Problem: Heavy shudder upon braking

[Big T]

This is on my ‘99 Suburban. Have a shudder from the right front upon braking. It increases the heavier I hit the brakes.

This was happening before the broken tie rod incident which was on the right front. I rebuilt the front end with new ball joints, tie rods, ES poly bushings on forged replacement LCAs. It passes the dry park test with no play on the tie rods in the knuckles. Ball joints are tight. It drives smooth and tight at highway speed, but this brake shudder persists.

Today I replaced rotors, pads (close to wear bars) and calipers, but the shudder persists. I am now at a loss as to what is causing this, so I’m reaching out for help.

 

[MrMarty51]

Only thing I know can cause that is warped rotor.
Jack it up, remove front tire/wheel.
Hold a center punch real close to rotor and turn the rotor.
See if the punch drags on the rotor.
Could maybe also be created from an out of round rear braking drum.

 

[Big T]

Only thing I know can cause that is warped rotor.
Jack it up, remove front tire/wheel.
Hold a center punch real close to rotor and turn the rotor.
See if the punch drags on the rotor.
Could maybe also be created from an out of round rear braking drum.

Old rotors did it and brand new rotors are doing it. Do not feel it in the pedal nor at stops at slow speed.

 

[ak diesel driver]

I'd look closely at the tires.

 

[Big T]

I'd look closely at the tires.

Same thing happened when I put new balanced tires on the front. They are on in the video. Feel nothing from the tires while driving at highway speed.

 

[jrsavoie]

Flex hose?

 

[Big T]

Flex hose?

?

 

[jrsavoie]

?

Brake flex lines. Sometimes collapse intermittently

 

[Big T]

Brake flex lines. Sometimes collapse intermittently

These are new braided stainless lines.

 

[Big T]

Same thing happened when I put new balanced tires on the front. They are on in the video. Feel nothing from the tires while driving at highway speed.

The spare is brand new. I can try putting that on, but I know the result will be the same.

 

[EWC]

I'd be putting a scanner on that and check the ABS readings .

 

[Big T]

I'd be putting a scanner on that and check the ABS readings .

ABS light is on. Occasionally it goes off and the system works. I had similar thoughts. I do not have my Tech 2 with me. Tests I did over the weekend indicated the ABS pump motor is shot. I’ve ordered a reman ABS unit which is all that you can get now. I could pull a plug and disable the ABS altogether.

 

[ak diesel driver]

That would be a quick easy elimination process.

 

[Big T]

That would be a quick easy elimination process.

Unplugging the ABS did not change a thing other than my ABS and Service 4wd lights turned off.

I continued my drive over to Wayne at Eagle Watch Automotive and we went for a test drive. I showed him the shudder on heavy braking. He asked me to brake more moderately. Then he asked me to do the same from a slower speed. He looked at me and said “although it vibrates here up in the front, I think it’s from the rear and it’s probably a warped drum from heating up when just the one was locking up.” He asked to drive it so he could show definitively. Driving about 10 mph he pulled the parking brake handle, then braked moderately and you could feel the wop, wop, wop. He said “It’s definitely in the rear. Change the drums and you should be good.” Did not take more than 5 minutes.