Brakes issue.

[vadimv]

Hi everyone.

I have an issue with brakes system. can't allocate the issue.

Just replaced front rotors and brake shoes. Bleed the system 3 times with computer.
The brakes are solid for couple miles and then ABS/DSC starts pumping right away even I push brakes even lightly.

I have one boot broken and the grease all over the hub. Can it be a problem?

Car off - brake pedal hard
Car on - brake pedal working with buster.
checked calipers, all looks dry. No leaks.
Fluid level always the same level.
No ERRORS

any ideas what can be wrong?

[upallnight]

Originally Posted by vadimv

Hi everyone.

I have an issue with brakes system. can't allocate the issue.

Just replaced front rotors and brake shoes. Bleed the system 3 times with computer.
The brakes are solid for couple miles and then ABS/DSC starts pumping right away even I push brakes even lightly.

I have one boot broken and the grease all over the hub. Can it be a problem?

Car off - brake pedal hard
Car on - brake pedal working with buster.
checked calipers, all looks dry. No leaks.
Fluid level always the same level.
No ERRORS

any ideas what can be wrong?

Normally if I am replacing just pads and rotors there is no need to bleed the system.

When you stated that you bleed the system with a computer, are you using the computer to activate the ABS pump?

My guess will be that you have air in the system, most likely the ABS pump.

[vadimv]

Yes, used comp to activate ABS.

How air gets to the system thru ABS pump?

[upallnight]

Originally Posted by vadimv

Yes, used comp to activate ABS.

How air gets to the system thru ABS pump?

Did you unhook any lines when you did the brake job and did you try to stop any leaks when the lines were unhooked?

You never let the brake system run dry if you do unhook a line because eventually, the fluid in the ABS pump will drain out.

Air get into the system through the master cylinder cap since as the piston moves out, the brake fluid must also move so air is vented into the Master Brake Cylinder.

I would just take it in and let someone else who knows what they are doing fix it.

[vadimv]

I did install new master cylinder, but still have the same issue.
Can it be hydralic pump issue?

[crystalworks]

Originally Posted by upallnight

Did you unhook any lines when you did the brake job and did you try to stop any leaks when the lines were unhooked

^

Also, did you ever take it to a pro to have system flushed/bled? Just curious as to what made you think the master needed to be replaced.

[vadimv]

I was thinking master cylinder leaking.
That why I replace it.


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[Joshdub]

Did you bench bleed the master cylinder?

[iansanderson]

Originally Posted by vadimv

Hi everyone.

I have an issue with brakes system. can't allocate the issue.

Just replaced front rotors and brake shoes. Bleed the system 3 times with computer.
The brakes are solid for couple miles and then ABS/DSC starts pumping right away even I push brakes even lightly.

I have one boot broken and the grease all over the hub. Can it be a problem?

Car off - brake pedal hard
Car on - brake pedal working with buster.
checked calipers, all looks dry. No leaks.
Fluid level always the same level.
No ERRORS

any ideas what can be wrong?

Yes, grease/debris covering the hub speed sensor ring can cause a false wheelslip event. Clean the hub area and speed sensor off with some brake parts cleaner. You could also have a DXC module going bad.

[vadimv]

Yes, we did master cylinder bleeding.

DXS module bad - Computer or hydralic inut bad