Brakes - Clunk Clunk Clunk - Low Speed

[sc mustang]

My son and I have been picking things off the list one at a time on a 94 GT - thanks to the help of people on this forum. The last (for now) significant issue we have is a very loud pulsing/clunking from the front brakes at very low speeds. When braking from high speeds the brakes feel good but get below about 7 mph or so and they begin to clunk very heavily in a slow pulsating way. You can both hear it and feel it dramatically in the foot pedal. Take your foot off the pedal and it goes away and then you can usually reapply light brakes without it reocurring. There appears to be no wobble, pulsating, noise or any other problems on normal braking until speed gets very slow - like when rolling up to a stop sign. We've looked at the pads rotors and they don't appear badly worn.

Any ideas on where to start with this one?

 

[sc mustang]

I should add that the brakes are not stock. Brembo front and back

Jake

 

[94Cobra69SS396]

I have this same issue with the stock PBR calipers on my Cobra but only on the drivers side. Mine only happens every once in a while so I haven't taken the time to invetigate it further. I believe the issue with mine is the ABS sensor at the wheel. The reason I say this is because when the clunking occurs that wheel will lock up if I brake hard.

 

[HISSIN50]

Because of the pedal feedback, I was also thinking ABS like SS396 is. The pedal feel during that is unlike anything else that occurs.

If it's less dramatic than that, I'd make sure the caliper moves easily on its slide pins.

 

[sc mustang]

Its very dramatic.

Is there an ABS module that can be replaced? We've replaced about every other electronic module - might as well add that one. If no module, any ideas on what else to consider in the way of rectifying the situation?

 

[94Cobra69SS396]

Its very dramatic.

Is there an ABS module that can be replaced? We've replaced about every other electronic module - might as well add that one. If no module, any ideas on what else to consider in the way of rectifying the situation?

Check the sensors at the wheel first and make sure there isn't a bunch of gunk on them. I've had that happen on my Explorer after taking it in the mud. It didn't do the clunking like my Cobra does but the ABS light came on until I cleaned all the mud off.

 

[the boost creep]

On one of my rear axles, the ABS sprocket has some ground-down teeth causing a pulsing in the brake pedal and light ABS-type braking at low speed braking. Like others said, check the ABS sensor at the hubs as well as the sprockets.

Not to hijack, but does anyone know if the rear axle ABS sprocket can be replaced without having to replace the whole axle? It doesn't look like it can to me.

 

[sc mustang]

I'll check this weekend and will post if I find anything

 

[sc mustang]

We tried cleaning the front ABS sensors this weekend and didn't seem to help at all. Anyone every put in new sensors? Is this difficult?

 

[maypo59]

you say the brakes are not stock.. do you have plain rotors? if not you may be hearing/feeling the pads pass over slots or holes in the rotor.

 

[sc mustang]

rotors aren't drilled or slotted.

Clunking is very heavy but only at low speeds.

Anyone had to change out ABS sensors before?