front brakes still only have a pair of skinny front runners trying to hold the car and can easily slide.

I'm changing master cylinder and rubber hoses going to rear brakes first.