I am getting a strange sound out of my brakes in my 1993 Jeep Cherokee. It does not have ABS. On hard braking, I get a thumping sound that seems to be coming from under/near the driver's side lower firewall/floor. It kind of is a "grrr" sound. The pedal feels a bit mushy even though I have bled the brakes several times. Vehicle has 204,000 miles on it and it is stock. It was well maintained by the previous owner.

I have replaced the following: (I've replaced a lot of other items but the following are relevant to the brakes.

Front Rotors
Front Discs
Front Wheel Bearings
Rear Drums/Pads, springs, adjusters etc...
Master Cylinder
Brake Fluid flushed and replaced.

Brakes have been bled.

The last components I have not replaced are the actual lines and the following:

Brake Vacuum Assist
Front Calipers
Rear Slave Cylinders
Proportioning Valve

Is it possible for a bad caliper to make a noise? Or the proportioning valve? Thoughts or other ideas?

Thanks in advance for any suggestions.

Dave

 

You changed the rotors and the discs? the rear drum pads were replaced, what of the rear shoes?

perhaps tell us again what has been replaced, I am in a fog here.

 

Yes, I replaced the rotors and the disks on the front and the drums and shoes on the back.

The only things not replaced are the lines themselves, the proportioning valve, the vacuum assist thing, the front calipers and the rear slave cylinders.

 

for the pedal being mushy, buy one of those brake master/brake booster sets. i had mushy pedal on my 87 from when i purchased it so i bought a master and put it on because who knows what was up with the original one. still had push pedal so i bought a brake booster and put it on and than i had trouble with the brakes activating on their own. turns out the rod between the booster and master was not the right size since they were different brand parts. i ended up having to get a master/booster combination replacement and then the brakes were fine.


for the noise though, i have no idea yet

 

Rotors are discs in regards to the front brakes. I dont understand how you are using the terminology here.

as for the power assist, there are ways to check its operation, one is to with the engine off, pump the brake pedal a couple times to release vacuum, then with foot firmly on the pedal, start the engine, if the power brake is working, upon start of motor the pedal should go down a bit if you had been pressing on it. if it dont go down, the vacuum boost is not working right. you can also do a vacuum test on the booster with a hand vacuum pump and gage.

noises and pulsating can be do to bad pads, warped rotors or drums, loose mounts of the parts, etc.. recheck tightness of the part mountings, raise up jeep and spin wheels to check for dragging, romp on brakes and note if the wheels still spin free or not after release of pedal, check wheel bearings for correct play, make sure your wheels are properly attached via the lug nuts.

 

By disks I meant the pads. By rotors I meant the round metal component that the wheel studs go through. The disk pads squeeze against what I called the rotor. Pic of what I called the rotor is below. Rotor and pads are new.

 

Pull the wheels and take pictures. I'd also like to see inside the drums.

What value did you torque the lug nuts to?