Slow speed brake grabbing

I’ve looked over some of the problems related to my issue and not found my exact problem. My vehicle is a 1989 in extremely nice shape with nearly 300k miles. I generally stay ahead of maintenance issues, change the oil and filter every 3000 mi, change antifreeze every two years and don’t allow little problems becoming big problems from neglect.

When I first drive the vehicle, I get a very rapid 2-3 grabs real fast just before stopping. This isn’t a panic stop but generally as I’m leaving the house first thing in the morning. This happens just before the vehicle comes to a complete stop. The brakes don’t lock up, they just do a rapid staccato grab and then the vehicle stops. After 2 or 3 times of this grabbing action the issue goes away.

The pads are nearly new, rotors look smooth (no pulling or pulsing while normal braking), fresh brake bleed with new fluid. I replaced the booster and master cylinder recently because of a failed booster. The wheels turns freely when the vehicle is jacked up and after the brake is applied and released.

I’m at a loss as to what would cause this and why the problem would go away after several brake applications. Doesn’t appear to be life threatening but it is big time annoying and my wife can’t understand why I can’t fix it.

Any help greatly appreciated.

 

Maybe axel seal leaking slightly.

 

Hi John,
Thanks for the reply. It feels and sounds like the disc brakes.

Tom

 

Good morning John,
You might be right. I found a bit of oil(?) residue on one of the rear backing plates. I dismissed it as brake fluid after bleeding the brakes recently. I'll pull that wheel and give it a closer look in a few days. I bought shoes for both sides and a axle seal just in case. While it's down, I'll change out the shoes regardless. It's probably been forever since they were change, if ever.

Thanks for your suggestion and happy Thanksgiving to you and your family.

BTW, same era of military service just a different branch (US Navy Seabees).

 

Another thought...if it sits for a while the pistons on the calipers do get rusted...and can be bad enough to cause the issue you are experiencing...just a thought if your looking for something to try...when you roll out of your drive way take notice if your 4 Runner doesn't coast very well...mine did this and it does squeegee the rust off of the caliper cylinder after a few stops...and also the pads squeegee's off the rotors...they always get rusty after high moisture in the air if not driven often...I hope this helps

 

Thanks all for the help!!
As it turns out , the driver rear axle seal had a small leak. I changed both of them out because the other was sure to follow sooner or later. SlvrSlug gets the gold metal. I really appreciate the help.

 

Nice... and thanks for the follow up...I always like knowing what fixed the problem because mine could be next...be well and have a Great Holiday!!!